bluuebunny/crossref_metadata_2025 huggingface dataset:
Albian-Cenomanian Palynology, Paleoecology and Organic Thermal Maturity of Well DK-B in the Dukhan Oil Field of Western Qatar
Authors: Ibrahim Mohamed I.A. , Al-Hitmi Hind H.A. , Kholeif Suzan E.
Published: October 2021

A palynological investigation of the Nahr Umr, Mauddud and Ahmadi formations of the middle Cretaceous Wasia Group in Well DK-B in the Dukhan oil field of Qatar, yielded 30 species of dinoflagellate cysts, 18 of pteridophytic spores, 14 of gymnosperm pollen, and 16 of angiosperm pollen. Based on the investigation, the age of the Nahr Umr Formation is middle to late Albian. The basal part of the Formation was deposited in a marine prodelta or shallow shelf environment, whereas sedimentation of the upper part took place in normal marine conditions of an inner to middle shelf at depths of 10 to 80 meters. The carbonates of the Mauddud Formation are of late Albian (Vraconian) to early Cenomanian age and were deposited in an inner-middle shelf environment (20–100 meters). The shales and limestones of the Ahmadi Formation are of early to middle Cenomanian age and accumulated in open-marine conditions within an outer-shelf environment (100–200 meters). Two regressive pulses or lowstand system tracts can be detected in the lower and middle parts of the Ahmadi Formation that are consistent with published short-term global eustatic curves. Rocks of the Wasia Group studied in Well DK-B are in general enriched in kerogen type II (oil-prone material) except for the lower part of the Nahr Umr Formation that can be attributed to kerogen type III (gas-prone material). The thermal alteration index range of 2, 2+ to 3− suggests that the sediments of the Ahmadi Formation are immature whereas those of the Mauddud and Nahr Umr formations are slightly mature. The Albian-Cenomanian palyno-assemblage of western Qatar is referable to the African-South American Phytogeoprovince as shown by the presence of Crybelosporites pannuceus, ephedroid pollen, elater-bearing pollen, Afropollis, Stellatopollis, Reyrea and Cretacaeiporites species. Arid to semi-arid (tropical to subtropical) climatic conditions prevailed in the African-South American province at this time. Dinoflagellate cysts suggest a Tethyan connection.
Essay: applied cyclo-stratigraphy for the Middle East E&P industry
Authors: Mattner Joerg , Al-Husseini Moujahed
Published: October 2021

The modeling of ordered sedimentary cycles through orbital forcing (cyclo-stratigraphy) could impact the Middle East E&P industry practices from regional exploration to reservoir engineering. The correlation of longer period cycles could detect thinning or disappearing reservoir intervals over structures. These terminations may be due to erosion or non-deposition, and used to guide exploration for stratigraphic traps. The correlation of shorter period cycles may be used to map the disappearance or diagenetic alteration of reservoir flow units between wells. The Permian and Mesozoic carbonates and evaporites that constitute the main Middle East hydrocarbon reservoirs and seals, manifest cycles at many scales, and are particularly suited for cyclo-stratigraphic analysis.
Genesis and characterization of dolomite, Arab-D Reservoir, Ghawar field, Saudi Arabia
Authors: Cantrell David , Swart Peter , Hagerty Royal
Published: October 2021

This study reports the results of an investigation into the nature, origin and significance of linear dolomite trends across the Arab-D reservoir in Ghawar field. In the course of this study, three distinct types of dolomite were identified based on petrographic and geochemical criteria: fabric-preserving (FP), non-fabric-preserving (NFP) and baroque dolomite. Fabric-preserving (FP) dolomite is very finely crystalline dolomite in which details of the original limestone fabric are usually well preserved. Beds of FP dolomite typically occur as thin, sheet-like or stratigraphic layers that are always intimately associated with the overlying anhydrite. This dolomite is interpreted to have formed very early in the diagenetic history of the sediment, by dense, highly evaporated magnesium-rich brines associated with the overlying anhydrite. In contrast, NFP dolomite is a medium crystalline, non-baroque dolomite in which all traces of the original limestone fabric have been obliterated. This dolomite also typically occurs as stratigraphic beds, although it is not restricted to the uppermost part of the Arab-D but occurs throughout the reservoir. The NFP dolomite is the most common type present in the reservoir, and is interpreted on the basis of its general geochemical similarity to the FP dolomites to have mostly formed from hypersaline fluids, although some NFP dolomite is thought to represent a transitional form with the third dolomite type, baroque dolomite. Strontium isotopic ratios suggest that both the FP and most of the NFP dolomite formed very early, at or shortly after deposition of the original sediment. The third type of dolomite, baroque, is a coarsely crystalline dolomite with “saddle-shaped” crystals displaying undulose extinction in thin section. It is rare in the reservoir and appears to be limited to wells that contain abnormally thick sections of dolomite; in extreme cases, baroque dolomite is vertically pervasive. Geochemically, baroque dolomite is distinctive with high iron and very low oxygen isotopic compositions, and is interpreted to have formed from high temperature fluids during burial diagenesis. These fluids are suggested to have ascended up into the reservoir from depth along a fault/facture system, relatively late in the diagenetic history of the rock.
Preferential deposition and preservation of structurally-controlled synrift reservoirs: Northeast Red Sea and Gulf of Suez
Authors: Stephen R.Polis , Michael T.Angelich , Charles R.Beeman , William B.Maze , David J.Reynolds , David M.Steinhauff , Andrei Tudoran , Mark V.Wood
Published: October 2021

