صفحة جديدة 1

4.4 THE FIRST ELECTRONIC AND ATTRIBUTE TABLE ON THE WHOLE YEMENI LITHOSTRATIGRAPHIC UNITS AND NOMENCLATURE 122

4.1 INTRODUCTION

I am of the opinion that to solve the chronic problem related to the Yemeni Lithostratigraphic Units and Nomenclature, we must introduce the whole work done on its development. Here, I used my new classification and division to write about the whole work and the whole geological activities done on studding the development of lithostratigraphic and nomenclature in Yemen. This research study work as a result led to my new and first electronic and attribute table on the whole Yemeni Lithostratigraphic Units and Nomenclature (See Table. (4.1), attached to this study).

Before, I am going to introduce this new and first table on the whole Yemen Lithostratigraphic Units and Nomenclature. I would like to acknowledge the reader of my Ph.D. Thesis on the known stratigraphic principles and procedures: related to the development of any lithostratigraphic nomenclature and also the whole previous and present activities done on the development of the Yemen Lithostratigraphic Units and Nomenclature.

4.2 STRATIGRAPHIC PRINCIPLES AND PROCEDURES: A SUMMARY

Based on (Whittaker et al., 1991) Stratigraphy provides methods of analysis and interpretation, which are central to many fields of geological investigations. Lithostratigraphy (the description, definition and naming of rock units) is fundamental to all other branches of stratigraphy as it permits the correct recognition of the spatial relationship of rock units both vertically (in time) and laterally (in space) and thus promotes more accurate biostratigraphical and chronostratigraphical correlations and conclusions.

Due to the North American Commission on Stratigraphic Nomenclature (NACSN, 1983) a stratigraphic unit is a naturally occurring body of sedimentary rock that is distinguished from the adjoining bodies of rock on the basis of some stated

properties, principally lithological. Stratigraphic classification, therefore, provides the

understanding of the geometry and sequence of rock bodies (units). Formalisation in

nomenclature is particularly appropriate for units requiring stability, especially where these extend well beyond the area where they were first recognised. In consequence, formalisation should only be carried out according to established and internationally recognised rules in order to safeguard these objectives. Change for the sake of change, either in creating new formal names because of inadequacies in existing ones, or abandoning well-established existing names because they do not fully meet modern criteria, is to be avoided because it leads to instability and confusion. Apparent inadequacies not catered for are correctable by redefinition or revision.

Four principal categories of Stratigraphic units are internationally recognised: lithostratigraphical, biostratigraphical, chronostratigraphical and geochronological. One of the main concern of this Ph.D. Thesis topics is to deal with the Lithostratigraphic unit and with the application of the principal rules and procedures that are to be followed in lithostratigraphical usage in Yemen, in the light of what has been stated above. I would like to drew the reader attention to referred to the North American Stratigraphic Code (NACSN, 1983) for more information and details, especially to Articles 1, 3-5, 7-20, 22, 24-25, 28 and 30.

Many of the lithostratigraphic problems that arose in Yemen in recent years came about through very loose application of nomenclature rules. For this reason any summaries related on solving the above mentioned mater must be based on the North American Commission on Stratigraphic Nomenclature (NACSN, 1983) which in turn takes into account the rulings of the International Subcommission on Stratigraphic Classification (ISSC, 1976). (Beydoun, et al., 1998)

i) No geological unit should be established or defined formally (or informally), unless its recognition serves a clear purpose.

ii) A Lithostratigraphic unit (rock unit) is a naturally occurring body of sedimentary rock distinguishable from adjacent bodies or rocks on the basis of its stated properties, which is described and defined on the basis of its gross lithological characteristics and its inter-relations with adjacent units (Stratigraphic position). It is generally tabular, stratified and, in contrast to igneous rock units, conforms to the Law of Superposition. Stated properties include composition, texture, mineralogy, geochemistry, petrography, and general fossil content and, to varying extents, age. Additional modern properties such as magnetic signature, radioactivity, seismic velocity, further help to distinguish it. Care should be taken in defining boundaries so as to enable others to distinguish these.

iii) In lithostratigraphical nomenclature a unit hierarchy exits, with the Formation as the basic unit of general, initially surface, geological work constituting the smallest,

most used mappable or traceable unit (physical continuity), although this depends on

the scale of the mapping continuity of exposures or control points. A Formation may stand-alone or several may form a group, and it may be divided into smaller divisions called Members, which commonly wedge out but possess distinctive lithologies. Individual lithostratigraphic units may be diachronous and are defined/described independently from time concepts and independently from inferred geological history.

iv) In defining and describing establishing, revising, redefining or abandoning formal units, certain procedures have to be followed which include publication with a clear statement of intent (to define, revise, etc.) in a recognized scientific medium that must be readily available.

· Name: a geographic name combined with rank or descriptive term (capitalized), the name being chosen for uniqueness and convenience in usage. (The same name for different units-homonym-or different names for the same unit-synonym-must be avoided). A name should not be modified without explaining the need for this, precision by redefinition being preferable to abandonment. Thus, priority in publication must be respected, particularly as preservation of established name leads to stability of nomenclature. Priority on its own, however, does not justify displacing a well-established name by one neither well known or commonly used, nor does an inadequately established name need to be preserved because of priority.

· Stratotype: a type section or locality with exacts geographic coordinates; this is essential to ensure accessibility for study by others. A subsurface type section in a borehole or an oilfield (names after a nearby geographic feature) is acceptable if there are no appropriate surface exposures, provided borehole rock and fossil samples are stored for public availability at an appropriate accessible repository, and borehole geophysical logs are also made accessible. All other criteria for a surface type section apply for a subsurface one. A Stratotype once properly established should never be changed although additional reference sections to supplement or illustrate critical features not evident or inadequately demonstrated at the original Stratotype, including boundary contacts, may be selected.

· Description of distinguishing lithological characteristics. These include internal variations, dimensions, shape and other regional aspects, thickness at the type section and elsewhere and, as a useful characteristic, age based on fossil content or other criteria, and correlation. History or environment of deposition is

(only objective data are used in definition). They constitute, however, observations and inferences bearing on genesis and should be discussed at they are of value in regional understanding.

vi) Revision or abandonment of formally defined and named units requires as much justification as establishment of a new unit. Redefinition, however, may be undertaken in order to change a view or emphasize content without a change in rank or in boundaries; redescription expands or corrects an inadequate or inaccurate former description. Neither of these is considered revision, hence it is possible to undertake either without the application of the stringent requirements for revision.

vii) Instrumentally defined units (i.e. based on borehole geophysical logs/remotely sensed physical properties) are always considered informal. Most economically exploited units are in this category unless they are shown to be important in the elucidation of regional stratigraphy, in which case they may receive formal status by being named according to the rules summarized above.

viii) A marker-defined unit or format (Forgotson, 1957) is also informal and applies to operational units representing strata sandwiched between observable markers considered as isochronous surfaces, irrespective of the spatial lithological changes in between these. Formats are useful for correlation, especially in the subsurface where they can provide a lateral link between different units of formal stratigraphy.

According to my classification and division to the geological research history work in the Republic of Yemen to four stages, (Nedham M Darsi, 2000). We can record and notify the whole development history of the Yemeni Lithostratigraphic Units and Nomenclature as follows:

On the FIRST STAGE: The First Systematic Geological Observation Stage or Carter’s Stage, (1852-1901)

Although, no kind of activities done on studding and developing the Yemeni Lithostratigraphic Units and Nomenclature during this stage. It is known, that on 1852, Carter, H.J., was the first man, who made the First Systematic Account of observations at variety of selected locations along the south Arabian coast from Muscat in Sultanate of Oman to Aden in the Republic of Yemen.

Note (1): On this stage various writers, who published their works mostly on the lavas of Aden, made geological observations. On 1844 Burr F. wrote a sketch of the Geology of Aden. On 1871 Mallet, F.R. wrote about the Geological Structure of the country near Aden with reference to the practicability of sinking Artesian Wells and on the same year Miles, S. B., Munzinger and Werner, M. made an account of an excursion into the interior of former South Yemen. On 1883 McMahon, C.A. wrote about the lavas of Aden.

On 1902, Raisin, C.A. wrote the first notes on the Geology of Perim Island, on 1907, Kossmat, F. made the First Systematic Geological Investigation of Socotra archipelago and on the next year Crick, G.C. and Newton, R.B. published their first determinations of Jurassic mollusks. On 1910, Lloyd, R.E. published observations on the sedimentary and volcanic rocks from the area between Aden and Ad-Dali and on the same year Tipper, G.H. and Vradenberg, E.W. respectively publishing paleontological and petrologic determinations of Lloyd's sample collection. On 1912, Botez, G. carried out the first Hydrogeological studies in the sector between Hodaida and Sana’a.

The most important thing happened during this stage, that Lamare, P. (1923) made the First Lithostratigraphic Accounts of the sedimentary successions in accordance to his First Systematic Geological Investigation on the southwestern and central parts of former North Yemen. On the same year Roman, O. (Rotman) carried out first petrologic studies on the samples, that Botez, G., had collected.

Also, Little, O.H. (1925) carried out a through geological reconnaissance of the Mukalla hinterland in the coastal and plateau region. On 1929, Rathjens, C. and Von Wissmann, H. carried out more regional geographical /geological/ cartographic investigations in various sectors of the interior of Yemen. On the next year, Basse, E. made a specific reference to the western part (the high plateau) augmented by paleontological determinations and on 1932, Carpentier, C. published paleontological determinations. On 1939, Gardner, E.W. wrote an article on Climate, Irrigation and Early Man in Hadhramawt with Caton-Thompson Group.

Note (2): Although Lamare (1930) established well names for former North Yemen. It was so clear, that on The First stage, (the First Systematic Geological Observation Stage or CARTER, H.J. Stage) and the Second Stage (The Hinterland Studies Stage) early maps were based on photographs and on isolated visits generally to the coastal region.

must be realised that it was not until after the Second Stage or the Hinterland Studies Stage that it was possible to compile of the region.

On the THIRD STAGE: The First systematic more detailed Stratigraphic and Geological Studies Stage or Beydoun, Z.R., 's Stage, (1947-1967)

On this stage more regional, extensive and relatively detailed investigations have taken place covering most aspects of geological studies, where a great number of stratigraphic sections were measured and a considerable number of field samples collected for palaneontological, microfacies study, geological and photogeological mapping.

On 1947, Thesiger, W. wrote about his Journey to the Southern Arabia and the Empty Quarter. Wetzel, R., started the field-based geological mapping and stratigraphic description on 1947-1948. On 1948-1950, Morton, D.M. with Wetzel, R. continued the same work, concentrated mainly on the southern part of Mahra with some work near Mukalla, in Wadi Hadhramawt and they also carried out work on the salt dome of Bayhan. On the same year, Heybroek made reconnaissance trips in the Shuqra and Dathina areas and also to the area between Aden and Dhala and on the next year, Bagnold, R.A. studied the Sand Formation in the former south Yemen. On 1952, Jaques, E. H. made a reconnaissance survey mainly in the Western Aden Protectorate (in former South Yemen), devoting considerable attention to economic mineral occurrences and wrote notes to accompany the provisional geological map of the Western Aden Protectorate. On 1953, Bunker, D.G., wrote about the southwest Borderlands of Rub al Khali.

On late 1953, Beydoun, Z.R. ONE of the most famous geologists gave his time and life on studying the geology of Yemen. We (Yemeni Geologists) are highly and greatly appreciated him as brilliant mind, wrote many publication about Yemen, which distinguished services to geological exploration and research. He died on 7 March 1998 in Beirut, at age of seventy-three.

On 1954, Hudson, R.G.S. published Notes on Jurassic stromatopora of former South Yemen and on the same year Lipparini, T. wrote about the geology of the southwestern part of Yemen.

