Lithostratigraphy, facies, mineralogy and diagenesis of the retrograding, syntectonic Neogene Barzaman Formation (Al-Khod, Sultanate of Oman)

2020 ◽  
Author(s):  
Frank Mattern ◽  
Shaima Al-Amri ◽  
Andreas Scharf
Keyword(s):  
Depositional Environment ◽  
High Energy ◽  
Silica Content ◽  
Slope Instability ◽  
Coarse Grained ◽  
Tectonic Activity ◽  
Shallow Marine ◽  
Ephemeral Ponds ◽  
Terrestrial Environments ◽  
Calcite Cement

<p>The Barzaman Formation is 150-200 m thick and subdivided into five lithostratigraphic/facies intervals recording syndepositional thrusting and changes from shallow marine to terrestrial environments and from arid/semiarid to more humid conditions.</p><p>(1) The basal lower conglomerate and sandstone unit is >36 m thick, marked by beige and gray/greenish colors, thick-bedded pebbly, calciclastic litharenites which may display parallel lamination and thick-bedded matrix-supported pebble to cobble conglomerates with subrounded clasts of chert, basalt, gabbro, quartzite and carbonates. Pores may be lined by isopachous, microcrystalline calcite cement. The depositional environment is shallow marine with one coarse-grained fill of a high-energy tidal inlet.</p><p>(2) The light-colored carbonate facies unit is 1-15 m thick, consisting of thick-bedded coral limestone, a very thick limestone coral and algae debrite and some minor beds of conglomerate and sandstone. The corals may be partly silicified by brown-stained silica. This unit was deposited in a warm, shallow marine, nearshore environment with clear water which may indicate an arid climate.</p><p>(3) The varicolored thick sandstone and conglomerate facies unit is 14-28.5 m thick. These clastic deposits are similar to those of unit 1, but more colorful, slightly coarser grained (presence of boulders) and include also thin and medium beds. The sandstones may exhibit cross-bedding. The depositional environment is shallow marine as indicated by coral debris.</p><p>(4) The claystone and conglomerate facies unit is 19 m thick. The clastic sediments are similar to those of unit 1, but pebbly sandstones are comparatively rare, and claystone beds are present, including a 20-cm-thick cellular claystone (palygorskite, vermiculite with some calcite) as well as light gray, medium-bedded claystone beds, consisting mainly of palygorskite with some saponite and/or clinochlore, associated with minute, euhedral dolomite or ankerite crystals. All claystone beds are evaporitic, lacustrine deposits of ephemeral ponds and pools on wadi floors whereas the coarser beds represent wadi conglomerates. Some beds are imbricated slide units. The paleoclimate was hot, semiarid or arid.</p><p>(5) The dolomitic conglomerate facies unit may measure >61 m in thickness. The respective pebble conglomerates consist of clasts that seem to “float” in cement. The cements of the basal >10 m are brown-stained silica and some white dolomite. The silica content gradually decreases upward. The upper part is dominated by white dolomite and some calcite. The dolomite cement may have formed under phreatic conditions (groundwater) during the Late Miocene to Pliocene when the arid/semiarid Miocene climate became more humid.    </p><p>Close to the base of unit 4, the upper part of an east-dipping syndepositional thrust is exposed (Mattern et al., 2018). Faulting approximately coincides with the change from marine to terrestrial conditions. In addition, the syndepostional tectonic activity may explain aspects of slope instability: debrite in unit 2, slide units in unit 4.</p><p> </p><p>References</p><p>Mattern, F., Scharf, A., Al-Amri, S.H.K., 2018. East-west directed Cenozoic compression in the Muscat area (NE Oman): timing and causes. Gulf Seismic Forum, 19-22 March 2018, Muscat, Oman, Book of Abstracts, p. 4-7.</p>

scholarly journals Grain Size Analysis, Textural Characterisation and Depositional Environment of Turonian Amasiri Sandstone, Southern Benue Trough, Nigeria

2021 ◽  
Vol 4 (2) ◽  
Keyword(s):  
Grain Size ◽  
Depositional Environment ◽  
Function Analysis ◽  
High Energy ◽  
Coarse Grained ◽  
Grain Size Analysis ◽  
Size Analysis ◽  
Benue Trough ◽  
Shallow Marine ◽  
Wide Range