An integrated GIS-based play evaluation, which incorporates restorations of the North Red Sea and Gulf of Suez, has helped to identify potentially prospective areas in the Northeast Red Sea associated with point-sourced synrift sandstone reservoirs. The three largest synrift Gulf of Suez fields (Belayim Land, Belayim Marine, and Morgan) are located along major fault-transfer zones that optimized the conditions for the deposition and preservation of thick point-sourced sands adjacent to extensive hydrocarbon source kitchens. Belayim Land and Morgan fields contain stacked submarine fan, delta, and alluvial fan systems that developed during the deposition of the Miocene Rudeis, Kareem, and Belayim-South Gharib formations, respectively. This continuous, point-sourced sedimentation is indicative of stable drainage and by inference, a stable eastern border fault system. We attribute this stable border fault system to a stress heterogeneity related to the pre-existing Najd Shear Zone, and polarity reversals in upper-plate transport direction.

Tectonic restorations indicate that the North Red Sea, like the Gulf of Suez, should have reservoir facies deposited in similar structural positions, but preservation is a significant risk due to additional crustal extension. Although crestal block erosion remains a great concern for reservoir preservation, seismic mapping indicates that block size along the coastal region and inboard areas are similar to the Gulf of Suez. This suggests that most of the strain may have been accommodated along the warmer axial portion of the rift where weaker crustal rheology exists.

Landsat mapping of the Northeast Red Sea border fault system has found a high degree of variability in structural styles. The southern Yanbu-Jeddah and Umm Luj-Al Wajh sub-basins are bound by listric, down-to the west-southwest border faults, separated by suture-controlled accommodation zones. To the north, the Midyan-Ifal sub-basin is located along the Miocene flexural margin, and is structurally more complex. Northwesterly-trending (Najd Shear Zone) planar faults are overprinted by a strong northeasterly (Aqaba) trend, such that transpressional and transtensional features exist. Although structurally complex, the offshore northern flexural margin has been determined to have the best potential for localized, second-generation, thick, synrift sediments similar to that of the Gulf of Suez.
Lithostratigraphy of the Red Sea Region
Authors: Hughes Geraint Wyn ap Gwilym , Johnson Robert S.
Published: October 2021

The onshore and offshore Saudi Arabian Red Sea region contains a series of lithostratigraphic units that have not previously been formally defined and described. Based on an intensive study of the succession, a lithostratigraphic scheme is proposed in a lexicon format that integrates biostratigraphic, sedimentological, seismic and field studies from the Midyan Peninsula in the north, to the Jizan Coastal Plain in the south. In view of the economic aspect of the Neogene succession and greater accessibility to Neogene subsurface samples, emphasis has been placed on a revision of the Neogene lithostratigraphy. Resting upon Proterozoic Basement, the sedimentary succession was deposited during the Cretaceous to Pleistocene times. The oldest pre-rift Suqah Group nonconformably overlies the Proterozoic Basement and consists of Upper Cretaceous shales of the Adaffa Formation and Cretaceous to Palaeogene sandstones, shales and thin limestones of the Usfan Formation. A series of volcanics includes the early to middle Oligocene Matiyah Formation and the late Oligocene-early Miocene Jizan Group.

The Neogene succession displays a great lithological diversity. The Tayran Group (Al Wajh, Musayr and Yanbu Formations) includes marginal marine siliciclastics of the Al Wajh Formation, and represents the earliest rift-associated sediments deposited during the earliest Miocene. These are conformably overlain by lower Miocene shallow-marine carbonates of the Musayr Formation. In some of the central Red Sea onshore basins, thick lower Miocene submarine evaporites of the Yanbu Formation were deposited under locally restricted conditions and form the third formation of the Tayran Group. Rapid subsidence during the early Miocene caused deposition of deep-marine, planktonic-foraminiferal mudstones and thick submarine fan sandstones of the Burqan Formation. Carbonates, marine mudstones and submarine evaporites of the Maqna Group (Jabal Kibrit and Kial Formations) unconformably overlie the Burqan Formation and were deposited during latest early Miocene to earliest middle Miocene. The Jabal Kibrit Formation consists of an anhydrite-carbonate facies, of which the carbonates form the Wadi Waqb Member. Siliciclastic facies of the Jabal Kibrit Formation are termed the Umm Luj Member. Above the Jabal Kibrit Formation, the Kial Formation is typified by interbedded anhydrites, calcareous siltstones and carbonates, and includes the Sidr, Nakhlah, Yuba, Rayaman and Sabya Members. Within the region, thick evaporites of the Mansiyah Formation were deposited extensively during the middle Miocene, and are overlain by poorly exposed sands, shales and thin anhydrite beds of the middle to upper Miocene Ghawwas Formation. The Lisan Group unconformably overlies the Ghawwas Formation and consists of coarse alluvial sands and gravels of possible Pliocene to Holocene age.
Iran’s crude oil reserves and production
Authors: Al-Husseini Moujahed I.
Published: October 2021

The Government of Iran estimates the country’s initial-oil-in-place and condensate-in-place are about 600 and 32 billion barrels (Gb), respectively. In 2004, the official estimate of the proved remaining recoverable oil and condensate reserves was about 132.5 Gb, of which crude oil accounted for about 108 Gb. Cumulative crude oil production is expected to cross the 60 Gb mark in 2007, implying that the estimated ultimate recoverable reserves of crude oil are about 168 Gb (cumulative production plus remaining reserves) and the total recovery factor is about 28%. The main Oligocene-Miocene Asmari and Cretaceous Bangestan (Ilam and Sarvak) reservoirs contain about 43% and 25%, respectively, of the total crude oil-in-place. Recovery factors for the Asmari range between about 10–60%, and for the Bangestan between 20–30%. Between 1974 and 2004 remaining recoverable reserves have increased from about 66 to 108 Gb, while the ultimate recoverable reserves have increased from 86 to 168 Gb.

