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The West Java Basin is a typical back-arc basin in Southeast Asia and one of Indonesia's main petroleum provinces. In the past ten years, it has been found that the new hydrocarbon reserves are on the rise, and a amount of resources to be discovered is significant. The distribution of hydrocarbon resources and the tectonic evolution characteristics of the basin are systematically explored, and the differences in hydrocarbon distribution and its main controlling factors in the back-arc basin of West Java are analyzed. The uneven distribution pattern of hydrocarbon is mainly controlled by the differential distribution of source rocks in the subsidence period. The distribution of the main source rocks is influenced by the "three-stage" tectonic development process that governs the distribution of sedimentary facies in various sedimentary environments throughout the tectonic subsidence period. Second, the weakening of the crust and magmatism facilitates the production of high heat flow values in the shallow strata of the back-arc area, thereby accelerating the pyrolysis and hydrocarbon generation of source rocks. The study delineates the formation and distribution of various types of oil and gas across various blocks. Prospective basin exploration sites include the shallow-deep water zones in the basin's south-central sector, as well as underexplored terrestrial regions. The exploration history and hydrocarbon resources identified within the West Java back-arc basin support these findings. [ABSTRACT FROM AUTHOR]

The Paleogene-Neogene strata in the Western Depression of the Qaidam Basin represent a primary focus for oil and gas exploration and development. Influenced by both terrigenous clastic influx and endogenic carbonate deposition, these strata exhibit significant variation in sedimentary systems and reservoir characteristics. This study comprehensively examines the depositional patterns and reservoir properties of the Paleogene-Neogene sequence across the inner, middle, and outer belts of the basin, employing core analysis, thin section petrography, and physical property assessment of reservoirs. Key findings include 1) The development of a concentric sedimentary system in the Western Depression during the Paleogene-Neogene period, characterized by increased carbonate mineral content and decreased clastic material from the periphery to the center of the basin. 2) Varied sedimentary facies associations across different zones, with the outer belt dominated by fan delta and braided river delta deposits, and the middle and inner belts characterized by near- shore shallow lacustrine carbonates and algal mat deposits, and offshore semi-to deep-lacustrine fine sediments, respectively. 3) The outer belt exhibits reservoirs with favorable physical properties and connectivity, while the inner and middle belts show high heterogeneity, indicating potential for lithological traps and shale oil exploration. These insights offer scientific guidance for further investigation into the depositional systems of lacustrine basins in the Western Depression of the Qaidam Basin and for identifying promising reservoirs. [ABSTRACT FROM AUTHOR]

Understanding the depositional processes on the inner shelf of Antarctica is a significant challenge. This difficulty arises from the heterogeneity of sediment sources, their poor preservation potential due to the advance and retreat cycles of ice bodies, and the impact of relatively strong bottom currents generated by high density contrasts in the water column. These factors contribute to the overall complexity of the glacio-influenced marine environment, particularly below present-day floating ice shelves in correspondence of areas draped in sediments related to Late Pleistocene-Holocene glacial variations. These locations provide crucial information for reconstructing past glacial dynamics driven by global changes. In this study, we present an analysis of glaciomarine deposits collected from the Western Ross Sea, offshore Mario Zucchelli Station, in a protected indentation of the Victoria Land Coast that hosts the Terra Nova Bay polynya. We conducted multi-proxy analyses on three sediment cores sampled from selected seafloor morphological units associated with fluctuations of the grounded ice, which preserve sedimentary facies representative of this distinctive depositional environment. We identified and described six depositional facies, characterized by diagnostic sedimentological, textural and geochemical patterns. Direct observations were integrated with high-resolution geophysical data and geomorphological seafloor analysis. Our findings highlight a Late Pleistocene-Holocene depositional sequence linked to fluctuations in grounded ice, with unconformities and sedimentary patterns potentially related to climatic variations driving ice advances and retreats. [ABSTRACT FROM AUTHOR]

The biostratigraphic analysis of the Paleozoic sedimentary successions in Mexico is crucial for understanding their age, depositional setting, and paleogeographic implications. This study examined conodonts and microfacies of calcareous strata within the Del Monte Formation of the Tamatán Group in northeastern Mexico. Field observations have led to the identification of three units within the Del Monte Formation: Unit 1, characterized by calcareous sandstone, bioclastic limestone, shale, occasional conglomerate, and dolomitized beds; Unit 2, consisting of conglomerate and/or breccia associated with debris flows; and Unit 3 including turbiditic sandstone and shale. Conodonts were only recognized in Unit 1, with such genera as Idiognathoides, Neognathodus, Idiognathodus and less frequently, Streptognathodus, Adetognathus, and Diplognathodus. The faunal associations include Idiognathoides cf. Id. corrugatus Harris & Hollingsworth, 1933, Idiognathoides sulcatus sulcatus Higgins & Bouckaert, 1968, Idiognathoides convexus (Ellison & Graves, 1941), Idiognathoides asiaticus Nigmadganov & Nemyrovskaya, 1992, Neognathodus cf. N. atokaensis Grayson, 1984, Neognathodus aff. bothrops Merrill, 1972, Neognathodus nataliae Alekseev & Gerelzezeg, 2001 (in Alekseev & Goreva 2001), Streptognathodus parvus Dunn, 1966, Idiognathodus incurvus Dunn, 1966, and Idiognathodus aff. delicatus Gunnell, 1931, suggesting Morrowan and Atokan (Pennsylvanian) ages for the dolomitic limestone and grainstone beds. Five types of microfacies (MF) and several marine facies zone (FZ) have been detected: MF1-bioclastic grainstone and MF2-wackestone deposited at the platform margin (FZ 6 and FZ 7), MF3-dolomitized wackestone representing an inner restricted platform (FZ 8), MF4-mudstone from a deeper water zone (FZ 4), and MF5-siliciclastic beds with bioclasts indicating a high-energy barrier associated with a platform margin (FZ 6). The findings confirm a shallow to deep platform and imply a connection among Mexican peri-Gondwanan basins, including the Tamatán Basin, indicating similarities in sedimentary facies and/or depositional environments linked to the Rheic Ocean during the Early to Middle Pennsylvanian. [ABSTRACT FROM AUTHOR]

Long, J.H.; Hanebuth, T.J.J.; Durica, J.T., and Hawkes, A.D., 2024. Late Holocene stratigraphy and sedimentary facies distribution of an anthropogenically modified delta plain (Santee River Delta, South Carolina, U.S.A.). Journal of Coastal Research, 40(4), 623–646. Charlotte (North Carolina), ISSN 0749-0208. The Santee River of South Carolina has the second largest watershed in the eastern United States and forms the largest river-fed delta along the U.S. east coast. Anthropogenic modifications to the delta plain of the Santee River, and in many coastal environments within the region, have significantly altered the natural configurations of floodplains, channels, and shorelines. This study incorporated historic and modern state-of-the-art data sets and methods to evaluate the sediment distribution within the modern delta plain as well as the record of environmental change throughout the late Holocene as it is preserved within the subsurface stratigraphy. The study incorporated high-resolution seismo-acoustic and bathymetric data, detailed sediment core analysis, accelerator mass spectrometry 14C dating, micropaleontological analysis, and surface sediment samples to define geomorphic zones based on dominant depositional processes related to fluvial discharge, tides, and waves. Tidal- and wave-influenced conditions were established in the delta plain by around 3 kyr BP and continued into historic times, when the construction of rice fields across most of the delta plain fixed channel positions and isolated floodplains from flood-related sedimentation. Sediment distribution in the modern delta plain is significantly influenced by the maintained network of artificial canals and embankments associated with these historic fields. The influence of these modifications can also be seen within the stratigraphy beneath the delta plain, recording local changes in deposition and erosion that resulted from a modification in water circulation and sediment supply. [ABSTRACT FROM AUTHOR]