On 1955, Geukens, F. traveled much to former North Yemen for the United Nations Development Programs and augmented the lithostratigrafic data obtained by Lamare and his colleagues, on 1960, wrote about Yemen geology and in 1966, wrote a Professor Paper on the Geology of the Arabian Peninsula, Yemen.

0n 1958, Greenwood, J.E.G.W. carried out field investigations and photogeological mapping, mainly on basement rocks in the western part of then Aden Protectorate (former South Yemen), this work has been published as two geological map sheets on 1:250,000 scale, on 1967.

On 1960, Schott, W. provided an additional observations, but of more local nature on the lithology of the stratigraphic succession, together with paleontological / palynological age dating in connection, generally with economic objectives, for the former North Yemen.

One of the most important thing happened during this stage was the formalization of nomenclature according to internationally recognized rules, which took place in the same year for the area formerly known as the Aden Protectorate (‘’South Yemen’’) (Beydoun, 1964, 1966).

On 1961, Bleackley, D. with Greenwood supplemented fieldwork started by Greenwood on 1958 and after that they wrote a Professor Paper on the Geology of the Arabian Peninsula, Aden Protectorate, on 1967. On the same year, Irving, A. and Tarling, T. H. made a study on the Palaeomagnetism of the Aden Volcanoes and on 1966, Gass, I.G. and Mallick; D.I.J. published a study on the Acid volcanism on the former South Yemen coast.

On 1967, Bichan, H.R. was the first one, who concentrated his study principally on the basement rocks of the Socotra archipelago, which were reported on by him and Beydoun, Z.R., 1970.

The Years after the independent of the two former parts of Yemen have been an eventful years on the development of the Yemeni lithostratigraphic units and nomenclature. It is known that during this stage many Yemeni Geologists, played, play and still play a great role in the geological research history work of the Republic of Yemen. On 1968, Beydoun and Greenwood published the formalized nomenclature for the whole of the Aden Protectorate in a special fascicle of volume III of the International Lexicon of Stratigraphy for Asia. The work incorporated and partly modified the semi-formally described but well established names for former North Yemen by Lamare (1930) and Geukens (1960, 1966), covering the Jurassic System (Kohlan and Amran ‘’Series’’ modified to Kohlan Formation and Amran Group) and the Cretaceous System (Taoulah ‘’Series’’ modified to Tawilah Group). On the same year Azzaroli, A. wrote about the evolution of the Gulf of Aden.

On 1969, Cox, K.G. with Mallick, D.I.J. made a Study on the volcano evolution of Aden and Little Aden and on the same year Mosely, F. wrote about the Aden Traps of Dhala, Musaymir and Radfan.

The exploration effort developed sporadically during the 1970s but was increasingly backed by both regional and detailed geophysical surveys by an increasing number of seismic parties. On 1970, Dubertret, L. made a review of Structural Geology of the Red Sea and Surrounding Area and on 1973, Fairhead, J.D. wrote about the Crustal Structure of the Gulf of Aden and the Red Sea. On 1978, Grolier, M.J. and Overstreet, W.C. worked on the geologic map of former North Yemen (San’a) 1:500,000 scale.

On 1980, Kruck, W. worked on different geological maps of former North Yemen and he with Thiele, J. made a study on the Late Paleozoic glacial deposits. On 1982, Abou Khadrah, A. wrote about the sedimentological evolution and the stratigraphy of former North Yemen, on 1983, Aboul Ela, M. wrote about the geology of the area northwest of San’a, San’a -Wadi Zahr district and on 1984, El- Anbaawy, M.I.H. wrote a contribution to the lithostratigraphic subdivision of the Amran sequence in former North Yemen.

It is so clear, that a number of attempts were subsequently made in the 1980s to formalize the Lamare and Geukens nomenclature used in former North Yemen by renaming / redefining / revising /abandoning various units in accordance with international rules, the most consistent attempt being by El-Nakhal (1987, 1988, 1990, 1996).

During the period from 1984 to 1996, Nakhal, H., El- wrote about the possibilities of late Paleozoic glaciating in centered parts of former North Yemen (1984), his observations on polygonal patterns in Jurassic sandstone (Kohlan group-1985), the lithostratigraphic subdivision of Kohlan Group (1987), the stratigraphy of the Tawilah Formation (1989), about Surdud Group, a new lithostratigraphic unit of Jurassic age (1990), the earliest eruptions of the Yemen Volcanic (1991), the Pleistocene cold episode (1993), the subdivision and formal nomenclature of the Cenozoic sedimentary rocks (1993) and about the preliminary review of the stratigraphy of the outcropping Mesozoic erathem in the northern part of Yemen (1996).

The stratigraphic nomenclature schemes utilized for the sedimentary column of Yemen up until the middle of the 1980s were based entirely on formal to semiformal lithostratigraphic units. Described from measured surface sections exposed mainly in the dissected and faulted shoulders of the Gulf of Aden and Red

Sea Rifts and in the high plateau of the western part of Yemen for the Mesozoic and

older successions (Figs. (2.1), (2.1A), (2.1B) and (2.5)). For Paleogene units, the dissected plateau tableland covering the eastern part of the country provided the type localities, whereas embayments along the Gulf of Aden and Red Sea coastal areas furnished the type localities for the Neogene sedimentary successions.

Note (3): Here, I would like to draw the reader attention on the first try done by Haq and van Eysinga (1987), on doing the first historical development of stratigraphic nomenclature schemes (Figs. (4.1) and (4.2)). The above mentioned nomenclature schemes based mainly on the surface observations and subsurface well control with surface data. It is very clear, that a rapid look at Figs. (4.1) and (4.2) will illustrate the point being made, namely that one can hardly make a straight time line correlation between the same formations even in contiguous blocks of small areal extent.

Fig. (4.1) Yemen: Historical development of selected Jurassic stratigraphic nomenclature schemes (Beydoun, et al., 1997; based on Haq and Van Eysinga, 1987; U= Unpublished / restricted circulation with year in circulation where known; P= Published with year publication)

Fig. (4.2) Yemen: Historical development of selected cretaceous stratigraphic nomenclature schemes (Beydoun, et al., 1997; based on Haq and Van Eysinga, 1987; U= Unpublished / restricted circulation with year in circulation where known; P= Published with year publication)

On 1987, Isaev, E.N. wrote about the structural-geophysical model of the basement complex of the Aden-Red Sea region. On the same year, Maycock, I.D. wrote about the exploration and development in Marib/Al Jawf area of Marib Al- Jawf Shabwa basin. And also on the same Year Al-Thour, K.A. with El- Anbaawy, M.I.H. wrote about the sedimentological evolution and sedimentology of the Salif halite and with Simmons, M.D. made a study on the Micropalaeontological biozonation of the Amran Series (Jurassic) in the Sana’a region, (1994).

The situation has also been partly aggravated in two other ways. Firstly, by increased research by academics from universities within and outside the country (having little or no access to the new subsurface data acquired since the late 1980s) who carried out more detailed investigations of surface exposures in relatively small areas mainly in the high plateau, or areally disconnected investigations of varying detail over wider areas. Some of these researchers also proposed alterations to nomenclature without due regard to formal procedures while others proposed alterations or formalizations which could not take into full account the stratigraphy of the whole country becoming known from the subsurface data. Secondly, by some of the service companies and contracted groups working for operating oil companies and/or governmental agencies on specific projects such as biostratigraphic studies, geochemical source rock analysis, mineral investigations, integration of geological mapping, or hydrocarbon exploration promotion.

On 1989, Husseini, M.I. wrote about the tectonic and depositional model for the Late Precambrian-Cambrian Arabian and adjoining plates and on 1991, he with Dyer, R.A. made a study on the western Rub ‘al-Khali Infracambrian graben system.

On 1990, Jungwirth, J. with As-Saruri, M., wrote about the structural evolution of the platform cover on southern Arabian Peninsula (former South Yemen) and on the same year made a study on the Karst phenomena on the south Hadramawt plateau with Schramm, H.

More intensive exploration activity from the 1980s, and especially during the early 1990s after unification, has gradually unraveled a complex Mesozoic tectonic history and basin evolution, the distribution and outlines of, which had hitherto been masked under the overlying tabular Tertiary blanket of sediments and/or extrusive, flood basalt’s. This tectonic evolution was principally linked to the Late Jurassic-Early Cretaceous breakup of Gondwana and was initiated along ancient lines of crustal weakness related to a basement grain developed during the final stages of cratonization of the Arabian Shield. Rejuvenation of these NW-SE and E-W oriented fracture systems during the Mesozoic breakup of Gondwana was mainly in the form of extensional polyphase tectonics.

Individual basin inception has been time-staggered, with the NW-SE fracture system rejuvenation along the ancient Najd fault trend commencing in Kimmeridgian times in the Ad-Dali basin and Sab’atayn basin (Marib-Shabwa-Hajar sectors) (Beydoun et al., 1996; Ellis et al., 1996; Schlumberger, 1992). And propagating into the Belhaf basin in Cretaceous time (Beydoun, et al., 1993, 1996).

By contrast, Say’un-Al Masila basin appears to have evolved principally during the Late Jurassic to Early Cretaceous with the Jeza-Qamar basin. Subsiding rapidly as a depression principally during the Cretaceous but continuing well into the Tertiary in its eastern sector (Bott et al., 1992; Beydoun et al., 1993, 1996; Redfern and Jones, 1995; Ellis et al., 1996; Jungwirth and As-Saruri, 1990).

Episodic subsidence movements punctuated by sporadic and localized short pulses of inversion and erosion appear to have affected some basins or sectors of basins but there is as yet insufficient regional control to enable more specific preciseness, particularly as Tertiary movements have overprinted their signature on the earlier picture.

This history of Mesozoic extension and partial inversion in basin development has given rise to considerable variations in the details of sedimentation at the local level but, nevertheless, it does not obscure overall broad patterns of sedimentation. These were, however, only very generally understood prior to subsurface exploration and even then were incompletely grasped as exploration proceeded, because of confidentiality considerations, with individual operating companies arriving at conclusions which were principally based on results within the limits of their concession area blocks and on any traded data. This, understandably, lead to the development of company-centered informal stratigraphic nomenclature schemes as mentioned before, whose principal objective was to facilitate operations within the individual company’s concession area rather than facilitating scientific research and any ultimate communication in journals. It was inevitable that such convenience approaches should result in the proliferation of expediently designed informal nomenclature schemes; these, regrettably, have been extended beyond their intended in-house usages to neighboring and distant concession areas through data exchange. Unfortunately (although again understandable in competitive hurry), in developing these various in-house schemes, only cursory lip service could be paid to comparisons with the established surface nomenclature, which was initially erected and described in order to facilitate correlation. It was either dismissed as inappropriate to the local requirements of the subsurface and substituted by locally applicable schemes (e.g. Figs. (4.1) and (4.2), Hunt Oil column) or else hurriedly amended as desired for reasons of expediency without the proper consideration of accepted international guidelines and procedures. As some operators made more successful new hydrocarbon discoveries, increased activity by hopeful newcomers resulted in further adaptations

During the period from 1990 to 1997, As-Saruri, M. with Langbein, R. wrote about the Habshiyah Formation and the Shihr Group. The lithostratigraphic subdivision of the outcropping Late Cenozoic Shihr Group with Beydoun, Z.R., the lithology and microfacies of Umm er Radhuma, Jiza and Rus Formation with Langbein, R., the lithological-structural provinces of the basement in the central region with Wiefel, H. and so on.

On 1990, Nani, A.S.O., with Haitham, F.M.S. wrote about hydrocarbon potential of the Gulf of Aden Rift, on 1993, he with Beydoun, Z.R wrote about Qishn Formation lithofacies and hydrocarbon habitat and on 1997, wrote about the Paleozoic Clastic Reservoir in Oman, Saudi Arabia and Yemen. He published more than 18 scientific articles in and outside Yemen.