In contrast to 1974 when Iran’s production peaked at 6.0 Mb/d, production in 2005 averaged about 4.1 Mb/d. The 1974 peak occurred when production from most of the giant fields was ramped-up to very high but unsustainable levels. Current plans are to increase the crude oil production rate to 4.6 Mb/d by 2009. This is a significant challenge because this production capacity has to offset a reported total annual decline rate of 300–500,000 barrels/day (Kb/d). This high decline rate is attributed to the maturity of the giant fields, many of which attained their peaks in the 1970s and have produced about half or more of their estimated ultimate recoverable reserves. Therefore to achieve the 2009 production target within the next three years, Iran has to add about 680 Kb/d of capacity per year from its developed fields (infill drilling, recompletions, enhanced and improved oil recovery), while also adding net new surface facilities and well capacity from undeveloped fields and reservoirs.
Microfacies and sedimentary environments of the late Oligocene-early Miocene Qom Formation of the Gooreh Berenji region (Jandaq area, central Iran)
Authors: Alireza Shakeri , Jalal Douraghinejad , Mehran Moradpour
Published: October 2021

The late Oligocene-early Miocene Qom Formation in the Central Iran Basin contains oil and gas in the Alborz and Sarajeh fields. Organic geochemical analyses in previous studies indicated that the hydrocarbons migrated from deeper source rocks, likely of Jurassic age. In the Central Iran Basin, the Qom Formation is 1,200 m thick and is bounded by the Oligocene Lower Red Formation and the middle Miocene Upper Red Formation. In previous studies, the Qom Formation was divided into nine members designated from oldest to youngest: a, b, c to c4, d, e and f, of which “e” is 300 m thick and constitutes the main reservoir. Our study focused on a Qom section located in the Gooreh Berenji region of central Iran which is 294 m thick. The lower part of the formation was not deposited, and only the following four members of early Miocene age (Aquitanian and Burdigalian) were identified between the Lower and Upper Red formations: “c2”? (mainly greyish to greenish gypsiferous marls); “d” (thin- to thick-bedded anhydrite with intercalation of thin-bedded sandstone); “e” (argillaceous or sandy limestone); and “f” (fine-grained coral and bryozoan boundstone). In contrast to the Central Iran Basin, the “e” member in Gooreh Berenji is only 15 m thick and does not have a good reservoir potential.

A detailed petrographic analysis of the Gooreh Berenji section resulted in the identification of 13 microfacies (MF) that were interpreted in terms of their depositional environments according to the following categories: MF1 (sabkha), MF2 (intertidal river channel), MF3 (lower intertidal), MF4 (peritidal), MF5 (supratidal), MF6 and MF7 (shallow restricted lagoon), MF8 and MF10 (proximal open-marine), MF9 (leeward lagoon), MF11 (shoal), MF12 (reef and patch reef formed within lagoon), and MF13 (open-marine). The Qom Formation constitutes a regional transgressive-regressive sequence that is bounded by two continental units (Lower and Upper Red formations). The transgression started from the south in the late Oligocene and by the early Miocene the sea covered all of central Iran. In the Gooreh Berenji area, carbonate deposition occurred on a shallow-marine ramp. The presence of a wide range of lagoonal facies indicates that reefal facies (“f”) developed in a narrow elongated strip away from the shoreline.
Colour change in the acritarch Veryhachium as an indicator of thermal maturity
Authors: Duggan Catherine M. B. , Clayton Geoff
Published: October 2021

Veryhachium is an acritarch genus that occurs commonly in marine shales from the Ordovician to the Tertiary, with morphologically closely related forms appearing in the Cambrian. Its simple morphology together with its long stratigraphic range and abundance makes it attractive as a potential thermal maturity indicator. The colour of Veryhachium is characterised in terms of red, green and blue intensity of transmitted white light. With increasing thermal maturity, Veryhachium changes from almost colourless to black, with the most rapid change taking place in rocks that are marginally postmature with respect to the oil window. The cutoff point for Veryhachium fluorescence lies between 1.5% and 2.0% in terms of vitrinite reflectance (Rr), providing another useful tie-point in terms of thermal maturity. This technique is simple, inexpensive and has potential for establishing the thermal maturity of both marine Lower Palaeozoic rocks and younger marine sections deficient in vitrinite.
Possible seismic hydrocarbon indicators in offshore Cyprus and Lebanon
Authors: Semb Per Helge
Published: October 2021

A multi-client 2-D seismic survey, consisting of 6,770 line-kilometer of 2-D data, was acquired by Norway’s PGS Geophysical offshore Cyprus in 2006. It was followed in 2006 and 2007 by the acquisition of two 3-D surveys, located offshore Lebanon (1,500 square kilometers), and offshore Lebanon and Cyprus (1,300 square kilometers). Further, in 2008 an additional 2-D survey was acquired offshore Cyprus to fill in the existing 2006 seismic 2-D grid. The 2008 2-D survey consist of 6,500 line-kilometer and was acquired with the PGS dual sensor GeoStreamer® technology (The 2008 2D data is still being processed so no GeoStreamer® examples are shown in this article). Since 2007, some of the deep-water areas (1,500–2,000 meters deep) offshore Cyprus have been offered for exploration and producing bid licenses by the government, while the Lebanese government is in the stage of preparing its offshore region for exploration and licensing.