Identifying and characterizing sedimentary evolution patterns are crucial for assessing the distributions of source and reservoir rocks, which are fundamental to hydrocarbon exploration. This study analyzed the stratigraphic sequence, lithological characteristics, sedimentary lithofacies, individual well sedimentary sequences, and seismic reflection properties. The analysis revealed six fourth-order sequences, including progradational and regressive sequences, indicative of water level changes. The sediment sources for the second and third sub-members of the Eocene Shahejie Formation's third member (Es32+3) in the Nanpu Sag were identified as the Baigezhuang and Xinanzhuang Uplifts. Predominantly, the sandstones are lithic arkose and feldspathic litharenite, both of which exhibit low compositional and structural maturity. Notably, 22 lithofacies and 8 lithofacies associations suggest fan delta processes. This study identified three fundamental seismic reflection package reflection types. These lithofacies associations, sedimentary sequences, and seismic reflections serve as critical indicators for determining sedimentary environments. The results from the sedimentary facies analysis indicate that the Es32+3 Formation developed fan delta deposits, controlled by the sequence of the sedimentary evolution pattern. The potential of these fan delta sediments to form oil and gas reservoirs is significant. Therefore, precise characterization of the sedimentary evolution pattern is essential for a comprehensive understanding of basin dynamics and hydrocarbon potential. [ABSTRACT FROM AUTHOR]

The evolution of submarine canyons is primarily controlled by turbidity currents, which erode and fill them over time; however, many other hydrodynamic currents operate within canyons. Bottom currents from these other hydrodynamic processes, including internal tides, can be dominant processes, but their deposits are seldom recognized in sediment cores or the rock record. This study combines autonomous underwater vehicle swath bathymetry imagery and sub‐bottom profiles, high‐resolution sediment core analyses (X‐ray imagery and thin sections), and previously collected seabed video and flow measurements within Logan Canyon head (eastern Canada) to provide a detailed, modern record of facies associated with hydrodynamic processes in a canyon head. These results suggest that bottom currents are responsible for maintaining gullies on canyon sidewalls and an axial channel on the canyon floor. Thin sections of sediment cores reveal that muddy sand in the canyon head consists of mud aggregates and silt and fine‐grained sand, both behaving similarly in terms of flow dynamics. Three facies are present at macro‐scale and micro‐scale: laminated, partially laminated and bioturbated sandy mud. Sedimentary structures include rhythmic sand and mud aggregate couplets, planar to wavy laminations, current ripple cross‐laminations and fining‐upward successions, which are attributed to bottom currents induced by internal tides. Bioturbated facies, characterized by discrete biogenic structures and cross‐cutting relationships, predominate and overprint a mottled background. A mottled bioturbation fabric also alternates with or locally disrupts layering within the partially laminated facies. Internal tide currents, capable of bedload transport and forming ripples, were measured during a monitoring period in the canyon head, followed by rapid re‐establishment of benthos and associated biogenic structures, supporting the core interpretations. Preservation of sedimentary facies associated with these internal tides occurs when the sedimentation rate outpaces the rate of bioturbation, likely during stormier conditions on the shelf. These results represent observations of sedimentary facies associated with modern bottom currents and internal tides, and can be used to interpret similar occurrences within the rock record. [ABSTRACT FROM AUTHOR]

[Objective] The Carboniferous system of the Ounan Depression in the eastern Qaidam Basin is a key area for oil and gas exploration in new regions and strata. Drilling and outcrops reveal significant differences in the sedimentary characteristics of the Upper Carboniferous strata across the plane. Previous research, mainly based on outcrop and drilling data, has focused on longitudinal sedimentary evolution and the overall sedimentary background, leaving the distribution characteristics of sedimentary facies unclear. This uncertainty affects the deployment of oil and gas exploration in the Upper Carboniferous of the eastern Qaidam Basin. [Methods] The article focuses on the Upper Carboniferous strata of the Ounan Depression. It predicts the distribution characteristics of sedimentary facies under the guidance of sedimentary model theory using a limited amount of drilling data and 2D seismic data. Utilizing 2D seismic data from the Ounan Depression, it also conducts a detailed study of the internal structure and external geometric features of seismic reflections using seismic facies identification technology. [Results] The comprehensive study identifies six types of seismic facies within the Upper Carboniferous of the Ounan Depression: parallel sheet, sub-parallel sheet, mounded, wedge-shaped, oblique foreset, and chaotic. A planar assemblage map of the seismic facies was developed. By integrating regional geological data, outcrops, well logs, and seismic data, and under the guidance of seismic sedimentology and continental shelf sedimentation theory, the relationship between seismic facies and sedimentary facies in the Upper Carboniferous of the Ounan Depression was established, and the distribution characteristics of sedimentary facies in the study area were predicted. [Conclusion] The results indicate significant differences between the seismic facies in the western and eastern regions of the Ounan Depression. Overall, the western part exhibits lower frequency and more continuous phases compared to the eastern region; the western region also has greater monolayer thickness and a more stable sedimentary environment. From east to west, the Ounan Depression develops a sequential fluvial-delta plain sedimentary system, delta front sedimentary system, and prodelta-deep water shelf sedimentary system. [Significance] The research findings provide a scientific basis for predicting favorable reservoir distribution areas and deploying exploration targets for Carboniferous oil and gas exploration in the eastern region of the Qaidam Basin. [ABSTRACT FROM AUTHOR]

The volcanic rocks in the deep depth of Nanpu sag is the main formation of oil and gas enrichment. It has huge resource potential and prospects for exploration and development. Accurate characterization of lithology and pore space is the basis of reservoir quality prediction. Through petrography studies of cores and thin sections, explosive and sedimentary facies represent the dominant oil and gas-bearing reservoirs, and intergranular pores and fractures are major pore and seepage space. In order to predict favorable reservoirs and improve the efficiency of fracturing, according to composite well loggings and electrical images, logging response features of different lithofacies are characterized and five types of pore structure facies are classified. Further, five types of petrophysical facies are proposed. Among them, Type I and Type II are the most favorable petrophysical facies in the study area. The petrophysical facies typing approach show consistency with oil test data, which verifies that this approach can well predict reservoir quality and provide technical support for the exploration and development of the oil and gas-bearing volcanic rocks. [ABSTRACT FROM AUTHOR]

The Cambrian pre-salt dolomite sequence in the Tarim Basin is a target zone of great strategic significance for hydrocarbon exploration in the basin. Using the results of the interpretation of 3D seismic data from Lunnan and 2D seismic data covering the whole basin, and based on a synthesis of outcrop data, drilling data, well logs, core data, and thin-section data, and the findings from previous studies, this paper studies the characteristics of the facies of the Middle–Lower Cambrian in the platform area in the Tarim Basin, the formation and evolution of platform margins, and the sedimentary characteristics, lithofacies, and paleogeographic characteristics of the Middle–Lower Cambrian series. Based on the types of lithofacies and the seismic facies analysis, the sedimentary facies of the Middle–Lower Cambrian strata can be classified into the five types. From bottom to top, the Middle–Lower Cambrian have experienced several development stages, including the deposition of continental shelf sediments of the Yuertusi Formation, gently sloping non-rimmed platform margin sediments of the Xiaoerbulake Formation, weakly rimmed platform margin sediments of the Wusongger and Shayilike formations, and strongly rimmed platform margin sediments of the Awatage Formation. In each stage, the platform margin shifted further east relative to its location in the previous stage. Based on these results and previous studies, the lithofacies and paleogeography maps of the Middle–Lower Cambrian in the Tarim Basin are modified, and the implications for hydrocarbon exploration in this area are discussed. [ABSTRACT FROM AUTHOR]