Grain size analysis of Turonian Amasiri Sandstone in southern Benue Trough has been undertaken to determine the controversial depositional environment of the formation. The formation was first studied on outcrops and 26 representative samples were collected and subjected to particle size analysis in line with standard procedures for dry sieving. Various methods of environmental interpretation of grain size distribution data were applied to constrain the depositional of the sandstones. The result indicates that the sands are medium and coarse-grained with mean size ranging from 0.15 to 1.87φ and averaging 0.96 φ. The sandstones are moderately to poorly sorted with standard deviation values ranging from 0.72 to 1.38 φ and averaging 1.07 φ. They exhibit a wide range of distribution from strongly coarse skewed to strongly fine skewed with skewness values ranging from -2.31 to 1.52 φ and averaging -0.04 φ but indicate a narrow range of kurtosis from mesokurtic to leptokurtic distribution with values ranging from 0.99 to 3.49 φ and an average of 2.06 φ. The sediments have bimodal with minor polymodal and unimodal distribution with primary modal size of 1.2 φ. The bivariate plots of size statistical parameters indicate fluvial environment of deposition. However, linear discriminant function analysis and the interpretations of log-probability plots indicate deposition in a fluvial, beach, and shallow marine settings, and thus suggesting a possible deposition in high-energy transitional environment. The C-M pattern of the samples indicates that sediments were transported mainly by rolling and suspension with subordinate fractions moved by rolling as well as suspension. Thus, it is deduced that Amasiri Sandstone was deposited in fluvial, beach, and agitated shallow marine environments.

scholarly journals A Deep Marine Origin for the Tajau Sandstone Member of the Kudat Formation, Kudat Peninsula, Sabah: Evidence from Facies Analysis and Ichnology

2021 ◽  
Vol 50 (2) ◽  
pp. 301-313
Author(s):  
Hafzan Eva Mansor ◽  
Meor Hakif Amir Hassan ◽  
Junaidi Asis
Keyword(s):  
Depositional Environment ◽  
Facies Analysis ◽  
Sedimentary Facies ◽  
Coarse Grained ◽  
Hydraulic Jumps ◽  
Marine Origin ◽  
Shallow Marine ◽  
Depositional Settings ◽  
Density Flow ◽  
Slope Topography

There have been many disagreements regarding the depositional environment of the Oligocene Tajau Sandstone Member of the Kudat Formation, Northern Sabah. We present here, the first detailed sedimentary facies analysis for the Tajau Sandstone Member, exposed on the Kudat Peninsula. The identified facies are interpreted as the deposits of subaqueous sediment density flows, which are common processes in deep marine depositional settings. These include debrites, hyperconcentrated density flow deposits, and turbidites. Several of the turbidite facies display evidence for hydraulic jumps, which are also common processes in deepwater settings and probably indicate changes in slope topography or loss of flow confinement. Trace fossils characteristic of the Nereites ichnofacies are also diagnostic of a deep marine depositional environment. Facies previously identified by previous workers as hummocky cross-stratification in the Tajau Sandstone Member, which was used to support a shallow marine interpretation, is better interpreted as supercritical antidunes developed in high density turbidites, based on the coarse-grained texture, spaced layering and association with other subaqeuoues density flow deposits.

Stratigraphic Trap Potential in the Lower Cretaceous Ratawi Interval, Partitioned Zone PZ, Saudi Arabia and Kuwait

2021 ◽  
Author(s):  
Ibrahim Hakam ◽  
Niall Toomey ◽  
Sujoy Ghose ◽  
Joe Ponthier ◽  
Jeremy Zimmerman
Keyword(s):  
Lower Cretaceous ◽  
Depositional Environment ◽  
High Energy ◽  
Seismic Inversion ◽  
Seismic Facies ◽  
Reservoir Quality ◽  
The North ◽  
Reservoir Development ◽  
Calcite Cement ◽  
Effective Seal