In this paper, several representative seismic lines are shown to illustrate the quality of the seismic data over this large region. The data shows that a Pliocene to Recent succession overlies a thick Upper Miocene evaporite section, known as the Messinian Salt. The blanketing salt-dominated interval is up to one kilometer thick and provides a regional seal over the area; although some faults are known to penetrate the salt and may allow seepage to occur. The pre-Messinian Salt section is highly structured, with both horsts-and-grabens as well as large folds. In particular, several examples of seismic reflections are presented, which are interpreted as possible Direct Hydrocarbon Indicators (DHI). Some four-way structural closures are highly prospective as they are characterized by multiple DHIs; for example, a bright spot at the base of the Messinian Salt overlying a flat spot. Other examples consist of phase changes, dim spots, velocity pull-downs, low-frequency shadow zones and gas chimneys. Also shown are how some of these interpreted DHIs can be characterized in the 3-D surveys. The 3-D example illustrate a correlation between pre-Messinian four-way structural closure and the root-mean square amplitude of the base Messinian Salt reflection.
MIDDLE EAST GEOLOGIC TIME SCALE 2010: Early Cambrian Asfar Sequence
Authors: Al-Husseini Moujahed I.
Published: October 2021

This paper is the first in a series dedicated to the Phanerozoic Cambrian Period, and Neoproterozoic Ediacaran and Cryogenian periods, as represented in the Middle East Geologic Time Scale (ME GTS, see enclosed Chart). It introduces the term Asfar Sequence to represent a regional Early Cambrian time-rock unit, consisting mainly of continental quartz-rich arkosic sandstone, shale and siltstone, which attain a thickness of at least 750 m in Jordan and more than 700 m in Oman. The term “Asfar”, meaning yellow in Arabic, was chosen because it is the standard color for sandstone in ME GTS. To describe its stratigraphy, four representative formations are reviewed in lexicon format: Salib Arkosic Sandstone of Jordan, Siq Sandstone of Saudi Arabia, Amin Formation of Oman and Lalun Sandstone of Iran. The stratigraphic geometry of the lower boundary of the Sequence varies considerably by locality. In some regions in Iran it is conformable above the shales of the Zaigun Formation. In other regions, such as western Jordan, it is an onlap surface over Proterozoic and/or Lower and Middle Cambrian paleohighs, or a pronounced angular unconformity (e.g. central and southern Saudi Arabia). The paleo-relief represented by the unconformity surface, in many regions, forms a regional peneplain (e.g. central and eastern Jordan) implying erosion; in other paleohigh regions, the Sequence is absent by non-deposition. The age of the base Asfar Sequence is estimated at ca. 530 Ma, based on radiometric data and depositional rates in basinal areas. The top boundary of the Sequence, in Iran, Jordan, and northern and northeastern Saudi Arabia, is represented by a sequence boundary (or its correlative unconformity), above which marine, fine-grained siliciclastics and carbonates of late Early to early Mid-Cambrian age were deposited: Mila Formation in Iran, and Burj Formation in Jordan and Saudi Arabia, implying an age older than ca. 510 Ma in GTS 2004. In Oman, however, continental rather than marine deposition (Miqrat and coeval Mahwis formations) continued above the unconformity in ?Middle Cambrian. For the purpose of regional correlations it is proposed that the Angudan Unconformity of Oman be taken as the name for the basal boundary of the Sequence and the Burj Sequence Boundary for its top.
Sequence stratigraphy of the Late Campanian – Early Maastrichtian Shiranish Formation, Jabal Sinjar, northwestern Iraq
Authors: Al-Banna Nabil Yousif
Published: October 2021

The Late Campanian – Maastrichtian Shiranish Formation consists of deep-marine marls and limestones that were deposited in northern and central Iraq. In northwestern Iraq, in the core of EW-trending Jabal Sinjar, a 430-m-thick section of the Shiranish Formation crops out. The base of the Shiranish section is not exposed here. It is unconformably overlain by Paleocene – Lower Eocene formations: Sinjar Formation along the northern part of the Jabal, and Aaliji Formation along its eastern side. Eighty samples were collected from the section and used for facies analysis and biostratigraphic calibration. Previous studies of planktonic foraminifera recognized four biozones, which were confirmed in the present study: Globotruncanita calcarata Interval Zone, Globotruncanella havanensis-Rosita fornicata Partial Range Zone, Globotruncana aegyptiaca Interval Zone and Gansserina gansseri Interval Zone. These zones are here calibrated in several geological time scales. Six facies were distinguishable throughout the section, representing shallow-marine, middle-shelf, outer-shelf and upper-bathyal environments. These environments were used to interpret six depositional sequences. The older five Shiranish sequences are fourth order and grouped into one third-order sequence, while the sixth and youngest Shiranish Sequence was of third order. This suggests that the studied section was deposited in about 5 million years between ca. 76.0–74.4 and 69.5–69.8 Ma. The correlation between the Shiranish sequences and those of the Aruma Formation in Saudi Arabia implies that the northern Arabian Platform was regionally flooded starting in the Late Campanian and ending in the Maastrichtian. In the study area, an unconformity straddles the Cretaceous – Tertiary (K/T) boundary and represent a hiatus of ca. 10 or more million years.
Facies and stratigraphic framework of a Khuff outcrop equivalent: Saiq and Mahil formations, Al Jabal al-Akhdar, Sultanate of Oman
Authors: Koehrer Bastian , Zeller Michael , Aigner Thomas , Poeppelreiter Michael , Milroy Paul , Forke Holger , Al-Kindi Suleiman
Published: October 2021