High‐resolution 2D and 3D data remotely acquired by SuperCam's Remote Micro‐Imager and Mastcam‐Z aboard the Perseverance rover enabled us to characterize the stratigraphic architecture and sedimentary record of the Kodiak butte, an isolated remnant of the western delta fan of Jezero crater. Using these data, we build up on previous interpretations of the butte interpreted as a prograding Gilbert‐type deltaic series. We characterize three individual stratigraphic Units 0 to 2 on the eastern and northern faces of the butte. Each Unit displays the same vertical succession of prodeltaic/lacustrine bottomsets, delta slope toesets and foresets, and fluvially influenced topsets of a deltaic plain with a braided river pattern, shown by 11 individual sedimentary facies. We infer that these individual Units record the formation of three distinct deltaic mouth bars successively across time and space. For the first time on another planet than Earth, we are able to construct a precise sequence stratigraphic framework to highlight lake‐level fluctuations at the time the Kodiak butte was emplaced, during the latest stages of deltaic activity. We identify four hydrogeological cycles indicated by alternating rises and falls of the lake‐level on the order of 5–10 m. These were most probably linked to climatic events and variations controlling lake water inputs in probable relation to an astronomical control. Plain Language Summary: Kodiak butte is an isolated remnant of the main western sedimentary fan of Jezero crater. It displays the characteristic structures of a Gilbert‐type delta, a structure that shows deposition of fluvial material into a standing body of water, here interpreted to be a lake within Jezero crater. 11 individual sedimentary facies (textures, grain‐sizes, and structures) of the rocks exposed at Kodiak suggest that the depositional environments ranged from the fluvial plain to a steep subaqueous slope and into the bottom of the shallow Jezero lake. Our observations further show that Kodiak butte is organized into three distinct stratigraphic Units (0–2), each displaying the same vertical succession of bottomsets, toesets, foresets and topsets. This architecture is interpreted as reflecting three distinct deltaic packages, formed consecutively and not at the same time. Using these facies and stratigraphic architecture data, we are able for the first time on another planet than Earth, to precisely construct a sequence stratigraphic framework for the formation of Kodiak. This framework illustrates with unprecedented precision successive episodes of rises and falls of the paleo‐lake‐level (in the order of 5–10 m) involved in the construction and evolution of the western Jezero delta. Key Points: New observations on the Kodiak delta remnant were carried out to characterize its detailed facies and stratigraphic architectureThree deltaic mouth bars are identified showing 4D succession of depositional settings ranging from deltaic plain to slope to shallow lakeThe first ever sequence stratigraphic framework on Mars shows four cycles of alternating rises and falls of the lake‐level within 5–10 m [ABSTRACT FROM AUTHOR]

Due to the influence of multiple tectonic movements in rift basins, the sequence and sedimentary filling modes of continental petroleum reservoirs are complex, which makes it difficult to establish isochronous stratigraphic frameworks and thus affects the accuracy of subsequent predictions of effective sand bodies. Taking the Guantao Formation of the Binxian uplift and the surrounding areas as an example, this study established the sequence stratigraphic framework of the Guantao Formation and discussed the controlling effect of sequence stratigraphy on sedimentary filling. According to a combination method of seismic data, well log data, the wavelet transform technique (WTT), and Integrated Prediction Error Filter Analysis (INPEFA) methods, the Guantao Formation in the study area can be divided into 1 long-term cycle (LNG), 4 mid-term cycles (MNG1–MNG4, from bottom to top), and 11 short-term cycles (SNG1–SNG11, from bottom to top). Based on comprehensive analysis of geological and seismic data, three sedimentary facies can be classified: alluvial fan facies, braided fluvial facies, and meandering fluvial facies. The sequence stratigraphic style of the study area has a significant controlling effect on sedimentation and sand body distribution. Different levels of cycles have different impacts on sedimentary facies/microfacies types, the development degree of each sedimentary microfacies, and sand body distribution. The long-term cycle controls the distribution of sedimentary facies, while the mid-term and short-term cycles control the distribution of sedimentary microfacies. The bottom interface of the Guantao Formation (T1) served as the dominant migration channel in the study area, connecting the reservoir and source rocks. When the base-level was in the low stage (MNG1), a large amount of sand bodies developed, forming favorable reservoirs for petroleum. The interlayers at the top of the long- and mid-term cycles served as seal layers to prevent oil and gas from escaping. The MNG1 cycle has a good combination of reservoir and seal, resulting in the accumulation of oil and gas in the MNG1 strata, which became the main oil- and gas-producing layer in the area. These study results can provide effective guidance for future prediction of the distribution of sand bodies and high-quality reservoirs. [ABSTRACT FROM AUTHOR]

Neoproterozoic strata are widely developed in the Upper Yangtze region of South China, among which the Sinian Dengying Formation has been discovered with numerous large gas fields in the Sichuan Basin, and hence they have become an essential domain for natural gas exploration and development. The early‐to‐middle Neoproterozoic Nanhua System and Doushantuo Formation are characterized by rifting deposits in the northeastern margin of Sichuan Basin, but their depositional succession and sequence architectures are still unclear, which has largely restricted our understanding of the resource potential of these strata. In this paper, based on the outcrops of the Neoproterozoic Nanhua System and Doushantuo Formation in the northeastern margin of Sichuan Basin, we describe the stratigraphic distribution and sedimentary evolutionary characteristics, and establish the regional stratigraphic framework, sedimentary cycle and evolutionary sequence of the Nanhua System and Doushantuo Formation. The results show that the lithology of the Nanhua System and Doushantuo Formation is primarily composed of conglomerate, conglomeratic sandstone, medium‐fine sandstone, siltstone, mudstone, shale and tillite; a variety of sedimentary facies including alluvial fan, river, delta, coastal shore, shelf, basin and tillite were developed; five third‐order sequences could be identified, representing multiple cycles of marine transgression and regression. The climate during the deposition of the Nanhua System and Doushantuo Formation underwent from a warm and humid pre‐glacial period through cold and arid multiple glacial periods to a warm and humid interglacial period, which consequently formed a sedimentary sequence of alluvial fan and fluvial delta to tillite during the early period, shelf basin to tillite during the middle period and slope basin to delta facies during the late period. In terms of a plan view, the depositional pattern is composed of alluvial fans and deltas at the proximal part of the rift, deep‐water shelf to slope at the middle part of the rift and slope to basin facies at the central part of the rift. Finally, we propose that large‐scale distribution of high‐quality source rocks developed in the interglacial Datangpo and Doushantuo formations, while fluvial‐deltaic reservoirs occurred in the Gucheng, Nantuo and Doushantuo formations, thus showing favourable resource potential and exploration prospects within the Sichuan Basin. [ABSTRACT FROM AUTHOR]

The Ordos Basin is rich in oil and gas resources in the Paleozoic strata. The southern part of the basin boasts a thick Paleozoic sedimentary sequence, enriched organic matter, favorable sedimentary facies, and hydrocarbon source rocks with an over-mature thermal evolution stage. However, the lack of in-depth study of the tectono-thermal evolution in the southern basin limits regional oil and gas exploration. In this study, drill core and outcrop samples were collected from the Shanbei Slope and the Weibei Uplift, respectively. These samples were subjected to apatite fission track (AFT) and (U-Th)/He dating (AHe). The results were used to reconstruct the thermal history of the southern basin, calculate exhumation rates, and analyze the tectonic evolution of the basin. The seven annealed AFT data values from the Shanbei Slope range from 21.4 to 52.8 Ma, with mean track lengths of 13.24 μm, and the twelve unannealed AFT data values from the Weibei Uplift range from 111.9 to 204.6 Ma. The seven AHe data values from the Shanbei Slope range from 17.0 to 31.8 Ma, and the eight AHe data values from the Weibei Uplift range from 31.7 to 47.5 Ma. The thermal history is characterized by a prolonged phase of burial and heating from the Triassic to the Late Early Cretaceous, followed by a phase of uplift and cooling that continued into the Cenozoic. This cooling phase exhibits three distinct stages with varying rates of uplift and cooling. According to the dating results, the cooling timing of the southern basin was earlier than that of the central part, and the southern basin experienced higher uplift rates during the Paleogene than in other periods of the Cenozoic. This may be attributed to the far-field effects of the collision between the Indian Plate and the Eurasian Plate during the Paleogene. [ABSTRACT FROM AUTHOR]