On the same year, Paul, S.K. wrote about the future oil province in former South Yemen, Vesolov, V.V., wrote an explanatory note to prediction mineragenic map of the southern part of the Republic of Yemen. Wienholz, R., with Weigelt, G. wrote about the Cretaceous sediments (Tawilah Group) in the Habban-Mukalla area and the development of the Tertiary in the Habban Al Mukalla area with Schuppel, D.

On 1991, Mohr, P.A. made a study on the structure of Yemeni dyke swarms. On 1992, Hughes, G.W. with Beydoun, Z.R. wrote about the biostratigraphy, lithostratigraphy, and palaeoenvironment of Red Sea-Gulf of Aden and on the same year Sikander, A.H. with Beydoun, Z.R. wrote a re-assessment of hydrocarbon potential on Red Sea-Gulf of Aden. On 1994, Mattash, M.A. and Balogh, K. made a study on the K-Ar radiometric age data on Cenozoic volcanic and their associated intrusions from Yemen.

On February 1995, the Yemeni Ministry of Oil and Mineral Resources with the creation by Ministerial Degree No 4 for 1995 establishing an official Yemen Stratigraphic Commission and on 1998 a Lexion of Stratigraphy for the Republic of Yemen was the outcome of the deliberations and work of the Yemen Stratigraphic Commision. (Beydoun, Z.R., Mustafa A.L. As-Saruri, Hamed El-Nakhal, Ismail N. Al-Ganad, Rasheed S. Baraba, Abdul Sattar O.Nani and Mohammad H. Al-Aawah, 1998).

Note (4): In my opinion, one of the most important things happened during the Fourth Stage or The Yemeni Geologists Stage, was the Yemeni Ministry of Oil and Mineral Resources ‘s Ministerial Degree No 4 for 1995 on establishing an official Yemen Stratigraphic Commission. This wise declaration was the first step in the right direction to solve the chronic problem related to the Yemeni Lithostratigraphic Units and Nomenclature.

4.4 THE FIRST ELECTRONIC AND ATTRIBUTE TABLE ON THE WHOLE YEMENI LITHOSTRATIGRAPHIC UNITS AND NOMENCLATURE

Based on my work experience for 8 years in the area, the huge material collected by me during my work and my research study. Especially, the following material:

1. Most of the whole publication written on the previous and present geological activities in the Republic of Yemen. (See attached references). (1852 – today)

2. Most of the material related to the eastern Yemeni province. (Beydoun, Z. R. works and especially Beydoun et al., 1998).

3. Most of the material related to the northern Yemeni province. (Geukens, 1960, 1966).

4. Pan American Hadhramawt Oil Company (the Yemeni sector of Rub al Khali basin (Thamud – Sanau areas) enclosed the last work done on the north Hadhramawt basin or the Yemeni sector of Rub al Khali basin by the P.E.B.P ’s Engineers (Petroleum Exploration and Production Board ’s Engineers). (Faisal et al., 1998)

7. A material on Tihama area in the Red Sea area. (Davison, et al., 1994, 1996; Doornenbal, 1991; … , and Beydoun, et al., 1996, 1997)

8. Braspetro company material in the Jeza area (Wadi Al-Ghyda). (Braspetro, 1983)

10. Technoexport material (of the former Sovit Union company, worked in Yemen) in Shabwah area of the Marib Al-Jawf Shabwa basin. (V.O. Technoexport, 1988)

11. Yemen Hunt Oil company material in Marib Al-Jawf area of the Marib Al-Jawf Shabwa basin. (Hunt Oil Company Yemen, 1992)

13. CanadianOxy Company material on the Masila block area of Sey’un Al-Masila basin. (Mills, S.J., 1992)

15. My scientific papers published on the whole Yemeni geological research history work. (Nedham, M. Darsi, (2000, 2001))

16. My scientific papers published on the oil and gas prospect in the Yemeni sector of Rub al Khali basin. (Nedham, M. Darsi, (2000))

c. Marib Al-Jawf Shabwa basin ( Marib, Jannah and Shabwah areas). (1992 – 1999)

18. My personal visits to the Tihama basin (Al-Tohaita, Zabid and Al-Khawkha areas) of the Red Sea area. (1992 – 1999)

19. My born in Crater and my whole life in Aden (Aden – Abyan basin, Gulf of Aden area).

20. All the above mentioned materials plus my research study and checks for more than 210 wells drilled in the area, as a geologist who greatly and strongly interested in the subsurface geology of Yemen, especially the eastern part of Yemen which occupy more than 75% of Yemeni sedimentary cover.

The first electronic and attribute table for the whole Yemen Lithostratigraphic Units and Nomenclature (See Table. (4.1), attached to this study or see the same table without the suggested lithostratigraphic coloumn on the next pages (105 - 128)) is the outcome of my work-study with the above-mentioned material. Due to my new table, it is easy now to make a straight time line correlation between some of the different formations. As with all compromises, the end result is incomplete and does not really address the problem in depth but it does constitute a step in the right direction.

Note (5): This note is on the transliteration and romanization of Arabic names, where the system of romanization of Arabic names adopted in this Ph.D. Thesis and in my new table is based on the last present methods of study done for the whole area (Beydoun, et al., 1998). It is a very simpilified version of the BGN/PCGN 1956 System which has been applied in the systematic romanization of geographical names throughout much of the Middle East, and covered by published BGN gazetteers which can be referred to in the library of the Royal Geographic Society in London. Simplification has been achieved by elimination of various diacritical symbols such as cedillas, apostrophes, dots or dashes above or below certain letters to denote shortness or length of sound and aid in phonetic pronunciation, simply because these are frequently unavailable on English language-designed manual typewriters and many word processing systems. Only the raised comma, inverted or regular and used with the letters (a,i,u), respecively denotes the Arabic letter (ain) or (hamza), while certain others are expressed by a combination of two roman letters (e.g. kh for kha, gh for ghayn, sh for sheen, and so on). It is known, that all revised lithostratigraphic names in current usage in the Republic of Yemen have been modified in accordance with this revised system. Lithostratigraphic names difined outside Yemen have been retained according to the original and established spelling (e.g. Umm er Radhuma, Sudair, Qusaiba, etc.) With regard to well known place or country names such as Aden and Yemen, these have been retained because of their long-established usage, but an attempt has been consistently made to change the spelling of Sana’a to San’a which is closer to the true pronunciation, as also is Hadramawt rather than Hadhramaut. Other less well known names have also been modified where possible. Exploration well names have, on the whole, been left alone at this stage.

The Republic of Yemen is underlain by an Upper Proterozoic to Lower Cambrian metamoprphic basement covered by unmetamorphosed Phanerozoic deposits (Fig. (5.1)). The regional distribution of the Phanerozoic cover is strongly influenced by the Hadramut Arch (Fig. (5.2)). South of this arch, no Paleozoic rocks are known, whereas to the north a more or less complete Paleozoic section was encountered in various wells. In the southern area, differentation into a western and an eastern realm was most prominent during the Upper Jurassic and Lower Cretaceous.

As a result of my work done on, the new classification and division to the Geological Research History Work of the Republic of Yemen (see Chapeter 1) and my new table for the whole Yemeni Lithostratigraphic Units and Nomenclature (see Chapeter 4 and taple (4.1), attached to this study) I am shore, that a new look to the Yemeni Geology is created and a need for a summary on the Yemeni Stratigraphy is wanted.

3. TECTOSTRAT propritary data on the regional geology of the Arabian Peninsula and eastern- and north eastern Africa. as based on extensive literature reviews and fieldwork during the last decade Over 10 years of TECTOSTRAT theoretical and practical research on Rift Tectonics and Reactivation of basement structures LANDSAT-data interpretation of the Arabian Peninsula and adjoining areas

6. My new table on the whole Yemeni Lithostratigraphic Units and Nomenclature. (Table. (4.1), attached to this study)

7. My suggestion for one ideal Stratigraphic Coulmn for the whole Yemeni Formations as a result of my correlation for the whole Yemeni lithostratigraphic units and nomenclature, espicially for the whole Yemeni Formations.

8. My high interest in the subsurface geology of the whole area and especially the eastern part of Yemen, which contain ~75% of Yemeni sedimentary cover, where I made a sum of 60 maps for an area of 40.000 sq. km. (thickness and 3D maps) from the basement to the surface.

9. My personal field notices and records, which proved and suborted by my geological field work in the area as a representative for the Petroleum Exploration and Production Board, Aden Branch, Ministry of Oil and Mineral Resources.

Fig. (5.1) Simplified geological map of the southwestern part of the Arabian Peninsula

The Basement of the Republic of Yemen is represented by the following units (young to old):

My personal field records show that the basemen as a formation characterised by:

3. A decrease in background gas with an average of 2.1 API units to 0.6 API units.

· See, my work result on mapping and modelling the whole eastern part of Yemen, especially Figs. (5.32A) and (5.32B)

The Paleozoic of the Republic of Yemen is represented by the following units (young to old):

The Paleozoic is known only from limited well-data in the northern part of the Republic of Yemen and appears to be a continuation of the Paleozoic as developed in the neighbouring area of the Saudi Arabia and Oman. (See, my work result on mapping and modelling the whole eastern part of Yemen, especially Figs. (5.29A),(5.29B), (5.30A), … (5.31B)).

The Lower and Middle Paleozoic of the southern Arabian Peninsula comprises a sequence of (epi) continental deposits, mainly sandstones and conglomerates, generally referred to as the Wajid Sandstones which may range in age between Cambrian and Permian. The equivalent of Cambrian evaporites as found towards the east of the Arabian Peninsula (Hormuz Salt) have not been found yet, but Beydoun (1982) infers such a sequence to be present in the subsurface of the eastern RY on the basis of geophysical data.

The Upper Paleozoic of southern Arabia is marked by extensive glacial deposits which relate to the Dwyka glaciation of Gondwanaland in Upper Carboniferous-Permian times. In the north part of Yemen these are known as Akbra shales (tillites overlain by intercalated sandstones and carbonates) which unconformably overlie the Wajid sandstones.

The Mesozoic of the Republic of Yemen is represented by the following units (young to old):

· See, my work result on mapping and modelling the whole eastern part of Yemen, especially Figs. (5.11A), (5.11B), (5.12A), … (5.28B).

The Triassic of Hadramaut area is a continuation of the Triassic of the southernmost Saudi Arabia where it comprises sandstones and shales with minor limestones and gypsum. In the coastal zone of the Republic of Yemen, the mainly Jurassic Kohlan Formation may include a basal, Upper Triassic part.

In the Hadramaut area only undifferentiated Jurassic is known from the Jeza syncline.In the coastal area, the Jurassic comprises the Kohlan Formation transitionally overlain by Amran Group.

The Kohlan Formation of Triassic(?)- Malm age has an average thickness of ca. 70m.; it comprises sandstones and conglomerates transgressively overlying Precambrian basement or Paleozoic rocks.

The mainly carbonates Amran Group consists of the following formations which are all of Malm age:

Nayfa: limestones and marls deposited in a shilf environment, variable thickness (max.570 m) due to pre-Barremian erosion. (See, my work result on mapping and modelling the whole eastern part of Yemen, especially Fig. (5.23A) and (5.23B)).

My personal field records show that Nayfa, marked as two formation Nayfa ‘A’ and Naifa ‘B’, where:

Madbi: (E) shales and marls with interbedded limestones; shelf envir., variable thickness of 760 m max. (See, my work result on mapping and modelling the whole eastern part of Yemen, especially Figs. (5.26A) and (5.26B)).

2. The presence of the black shale as its main lithological factor (considered as a potential source rock).

Shuqra: limestones with intercalated marls of littoral to restricted platform environment, thickness ca. 60 m. (See, my work result on mapping and modelling the whole eastern part of Yemen, especially Figs. (5.27A) and (5.27B)).