The Middle Permian to Lower Triassic Khuff Formation is one of the most important reservoir intervals in the Middle East. This study presents a sequence stratigraphic analysis of the Khuff Formation of a well-exposed outcrop in the Oman Mountains, which may provide a reference section for correlations across the entire Middle East. On the Saiq Plateau of the Al Jabal al-Akhdar, the Permian Upper Saiq Formation is time-equivalent to the Lower and Middle Khuff Formation (K5–K3 reservoir units in Oman). The Permian section is dominated by graded skeletal and peloidal packstones and cross-bedded grainstones with a diverse marine fauna. The Lower Mahil Member (Induan Stage), time-equivalent to the Upper Khuff Formation (K2–K1 reservoir units in Oman), is dominated by grainstones composed of microbially-coated intra-clasts and ooids. In general, the studied outcrop is characterized by a very high percentage of grain-dominated textures representing storm-dominated shoal to foreshoal deposits of a paleogeographically more distal portion of the Khuff carbonate ramp.

A sequence-stratigraphic analysis was carried out by integrating lithostratigraphic marker beds, facies cycles, bio- and chemostratigraphy. The investigated outcrop section was subdivided into six third-order sequences, named KS 6 to KS 1. KS 6–KS 5 are interpreted to correspond to the Murgabian to Midian (ca. Wordian to Capitanian) stages. KS 4-Lower KS 2 correspond to the Dzhulfian (Wuchiapingian) to Dorashamian (Changhsingian) stages. Upper KS 2–KS 1 represent the Triassic Induan stage. Each of the six sequences was further subdivided into fourth-order cycle sets and fifth-order cycles. The documentation of this outcrop may contribute to a better regional understanding of the Khuff Formation on the Arabian Platform.
Structures of the Kirkuk Embayment, northern Iraq: Foreland structures or Zagros Fold Belt structures?
Authors: Kent W. Norman
Published: October 2021

Several anticlines in northern Iraq and Syria have been studied through the construction of balanced and restored cross sections. Based upon structural analysis, each of the studied anticlines is a fault-propagation fold that developed due to Zagros-related, recent inversion of much older normal faults. Studies on the Iranian part of the Zagros Fold Belt have suggested that the regional variation in the character of the fold belt is related to weak detachment surfaces in the stratigraphic section, primarily the decollement developed near the top of the Hormuz Salt where the salt is present. No evidence for Hormuz Salt has been found within the Kirkuk Embayment, and although detachment surfaces contribute the area’s structural character, the prominent folds seem to originate mainly from basement involved faults.

Two distinct inversion structural trends exist: E-W system and a NW system of inverted grabens. In Syria, several of the faults associated with the EW-trending system cut the basement on seismic data and have stratigraphic relationships indicating that their displacement originated in the Neoproterozoic. In Iraq, the thicker sedimentary section did not allow the deep parts of the fault systems to be imaged on the available seismic. While the NW fault system of inverted normal faults could be linked to the Zagros Orogen by a decollement surface in the sedimentary section, regional relationships and potential-field data suggest that this trend also is basement involved and has a Neoproterozoic origin.
Marine flooding events of the Early and Middle Ordovician of Oman and the United Arab Emirates and their graptolite, acritarch and chitinozoan associations
Authors: Rickards Barrie R. , Booth Graham A. , Paris Florentin , Heward Alan P.
Published: October 2021

Graptolites and their associated acritarch floras and chitinozoan faunas are described from three localities in Oman and the United Arab Emirates (UAE). They are characteristic of intervals of deeper water sediments in the Floian – Dapingian (Arenig, identified here as maximum flooding surface MFS O25) and mid Darriwilian (Llanvirn, MFS O30). These marine flooding events have distinctive and unique palynological signatures. Most of the recorded Darriwilian fauna and flora have northern Gondwana affinities. Oman and the UAE seem to have occupied relatively elevated positions during the Ordovician and only to have been inundated at times of highest sea level. Exotic rafts of Ordovician Rann and Ayim formations that crop out in the Kub Melange of the Dibba Zone range in age from Floian – Dapingian, through Darriwilian, to Katian (Arenig – Llanvirn-Caradoc) and may provide a glimpse of a relatively condensed Ordovician stratigraphy that occurs at depth beneath Musandam Peninsula and the Arabian Gulf.
2-D Basin modeling study of petroleum systems in the Levantine Basin, Eastern Mediterranean
Authors: Marlow Lisa , Kornpihl Kristijan , Kendall Christopher G. St. C.
Published: October 2021