This study provides a sedimentological, stratigraphic and palaeocurrent investigation of Upper Eocene to Lower Oligocene deep-sea fan deposits found in the central part of the Pindos foreland basin in western Greece. According to facies analysis, the examined succession at Amfilochia area has 13 sedimentary facies and 10 facies and sub-facies associations. Depositional elements include abyssal plain pelagics, outer fan, inner fan, and slope deposits. Outer fan sediments are classified as lobe-axis, lobe-off-axis, lobe-fringe, and distant lobe-fringe deposits, while inner fan sediments are classified as channel-fill, crevasse-splay, internal and external levee deposits. The stratigraphic study shows an upward shift from abyssal plain pelagics to outer, inner fan, and finally slope deposits, implying submarine fan system progradation and progressive infilling of a deep-water sediment depocentre. The sediments were deposited in the foredeep of the Pindos foreland system and correspond to the system's underfilled stage, when sedimentation was unable to exceed the accommodation provided by lithospheric flexure. They point to deposition near the onset of the Pindos orogen, after the closure of the Pindos basin because of the collision of the Apulian with the Pelagonian microplate during the Cretaceous-Palaeogene period. Palaeocurrent data from sole marks show bipolar directions associated with two distinct spreading sub-marine fan deposits. As a result, the study region was split into Upper (major SE-direction flow) and Lower (major NW-direction flow) parts, indicating that axial flows were predominant during sediment deposition. However, as the deposition of the elements continued, the progradation of both systems constrained the space accommodation because of the increased basin sediment supply and forced an increase in the degree of basin confinement that changed the compensational to aggradational stacking pattern. The goals of this research are to develop an updated facies model for these deep-sea fans as well as a robust correlation framework for the various stratigraphic units in the central Pindos foreland basin. This research also connects the stratigraphic development of deep-sea fan deposits to the evolutionary phases of the Pindos foreland system, providing fresh insights into the palaeogeographic circumstances in the Pindos foreland basin. [ABSTRACT FROM AUTHOR]

Late Eocene artiodactyl and creodont tracks have been reported from the Jianchuan Basin, southeastern Tibetan Plateau, representing the first and the oldest reported mammal tracks in Yunnan Province, China. Sedimentary facies analysis indicates that tracks from the upper Baoxiangsi Formation and the lower Shuanghe Formation occurred in lake shore and flood plain environments, respectively. Based on the morphological analysis, the artiodactyl tracks from the Baoxiangsi Formation are attributed to Anoplotheriipus zeuctus. Combined with fossil records and morphological characteristics, the artiodactyl and creodont tracks were probably produced by entelodonts and mesonychids, respectively. The superimposition of artiodactyl tracks with varying sizes indicates coexistence of juveniles and adults as well as their gregarious behaviour. The co-occurrence of artiodactyl tracks and creodont tracks suggests the predator–prey relationship and ecological chain during the late Eocene. The presence of mammal tracks in the Jianchuan Basin coincides with the climate change from dry to wet in the late Eocene, implying the climatic and ecological effects of the uplift of the Tibetan Plateau. [ABSTRACT FROM AUTHOR]

The deposits of the upper Neoproterozoic Zerrissene Group of central‐western Namibia represent a large siliciclastic deep‐water depositional system that showcases the intricacies of facies and architectural relationships from bed‐scale to fan‐system‐scale. The lack of vegetation in the Namib Desert and regular east–west repetition of folded stratigraphy (reflecting ca 50% tectonic shortening) provides quasi‐three‐dimensional exposure over a current area of approximately 2700 square kilometres. The Brak River Formation, the middle sand‐rich unit of the Zerrissene Group, consists of nearly 600 m of strata exposed in multiple parallel continuous outcrops up to ca 10 km in length and oriented obliquely to depositional dip. Ten stratigraphic sections are correlated ca 32 km (ca 64 km restored) across the basin and offer exposure comparable in scale to modern submarine fans. Six sedimentary facies are identified and grouped into four facies associations that represent axial‐to‐marginal portions of deep‐water lobes in an unconfined submarine fan system. Spatial facies patterns, regional thickness variations, and palaeocurrents indicate that Brak River Formation sediments were transported primarily from the north to south–south‐west through a trough‐like basin, and deposited within an unconfined basin plain at the junction of the Adamastor and Khomas oceans. The unique outcrop exposure and extent permits the documentation of system‐scale architecture and basin configuration of the Brak River submarine fan system. A transition from the sand‐rich lower Brak River Formation to more intercalated mudstone‐dominated intervals in the middle and upper Brak River Formation is interpreted to record a change from aggradational to compensational stacking of lobe deposits. This records the evolution of a large submarine fan as it filled the subtle seafloor topography and became less confined at the system‐scale. The documentation of these deep‐water deposits from centimetre‐scale to basin‐scale provides a new model for a system with extensive long‐distance transport of sand‐rich sediment gravity flows to submarine lobes without apparent channelization. [ABSTRACT FROM AUTHOR]

We report the first discovery of vase-shaped microfossils (VSMs) and possible multichambered foraminifera from the Ediacaran rocks of Saudi Arabia. The Ediacaran successions of Saudi Arabia are well exposed in the northwestern and central part of the Arabian plate but are relatively understudied due to the lack of economic potential. The exposures can be found in different small sedimentary basins distributed along the flanks of Najd Fault system of the western Arabian Plate. The Dhaiqa sub-basin located near the historic city of Al-Ula contains some of the best exposures of Ediacaran Mattar and Dhaiqa Formations with collective exposure almost 400 m thick. These formations (especially the Dhaiqa Formation) were investigated to describe sedimentary facies, depositional environment, and possible microfossils. This study focuses on the identification of vase-shaped microfossils and possible trochamminid foraminifera of Ediacaran age that are herein recognized for the first time in Saudi Arabia. Outcrop samples were thin-sectioned and analyzed to reveal nine sedimentary facies belonging to four facies associations. The observed microfossils were found in a total of four samples from the cherty/siliceous carbonate and sandy microbialite facies. The microfossils are observed to be associated with diagenetic chert, which is abundant in these facies. The two facies contain a sparse microfossil assemblage with vase-shaped microfossils, which are single-chambered microfossils of uncertain taxonomic affinity, and possible multichambered agglutinated foraminifera that resemble trochamminids. [ABSTRACT FROM AUTHOR]

Based on detailed field surveys, numerous sections and drillcores as well as analyses of lithofacies and sedimentary facies, sedimentary differentiation in the Middle Permian Zunyi (northern Guizhou, South China) trough basin was studied in detail. Caused by activities of the Emeishan mantle plume, the regional extensional setting and the extinguishing of carbonate production factories were shown from Guizhou to Yunnan. Three types of sedimentary enironments were developed in the study area: platform, slope, and basin. In this work, we established a sedimentary model for the study area, identified 14 syndepositional faults, and created the detailed reconstruction of the trough basin via a sedimentological investigation. It is found that the paleogeographic evolution of the study area can be divided into six stages: (1) a pre-rifting stage, (2) rapid rifting and subsidence, (3) stable rifting and subsidence, (4) the second stage of rifting and subsidence, (5) silicification, and (6) regional uplift and denudation. The sedimentary features and paleogeographic evolution of the Maokou Formation in Zunyi show that the platform, slope, and basin sedimentary features coexisted. In addition, the extensional setting and extinguishing of carbonate production factories were important preconditions for the evolution of the platform region in the study area, and the activity of syndepositional faults also played an important role in the paleogeographic evolution of this area. [ABSTRACT FROM AUTHOR]