In this area the Cretaceous is represented by the Barremian –Maastrichtian Tawilah and Mahra Groups. (See, my work result on mapping and modelling the whole eastern part of Yemen, especially Figs. (5.11A), (5.11B), (5.13A), (5.13B), (5.15A), … (5.16B).The Tawilah Group is a series of dominantly clastic rocks deposited to the west of longitude 50E; the Mahra Group is dominantly calcareous and accurs east of 50E. The groups are subdived into formations as shown below:

The limestone as a its main contents, being dolomitic in places grading to dolomite, interbeds with frequent shale becoming thicker with depth.

An average of background gas from 0.5 API unit at the top to 5.0 API unit at the base.

· (See, my work result on mapping and modelling the whole eastern part of Yemen, especially Figs. (5.22A) and (5.22B)).

a. A main section of Sandstone, streaks of Claystone and traces of Anhydrite (with a logged trace of Coal).

1. A main section of Limestone-Mudstone to Limestone-Wackstone with thins streaks of Shale.

· (See, my work result on mapping and modelling the whole eastern part of Yemen, especially Figs. (5.18A), (5.18B), (5.19A), … (5.20B)).

2. Inter bedded pattern of Sand / Sandstone and Claystone grading to Shale towards the base.

3. Average gas reading ranged from 0.05 to 0.06 API unit, mainly methane due to chromatographic analysis.

· (See, my work result on mapping and modelling the whole eastern part of Yemen, especially Figs. (5.16A) and (5.16B)).

2. A main section of interbedded Limestone and Dolomite with thin streaks of Claystone.

· (See, my work result on mapping and modelling the whole eastern part of Yemen, especially Figs. (5.15A) and (5.15B)).

· (See, my work result on mapping and modelling the whole eastern part of Yemen, especially Figs. (5.13A) and (5.13B)).

· (See, my work result on mapping and modelling the whole eastern part of Yemen, especially Figs. (5.11A) and (5.11B)).

In this area, the Cretaceous is divided into the following groups and formations (young to old):

Aruma Formation: equivalent to the Mukalla and (probably) Sharwayn formations, thickness ca. 100 m on Hadramut Arch, increasing rapidly towards Jeza syncline. (Table (4.1), attached to this study)

- Lower Wasia group, incorporating the Mudud formation the maximum total thickness reaches about 500 m. (See, my work result on mapping and modelling the whole eastern part of Yemen, especially Figs. (5.17A) and (5.17B)).

Shuaiba Formation: equivalent to the top of Qishn formation; max. thickness is 70 m. (Table (4.1), attached to this study)

Biyad (W) and Thamama (E) formations: Lateral equivalent units of which the Biyad represent the westerly clastic-, and Thamama the easterly calcareous facies; the trasition between the two lies at approximately 50E (cf. Coastal zone, previous paragraph) and the formations can be regarded as equivalent of Qishn formation.

The Cenozoic of the Republic of Yemen is represented by the following units (young to old):

· See, my work result on mapping and modelling the whole eastern part of Yemen, especially Figs. (5.3A), (5.3B), (5.4A), … (5.10B).

This period is represented by sediment of the Hadramut Group in both the Coastal – and the Hadramut Areas. The base of the sequence rests conformably upon the Cretaceous, but from paleontological evidence an age gap is assumed; the top is cut by erosion. The Hadramut Group as a whole is divided into the following formations (young to old):

Habshiya Formation: marls and shales with interbedded limestones; restricted shallow platform.

Rus Formation: gypsum and anhydrite with some bands of gypsiferous limestone; tidal flat complex.

Jeza Formation: shales and marls with interbedded limestones; restricted shallow platform.

Umm er Radhuma Formation: limestones with interbedded marly limestones; restricted- to open shallow platform.

· See, my work result on mapping and modelling the whole eastern part of Yemen, especially Figs. (5.7A), (5.7B), (5.8A), … (5.10B).

My personal field records show that Umm er Radhuma as a formation characterised by:

· See, my work result on mapping and modelling the whole eastern part of Yemen, especially Figs. (5.3A), (5.3B), (5.4A), … (5.10B).

The Oligocene and Miocene are represented by the Shir Group, or Gaydah formation, (See, my work result on mapping and modelling the whole eastern part of Yemen, especially Figs. (5.6A) and (5.6B)) a heterogeneous assemblage of spatially restricted deposits occurring along the present coastline and off shore. The group comprises continental, restricted- and open shallow marine deposits. Both base and top of the sequence are defined by unconformities.

The youngest sediments are formed by a series of continental to shallow marine deposits which unconformably overlie all older deposits from Miocene to Precambrian.

Following the latest Pan African (early Paleozoic) intrusions, no further igneous activity is known in the Republic of Yemen until the end of Mesozoic.

In late Cretaceous time, mainly mafic volcanicity began episodcally and reached a climax in the Oligocene –Miocene. These rocks are known as the Trap Series and consist primarily of fissure and vent basaltic flows.

A further phase of basaltic flows and pyroclastic eruptions, referred to as the Aden Volcanic Series followed in late Miocene or Pliocene to Recent time. The rocks of this series are mainly confined to the coastal region and broken plateau edges. Associated with this volcanicity also some Tertiary granitic intrusions are known.

Fig. (5.3A) Thickness Map for the Youngest Sediment or Formation (Layer No. 1); (Done by: Nedham M. Darsi)

Fig. (5.5A) Thickness Map for Taqah/Hami Formation ( Layer No. 3 ); (Done by: Nedham M. Darsi)

Fig. (5.12A) Thickness Map for Fiqah Formation ( Layer No. 10 ); (Done by: Nedham M. Darsi)

Fig. (5.16A) Thickness Map for Harshiyat Formation ( Layer No. 14 ); (Done by: Nedham M. Darsi)

Fig. (5.24A) Thickness Map for Sab'atayn Formation ( Layer No. 22 ); (Done by: Nedham M. Darsi)

PHANEROZOIC SIDIMENTARY SEQUENCE SUBDIVISION /STRATIGRAPHIC/SEDIMENTOLOGIC ANALYSIS 226

PHANEROZOIC SEDIMENTARY SEQUENCE SUBDIVISION /STRATIGRAPHIC / SEDIMENTOLOGIC ANALYSIS

First of all, quick look to the pervious 60 maps done on the eastern part of the Republic of Yemen, (based on my study to the subsurface geology for an area of 40.000 sq. km), show that the eastern part of the Republic of Yemen stratigraphy seems to by comparable. Especially the same stratigraphic units deposited in the same time and having different names.

This result proves and supports the work done by the International Tectostrat Geoconsultants (1987) in the Hadhramawt Region in the eastern part of the Republic of Yemen, where their study led to, that the stratigraphy of Hadhramawt Region seems to be comparable with that of the Southern Region. Based on available stratigraphic sections and well data from eastern part of Yemen, data from the southern part of eastern Republic of Yemen, i.e. The Coastal Region, have been collected by Agip during field-surveys in 1978 and 1980 (Agip, 1981; 82). Another set of data concerning the Hadhramawt Region consists of drilled well sections provided by Canadian Oxy.

1. My Lithostratigraphic Units and Nomenclature table (Table. (4.1)) supported with my ideal stratigraphic column suggested for the whole Yemen.

3. The huge material used by me during my work and study to the most of Yemeni area.

All above-mentioned works, data and materials give me the whole right to introduce a new look to the area and suggest a new subdivision to the whole Phanerozoic sedimentary sequence of the Republic of Yemen. The whole Phanerozoic sedimentary sequence of the Republic of Yemen can be subdivided into five depositional sequences, i.e. from young to old:

d. CRETACEOUS (Lower Hauterivian to Maastrichtian) / PALEOCENE – MIDDLE EOCENE

This new subdivision to the whole Phanerozoic sedimentary sequence of the Republic of Yemen, particularly support the pervious subdivision done to the Phanerozoic sedimentary sequence of the eastern part of the Republic of Yemen by the International Tectostrat Geoconsultants (1987). They subdivided the Phanerozoic sedimentary sequence of the eastern part of the Republic of Yemen into five depositional sequences, from young to old.

In the following paragraphs the general outline of the stratigraphic history of the Republic of Yemen is described on the basis of the study done by the International Tectostrat Geoconsultants (1987), these new five depositional sequences, summarised in my Lithostratigraphic Unit and Nomenclture Table, and on the sixty maps done on the eastern part of the Republic of Yemen. In that table and at those maps, depositional environment and thickness of the described formations throughout the Republic of Yemen and especially the eastern part of the Republic of Yemen are plotted in order to locate areas of subsidence and uplift. These new steps show and prove the pervious idea that the descriptions of the environment of deposition are too general especially to the eastern part of Yemen.

Source rock/reservoir characteristics, as derived from the literature have been for every depositional sequence.

Paleozoic sediments have been encountered in the Yemeni sector of Rub al Khali basin, north part of Yemen and on Soqatra Island (?).

In the eastern part of the Republic of Yemen Paleozoic sediments have been encountered only in the subsurface of north Hadhramawt Region. Paleozoic sediments are probably of (epi) continental origin and can be correlated with the Wajid sandstones and Akbra shales found in the north part of the Republic of Yemen. Within this sequence Devonian / Carboniferous strata are cut off by Permian strata along the northern Hadramut Arch. Furthermore the whole Paleozoic sequence thickens in a northerly direction. This implies that the arch became pronounced during the Paleozoic as a result of uplift in Devonian / Carboniferous times as suggested by the International Tectostrat Geoconsultants (1987)

Here, I would like to suggest a new subdivision to the Paleozoic sediments of the whole Republic of Yemen, into two depositional sequences, i.e. from young to old:

1. The above-mentioned works, data and materials, which gave me the whole right to introduce and suggest a new subdivision to the whole Phanerozoic sedimentary sequence of the Republic of Yemen into five depositional sequences.

2. The evidence of an age gap for the Middle and Upper Silurian rocks and an evidence of an age gap for the Middle and Upper Triassic rocks (?) in whole Yemen is assumed, they cut by erosion.

3. The absence of (Middle and Upper Silurian rocks) and (Middle and Upper Triassic rocks (?)) in whole Yemen reflects a period of general uplift throughout the Southwestern Arabia during above mentioned times.

4. This 2 age gaps are strongly supporting my new subdivision to the Paleozoic sediments into two depositional sequences.

In my opinion, presence of Lower Paleozoic (Cambrian (?) - Lower Silurian (Llandoverian)) depositional sequence, which cut off by Upper Paleozoic (Devonian –

Permian) / Triassic (Lower Triassic) (?) depositional sequence along the northern

Hadhramawt Arch. Furthermore the whole depositional sequence thickens in a northerly direction. This implies that the arch became pronounced during the Lower Paleozoic as a result of uplift in Cambrian (?) - Lower Silurian (Llandoverian) times.

Dependable on the intensity of the Karroo rifting, source rock potential may exist in the Permian sediments.

The presence of Qalibah Formation of Lower Silurian age in Yemen has an important meaning. It is known that one of the most famous oilfield all over the world, i.e. Ghawar in Saudi Arabia and Messaoud in Algeria contain oil from Silurian source rocks.

During the lower to Middle Jurassic (possibly Late Triassic (?)) the region was transgressed from the East. The Kohlan, Shuqra and Madbi sediments were deposited in a gradually subsiding and deepening basin with uniform conditions throughout the area.

Slumping features and erosional channels, which developed during Naifa sedimentation, indicate tectonic activity during the Tithonian. (See my Lithostratigraphic Units and Nomenclature table (Table. 4.1), attached to this study). A general uplift between Tithonian and Barremian times caused differential erosion, which, in general removed the entire Middle and Upper Valanginian rocks in the whole Republic of Yemen. (See the same table, (Table 4.1)) and in places (e.g. The Mukalla region), removed the entire Jurassic sequence.

These data suggest that tectonic activity between Kimmeridgian and Barremian times give rise to highs and lows.

(Sab’atayn Formation). These sediments are exposed in salt domes, which are though to be related to the opening of the Gulf of Aden. Tectonism caused by older salt movement can not be excluded.