The Levantine Basin has proven hydrocarbons, yet it is still a frontier basin. There have been significant oil and gas discoveries offshore the Nile Delta, e.g. several Pliocene gas plays and the Mango Well with ca. 10,000 bbls/day in Lower Cretaceous rocks and recently, Noble Energy discovered two gas “giants” (> 5 TCF and one estimated at 16 TFC) one of which is in a pre-Messinian strata in ca. 1,700 m (5,577 ft) water depth. Regional two-dimensional (2-D) petroleum system modeling suggests that source rocks generated hydrocarbons throughout the basin. This paper provides insight into the petroleum systems of the Levantine Basin using well and 2-D seismic data interpretations and PetroMod2D. Tectonics followed the general progression of the opening and closing of the Neo-Tethys Ocean: rift-extension, passive margin, and compression. The stratal package is up to 15 km thick and consists of mixed siliciclastic-carbonate-evaporite facies. Five potential source rock intervals (Triassic – Paleocene) are suggested. Kerogen in the older source rocks is fully transformed, whereas the younger source rocks are less mature. There are several potential reservoir and seal rocks. The model suggests that oil and gas accumulations exist in both structural and stratigraphic traps throughout the basin.
Regional seismic interpretation of the hydrocarbon prospectivity of offshore Syria
Authors: Bowman Steven A.
Published: October 2021

Analysis of 5,000 km of multi-client long-offset 2-D seismic data has led to the identification of three sedimentary basins, Levantine, Cyprus, and Latakia, located in offshore Syria. Each basin has a unique structural and stratigraphic history. They are separated from each other by the middle to Late Cretaceous aged Latakia Ridge System that initiated as a compressional fold-thrust belt and was re-activated under a sinistral strike-slip regime that developed during the Early Pliocene in response to a re-organisation of the plate-tectonic stresses. There is significant evidence for a working petroleum system in offshore Syria with numerous onshore oil and gas shows, DHIs (direct hydrocarbon indicators) observed on seismic, and oil seeps identified from satellite imagery. Prospective reservoirs range in age from Triassic to Pliocene – Quaternary and include Lower Miocene deep-water turbidite sands as encountered in recent discoveries in the offshore southern Levantine Basin. The complex structural evolution of each of the three sedimentary basins has produced an array of potential structural and stratigraphic trapping mechanisms.
Tectonostratigraphic overview of the Zagros Suture Zone, Kurdistan Region, Northeast Iraq
Authors: Al-Qayim Basim , Omer Azad , Koyi Hemin
Published: October 2021

The northwestern segment of the Zagros Orogenic Belt of the Kurdistan Region of Iraq includes the Zagros Suture Zone which is consisting of allochthonous Tethyan Triassic–Eocene thrust sheets. The zone is bounded by the Zagros Main Reverse Fault in the northeast, and the Zagros Thrust Front in the southwest. Parts of this zone’s rocks are represented by stacks of thrust megasheets obducted over the autochthonous Cretaceous–Cenozoic sequence of the Arabian Plate margin. Each sheet represents a specific Tethyan tectonostratigraphic facies, and includes (from older to younger): isolated Triassic carbonate platforms (Avroman Limestone), Jurassic carbonate imbricates (Chia Gara, Sargelu and other formations), radiolarites (Qulqula Group), sedimentary mélange (sedimentary-volcanic units of the Qulqula Group), ophiolites (Mawat and Penjwin ultramafics complexes), and Cenozoic fore-arc volcano-sedimentary sequences (Walash Group). Petrography, facies interpretation and lithostratigraphic correlation of these allochthons along four traverses across the Zagros Suture Zone of the examined area indicate that they evolved during the closure of the Neo-Tethys Ocean. Their stacking pattern and tectonic association resulted from two important events: the Late Cretaceous obduction processes, and the Late Miocene–Pliocene collision, uplift, folding and suturing between the Arabian Plate and the Sanandaj-Sirjan Block of Iran. Based on these field observations and by using the model of the Iranian Zagros evolution, a tectonic scenario is proposed to explain the history and evolution of the Zagros Suture Zone in this area.
Late Permian to Late Jurassic “microproblematica” of Saudi Arabia: Possible palaeobiological assignments and roles in the palaeoenviromental reconstructions
Authors: Hughes Geraint Wyn
Published: October 2021

Palaeoenvironmental interpretation of Permian and Jurassic intertidal to very shallow-marine carbonates is difficult where typical shallow-marine microfossils are either absent or sparse. A collection of microfossils originally considered as “microproblematica” because of their uncertain biological affinities are, however, often present. These include species of Aeolisaccus, Gakhumella, Prethocoprolithus, Thaumatoporella, Favreina and Terebella. Observations of their vertical distribution and relationship with carbonate fabrics reveal their environmental preferences, and these contribute to palaeoenvironmental interpretation within a spectrum of very shallow-marine settings that previously precluded refinement. The recognition of high-frequency depositional cycles and definition of cryptic reservoir layering in such shallow to marginal-marine carbonates is now facilitated by the use of these microfossils from the Khuff, Hanifa, Jubaila, Arab and Hith formations.