Based on the measurements of petrological, petrophysical and elastic properties of the samples of different sedimentary facies in the fourth member of Sinian Dengying Formation (Deng 4 Member) in the Sichuan Basin, the diagenetic processes of reservoirs of different sedimentary facies and their controls on the petrophysical properties were discussed. The results show that cracks and mineral composition jointly control the petrophysical properties, and both are significantly influenced by sedimentary environment and diagenesis. The microbial dolomite of mound-shoal facies mainly experienced multi-stage dolomitization, penecontemporaneous dissolution, tectonic rupture and hydrothermal/organic acid dissolution processes, giving rise to cracks and dissolved pores. The grannular dolomite of inter-mound-shoal bottomland or dolomitic lagoon facies mainly underwent mechanical compaction, burial dolomitization and tectonic-hydrothermal action, creating cracks and intercrystalline pores. The diagenesis related to crack development increases the pressure- and saturation-dependent effects of samples, leading to significant decrease in the compressional wave impedance and Poisson's ratio. Dolomitization changes the properties of mineral particles, resulting in a Poisson's ratio close to dolomite. The muddy, siliceous and calcareous sediments in the low-energy environment lead to the decrease of impedance and the differential change of Poisson's ratio (significantly increased or decreased). The samples with both cracks and dissolved pores show high P-wave velocity dispersion characteristics, and the P-wave velocity dispersion of samples with only fractures or pores is the lowest. [ABSTRACT FROM AUTHOR]

This study focuses on the analysis of the sedimentary facies of the Middle–Late Permian, including the Qixia, Maokou, Wujiaoping/Longtan, and Changxing/Dalong Formations, in the Sichuan Basin, southwest China. Integrating drilling data and field outcrop data, various sedimentary facies indicators were employed to define eight sedimentary facies types in the Sichuan Basin during the Middle–Late Permian, namely, mixed tidal flat, tidal flat, restricted platform, open platform, platform margin, slope, basin, and volcanic facies. Detailed facies analysis was conducted on selected well logs, and sedimentary facies distribution maps were compiled for different time intervals, establishing depositional models. During the Qixia to Maokou stages, an extensive open platform was developed in the Sichuan Basin, accompanied by shallow intra-platform shoals. Towards the west along the Dayi–Ya'an line, platform margins were developed, followed by slope facies and basin facies in a northwest direction. During the Changxing stage, the Kaijiang–Liangping fault block subsided, forming the "Kaijiang-Liangping" paleochannel, which controls reef–shoal deposition in the region. This study provides comprehensive insights into the sedimentary facies characteristics and depositional environments of the Middle–Late Permian in the Sichuan Basin, contributing to the understanding of the regional sedimentary history and geological evolution. [ABSTRACT FROM AUTHOR]

The Middle Jurassic syn-rift sediments of the Khatatba Formation contain not only the principle source rock organofacies in the north Western Desert (NWD), but also several potential sandstone reservoir targets. However, controls on the reservoir quality of the Khatatba facies and spatiotemporal evolution of the reservoir rock types (RRTs) are still blurred. This study integrates seismic, wireline logs, and conventional core data from some wells in the Meleiha development lease in the NWD to investigate the petrophysical characteristics of the Khatatba reservoir facies, and determine the different RRTs. On seismic, Khatatba Formation consists of high reflectivity, continuous reflections displaying an upward decrease in seismic amplitude corresponding to a fining-upward clastic succession of fluvial–tidal facies. These facies display a large-scale pore system heterogeneity, thereby comprising three different RRTs. RRTI and RRTII rocks have a well-connected pore network dominated by capillary and super-capillary pores (> 10 µm), whereas sub-capillary pores (< 10 µm) are more common in RRTIII sediments. RRTI rocks consist of quartzose sandstones with a clean pore network (cement < 20%). The open pore system of RRTI allows a displacement of more than 80% of the pore water at entry pressure levels < 500 psi. Carbonate and clay components are more common in RRTIII rocks (average = 5.6% and 13%, respectively). These components adversely impact the pore system connectivity of RRTIII sediments. Fluvial channel sandstones host the principal fluid flow conduits where RRTI sandstones account for more than 95% of the reservoir flow capacity. The present study provides the first reservoir rock typing for the Khatatba clastic reservoir facies and highlights the link between depositional, compositional attributes and the spatial distribution of the different RRTs. [ABSTRACT FROM AUTHOR]

The depositional environment of Asara Shale is discussed in this paper through the detailed analysis of outcrops from the Alborz Basin, NW of Tehran, Iran. The Asara Shale is composed of fine-grained clastic and carbonate (marlstone) strata interbedded with tuff levels. Sedimentary structures include mm- to cm-scale parallel and cross laminations, basal gutter cast, Thalassinoides burrows, bioturbation, clastic/biogenic particle alignment, and normal-size grading. Facies analysis suggests an accumulation dominated by periodic flood energy fluctuations, here related to shallow-marine hyperpycnal discharges. Based on the sedimentary architecture and analysis of the facies associations, five main sedimentary facies have been defined in these outcrops, corresponding to S1, S2, S3, S4, and MM. Suspended‐load‐dominated facies (Facies S) are related to sedimentation from weak turbulent suspensions and consist of massive sandstones (S1), parallel and low-angle-laminated sandstones (S2), ripple-marked sandstones (S3), parallel‐laminated/massive siltstones and mudstones (S4), and microbial mats (MM). Ratios of redox-sensitive elements indicate that the Asara Shale accumulated in an oxygenated depositional environment. This environment is associated with the presence of parallel-crested ripple marks, microbial-induced sedimentary structures (i.e., wrinkle structures), plant fragments, and surface-grazing gastropods. Based on a variety of sedimentary textures and structures, a shallow-water depositional environment is proposed. This study offers new insights into the depositional environment of Asara Shale. Due to the oxic character of this sedimentary basin, and the lack of significant organic matter, it is interpreted that the Asara Shale is not a potential hydrocarbon source for the future explorations. [ABSTRACT FROM AUTHOR]

The traces left by earthquakes in the unlithified sediments, recorded as soft-sediment deformation structures (SSDS), are well reconstructed as palaeo-seismic signals, while the origin of SSDS, seismic vs. Aseismic, is challenging. The present study discusses the origin of SSDS and its implications on palaeoceanography and sediment architecture. In the Middle Jurassic succession of Spiti Himalayan region in India, the topmost part of the Ferruginous Oolitic Formation (FOF) consists of four layers of SSDS and is underlain by the lower member of the Spiti Formation (SF). The sedimentary facies analysis documents the palaeogeographic shift from the middle shelf (carbonate-shale repository: FOF) to the outer shelf (black shale: lower member of SF). The SSDS layers, exhibiting load casts, ball and pillow structures, indicate gravitational instability, while syn-sedimentary faults and insitu breccia are the results of brittle deformation. The dominance of storms in depositional sites often argues for a possible triggering agent for SSDS. Therefore, it was necessary to distinguish between seismic vs. aseismic triggering agents. The lateral continuity, vertical repetition, confinement of SSDS at the top part of FOF and sharp change of facies assemblage indicate seismicity-induced syn-sediment deformation, i.e. seismite. The transition from middle shelf to outer shelf at the onset of seismite indicates that seismic impact possibly caused the rapid subsidence, resulting in the palaeogeographic shift. The rapid transgression is recorded as carbonate-shale repository to anoxic black shale. This study highlights the importance of sedimentological analysis to distinguish the seismite and its implications on palaeogeographic evolution and sedimentary architecture. [ABSTRACT FROM AUTHOR]