Abstract The Lower Cretaceous Ratawi Oolite Formation is among the most prolific reservoirs in the PZ, having produced a significant amount of oil since the 1950's. The Ratawi is interpreted as a low angle carbonate ramp, with high-energy grainstone facies developing on structural highs. Production is focused on these structural highs, with very few well penetrations off structure. Recent work has identified potential Ratawi stratigraphic traps in prograding clinoforms along the flanks of the North Fuwaris structural high. Core data from Ratawi wells illustrate the interplay of depositional environment and diagenesis on reservoir quality. Gross depositional environment (GDE) maps created from the integration of seismic facies and core observations indicate the stratigraphic trap lies in the ramp slope. Reservoir quality variability of the ramp slope across the PZ is explained by the diagenetic history of the Ratawi. Early equant calcite cement develops from substantial meteoric runoff and lowers porosity, while later dissolution enhances reservoir quality. The area of interest is isolated from potential meteoric inputs; we do not expect equant calcite cement or the associated reduction in reservoir quality. Seismic interpretation was performed on recently acquired PZ 3D data to map the Ratawi section. Clinoforms (inclined geometry) were mapped along the western flank of the North Fuwaris high. These facies appear to have developed as a result of progradation to the NW and are indicative of good reservoir development. Leads were generated using the depth structure and GDE maps, supported by amplitude extraction and seismic inversion volumes. Amplitudes extracted from the clinoform shows that the strongest anomaly is along the structurally highest part of the horizon and the anomaly weakens downdip. High amplitudes could be a proxy for reservoir (porosity), and sharp turn-off in amplitude might indicate that lateral and updip facies changes to non-reservoir which is needed for an effective seal. Recent seismic inversion performed on the Ratawi interval shows a good match between the Acoustic Impedance (AI) from logs and the computed AI from the seismic. The Ratawi Oolite appears as a low impedance interval between overlying Ratawi Limestone and underlying Makhul. Porosity estimated from AI volumes appear to support possible Ratawi reservoir development along the flanks of North Fuwaris and Wafra highs.

scholarly journals Episodic Sedimentary Evolution of an Alluvial Fan (Huangshui Catchment, NE Tibetan Plateau)

Quaternary ◽  
2018 ◽  
Vol 1 (2) ◽  
pp. 16 ◽  
Author(s):  
Linman Gao ◽  
Xianyan Wang ◽  
Shuangwen Yi ◽  
Jef Vandenberghe ◽  
Martin Gibling ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
High Energy ◽  
Alluvial Fan ◽  
Low Energy ◽  
Coarse Grained ◽  
Tectonic Activity ◽  
Last Interglacial ◽  
Climate Conditions ◽  
Facies Associations ◽  
Semi Arid

Alluvial-fan successions record changes in hydrological processes and environments that may reflect tectonic activity, climate conditions and changes, intrinsic geomorphic changes, or combinations of these factors. Here, we focus on the evolution of a stream-dominated fan in a tectonic depression of the Xining basin of China, laid down under a semi-arid climate in the northeastern Tibetan Plateau (NETP). The fan succession is composed of three facies associations, from bottom to top: (1) matrix to clast-supported, poorly sorted, planar cross-stratified to crudely stratified sheets of coarse-grained sediments; (2) horizontal laminated sand, laminated layers of reddish fine silt and yellow coarse silt with stacked mounds of sand; and (3) clay-rich deposits with incipient paleosols. The succession shows rapid sediment aggradation from high-energy to low-energy alluvial fans and finally to a floodplain. The dating results using optically stimulated luminescence (OSL) method show that a gravelly, high-energy fan was deposited during MIS 6, after which a low-energy fan, mainly composed of sand and silt, was deposited and finally covered by flood loam during the MIS 6–5 transition and the warmer last interglacial. Stacked sand mounds are interpreted from their sediment structure and grain-size distribution as shrub-coppice dunes in low-energy fan deposits. They may be considered as a response to the interaction of alluvial and aeolian processes in a semi-arid environment.

scholarly journals Source and depositional processes of coarse-grained limestone event beds in Frasnian slope deposits (Kostomłoty-Mogiłki quarry, Holy Cross Mountains, Poland)

Geologos ◽  
2010 ◽  
Vol 16 (3) ◽  
pp. 153-168 ◽  
Author(s):  
Aleksandra Vierek
Keyword(s):  
Carbonate Platform ◽  
Transitional Zone ◽  
High Energy ◽  
Coarse Grained ◽  
Tectonic Activity ◽  
Fine Grained ◽  
Holy Cross Mountains ◽  
Depositional Processes ◽  
Platform Margin ◽  
Slope Deposits