Aeolisaccus dunningtoni is interpreted as either a fossilised cyanobacterial tube or possible foraminifera of Early Permian to Late Jurassic age. It is well represented within mudstones, wackestones and packstones of supratidal flats to very shallow intertidal palaeoenvironments with occasional freshwater influence. The microbialitic Gakhumella cf. huberi is locally present in these Upper Jurassic intertidal to very shallow-marine bioconstructions. Prethocoprolithus centripetalus is a faecal ribbon, considered to be of mollusk origin, within shallow subtidal grainstones and packstones. Thaumatoporella parvovesiculifera is considered a green alga that is typically found encrusting biocomponent fragments. It ranges from the Middle Triassic to Upper Cretaceous and is extensively present in intertidal, possibly hypersaline to shallow-marine, normal salinity lagoon grainstones and mud-lean packstones. Certain types of the distinctively canaliculate, microcoprolitic decapod crustacean faecal pellets, of the genus Favreina, are diagnostic of Late Jurassic intertidal to shallow subtidal conditions found within packstones. Terebella lapilloides is an agglutinated polychaete tube, typical of Upper Jurassic intertidal to shallow-marine packstones.
Mid-Permian Khuff Sequence KS6: Paleorelief-influenced facies and sequence patterns in the Lower Khuff time-equivalent strata, Oman Mountains, Sultanate of Oman
Authors: Bendias Daniel , Koehrer Bastian , Obermaier Michael , Aigner Thomas
Published: October 2021

Khuff Sequence KS6 was studied in the Al Jabal al-Akhdar, Oman Mountains, in an area of 30 x 50 square kilometers by means of detailed sedimentological logging of five time-equivalent outcrop sections of the Saiq Formation. KS6 represents one transgressive-regressive, third-order sequence, and is composed of four facies associations each representing particular environments of deposition (backshoal, shoal, foreshoal and offshoal) with distinct sedimentological characteristics. Facies stack to form cycles and cycle sets that were used for correlation at a subregional scale and to reveal the KS6 stratigraphic architecture. During the initial phase of basin-fill, clastic sediments (“Basal Saiq Clastics”) were deposited in paleolows above the “Sub-Saiq Unconformity”. In contrast to younger Upper Khuff sequences KS4 to KS1, the underlying paleorelief strongly affects the thickness and facies composition of KS6. The correlation strategy to follow paleolandscape surfaces using all available sedimentological, biostratigraphic and lithostratigraphic data resulted in a stratigraphic architecture with subtle shingle geometries.

Sequence KS6 shows a strong facies partitioning resulting in the necessity of two separate facies models for the transgressive (crinoidal ramp) versus regressive hemisequence (oolitic/peloidal carbonate ramp). This study revealed potential reservoir units in KS6, commonly regarded as non-reservoir in the subsurface of Oman and other parts of the Gulf region. The abundance, nature and lateral extent of reservoir facies strongly varies with stratigraphic position. In the transgressive part of KS6, crinoidal grainstones are concentrated around the margin of a gentle paleohigh. They might have the best reservoir potential, although early diagenetic cementation is common in most settings. Oolitic/peloidal grainstones in the upper regressive part have a much higher diagenetic reservoir potential and are laterally much more widespread. Thus, Khuff Sequence KS6 differs profoundly in its stratigraphic architecture from the more “layer-cake”-like KS4 to KS1 sequences. Facies and thickness patterns are controlled by a marked paleohigh to paleolow configuration, resulting from the antecedent uneven topography during the Neo-Tethyan syn-rift setting, in contrast to the post-rift setting with low tectonic activity during KS4 to KS1.
Stratigraphic control of the Aptian–Early Turonian sequences of the Levant Platform, Coastal Range, northwest Syria
Authors: Ghanem Hussam , Kuss Jochen
Published: October 2021

The predominantly carbonate Aptian–Lower Turonian succession of the Coastal Range in northwest Syria represents the northern edge of the Levant Platform. It was divided into 28 lithostratigraphic units, mainly reflecting shallowing-up and deepening-up intervals. We combined lithostratigraphy, biostratigraphy and carbon-isotope measurements, with facies interpretations, to establish a sequence-stratigraphic framework, adapted from outcrop data along two transects. The sequence-stratigraphic evolution records major transgressions-regressions and hiatuses that are compared with regional sequences of the Arabian and Levant platforms and the Tethyan realm. Age control, based on planktonic and benthonic foraminifera and ammonite biostratigraphies, is relatively good, despite changing diversities and occurrences. The chronostratigraphic framework is based on seven benthonic foraminiferal biozones (Aptian to Early Turonian) and six planktonic foraminiferal biozones (with two subzones) (latest Albian to Cenomanian). The studied carbon-isotope fluctuations record significant perturbations that are comparable with several global changes of the carbon cycle: OAE1d, LCE I-III, MCE and OAE2. The combined chemostratigraphic and biostratigraphic approach permits correlating the carbon-isotope curve of the Coastal Range with those from the Tethyan realm, England and South Palmyrides.
Depositional environment of Late Cretaceous to Eocene organic-rich marls from Jordan
Authors: Ali Hussein Mohammad , Alqudah Mohammad , Blessenohl Myrna , Podlaha Olaf G. , Mutterlose Jörg
Published: October 2021

Oil-shale beds formed under anoxic conditions that were controlled by various local, regional and global factors. The Jordanian oil shales, which were deposited during the Late Cretaceous to Eocene, are considered as an example for the interplay of these factors. Two cores of organic-rich marls were investigated and analyzed with respect to their lithology, ichnofabrics and carbonate microfacies. The first core (OS-01, 183.3 m; South Jordan) is of Late Cretaceous age, the second one (OS-23, 256.3 m; Central Jordan) is of Eocene age. Our studies revealed that the Upper Cretaceous oil shales were deposited in a shallow-water carbonate shelf. Oyster bioherms acted as physical barriers that reduced the water circulation with the open shelf, thereby causing anoxic conditions. The Eocene oil shales also accumulated on a shallow-water carbonate shelf. In this case, however, synsedimentary tectonics caused subsiding grabens and half grabens, which in turn gave way to anoxic conditions. Both deposition and richness of the Jordanian oil shales were affected by regional sea-level fluctuations and global climatic changes.
Cretaceous ammonites from the Sultanate of Oman (Adam Foothills)
Authors: Meister Christian , Piuz André
Published: October 2021