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With the exhaustion of the "easy to find" hydrocarbons, the search for hydrocarbons in Precambrian sedimentary basins has increased over the years. The Voltaian Basin of Ghana is part of the Neoproterozoic sedimentary basins of the West African Craton (WAC). Unlike the Voltaian Basin, other Neoproterozoic basins of the WAC are relatively explored. The study seeks to explore the hydrocarbon prospects of the Voltaian Basin using facies analysis, petrographic studies, and palynofacies. Shales and carbonate samples from the Oti-Pendjari and Kwahu-Bombouaka Group of the basin were sampled for studies. On the basis of sedimentary structures, the color of the shales and field associations were used in the facies classification. Ten facies were grouped, 1, 4, and 5 facies for the Kwahu-Bombouaka Group, the Kodjari Formation, and Pendjari Formation of the Oti-Pendjari Group, respectively. The sediments were deposited rapidly from sediment-laden currents into shallow marine and fluvial environments for the shales of the Pendjari Formation and Kwahu-Bombouaka Group. The sediments of the Kodjari Formation are of marine to deep marine settings. The petrographic compositions of the shales suggest euxinic conditions evolved into oxic conditions and the paleoenvironmental conditions were suitable for primary organic matter (OM) productivity. Pyrite framboid presence supports unaltered OM within the shales. The shales and carbonates contain phytoclasts and palynomorphs with no observable amorphous organic matter (AOM). Although generally in small quantity, the palynomorph content is relatively more than the phytoclast content. Although depositional conditions are dominantly shallow marine–marine, OM preservation was favored in the basin. [ABSTRACT FROM AUTHOR]

Greenstone belt dynamics are a key to understanding the formation and evolution of continental crust but the scarcity, commonly poor exposure, strong deformation, and high metamorphic grades of many Archaean supracrustal rocks preserved in greenstone belts often hinder geological insights. Exceptionally, the largely siliciclastic Palaeoarchaean (ca. 3.22 Ga) Moodies Group, uppermost unit of the Barberton Greenstone Belt (BGB) in South Africa and Eswatini, allows a detailed understanding of regional depositional processes and stratigraphic architecture due to its low degree of deformation, considerable thickness, generally good exposure, and diverse sedimentary facies. We here investigate the Powerline Road Syncline (PRS) and the adjacent Maid-of-the-Mists Syncline (MMS), two east-west-trending, tightly to isoclinally folded, locally northwardly overturned synclines in Moodies Group strata in the central BGB. The northern and southeastern margins of the PRS and the southern to southwestern margin of MMS are bounded by the bedding-parallel 24-Hour-Camp Fault. Along this fault, Moodies Group strata and stratigraphically underlying units of the Auber Villiers Formation of the upper Fig Tree Group structurally overlie lower Fig Tree strata above Onverwacht Group strata. Stratigraphic architecture and palaeocurrent analysis of Moodies Group strata in both synclines document a northeastward (depositionally downdip) facies transition from proximal fan delta conglomerates to fluvial- to coastal-plain and estuarine sandstones in which thick foresets likely represent subtidal channel fills. The overall deepening-and fining-upward trend in this sequence, corresponding to an increasing mineralogical maturity of sandstones, is partially obscured by local hydrothermal alteration which was contemporaneous with sedimentation, minor volcanism, and sill intrusion. Moodies Group conglomerates and sandstones were largely shed from the rising Onverwacht Anticline to the southwest. Lithologies and stratigraphy in the PRS-MMS region closely resemble strata of the lower Moodies Group in the Sadddleback Syncline, located nearby to the north but across the Inyoka Fault. If the 24-Hour-Camp Fault was part of a group of extensional faults accompanying the rise of the Onverwacht Anticline and of tonalitic-trondhjemitic-granodioritic plutons around the BGB margins at ca. 3 224 Ma, it would have acted as one of numerous basin-bounding normal faults during early Moodies time. This would place the deposition of Moodies Group strata in the PRS-MMS region in a supra-detachment fault environment which was subsequently tightly folded. [ABSTRACT FROM AUTHOR]

On Glorieta Mesa in San Miguel County, northern New Mexico, the lower Permian Glorieta Sandstone contains numerous sandstone cylinders from two areas and two stratigraphic intervals of interdunal sedimentary deposits in the lower part of the formation. Most of these cylinders are perpendicular to bedding, although some are slightly oblique to the layers of enclosing sediment. They range in diameter from 2.6 to 43 cm and are as much as 58 cm long. Most of the cylinders have smooth exteriors and, in cross section, have a structureless core surrounded by thin, concentric laminae. Some cylinders taper toward one end, which in situ specimens indicate is the lower end, and some are slightly curved. Some have one or more external grooves that demarcate a helical trajectory of flat to very slightly concave, slightly imbricated surfaces around the circumference of the exterior, sometimes with grooves spiraling in opposite directions. The lack of deformation of the sediment in and around the cylinders and the preservation of the external markings on some of the cylinders preclude their identification as inorganic dewatering structures or other forms of water conduits. Nevertheless, the concentric laminae of the cylinders are likely a diagenetic feature. The sandstone cylinders do not resemble any known cylindrical or plug-shaped trace fossils, and the lack of ornamentation (bioglyphs) on the cylinder walls is one of several reasons that preclude their identification as animal burrows. The most likely origin of these cylinders is as the fill of molds left by plant stems that were buried upright. However, the botanical affinity of these molds and casts is uncertain because they do not contain diagnostic features of anatomy or external morphology. By a process of elimination, the Glorieta sandstone cylinders are most likely to have been produced by woody calamitaleans. [ABSTRACT FROM AUTHOR]

This article studies the sedimentary characteristics and models of the delta and gravity flow system of the third member of the Shahejie Formation in the Niuzhuang Sag area. Through seismic, logging, and core observation methods, a thorough investigation is conducted to examine the lithologic characteristics, grain size characteristics, sedimentary structure characteristics, and sedimentary facies distribution characteristics of this region. The results show that the third middle member of the Shahejie Formation in the Niuzhuang Sag can be classified into four sedimentary types: sliding, collapse, clastic flow, and turbidity flow. This article aimed to establish the distribution characteristics and depositional models of the deltaic and gravity flow depositional systems within the study area. The findings reveal that slip deposition primarily occurs near the delta front, while collapse and clastic flow depositions are concentrated near the far slope. Moreover, turbidity flow deposition is found near the far slope. This study significantly contributes to our understanding of the sedimentary characteristics and models associated with deltas and gravity flow systems in faulted lacustrine basins. Furthermore, it enriches existing theories related to gravity flow and provides a valuable reference for the investigation of deep-water sedimentation in continental faulted lacustrine basins. [ABSTRACT FROM AUTHOR]

This article analyzes the key controlling factors and hydrocarbon distribution rules of lithologic reservoirs in a continental downfaulted basin according to the structural features, sedimentary evolution, types of sedimentary facies, source rock features, diagenesis evolution, reservoir features, hydrocarbon formation mechanisms, exploration status, and hydrocarbon resource potential. The results show that three major controlling factors (sandbody types, effective source rocks, and effective reservoirs) and one coupled factor (fractures that act as a tie) influence hydrocarbon accumulation in the lithologic traps in the Nantun Formation in Tanan Sag. With the increase in depth, sufficient hydrocarbon is generated in the source rock with thermal evolution. When the depth threshold is reached and critical conditions of hydrocarbon supply are met, hydrocarbon generation and expulsion are more intensive. Traps that are surrounded or contacted by source rock or connected by faults are able to form reservoirs. As the buried depth increases, the intensity of hydrocarbon generation–expulsion grows, and the trap is more petroliferous. Hydrocarbon accumulation and reservoir formation are also controlled by sandbody accumulation conditions. When the critical conditions for hydrocarbon generation are met and concrete oil and gas are charged in, the better physical properties of the sandbody will always indicate more hydrocarbon accumulation in the trap. The allocation of sand type, effective source rock, and an effective reservoir is optimized under the effect of fractures and the coupled hydrocarbon reservoir with these three elements. [ABSTRACT FROM AUTHOR]