1 The above-mentioned works, data and materials, which gave me the whole right to introduce and suggest a new subdivision to the whole Phanerozoic sedimentary sequence of the Republic of Yemen into five depositional sequences.

2 The evidence of an age gap for Middle and Upper Triassic rocks (?) and an evidence of an age gap for the Middle and Upper Valanginian rocks in whole Yemen is assumed, they cut by erosion.

3 The absence of (Middle and Upper Triassic rocks (?)) and (Middle and Upper Valanginian rocks) in whole Yemen reflects a period of general uplift throughout the Southwestern Arabia during above mentioned times.

4 The presence of a depositional sequence between the above mentioned 2 age gaps is an argument of subsidence period happened in the Jurassic to Cretaceous (Lower Berriasian to Lower Valanginian) time.

5 This subsidence period prove and support the above mentioned depositional sequences suggested by me as a new subdivision.

Naifa Formation: may be good source rock, often hydrocarbon smell on fresh fractures

A new transgression, again from the E, started in Barremian times and a wide restricted shallow platform was established (Qishn Formation).

Afterwards the western part of the area was covered by mainly clastic continental to shallow marine sediments (Harshiyat Formation), while in the eastern part mainly carbonatic sediments were deposited initially on a restricted to open marine platform, later followed by deeper platform deposits (Fartaq Formation).

There is a gradual transition between clastics in the W and carbonates in the E. The thick development of Fartaq Formation in the E may indicate active subsequence in this part of the area Aptian / Cenomanian times.

It should be noted that the thick development includes (the eastern part of) the Jeza Syncline, where according to the literature, subsidence did not start until Oligo-Miocene times (see also paragraph 6.6.1).

The Fartaq / Harshiyat sequence is overlain by clastics of the Mukalla Formation. The striking differences in thickness of this formation from area to area point to tectonic activity during the Turonian – Senonian.

Shallow restricted platform sediments (Sharwayn Formation) were deposited in the eastern part of the area but are absent in the west. This may indicate subsidence of the eastern part of the area during Maastrichtian times. A general uplift ended the Cretaceous sedimentation.

Fartaq Formation: may be both source rock and reservoir, some interbedded shaley layers could be considered as cap rock

During the Paleocene the region was transgressed from the E and uniform sedimentary conditions established over the area with deposition of shallow platform limestones (Umm Er Radhuma Formation).

Conditions became more restricted in Lower Eocene time (Jeza Formations), but in the easternmost part of the area no distinction is possible between the Umm Er Radhuma and Jeza Formations. This probably indicates the proximity of open sea.

Complete closure of the basin towards the end of the Lower Eocene gave rise to evaporitic sedimentation (Rus Formation), but in the eastern part of the region the sediments are more carbonitic and indicate open sea nearby. In the western part of the area an anomalous thick evaporitic sequence indicates strong local subsidence.

In Middle Eocene a shallow restricted platform established over the area (Habshiya Formation) until general uplift ended the sedimentary cycle.

Jeza Formation: good cap rocks (shales); may be reservoir (limestones) but often has insufficient thickness

Rus Formation: good cap rock; may be reservoir but often has insufficient thickness

d. CRETACEOUS (Lower Hauterivian to Maastrichtian) / PALEOCENE – MIDDLE EOCENE

2 The evidence of an age gap for Middle and Upper Valanginian rocks and an evidence of an age gap for the Upper Eocene rocks in whole Yemen is assumed, they cut by erosion.

3 The absence of (Middle and Upper Valanginian rocks) and (Upper Eocene rocks) in whole Yemen reflects a period of general uplift throughout the Southwestern Arabia during above mentioned times.

4 The presence of a depositional sequence between the above mentioned age gaps is an argument of subsidence period happened in the Cretaceous (Lower Hauterivian to Maastrichtian) / PALEOCENE – MIDDLE EOCENE

5 This subsidence period led to the above mentioned depositional sequences suggested by me as a new subdivision.

during Oligo-Miocene a transgressive sequence of very heterogeneous shallow marine character, i.e. The Gaydah Formation was deposited. The sediments contain a large amount of eroded material from the older formations. The Gaydah Formation unconformably (often angular) overlies the Habshiya and sometimes Rus, Jeza or Umm Er Radhuma Formation. Taken together, this implies tectonic activity before deposition of Gaydah Formation and strong erosion of the older formations.

In low-lying areas, corresponding to the present day coast- and offshore regions, erosion of the underlying Habshiya Formation is weak. The Oligo-Miocene strata are rapidly thickening towards the South

The phenomena described above indicate a drastic change in Palaeogeography before deposition of the Oligo-Miocene sequence: strong subsidence south of the Hadramut region; uplift of northern and southern Hadramut Arch; subsidence in Jeza syncline.

Deep erosion of the Oligo-Miocene strata indicates a period of tectonic activity before the deposition of the Pliocene-Recent sediments.

Fissure and vent basaltic flows (Aden Trap Series) have been in- and extruded during Late Cretaceous – Oligocene – Miocene.

The Pliocene-Recent sediments are transgressively and unconformably overlying Oligo-Miocene and/or older deposits. These sediments are of a shallow marine character and, according to the literature, are subhorizontal.

The Aden Volcanic Series have been extruded as vent basaltic flows and pyroclastic eruptions during the Miocene to Recent. In the western part of the RY they are associated with intrusions of granites.

The igneous rocks described above are not of minor importance for oil exploration due to absence of organic matter, immaturity and leaking of porous layers.

The Island of Socotra is the largest and most easterly of a group of islands, which includes Abd al Kuri, Samha, and Darsa. It is located 380 kilometers south-southeast of Ras Fartaq, the closest point on the Arabian Peninsula; and 250 kilometers east-northeast of Cape Guardaful, at the northeast tip of Somalia. The surface area of the islands is about 3.650 square kilometers; a broad continental shelf area, particularly well developed on the south side, surrounds the island chain, with an area of approximately 32,000 square kilometers. (Figs. (7.1), (7.2))

For the most part, the island of Socotra is covered by a veneer of Cretaceous and Tertiary limestones, up to 700 meters in thickness, which forms an undulating, irregular, and in part block-faulted upland plateau ranging from 300 to 900 meters in elevation, overlying an older igneous and metamorphic basement. Three main structural uplift areas from the central backbone of Socotra, culminating in the spectacular Haggier Range with peaks rising to 1.500 meters. In other areas, where part of the limestone cover has been removed, recent deposits largely obscure the earlier rocks, in particular along the northern and southern coastal plains and in some of the inland depressions.

1. On the First Stage: The First Systematic Geological Observation Stage or Carter’s Stage, (1852-1901)

On 1907, Kossmat, F. made the First Systematic Geological Investigation of the Socotra archipelago

3. On the Third Stage: The First Systematic more detailed Stratigraphic and Geological Studies Stage or Beydoun, Z.R.'s Stage, (1947-1967):

Z.R. Beydoun undertook the earliest systematic study of the geology of Socotra Island in 1953 for the Iraq Petroleum and Associated Companies. Field observations, measuring and sampling of outcrop sections, and reconnaissance field mapping were later supplemented by photogeological examination and mapping, and a simplified geological map of the island was made. This work, together with observations by H.R. Bichan, (the first one, who concentrated his study principally on the basement rocks of the Socotra archipelago) made as part of an expedition sponsored by the British Middle East Command in 1967, are summarized in a report published in 1970. (Beydoun, Z. R. & Bichan, H. R., 1970)

In the middle of 1975, Siebencs Oil and Gas Ltd. (after known as Dome Petroleum Ltd.) obtained a production-sharing contract area of offshore waters located south and southwest of Socotra. A reconnaissance aeromagnetic survey of the area indicated the presence of at least 2,000 meters of sedimentary rocks above basement. The basement topography was shown to be complex, with series of deep basins separated by high areas. The magnetic survey was immediately followed by a seismic survey and on November 1978, Siebens Samah-1 commenced, reaching a total depth of 2,620 meters.

Beydoun, Z. R. & Bichan, H. R., 1970 describes a maximum thickness of 300 meters of Lower and Middle Cretaceous limestones, with some basal sandstones, deposited on an igneous and metamorphic basement peneplain, followed without an apparent break by 400 meters of cliff forming shelf limestones of Paleocene and Eocene age.

Siebens geologists report finding Paleozoic Permian (?) limestone and sands below the Cretaceous unconformity in southeastern Socotra.

Based on the similarity of the composition of the Cretaceous section, Beydoun supports the hypothesis by Laughton (Laughton, A. S., 1966) and others that pre-rift Socotra was situated along the Arabian coast, close to Oman. He furthers postulates (Beydoun, Z. R., 1970) that the Socotra region may be ‘the eastern prolongation of the North Hadramawt Arch’’.

The structure of Socotra is dominated by three main uplifts, oriented in an east-west direction, involving the basement and overlying sediments. North-east-southwest

faulting separates these. In the western part of the island, west-northwest-east-southeast block faulting becomes dominant. South of the Socotra continental shelf, and east, off the Somalia coast, lies the deep North Somali basin.

In the offshore continental shelf region, Siebens’ seismic work shows a series of narrow uplifts separated by deep troughs, all trending in an east-west direction. The island of Samha and Darsa are situated on another block, Abd al Kuri is on a separate block. South of Samha and Darsa, and separated from them by a highly faulted trough area, an east-west-trending uplifted fault block, or horst, occupies the central part of the contract area. Structural movement along a series of north-south faults, accompanied by doming of the sediments, resulted in a series of high and low areas superimposed on the uplift. Siebens mapped three prominent seismic events:

· A limestone layer between sequence of claystones believed to be at the top of the Paleocene.

· And an event at the base of the Cretaceous section correlating with a thick layer of volcanics at the well location.

A basement reflection was also mapped locally. The Siebens seismic interpretation is questionable. Line location was determined by satellite navigation. At this latitude and longitude, satellite passes are infrequent and distant, and precise vessel location cannot always be accurately fixed. Bathymetric data in the area are not precise, and velocity determinations difficult. Serious misties with, intersecting lines were found throughout the area.

Siebens, Samah-1A was located on the most prominent of the structurally high features on the indicated horst block in a water depth of 115 meters. The well penetrated 938 meters of bedded clays, marls, and marly limestones identified as Eocene and Paleocene in age, and 1.334 meters of interbedded limestones, marls, and dolomites, with sandstone beds near the base, all of Cretaceous age. At the base of the Cretaceous section, 22 meters of volcanic tuff and lava were penetrated. Beneath the Cretaceous, 125 meters of sandstone and dolomitic marl were assigned a Triassic age, and 152 meters of granite wash with thin dolomite stringers were determined to be of

Permian age. A total of 46 meters of pink granite, cut by altered basic dike material,

were penetrated in the basement. No beds of Oligocene or Miocene age were identified, but it is possible that the uppermost shales in the Eocene section may be of later age.

Patchy minor oil shows were encountered in the lower Cretaceous section between 1,880 and 2,275 meters. Dolomitic beds within the Permian granite wash section had poor to fair porosity and displayed moderate dry gas shows. These shows increased within the basement, and were interpreted as fracture production. Log analysis indicates that the Permian section is gas saturated.

Sedimentological and geochemical analysis of samples and cores from the Samah well indicate that good reservoir beds are present in the Permo-Trias continental sandstones, in carbonate reef flank and shoal deposits, in secondary dolomites, and in sandstone interbeds, particularly in the lower Cretaceous section.

The well contained no thick, continuous sequence of potential source beds, although thin shales between 2,240 and 2,290 meters were determined to be fair to good source rocks for oil. And it is entirely possible that adequate oil sources can be expected to exist in Cretaceous and possibly Jurassic beds in deeper parts of the basin where their maturity can also be anticipated.