Twenty taxa are described from the Cretaceous of Oman (Adam Foothills). The genera Puzosia, Placenticeras, Cunningtoniceras, Nigericeras, Metoicoceras, Rubroceras and Hoplitoides and the subgenus C. (Gentoniceras) are recorded for the first time from the Arabian Peninsula. Based on the ammonite ranges, a sequence of nine bioevents of the Albian–Turonian is correlated within the zonation, and some markers allow correlations at a larger scale, at least along the southern Neo-Tethys margin. The ammonite data give new constraints for the correlations of the lithological units along the Adam Foothills West-East transect and they question the definition of the lithostratigraphic units within the Natih Formation, especially the Natih A and B members. From a paleogeographic point of view Oman is a landmark for the distribution of the ammonites between the western Neo-Tethys (Europe, North Africa, Middle East) and the eastern Neo-Tethys (Africa, Madagascar and India).
A semi-balanced section in the northwestern Zagros region: Constraining the structural architecture of the Mountain Front Flexure in the Kirkuk Embayment, Iraq
Authors: Hinsch Ralph , Bretis Bernhard
Published: October 2021

The Mountain Front Flexure or Fault (MFF) of the Zagros Mountains separates the foreland or foothills area from the morphological apparent mountain belt. Across this feature the regional elevations of Mesozoic to Neogene stratigraphic horizons substantially rise towards the mountain belt. Thin-skinned and thick-skinned structural styles have been proposed for this rise in other parts of the Zagros region. In our study area, in the Kurdistan Region of Iraq (KRI), we integrated surface and subsurface data and constructed a (semi-) balanced cross-section across the MFF. The section features duplex structures in the deeper subsurface, related to a deeper Palaeozoic and a shallower Triassic decollement horizon. On a smaller scale, layer-parallel shortening and intense deformation is observed in the incompetent lithologies, leading to an incipient disharmonic folding. Restoration of the section reveals a distinct imbalance between shortening in the upper part of the stratigraphic section (approximately 4 km or 16% on top Jurassic level) to the lower part (approximately 20 km or 49% on top Permian level). The imbalance can only be equalised on a regional section if the shortening is transferred from the lower to the higher decollement levels, which is connected to folds and thrusts in the foothills area. Based on observations from the mechanical stratigraphy, geometric relationships in map and cross-section, as well as morphological considerations, we argue that the origin of the MFF in the area of the considered section is related to active roof duplexes rather than basement-involved thrusting.
Facies analysis and sequence stratigraphy of the uppermost Jurassic– Lower Cretaceous Sulaiy Formation in outcrops of central Saudi Arabia
Authors: Wolpert Philipp , Bartenbach Martin , Suess Peter , Rausch Randolf , Aigner Thomas , Le Nindre Yves-Michel
Published: October 2021

Uppermost Jurassic–Lower Cretaceous carbonates of the Sulaiy Formation are well exposed at the type locality Dahal Hit, and along the entire natural escarpment near Ar Riyad, the capital of the Kingdom of Saudi Arabia. This study provides a facies and sequence-stratigraphic analysis based on detailed sedimentological and gamma-ray logging of 12 outcrop sections. The sections represent the Sulaiy Formation along a 60 km-long outcrop belt, including the Hith-Sulaiy transition in a large solution cavity named Dahal Hit, situated south of Ar Riyad. The latter section is studied in detail because it is the only locality in Saudi Arabia where the Hith Anhyrite (Hith Formation in this study) to the Sulaiy Formation transition crops out.

Ten lithofacies types were identified for the Sulaiy Formation including potential reservoirs such as oolitic cross-bedded grainstones, biostromal boundstones, and bioclast-rich, graded pack-to-grainstones. Lithofacies types are grouped into five facies associations: (1) offshoal, (2) transition zone, foreshoal, (4) shoal margin, and (5) shoal, distributed along a carbonate ramp. Their vertical stacking pattern revealed a systematic hierarchy of cyclicity consisting of small-scale cycles, medium-scale cycle sets and two large-scale sequences for the Sulaiy Formation. Four cycle motifs, with an average thickness of 2–4 m, are present: (1) offshoal to transition zone cycle motif, (2) offshoal to foreshoal cycle motif, (3) transition zone to shoal margin cycle motif, and foreshoal to shoal margin cycle motif.

A total of 15 cycle sets, ranging between 8 and 12 m in thickness each, were interpreted. They were correlated, where possible, across the study area. Three types of medium-scale cycle sets are observed: (1) offshoal to shoal cycle set motif, (2) offshoal to foreshoal cycle set motif, and (3) shoal margin to offshoal cycle set motif. The Lower Sulaiy Sequence consists of twelve cycle sets and is interpreted to contain two Arabian Plate maximum flooding surfaces (MFS): (1) Upper Tithonian MFS J110 (147 Ma) in its lowermost part, which is interpreted to be the time-equivalent of the Manifa reservoir in subsurface Arabia. (2) Lower Berriasian MFS K10 (144 Ma) in the seventh-up cycle set. The Upper Sulaiy Sequence is only represented in the Wadi Nisah Section and is believed to be incomplete because the Sulaiy/Yamama Formation boundary was not included in our study. It is presumed to contain Upper Berriasian MFS K20 (141 Ma).