The Kalumpang Formation was deposited in a delta plain setting. A Middle to Late Eocene age (Proxapertites operculatus zone) was inferred from palynological analysis, with a paleoenvironment in a coastal plain setting with a strong terrestrial influence. Samples from the Kalumpang Formation indicate a marginal to early mature stage for hydrocarbon generation. It is mostly composed of gas-prone to oil and gas-prone Type III kerogen facies. The biomarker character of both the rock and oil samples suggests a terrestrial origin, with a significant contribution of estuarine or bay organic material. The oil derives from a noncarbonate lithology, while the rock samples are from carbonate/calcareous shale origin. The abundance of oleanane compound and C30 resins suggests higher plant angiosperm input of Late Cretaceous or younger age for both the rock and the oil samples. The oil seep contains more abundant oleananes compared to the carbonaceous mudstone of the Kalumpang Formation. This suggests that the oil originated from more marine facies than the rock samples, which were deposited in a delta plain setting. This study demonstrated the agreement of depositional environment interpretation and age assessment between lithofacies, palynological, and organic geochemistry analysis. [ABSTRACT FROM AUTHOR]

To address the challenge of stratigraphic correlation and division in exploration and development caused by the diverse sediment sources, complex internal structure, and rapid lateral changes of gravelly fan deposits in the Guojuzi depression steep slope, a comprehensive technique for sequence-based stratigraphic correlation and division of complex reservoirs has been proposed. This technique includes several aspects such as the methodological basis, correlation method, and modification method. The methodological basis involves multi-well precise calibration of target layers, determination of high-frequency sequence stratigraphy division scheme, and seismic constraints. The correlation method includes several techniques such as stratigraphic correlation under the control of stratigraphic unconformity structure, sedimentary pattern control, facies sequence comparison, marker bed method, and contour stratigraphy correlation. The modification method mainly includes stratigraphic thickness method, fluid property method, and structural method, which are used to correct the results of stratigraphic correlation. Based on this technique, a high-order sequence stratigraphic framework has been established, which involved the precise calibration of target layers using seismic, stratigraphic structure, sedimentary facies, facies sequence, marker beds, and contour constraints, followed by the application of correction methods such as stratigraphic thickness, fluid property, and structural analysis. A total of 26 five-level sequence stratigraphic frameworks have been established through high-frequency sequence correlation. [ABSTRACT FROM AUTHOR]

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Copyright of Coal Science & Technology (0253-2336) is the property of Coal Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Coal Science & Technology (0253-2336) is the property of Coal Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Portus was the main port of imperial Rome from the 2nd century AD to the 5th century AD, with an inner, hexagonal port (Trajan basin) and an outer port (Claudius basin) linked by a channel bounded by quays. Six sedimentary facies have been differentiated in the geological analysis of a core extracted in this channel, basically composed of poorly classified bioclastic muds typical of restricted environments, accumulations of Posidonia oceanica (Linnaeus) Delile, 1813 and a final anthropic fill. The subfossil record of bivalves, foraminifera and ostracods is characteristic of Mediterranean brackish environments (lagoons, estuaries, deltas) with significant environmental stress, due to changes in the physical-chemical parameters and probably the periodic dredging of this seaway during a period of about 300 years. The presence of "Neptune balls" points to the development of probable stormy periods that deposit these unique structures in the internal areas of this historic port. [ABSTRACT FROM AUTHOR]

Cone penetration tests, a method that is typically used to determine the engineering properties of soils, can be used as an effective tool for refined subsurface stratigraphic investigations of alluvial and coastal plains, aside from the geographic location. High‐resolution calibration of piezocone penetration tests (CPTU) with 20 sediment cores enabled the detailed characterization of alluvial, deltaic and coastal depositional systems of the Po Plain. Twelve cored facies associations, typical of alluvial and coastal plain environments, were characterized based on four distinct CPTU profiles: basic cone resistance (Qc), sleeve friction (Fs), water pore pressure (U) and friction ratio (FR). Sandy facies associations (fluvial/distributary channel, bay‐head delta, transgressive barrier, delta‐front/beach‐ridge) typically have high (>4 MPa) Qc, low‐to‐negative U and low (<2%) FR. Muddy deposits (well‐drained/poorly‐drained floodplain, swamp, lagoon and prodelta) exhibit opposite trends. Heterolithic facies associations (crevasse‐levée, offshore/delta‐front transition) display characteristic seesaw profiles. Plotting of late Quaternary deposits onto the latest version of the cone penetration test typical soil behaviour chart (Robertson, 2010) enables the identification of distinctive facies associations reflecting distinctive grain size. CPTU interpretation leads to sedimentary facies recognition well beyond the simple lithological differentiation and, in particular, allows the refined characterization of clay‐rich and silt‐rich depositional units (swamp clays and peats, central‐inner and outer lagoon, proximal/distal prodelta deposits) that exhibit only subtle differences in lithology. CPTU data can also serve for the accurate detection of key stratigraphic surfaces with potential engineering applications, such as the Pleistocene–Holocene boundary. This latter, a common feature of several alluvial and coastal plain successions, is commonly marked by an abrupt upward decrease of basic cone resistance and sleeve friction from Late Pleistocene, pedogenized, stiff strata to overlying Holocene, organic‐rich, soft deposits. This study offers an updated CPTU‐facies characterization method that could be suitable for subsurface investigations of modern alluvial and coastal plains worldwide. [ABSTRACT FROM AUTHOR]

This study examines both vertical and lateral facies changes as well as petrographic characteristics of the outcropping section of the Upper Cretaceous Shendi Formation in the Musawwarat-Naga area with a view of interpreting the depositional environment, provenance, and tectonic setting that prevailed during the deposition of the sediments. Field studies revealed the presence of eight different sedimentary lithofacies. The predominant is the trough cross-bedded sandstone facies (St), representing 75% of the total succession. Four architectural elements were recognized: sandy bedforms (SB), channel fill (CH), gravelly bars and bedforms (GB), and overbank fines (OF). Moreover, the mean value of paleocurrent directions was 285.3°, suggesting a southeasterly located source area. The majority of the sandstones were classified as quartz arenites with subordinate sublithic-arenites. Ternary plots of quartz-feldspar-lithic fragments (QFL) revealed that the tectonic setting is predominantly within the interior craton. It can be suggested that the sediments were sourced from the southeast region and associated with a braided, proximal, fluvial depositional environment. The results of this study provide outcrop analog data that might be useful in exploring hydrocarbons. Specifically, it can enhance the understanding and prediction of the proximal fluvial depositional styles in the subsurface deposits in the Shendi-Atbara Basin and similar rift basins in Sudan and Africa. [ABSTRACT FROM AUTHOR]