Other structural feature is present on the horst block where the Samah-1A well was drilled. Reef buildups along the south side of the uplift are suggested by the seismic mapping, and an expand Paleozoic –Triassic section may be present along the flanks of the uplifted area. A large structure is present in the southern part of the area. Its location closer to the margin of the North Somali Basin, together with its size, are positive factors enhancing its favorability for further exploration?

In any case, the geology of the Yemeni Island of Socotra with Siebens, Samah-1A well has not just demonstrated that a sedimentary section with considerable petroleum potential is present in the Socotra area, but also put a big question on the presence of Eocene (? Upper Eocene), Triassic (? Middle and Upper Triassic)

8.2 THE YEMENI SECTOR OF RUB AL KHALI BASIN GEOLOGICAL RESEARCH HISTORY WORK 244

It is known that one of the world's largest exploration successes of the 1980s was the discovery, by Canadian Occidental and partners, of constellation of oil pools in the Masila region, Sayun Al-Masilla Basin, of Yemen (Fig. (2.3)). The presence of several hundred million barrels of recoverable oil has been proved by drilling within reservoirs ranging in age from Jurassic to Cretaceous, with most reserves in Lower Cretaceous sandstone of the Qishn Formation (Peter E. Putnam, George Kendall, and David A. Winter, 1997). The discovery of commercial oil and gas in several interior Mesozoic rift basins of Yemen in the late of 1980s and in the early 1990s after the Yemeni unification, spurred many oil companies to enter the exploration race and carry out detailed seismic surveys. This led to intensive explorations drilling in many areas (Figs. (2.1A), (2.1B) and (2.2)). The Yemeni sector of the Rub al Khali Basin, (Fig. (2.3)) the main subject of this chapter, is one of those areas, which found some care in the past and attracts many oil companies in the present time.

1. Al-Ghawar oil field one of the world's largest oil fields has been found in the Rub al Khali Basin.

3. Oil Companies, which drilled exploration wells in the Yemeni sector of Rub al Khali basin (in Qinab, Hathout and Shahr area), had penetrated Paleozoic clastic reservoirs with core porosity ranging between 5% and 25%, 120 md to 3,2 d (Darsi) permeability and age from Middle Cambrian to Early Permian (Nani A.S.O., 1998).

4. The Qusayba (lower Silurian) shales, which is the principal source rock for Paleozoic discoveries in Saudi Arabia is present in the above mentioned areas.

5. Much of the southern flank of the basin lies within northeastern Yemen, with the regional Paleozoic Hadramawt Arch forming the southern basin margin onto which all Paleozoic and Early Mesozoic sedimentary sequences pinch out.

1. Northward into the basin, the flank slopes gently but in a step-like manner and the sedimentary column thickness increases from about 2 km near the crest of the Hadramawt Arch to over 4 km by the Yemeni-Saudi border (Powers, et al.,1966; Beydoun, et al., 1998).

On this Chapter, I am going to introduce my research study work with Professor Wang Xi Kui. That work led to a new look to the area. That’s new look to the area depends on our study to:

3. A collection of satellite images, which had been taken of the Republic of Yemen during the period from 1994 to 1997 (Fig. (8.1; 8.2; … 8.27) ) with hundreds of airophotos and satellite images, taken to different part of the Peoples Republic of China. (As an exemplars to find a case study to the Yemeni Sector of the Rub al Khali Basin).

And this led us to introduce a new idea for a new project, which we hope is going to help future petroleum exploration activities and attract foreign exploration investment to work in the Yemeni sector of the Rub al Khali Basin.

According to my new division to the geological research history work of the Republic of Yemen to four stages (Nedham M. Darsi, 2000) It is so clear now, that:

1.On the First Stage (The First Systematic Geological Observation Stage or Carter's

No kind of geological studies had been detected in the Yemeni sector of Rub al Khali basin.

2. On the Second Stage or the Hinterland Studies Stage, (1902-1946) and the Third Stage

(The First Systematic more detailed Stratigraphic and Geological Studies Stage or Beydoun,

Geological field investigation, supplemented by photogeologic and ground mapping covering the entire territory, were carried out by the Petroleum Concessions Ltd, one of the Iraq Petroleum Company and associated companies (IPC and Associated companies) between 1937 and 1960.

3. On The Third Stage (The First Systematic more detailed Stratigraphic and Geological

Bunker, D.G. wrote about the southwest Borderlands of Rub al Khali, in 1953. From

1961 to early 1967, Pan American International Oil Company through a subsidiary, Pan American Hadhramawt Oil Company (PAHOC) drilled four wells (Hoowarin, Tarfayt and Core Hole 88 reached Precambrian basement and the forth was abandoned in the Cretaceous sediments).

4.1 It is known that, the Petroleum and Minerals Board (the PMB) was established, in 1970 in former South Yemen. During the period from 1970 to 1973, the joint of former South Yemen-Algerian Petroleum Company (SYAPCO) drilled Taur-1 in 1974 and Taur-2 was commenced. In 1974, a group of experts from Cuba assumed the drilling operation from SYAPCO and with former PMB completed Taur-2, Taur-3 and drilled Thamud-1 and Hathout-1. In September 1976, the functions of the PMB were broadened and the Petroleum Exploration Board (the PED) was created (The Petroleum Exploration and Production Board, Aden Branch, as known now), led different activities on studying the geology of this area. As a result of their work on the Yemeni sector of Rub al Khali basin, wells as Taur-2, Taur-3 and Hathout-1 was drilled. A group of the P.E.D.'s Engineers, Technician and workers, work hard on this area, and their work is highly appreciated. On Mar. 27 1979, B. Kuzin and Mohammed Ba'abad made a Stratigraphic Correlation, for wells drilled in that area correlative with wells located in the adjacent area at that time.

The Petroleum Exploration and Production Board (P.E.P.B.) is responsible for all petroleum exploration and related activities and is interested with the exploration for oil and gas in the Republic of Yemen on its own, or in association with foreign companies through production sharing agreements. The P.E.P.B. has a professional staff and other administrative personnel.

4.2 Between 1975 and 1979, as a part of its assistance program, TechnoExport, the former Soviet Technical Assistance Organization, had recorded aeromagnetic surveys covering most of former South Yemen and also a gravity survey had been conducted over specific areas of interest. CDP reflection and refraction seismic had been concentrated in the Yemeni sector of Rub al Khali basin and as a result of their work in the area, wells as Hathout-2 Shahr-1 were drilled in 1981-82.

The field investigation had been augmented from time to time by Czechoslovakian and German technical personnel.

4.3 In the Yemeni sector of the Rub Al-Khali basin, first Bahad flower structure was detected from the seismic interpretation and then later Qinab flower structure had detected from the seismic interpretation by Elf Acquitaine Petroleum B.V, during the first phase of exploration in their ex-block 11, in 1989.

4.4 A group of professional staff and other administrative personnel of the Petroleum Exploration and Production Board (P.E.P.B.) made a Geological Review of North Hadhramaut Basin (the Yemeni sector of Rub al Khali basin). (Faisal M.S. Haitham, Mohammed A. Abdellah, Hussain A. Fadel, Nagib S. Thabet, Sulaiman Khamis, Nabeel A. Saeed, Saleh A. Al-Dahi, Tareq Abdulrahman and Abdul Hakim Saroor, 1998).

The Rub al Khali sand desert or the Empty Quarter (as also known) is a huge region of sand

covering about c.225, 000-sq. mi. (582,750 sq. km). It is one of the largest sand deserts in the world and the great desert of the Arabian Peninsula. The desert occupies much of the southern interior of the peninsula, from the highlands of the Nejd (to the north) to the plateaus of Hadhramawt (to the south); it slopes from an altitude of 3,300-ft (1,006 m) in the west to near sea level in the east. The sand dunes in the Rub al Khali sand desert rise to over 660 ft (200 m) in the southwest (The Columbia Encyclopedia, 1993). The dunes are mainly distributed in parallel to sub parallel ridges (called uruq), separated by narrow flat stretches of gravel, gypsum, or silt (shuquq). The trend of the southern border of the desert is east-northeast, which is also roughly the trend of the dune ridges. Slip faces of the dunes are generally south, but some north-facing slip faces have been observed. Some migration of dunes takes place; however, the migration seems to be up by seasonal wind directions, so that migration in any specific direction is difficult to detect (World Bank, 1983).There are salt marshes and pans in the southeast. Rub al Khali is connected to the Nafud desert in the north by the Dahna, a narrow corridor, 800 mi. (1,287 km) long southwest. The desert comprises more than 25% of Saudi Arabia. It is extremely dry and virtually uninhabited. Only the southernmost fringe of which reaches into the Republic of Yemen (The Columbia Encyclopedia, 1993). A much smaller area is the Ramlat Sabatayn sand desert. It stretches eastward from the foothills in the north part of the Republic of Yemen and in Bayhan province, where it is some 100 kilometers wide,

into the Hadhramawt drainage basin, occupying roughly the western extension of the

Wadi Hadhramaut structural trough. The dunes lose both height and lateral extent eastward, until they die out as low isolated patches of sand some five kilometers in width near Shibam in Wadi Hadhramaut. The Ramlat Sabatayn area is again one of dune ridges which, however, are less regular than those of the Rub al Khali with a trend roughly east-northeast in the west, are some 50 meters in the height, and are eastward and become irregular toward the east. Migration of the sand is largely offset by seasonal changes in the prevailing winds and by thermal disturbances (World Bank, 1983).

Several depressions are superimposed on the Arabian Shelf and at one time for another have received thick deposits relative to adjacent parts of the platforms. Such basinal sags have formed in the northeastern Rub al Khali, northern Persian Gulf, Dibdibah, and Sirhan Turayf areas. Seismograph and structural drill work in the Rub al Khali Basin have outlined an elongate basin. Width of the basin is relatively uniform throughout its length, eraging about 300 km (Powers, B. W., Ramirez, L. F., and Redmond, C. D.,1966). It is known that the Yemeni sector of the Rub Al-Khali basin forms the southern flank of this huge structural downwarp, which originated in the early Paleozoic as intracratonic sag later in the Paleozoic (Sykes, R.M. and Abu Risheh, A.K., 1989; Beydoun, 1988, 1989, 1991; Husseini, 1989). This feature is bounded on the north by the sand dunes of the Rub al Khali and on the south by the Ramlat Sabatayn sand desert. Much of the southern flank of the basin lies within northeastern Yemen, with the regional Paleozoic Hadramawt Arch forming the southern basin margin onto which all Paleozoic and Early Mesozoic sedimentary sequences pinch out. Northward into the basin, the flank slopes gently but in a step-like manner and the sedimentary column thickness increases from about 2 km near the crest of the Hadramawt Arch to over 4 km by the Yemeni-Saudi border (Powers, et al.,1966; Beydoun, et al., 1998).

According to (Prof. Wang Xi Kui and Me) study on a collection of satellite images, which had been taken to the eastern part of the Republic of Yemen during the period from 1994 to 1997 (Figs (8.1), (8.2), … (8.27) ) and hundereds of airophotos and satellite images, which had been taken to different part of the People’s Republic of China. We concentrated our attention onto the following more important satellite images, (Figs. (8.16) and (8.22)), due to:

1. Those satellite images were related to the Yemeni sector of the Rub Al-Khali basin.

2. The very clear images of different faults types shown on the surface, which we

First type: Faults with a NE–SW directions (very clear on the satellite images).

Second type: Faults with E–W and ENE-WSW directions (clear to very clear on the satellite images).

Third type: Faults with an N–S and NNE-SSW directions (clear to very clear on the satellite images)

Forth type: Faults with a NW–SE directions (clear to a little clear on the satellite images).

3. According to the character of the Satellite images, we found a black material

filling these faults on the surface, which looks like natural asphalt (?). Here we want

The same example was found in Kelamayi oil field, a famous oil field in the Northwest of the Peoples Republic of China, located to the margin of Zhunger Basin (Jurassic Formation Ð oil and gas bearing layer, oil and gas stored in overthrust structures). This oil field first time discovered by the local villagers, who found that black material on the surface and then known as asphalt.