Source and depositional processes of coarse-grained limestone event beds in Frasnian slope deposits (Kostomłoty-Mogiłki quarry, Holy Cross Mountains, Poland)The Kostomłoty-Mogiłki succession is situated in the Kostomłoty transitional zone between the shallow-water Kielce stromatoporoid-coral platform and the deeper Łysogóry basin. In the Kostomłoty-Mogiłki quarry, the upper part of the Szydłówek Beds and Kostomłoty Beds are exposed. The Middle-Upper Frasnian Kostomłoty Beds are composed of shales, micritic and nodular limestones with abundant intercalations of detrital limestones. The dark shales and the micritic and nodular limestones record background sedimentation. The interbedded laminated and detrital limestones reflect high-energy deposition (= event beds). These event beds comprise laminated calcisiltites, fine-grained calcarenites, coarse-grained grain-supported calcirudites fabrics, and matrix-supported calcirudites. The material of these event beds was supplied by both erosion of the carbonate-platform margin and cannibalistic erosion of penecontemporaneous detrital limestones building the slope of this platform. Storms and the tectonic activity were likely the main causes of erosion. Combined and gravity flows were the transporting mechanisms involved in the reworking and redeposition.

Key Events in the Ecological Radiation of the Ostracoda

2003 ◽  
Vol 9 ◽  
pp. 181-202 ◽  
Author(s):  
David J. Horne
Keyword(s):  
Fossil Record ◽  
Early Carboniferous ◽  
High Energy ◽  
Marine Environments ◽  
Shallow Marine ◽  
Late Mesozoic ◽  
Ecological Adaptations ◽  
Terrestrial Environments ◽  
Ecological Radiation ◽  
Key Events

Ostracodes are ecologically diverse at the present day, inhabiting marine, nonmarine and (semi)terrestrial environments. Modern benthic faunas are dominated by Podocopa (marine and nonmarine Podocopida, marine Platycopida, and extremely rare marine Palaeocopida), while the Myodocopa (Myodocopida and Halocyprida) are diverse in the marine pelagic realm, as well as having many nektobenthic taxa. Their excellent fossil record facilitates reconstructions of their phylogenetic relationships and ecological adaptations throughout their Phanerozoic history. The earliest known ostracodes are of Ordovician age, when representatives of the extant orders Podocopida, Platycopida and Palaeocopida were already present, together with (possible) early Myodocopa and extinct orders such as the Leperditicopida. Cambrian bivalved arthropods such as bradoriids and phosphatocopids are no longer regarded as Ostracoda.Ordovician ostracodes were predominantly marine meiobenthos, diversifying into depth-related assemblages dominated by palaeocopids. The beginnings of podocopan radiations in marginal marine environments (brackish and hypersaline waters) are seen in the Silurian, as is an ecological shift of nektobenthic myodocopans to form the first pelagic ostracode faunas. Of the diverse marine Paleozoic palaeocopids, only a single lineage, the puncioids, survived beyond the Permian and today live interstitially in high-energy shallow marine environments. Post-Paleozoic marine benthic ostracode faunas are dominated by cytheroidean podocopids which gave rise to several radiations in the Mesozoic and Cenozoic. The healdiid metacopines (podocopans), of Devonian origins, enjoyed a marine radiation in the Triassic and Early Jurassic and then became extinct. Marine platycopids were also significant components of Mesozoic marine faunas and are relatively diverse in warm, shallow carbonate environments today.Suggestions that the first freshwater ostracodes were Devonian leperditicopids are controversial; undoubted nonmarine / freshwater radiations developed during the Early Carboniferous, including darwinuloidean and carbonitoidean podocopids and possibly some platycopids, together with cytheroidean podocopids (limnocytherids) in the Late Carboniferous. Of these only the darwinuloideans and limnocytherids survived the end-Permian extinctions and are still found in modern nonmarine waters; however, the dominant freshwater ostracodes today are the cypridoidean podocopids, whose radiation began in the Triassic and attained explosive proportions in the Late Jurassic - Early Cretaceous (although there are controversial suggestions of Paleozoic origins for this group). In addition to the limnocytherids there have been several other, separate invasions of nonmarine waters by cytheroidean podocopids, notably the cytherideids and the commensal entocytherids. Radiations in damp terrestrial environments have been initiated by both marine and nonmarine groups, but such invasions lack a recognized fossil record; (semi)terrestrial cypridoideans and darwinuloideans may represent Late Mesozoic radiations, while the Terrestricytheroidea, with marine affinities, may be much older, possibly Late Paleozoic in origin.

Stratigraphy and palaeoenvironments of the Red Crag and Norwich Crag formations between Aldeburgh and Sizewell, Suffolk, England

1988 ◽  
Vol 322 (1210) ◽  
pp. 221-272 ◽  
Keyword(s):  
Amino Acid ◽  
High Energy ◽  
Coarse Grained ◽  
Core Material ◽  
Stage System ◽  
Pollen And Spores ◽  
Shallow Marine Sediments ◽  
Amino Acid Chronology ◽  
Tectonic Origin ◽  
Borehole Core

This study uses a variety of criteria to examine short-range correlation within the Crag deposits in order to assess the validity of longer-range correlations within the British Pleistocene stage system. To this end, six rotary cored boreholes spaced at 0.5-1.0 km intervals were drilled along a north-south-aligned traverse between Aldeburgh and Sizewell, Suffolk. These show that the thick Red/Norwich Crag sequence is confined to a deep, sharply bounded basin, which is of probable erosional rather than tectonic origin. The undisturbed borehole core material enabled an assessment of the limits of stratigraphic resolution within these dominantly high-energy, shallow marine sediments to be made. Subdivision of the sequence was done on the basis of lithostratigraphical and biostratigraphical (foraminifera, pollen and spores, dinoflagellate cysts, and molluscs) criteria; chronostratigraphical methods (palaeomagnetism and amino acid chronology) were also applied. The various subdivisions indicated by each of these disciplines were in large part consistent, demonstrating that valid stratigraphic units had been identified. Only amino acid chronology did not indicate any obvious subdivision of the sequence. Three lithostratigraphical units were recognized within the thick Crag sequence. The lowest unit (AS-Lith 1) consists of coarse shelly sands interbedded with thinly laminated muds and fine sands. The middle unit (AS-Lith 2) consists of fine- to coarse-grained shelly sands arranged in two coarsening-upwards cycles. Units AS-Lith 1 and AS-Lith 2 are correlated on a lithostratigraphical basis with the Red Crag Formation of the adjacent Aldeburgh-Orford area to the south and are named the Sizewell Member and the Thorpeness Member respectively. The uppermost unit (AS-Lith 3) comprises fine- to medium-grained, well-sorted sands; it correlates with the Chillesford Sand Member of the Norwich Crag Formation of the adjacent Aldeburgh-Orford area. The Sizewell Member of the Red Crag Formation is normally magnetized and palaeontologically distinctive. The pollen, foraminifera and dinoflagellate assemblages firmly establish it as Pre-Ludhamian in age, and probably equivalent to an interval within the Reuverian C to Praetiglian Stages of the Netherlands. The Thorpeness Member of the Red Crag Formation is less easy to place within the British Pleistocene stage system. It is reverse magnetized, at least in part, and foraminifera assemblages suggest possible correlation with the Ludhamian Stage. No identifiable pollen or dinoflagellate assemblages were obtained. The Chillesford Sand Member of the Norwich Crag Formation is largely unfossiliferous but the borehole material has yielded a single pollen spectrum that suggests correlation with the Bramertonian Stage.

Ostracods as Tsunami Tracers in Holocene Sequences

2010 ◽  
Vol 73 (1) ◽  
pp. 130-135 ◽  
Author(s):  
Francisco Ruiz ◽  
Manuel Abad ◽  
Luís Miguel Cáceres ◽  
Joaquín Rodríguez Vidal ◽  
María Isabel Carretero ◽  
...  
Keyword(s):  
Population Structure ◽  
Species Diversity ◽  
Indian Ocean ◽  
High Energy ◽  
Indian Ocean Tsunami ◽  
Tsunami Deposits ◽  
Shallow Marine ◽  
Juvenile Stages ◽  
Marine Areas ◽  
Age Population Structure

This review analyses the ostracod record in Holocene tsunami deposits, using an overview of the 2004 Indian Ocean tsunami impact on its recent populations and the associated tsunamigenic deposits, together with results from numerous investigations of other Holocene sequences. Different features such as the variability of the local assemblages, population density, species diversity, age population structure (e.g., percentages of adults and juvenile stages) or taphonomical signatures suggest that these microorganisms may be included amongst the most promising tracers of these high-energy events in marshes, lakes, lagoons or shallow marine areas.