Based on our study to the geological research history work, the neotectonic movement, the new crust movement, and our interpretation for the satellite images, we have a new look to the area. This new look to the area depending on our new thinking, that during the successive rift phases, (The Karroo Rift Phase; The Somali Rift Phase; The Mascarene Rift Phase; The Yemen Rift Phase), the expected main extensional faults trend and the minor extensional faults trends changed their direction.

1. The first type of faults, which has the NE-SW directions, is a normal and oblique normal fault.

2. The second type of faults, which has the EÐW and ENE-WSW directions, is a divergent sinistral wrench faults and has the same trend of the southern border of the desert, which is also roughly the trend of the dune ridges.

3. The third type of faults, which has the N-S and NNE-SSW directions, is divergent

Note (4): The second type of faults and the third type of faults are a share faults type, with right and left hands.

1. As a result of our study, we think that a new rift phase started in the area during the recent time.

a. The first type of faults, which has the NE-SW directions, is a normal and oblique normal fault. They are parallel to the direction of the largest principle stress of the Arabian plate.

b. The forth type of faults, which has NWÐSE directions, is over thrust faults. Their

extensional fault trend resulted by the largest principle stress of the Arabian plate.

3. We think, that this new stage has the same main rift trends like the Karroo rifts phase (?).

4. The natural asphalt (?) shown on the surface of this area by the satellite images might be a very clue for looking for a new petroleum discoveries.

1. It is recommended that a very highly qualified team study the Yemeni sector of Rub al Khali basin for recognition of crustal zones of weakness, their trend and origin is thus of vital importance in the interpretation of rift structures. We believe that this area, which took some care in the past and attracts many experts in the present time, is not going just to surprise all with its oil and gas discoveries, but also with its very rich geological data in the future.

2. The most important thing, that we want to drew the Ministry of Oil and Mineral

Resources, foreign companies and all who are interested in this area to concentrate

their exploration attention on the following two coordinate points and the adjacent

Fig. (8.10) Satellite Images No.10: Yemen 1, Desert (Latitude Longitude at Image center N17.11-E50.67)

THE (3D.Y.G.M. – TIN FOR ALL): THE THREE DIMENSION YEMENI GEOLOGICAL MODEL – TIN FOR ALL 277

THE (3D.Y.G.M. – TIN FOR ALL): THE THREE DIMENSION YEMENI GEOLOGICAL MODEL – TIN FOR ALL

In 1985, I was admitted to the Patrice Lumumba Peoples’ Friendship University decorated with the order of friendship among Peoples and in 1991 completed the full course of the same University having specialized in ‘’Geology and Exploration of Mineral Deposits (Oil and Gas Fields).By the resolution of the state Examination Commission of May 29, 1991, I am qualified as: Petroleum Engineer, Geologist and by the special of the state Examination Commision I am awarded the degree of master of science in geology. During my studing in the Patrice Lumumba Peoples’ Friendship University decorated with the order of friendship among Peoples and especially when I finished my fourth course. I had a new modest idea for a new project on a new portable tin, which can be used in the field of geology. And as a result of my work done on improving this modest project, the above mentioned idea is already regestered in Yemen, in1995. I called the above mentioned Project Tin, The 3DYGM For All Tin.. The Term 3DYGM- For All Tin means (the Three Dimention Yemeni Geological Model For All Tin). This Projected Tin will be used to construct the following kind of models:

This new Projected Tin, which look like a mathimatical set is going to be used by secondry school students, and by the students of institutes, colages and universities as well as by the researchers and those working in the field of oil. This Projected Tin, which born in Moscow (Russia), grew, improved and registered in Aden (Yemen), published and introduced in brief, as a part of my Ph.D. Thesis, discussed for the first time outside Yemen, here in Changchun (China) is going to find a wild application in the near future. (See attached Figs. (9.1), (9.2), (9.3) and (9.4)) And then, the most interesting results and most important facts, we are going to receive as a result of using the 3DYGN For All Projected Tin in the field of geology is that, most of it users are going to like it and to ask for more and more specific serials of the above mentioned Tin. (For more information, I would like to ask interested reders in this Projected Tin to read the interview held by the 14^TH October Newspaper correspondent, (this newspaper is one of the most famous and more public newspapers in Yemen), with me on the 25^th of August 1994).

Suppose that you have a wall clock in your house. This wall clock tell and show you the whole scenario of earth history evolution supported with animated pictures and voices two times per day.

The First Hour on this clock introduce the Origin and the Early Evolution of the Earth; the Mountain Building and Drifting Continents, the Deep-Sea Floor and Plate Tectonics, the Pre Paleozoic History as an introduction to understand the Origin of the Continental Crust and the Organic Evolution. (This First Hour show, can be seen from 00:00 a.m. to 01:00 a.m., and from 00:00 p.m. to 01:00 p.m. every day).

The remaining hours on this clock show the Earliest, the Middle and the Late Paleozoic History; the Pangea its Makeup and Breakup; the Mesozoic Era; the Cenozoic History, the Pleistocene Glaciation and the Rise of Man and at the end the best of all possible worlds?

I believe in, that listening and looking to this kind of clock every where we go, two times per day, is going to make the Evolution of Earth History known by all. This new clock, (My new project), I called it Al-Tohaita Geological Time Clock (T.G.T.C.). (See Figs. (10.1) and (10.2))

* Al-Tohaita (or Ser Ya Koas) is the name of a small Yemeni historical village 10 km (ENE) from the famous Yemeni city, Zabid. I gave its name to the new projected clock to show our same origin.

I am shore, that using the above mentioned clock, the Al-Tohaita Geological Time Clock, in the near future is going to make it easy to produce another types of this clock with different functions.

1. Based on my new classification and division to the Geological Research History Work of the Republic of Yemen to four stages and my pervious published papers on the Yemen Times Newspaper I can confidently assume, that:

· it is easy now to wrote a book about the first and the most famous Geologists, who play a great role in the geological research history work in the Republic of Yemen during the period from 1852 until Today.

· it is easy now to teach our student in the university, this bright part of our geological research history work

· There are many Peoples, Researchers, and Foreigners, who are interested in this field, who would like to work in Yemen, at the same time they would like to know more about the geological research history work of the Republic of Yemen.

· It is so necessary now for every one, who would like to publish a book or a work on the geology of Yemen to mention the Four Stages of the Geological Research History Work in the Republic of Yemen.

· This study led to significant improvement in imaging about the geological research history in the Republic of Yemen, particularly about the first and the most famous geologists, who worked visits, worked and this has been key to understanding.

· On the whole, it is my belief that it is broad in scope so as to serve both the beginning geology major and the under graduate seeking to learn about or to make him read about the geological research history work in the Republic of Yemen.

2. It is known, that the main aim of my new table for the whole Yemeni Lithostratigraphic Units and Nomenclature is to solve chronic problem related to the Yemeni Lithostratigraphic Units and Nomenclature. I planned to use the same table as a whole or partly to introduce many interested geological issues in the near future.

of Yemen (from the basemenent to the surfase), show the huge conclusions and recommendation we can resieve from such work. In my opinion, I must continue this work and with one main aim to discover a new promising geological structures. This well lead to an increase in the Yemeni production, the reserve and oil prospects as well.

4. Using the two new projected patent methods, the (3D.Y.G.M. – Tin For All): The Three Dimension Yemeni Geological Model - Tin.For All and the (T.G.T.C.): Al-Tohaita (Ser Ya Kaos) Geological Time Clock are going to ease studing and understanding Modelling and the Whole.Evolution of Earth History.

1 A new classification and division to the Geological Research History Work of Yemen..

3 A new explanation to the anomaly in the Yemeni Lithostratigraphic Units and Nomenclature, having the same geological time line (the same age), by relating such anomaly to the geological history of the area, especially the anomaly in tectonics. activities and the process of sedimentation.

1. A new subdivision to the Yemeni Paleozoic sediments, into two depositional sequences, i.e. from young to old:

5. A new subdivision to the whole Phanerozoic sedimentary sequence of the Republic of Yemen into five depositional sequences, i.e. from young to old:

d. CRETACEOUS (Lower Hauterivian to Maastrichtian) / PALEOCENE – MIDDLE EOCENE

6. A new lithostratigraphic column suggested for the Whole Yemeni Phanerozoic sequence.

7. A new suggestion, implies that the North Hadhramawt Arch became pronounced during the Lower Paleozoic as a result of uplift in Cambrian (?) - Lower Silurian (Llandoverian) times.

8. My personal field notices and records show, that the Yemeni Lithostratigraphic Units characterised by some important factors, such as Lithology changes, Rate of Penetration (increase and decrease), background gas (increase and decrease) and the chromatographic analysis.

9. A new work done on mapping and modelling the whole eastern part of Yemen (from the basemenent to the surfase).

The above mentioned conclusions are the result of my work for 8 years in the Petroleum Exploration and Production Board (Aden Branch), Ministry of Oil and Mineral Resources (Yemen) and my research study work on my Ph.D. Thesis in Jilin University (Changchun City, Jilin Province, China). It is clear now, that this work gave, give and well give a new look to the Yemeni geology, It is time to say thank you for allowing me to contact you this past years. I have appreciated hearing from many of you. Your input and suggestions have been very helpful. Hope, it is the first step in right direction.

1. We in the Republic of Yemen must give a high attention to the Environmental Geosciences. It is known that the global warming issue poses a number of potential challenges and opportunities for the oil industry. Ongoing negotiations are defining not only targets for greenhouse gas reduction but also mechanisms to enable countries and companies to respond. A broad range of options exists to reduce or sequester emissions. So it is recommended to discuss some of the important technical, economic, and political questions that surround the ultimate viability of this option.

2. If we really want The Geological Research History Work in the Republic of Yemen to be easy to read and to understand. We must make a restudy on the history of the Exploration Activities, a restudy on the history of Companies 's Work and a restudy on the history of Scientific Expedition Work in the Republic of Yemen. And. This entire things in accordance to my classification and division to the Geological Research History Work in the Republic of Yemen to four stages.

1. It is recommended that a very highly qualified team study the Yemeni sector of Rub al Khali basin and the Yemeni Island of Soqatra.

2. Presence of gypsum on the surface of the Yemeni sector of Rub al Khali basin, give us the right to recommend for a new study on the presence of Uranium in the above mentioned area.

3. Looking to the future and with a long-term vision in mind, I am deeply confident of the great efforts needed to inter the Fifth Stage or (the Yemeni Geologists Golden Stage) as I hope. In that respect I would like to mention two of the steps that we must do:

(A) We in Yemen are highly in need to rebuild the National Crew or Team, who is already ready to solve any problem related to any branch of earth science.

(B) We in Yemen also are highly in need to make a restudy on the entire most famous Yemenis Geologists Job. First, to encourage the local work. Second, to connect the theoretical part with the practical part and by the way to answer the most interesting question, which I am shore every Yemeni geologist ask himself always, who is the suitable person, whom we can call the father of Geology in Yemen?

4. I believe in that Yemeni Geology, which took some care in the past and attracts many experts in the present time, is not going just to surprise all with its oil and gas discoveries, but also with its rich and useful data in the near future.

5. Interested people in Yemeni geology must contact the Petroleum Exploration and Production Board (P.E.P.B.). It is responsible for all petroleum exploration and related activities and is interested with the exploration for oil and gas in the Republic of Yemen on its own, or in association with foreign companies through production sharing agreements.

[1] Abdel-Gawad, M., 1970. Interpretation satellite photography of the Red Sea and Gulf of Aden: Phil. Trans. Roy. Soc. Lond., A267, p. 23-40.

[2] Abou Khadrah, A., 1982. A review of the sedimentological evolution of Yemen Arab Republic. Bulletin Faculty Science, San’a University, 2: 39-55.

[3] Abou Khadrah, A., El-Anbaawy, M.I.H. and El-Faisal, F., 1983. Stratigraphy of the Tawilah Sandstone in the environ of San’a, Yemen Arab Republic. Bulletin Faculty Science, Zagazig University, 5: 294-321.

[4] Aboul Ela, M., 1983. On the geology of the area N.W. of San’a, San’a-Wadi Zahr district, Yemen Arab Republic. Bulletin Faculty Science, San’a University, 3: 41-70.

[5] Agar, R. A., 1985. Stratigraphy and paleogeography of the Siham group: direct evidence for a late Proterozoic continental microplate and active continental margin in the Saudi Arabian Shield. Journal of the Geological Society, London, 142 (6): 1205 – 1220.

[6] Agar, R. A., 1987. The Najd fault system revisited – a two way strike slip orogen in the Saudi Arabian Shield: J. Struct. Geol., 9, p. 41-48.

[7] Agar, R. A., Stacey, J. S. and Whitehouse, M. J., 1992. Evolution of the Southern Afif Terrane – A geochronological study. Open File Report DGMR-OF-10-15, Ministry of Petroleum and Mineral Resources, Jiddah, Saudi Arabia, 41p.

[8] Agip, 1978, 1980. Report on stratigraphic surveys in PDR Yemen; Sayut, Mukalla and Qamar areas: Internal Reports Agip Overseas Branch PDR of Yemen.

[9] Agip Company, 1982. Unpublished subsurface reports on the offshore wells in the Mukalla-Sayhut offshore basin covering 1979-1982. PDRY: Department of Geology and Mineral Exploration, Aden.

[10] Ambraseys, N. N. and Melville, C. P., 1983. Seismicity of Yemen: Nature, 303, p. 321-323.

[11] Anbaawy, M.I.H., El- 1984. Contribution to the lithostratigraphic subdivision of the Amran sequence in the Yemen Arab Republic. Bulletin Faculty Science, San’a University, 4: 65-84.

[12] Anbaawy, M.I.H., El- 1984. Types and distribution of coastal sediments along Al-Hudaydah-Al-Salif areas and Kamaran Island, Red Sea, YAR, a preliminary study: Saad, Massoud A. H., ed., Proceeding of the symposium on Coral reef environment of the Red Sea, Jeddah, Jan. 14-18, 1984, King Abdulaziz University, Mar. Chem. Dep., Jeddah, Saudi Arabia, p. 195.

[13] Anbaawy, M.I.H., El- 1985. Geology of the Yemen Arab Republic: University of San’a, Yemen Arab Republic, El-Topgy Press, Lazoghly, Cairo, 303 p.

[14] Anbaawy, M.I.H., El- 1985. Geologic evolution of the Late Jurassic evaporites of the Al Gharas District, Yemen Arab Republic: San’a University, Faculty of Science Bulletin, v. 5, p. 40-58.

[15] Anbaawy, M.I.H., El-, Al-Aawah, M.A.H., Al-Thour, K.A., and Tucker, M., 1992. Miocene evaporites of the Red Sea Rift, Yemen Republic: sedimentology of the Salif halite. Sedimentary Geology, 81: 61-71.

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[287] Yelland, A., Menzies, M. A. and Hurford, A., 1994, Fission track analysis of a volcanic (Red Sea) and non-volcanic (Gulf of Aden) margin: International Conference on Geochronology, Cosmochronology and Isotope Geology, Berkeley (in press) (abs).

[289] Zhang Hongyou and Song Shouquan, 1983. Strong earthquake in North Yemen occurred on Dec. 13, 1982: Recent Developments in World Seismology 1983(9), p. 25-26.

[290] Zumbo, V., Feraud, G., Bertrand, H. and Chazot, G., 1995. 40 Ar/39 Ar chronology of the Tertiary magmatic activity in southern Yemen during the early Red Sea rifting Journ. Volcanolog. Geotherm. Research, 65 (3-4): 281-295.

310

Group	Age	Formation	Age
Ghabar	Infra-Cambrian to ?Lowermost Paleozoic
		Harut	Infra-Cambrian to ?Lower Cambrian
		Khablah	Infra-Cambrian to ? Lowermost Cambrian.
		Shabb	Infra-Cambrian
		Minhamir	Infra-Cambrian
Important Note: Mudayd Formation (Upper Proterozoic-Lower Cambrian) is discarded
Qinab	Infra-Cambrian to Lowermost Cambrian
(Subsurface of
Rub al Khali Basin)

Formation	Age	Member	Age	Remarks
Akbarah	?Lower Permian			Located in the outcrop in NW Yemen
Wajid	Paleozoic (Permian and older)			Located in the outcrop in NW Yemen
Juwayl	Upper Carboniferous to Lower Permian			They are lateral subdivisions of Wajid Formation in the Southern Flank of Rub al Khali basin.
Khusayyayn	Devonian-Carboniferous
Qalibah	Lower Silurian	Qalibah	Lower Silurian
Dibsiyah	Cambrian-Ordovician

Group	Age	Formation	Age	Member	Age
Mahra (Cretaceous)	Maastrichtian to Lower Campanian	Sharwain	Maastrichtian to Lower Campanian	Sharwayn	Maastrichtian
Mahra (Cretaceous)	Maastrichtian to Lower Campanian	Sharwain	Maastrichtian to Lower Campanian	Dabut	Lower Maastrichtian to Lower Campanian
Both groups: Cretaceous	Turonian	Mukalla	Turonian (?Maastrichtian to ?Upper Cenomanian)	Lusb	Turonian
Both groups: Cretaceous	Turonian	Mukalla	Turonian (?Maastrichtian to ?Upper Cenomanian)
Mahra (Cretaceous)	?Turonian to Cenomanian (to Lower Albian)	Fartaq	?Turonian to Cenomanian (to Lower Albian)	Maqrat	?Turonian to Cenomanian
				Tuhayr	?Turonian to Cenomanian
				Duha Suhis	Cenomanian
Tawilah (Cretaceous)	(Maastrichtian to Hauterivian	Harshiyat	Cenomanian to Lower Albian	Sufla	Cenomanian
Tawilah (Cretaceous)	(Maastrichtian to Hauterivian	Harshiyat	Cenomanian to Lower Albian	Rays	Albian
Both groups: Cretaceous	(?Lower Albian / ?Lower Aptian in the West) Upper Barremian to Hauterivian	Qishn	(?Lower Albian / ?Lower Aptian in the West) Upper Barremian to Hauterivian	Qishn Carbonates	?Lower Albian / Aptian to Barremian
				Qishn Clastics	?Lower Aptian in the West / Lower Barremian to Hauterivian
				Sa’af	Lower Barremian to Lower Hauterivian
		Important Note: Mithaf Formation (Campanian to Albian) and Hallah Formation (Campanian to Maastrichtian) are discarded

Mahra (Cretaceous)	Lower Valanginian to Middle Berriasian	Sa’ar (mainly in the east)	Lower Valanginian to Middle Berriasian	Al Ghayl	Lower Valanginian
				Qalana	Lower Valanginian to Upper Berriasian
				Samarma	Middle Berriasian
AMRAN JURASSIC	( Callovian) to Lower Cretaceous (Berriasian)	Nayfa	Berriasian to Upper Tithonian	Nayfa Breccia	Upper Tithonian
		Sab’atayn	Upper Jurassic (Tithonian)
		Sab’atayn in the NW	(Upper to Lower) Tithonian	Safir	Upper Tithonian
				‘’Alif’’	(Middle- Upper) Tithonian
				‘’Seen’’	(Lower to Middle) Tithonian
				‘’Yah’’	Lower Tithonian
		Sab’atayn in the centre and the South East	Upper Jurassic (Tithonian)	‘Ayad	Upper Jurassic (Tithonian)
				Maqah	Upper Jurassic (Tithonian)
				Layadim	Upper Jurassic (Tithonian)
				Shabwa	Upper Jurassic (Tithonian)
		Madbi	Middle and Lower Tithonian to Lower Kimmeridgian
		Madbi (in NW)	(Middle to Lower) Tithonian to Kimmeridgian	Upper Madbi Shales	(Middle to Lower) Tithonian
				Harib	Lower Tithonian
				‘’Lam’’	Lower Tithonian
				Raydan	Lower Tithonian
				‘’Meem’’	Lower Tithonian to Kimmeridgian
				Haniyah	Lower Tithonian to Kimmeridgian?
				Ayban	Lower Tithonian to Kimmeridgian
		Madbi (in outcrop)	(Middle to Lower) Tithonian to Upper Kimmeridgian	Rafad	Middle Tithonian
				Ma’abir	Lower Tithonian to ?Upper Kimmeridgian
				Lower Madbi Shales	Lower Tithonian to Upper Kimmeridgian

		Shuqra	Oxfordian to Callovian (it may range locally down to Bathon and up to Kimmeridgian)	Arwa	(Upper to Middle) Kimmeridgian


		Kuhlan	(Middle to ?Lower) Jurassic
		Sudair	Lower Triassic to ?Lower Permian

Group Name	Formation Name	Rrmarks
TAWILAH Gr. (W)	Top (disconformity)
	Mukalla:	Shallow marine- lagoonal environment max. thickness 1 km; but decreases strongly to W
	Harshiyat:	Shallow marine-littoral sandstones with some gypsiferous shale lenses max. 300 m thick
MAHRA Gr. (E)	Shawayn:	Limestone, shale and marl restricted shallow platform environment max. thickness: 60 m
MAHRA Gr. (E)	Mukalla Fm.
	Fartaq:	Shallow marine marls and shales with interbedded limestones max. thickness > 1500 m

Group	Age	Formation	Age	Member	Age
Tihamah	?Holocene / Pleistocene to Lower Miocene	Abaas	Pleistocene to Pliocene	Kamaran	?Holocene to Pleistocene-
		Salif	(Upper to Middle) Miocene	Ghawwas	(Upper to Middle) Miocene
		Maqna	Lower Miocene
		Zaydiyah	Lower Miocene
Shihr Group (onshore)	Pliocene to Oligocene	Irqah	Pliocene to Upper Miocene
		Fuwwah	Lower Miocene
		Buwaysh	Oligocene
		Libakhah	Oligocene	Ayn Ba Ma’bad	Oligocene
		Ambakhah	Oligocene
Shihr Group (offshore)	Pliocene to Oligocene	Sarar	Pliocene to Middle Miocene	Sarar	Pliocene to Middle Miocene
		Taqah	Miocene to Oligocene	Hami	Lower Miocene to Upper Oligocene
		Hami	Lower Miocene to Upper Oligocene	Ghaydah	Oligocene
		Ghaydah	Oligocene	Taqah	Miocene to Oligocene
Yemen Volcanic		Important Note: Rimah Formation (Oligocene to Upper Eocene) and Hamarah Formation (Oligocene to Upper Eocene) are discarded
Yemen Volcanic		Majzir	Paleocene-Lower Eocene	Lahimah	(?Oligocene to ?Lower Eocene)
Hadramawt		Habshiyah	Middle Eocene (Lutetian)
		Kaninah {westward lateral	Middle Eocene
		Mayfa’ah {variants	Middle Eocene	‘’Transitional Beds’’	Middle Eocene
		Rus	Lower Eocene
		Jiza	Lower Eocene	Jawl	Middle Eocene
		Umm er Radhuma	Upper Paleocene	Shammar	Upper Paleocene

4.2 STRATIGRAPHIC PRINCIPLES AND PROCEDURES: A SUMMARY 108

4.3 DEVELOPMENT OF THE LITHOSTRATIGRAPHIC UNITS AND NOMENCLATURE IN YEMEN 111

4.1 INTRODUCTION

4.2 STRATIGRAPHIC PRINCIPLES AND PROCEDURES: A SUMMARY

Siebens geologists report finding Paleozoic Permian (?) limestone and sands below the Cretaceous unconformity in southeastern Socotra.