scholarly journals Landslide susceptibility assessment in the Peloritani Mts. (Sicily, Italy) and clues for tectonic control of relief processes

2013 ◽  
Vol 13 (4) ◽  
pp. 949-963 ◽  
Author(s):  
G. De Guidi ◽  
S. Scudero
Keyword(s):  
Spatial Data ◽  
Landslide Susceptibility ◽  
Landscape Evolution ◽  
Statistical Technique ◽  
Slope Instability ◽  
Tectonic Activity ◽  
Medium Term ◽  
Tectonic History ◽  
Susceptibility Model ◽  
Morphological Processes

Abstract. Many destructive shallow landslides hit villages in the Peloritani Mountains area (Sicily, Italy) on 1 October 2009 after heavy rainfall. The collection of several types of spatial data, together with a landslide inventory, allows the assessment of the landslide susceptibility by applying a statistical technique. The susceptibility model was validated by performing an analysis in a test area using independent landslide information, the results being able to correctly predict more than 70% of the landslides. Furthermore, the susceptibility analysis allowed the identification of which combinations of classes, within the different factors, have greater relevance in slope instability, and afterwards associating the most unstable combinations (with a short–medium term incidence) with the endogenic processes acting in the area (huge regional uplift, fault activity). Geological and tectonic history are believed to be key to interpreting morphological processes and landscape evolution. Recent tectonic activity was found to be a very important controlling factor in landscape evolution. A geomorphological model of cyclical relief evolution is proposed in which endogenic processes are directly linked to superficial processes. The results are relevant both to risk reduction and the understanding of active geological dynamics.

scholarly journals Age and paleoenvironment of the Nukhul Formation, Gulf of Suez, Egypt: Insights from palynology, palynofacies and organic geochemistry

GeoArabia ◽  
2013 ◽  
Vol 18 (4) ◽  
pp. 137-174
Author(s):  
Haytham El Atfy ◽  
Rainer Brocke ◽  
Dieter Uhl
Keyword(s):  
Nile Delta ◽  
Organic Geochemistry ◽  
Regional Scale ◽  
Tectonic Activity ◽  
Gulf Of Suez ◽  
Spores And Pollen ◽  
Shallow Marine ◽  
History Of ◽  
Geochemical Analyses ◽  
Rock Eval

ABSTRACT Palynological results of a detailed study carried out on 56 samples retrieved from two selected wells (GH 404-2A and SA-E6A) of the Hilal and Shoab Ali fields within the southern part of the Gulf of Suez, Egypt, are presented. This study is mainly focused on the poorly dated Nukhul Formation, for which very little information from palynology is available despite its importance from a petroleum viewpoint. The assemblages discovered in our study are moderately preserved and reveal a sparse but significant record of spores and pollen and dinoflagellates together with highly diverse fungi and algal taxa, e.g. Botryococcus and Pediastrum. A latest Oligocene–Early Miocene (Chattian–Aquitanian) age has been suggested for the Nukhul Formation, based on compiling palynostratigraphic and ecologic data obtained from palynomorphs that have previously been assumed to be representatives for this period on a regional scale. In addition, the Oligocene/Miocene Boundary (OMB) could be lithostratigraphically defined within the studied formation, most likely at the boundary between the lower Shoab Ali Member and upper Ghara Member. A fungal/algal ‘event’ within the interval from 11,370–11,430 ft in the GH 404-2A Well may be associated with a strong regressive phase. Such a regression was previously observed in the Nile Delta and other locations around the Red Sea province, and may be assigned to the global Mi-1 glaciation event at the OMB. However, not only glacial-driven eustacy but also tectonic activity related to the Gulf of Suez rifting may have contributed in forming such an event. Palynofacies investigations were carried out under both transmitted and fluorescence microscopy and the results were partly supplemented by existing organic geochemical analyses (GH 404-2A Well) involving Rock-Eval pyrolysis and total organic carbon (TOC) measurements. The analysis was used to interpret the depositional regime, paleoenvironment and thermal maturation history of the studied succession. These results support the temporary existence of shallow, pond- or lake-like aquatic habitats during deposition of the lower Shoab Ali Member that evolved into a shallow-marine environment with the onset of the deposition of upper Ghara Member of the Nukhul Formation.

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