The Cretaceous ocean was significantly different from its modern counterpart due to its ice-free condition. Deep waters were primarily sourced by evaporation at the ocean surface, although their circulation pattern and bottom-current dynamics have been largely unknown. Here we present a study of deeply buried contourite drifts in the southern proto--Bay of Biscay to unravel the circulation pattern of the mid- and Late Cretaceous deep waters across the northeast Atlantic. The generation of plastered drifts (120 Ma to 100--90 Ma) and a mounded drift (100--90 Ma to 65 Ma) suggests that a significant change in deep-water source regions from the Tethys to the high-latitude region occurred at ca. 100--90 Ma. These contourite drifts were buried after ca. 65 Ma when the Cretaceous ocean circulation transitioned to the Cenozoic style in the northeast Atlantic. Tectonic configurations of the Pyrenean and the Equatorial Atlantic gateways were moreover tied to significant changes in northeast Atlantic deep-water circulation at ca. 100--90 and ca. 65 Ma. Northeastern Spain and France might be potential sites for the detection of Late Cretaceous contourite outcrops. These outcrops could have fundamental implications for the sedimentary facies and sequence model of contourites as well as shed light on the paleoceanography and paleoclimate of Cretaceous Earth. [ABSTRACT FROM AUTHOR]

Sedimentary facies, petrography, paleocurrent data and palynological biofacies were employed to determine the paleoenvironments, stratigraphy and paleogeographic setting of sediments in the southern Bida Basin, Nigeria. Two components of Upper Cretaceous lithostratigraphic units were identified: the Lokoja Formation (Campanian) and Patti Formation (Maastrichtian). Results of the sedimentary facies analysis revealed seven lithofacies grouped into subtidal/foreshore, estuarine mudflat and central estuarine delta facies associations. The lithofacies show estuarine tidal channels, central estuarine and littoral foreshore-upper shoreface settings. The palynological investigation revealed the lack or little abundance of the dinoflagellates and abundance of sporomorphs in mudstone and shale facies of the Lokoja and Patti Formations respectively. The mudstones and greyish shale facies of the Patti Formation marked a late Campanian marine transgression that extended into the Mid-Maastrichtian in the Patti Formation. Petrofacies analysis identifies the sandstones as feldspathic and arkosic arenites. The paleocurrents for the cross-stratified sandstones indicate southwest and northwest flowing fluvial/tidal systems. The sediment sources are near, probably from the Benue Trough, north-central and southwest Basement Complex rocks of Nigeria, respectively. A new understanding of the sources of sediment inputs and flux into the basin as well as the contemporary palaeogeographical setting of the southern Bida Basin has been gained through the integration of sedimentary facies, petrography, palynomorphs, and paleocurrent data in the study sections of the Agbaja axis. The direction of palaeocurrent flow for the subtidal sandstone facies of the Lokoja and Patti Formation in the Agbaja Plateau/Agbaja-Ahatu-Ibaru axis of the basin has thus been determined by these new findings to be a north-western and southwestern distributary pattern in a mixed depositional setting. [ABSTRACT FROM AUTHOR]

Based on the analysis of lithology, lithofacies combinations, sedimentary structures, and fossil types in five geological sections measured through fieldwork, this paper comprehensively elucidates the sedimentary evolution characteristics of the Jurassic period in the South Qiangtang area. The South Qiangtang Basin is renowned for preserving the most complete Jurassic marine sedimentary strata in China, and it primarily consists of a mixed platform environment of carbonate and clastic rocks. The Jurassic strata in the South Qiangtang Basin range from the Quse Formation at the base to the Suowa Formation at the summit, with sedimentary facies evolving from the outer shelf to the subtidal zone, and seawater depth gradually becoming shallower. This trend may be associated with the division and expansion of the Bangong–Nujiang suture zone during the Late Triassic, subduction in the Middle Jurassic, and the suture and splicing of the Qiangtang–Lhasa plate during the Late Jurassic tectonic movements. In conclusion, this research presents a comprehensive analysis of the sedimentary evolution of the Jurassic period in the South Qiangtang Basin for the first time. The findings offer significant contributions to the understanding of the region's geological history and serve as a valuable foundation for future investigations. [ABSTRACT FROM AUTHOR]

Bottom currents are key processes that contribute to the shaping of submarine slopes, with the redistribution of sediments in contourite systems. Despite numerous recent studies on contourite systems, the complexity and diversity of these sedimentary systems are still not fully understood and often underestimated. Their understanding requires comprehensive works integrating all scales from seismic architecture to microfacies. This paper focuses on a contouritic ridge located between 2000 m and 2500 m water depth on the Mozambique margin. Bathymetry, seismic data and piston cores collected during the PAMELA‐MOZ3 cruise allow a multi‐scale study from large depositional geometries to sedimentary facies. At the seismic scale, the contouritic ridge shows three stages of evolution with: (i) initiation and development of the drift/moat system; (ii) an intermediate stage with successive incisions and aggradations; and (iii) moat infill and drift erosion during the Plio‐Quaternary. Plio‐Quaternary deposits are composed of hemipelagic, turbiditic and contouritic facies filling the moat. Coarse‐grained contouritic facies, dominated by planktonic foraminifera, are identified on the western flank of the ridge between the moat infill and the erosional area at the top of the ridge. They consist of condensed deposits, with sedimentation rate about 0.3 cm/ka, indicating a strong and stable bottom current that winnows away the fine‐grained component. This facies could be present more generally in an intermediate position between erosion and depositional areas in contourite systems. At present, the contourite system is located at the transition depth between North Atlantic Deep Water and Antarctic Intermediate Water. Trajectories of bottom currents are complex and interact with sporadic turbidity currents and anti‐clockwise eddies that participate in reshaping the sea floor morphology. Although Plio‐Quaternary depositional geometries indicate the end of drift/moat development, the moat filling and drift erosion are also related to bottom currents and constitute atypical contouritic sedimentation. [ABSTRACT FROM AUTHOR]

An integrated study of sediments was conducted to examine the facies architecture and depositional environment of the Cretaceous Pab Formation, Rakhi Gorge, and Suleiman Ranges, Pakistan. This research focused on analyzing architectural elements and facies, which are not commonly studied in sedimentary basins in Pakistan. To identify lithofacies, outcrop analysis and section measurement were performed. The identified lithofacies were then categorized based on their depositional characteristics and facies associations, with a total of nine types identified within a stratigraphic thickness of approximately 480 m. These facies were mainly indicative of high-energy environments, although the specifics varied by location. Sedimentary structures such as planar and trough crossbedding, lamination, nodularity, load-casts, and fossil traces were found within these facies, indicating high-energy environments with a few exceptions in calm environments. The identified facies were grouped into seven architectural elements according to their depositional environments: delta-dominated elements, including laminated shale sheet elements (LS), fine sandstone elements (SF), planar cross-bedded sandstone elements (SCp), trace sandstone elements (ST), and paleosol elements (Pa); and river-dominated elements, including trough cross-bedded sandstone elements (SCt), channel deposit elements (CH), and paleosol elements (Pa). These architectural elements, along with their vertical and lateral relationships, indicate a transitional fluvio-deltaic environment within the Pab Formation. In conclusion, by interpreting facies and architectural elements, it is possible to gain a better understanding of the depositional history of the formation and the distribution of reservoir units. [ABSTRACT FROM AUTHOR]

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During the early Bajocian, a conspicuous coal-bearing siliciclastic succession was deposited in the northern Tabas Bock, which is important for understanding the regional geodynamics of the Central-East Iranian Microcontinent (CEIM) as well as for the Jurassic coal genesis in this part of Laurasia. Sedimentary facies analysis in a well-exposed section of the lower Bajocian Hojedk Formation (Kalshaneh area, northern Tabas Block) led to the recognition of ten characteristic sedimentary facies and three facies associations, representing channels with point bars and floodplains of a Bajocian meandering river system. Modal analysis indicates that the mature quartz arenites and quartzo-lithic sandstones of the Hojedk Formation originated from the erosion and recycling of older, supracrustal sedimentary rocks on the Yazd Block to the west. The coal petrography and maturity show an advanced maturation stage, whereas the great thickness of these continental strata points to a pronounced extension-related subsidence in the northern Tabas Block. The rapid rate of differential subsidence can be explained by accelerated normal block-faulting in the back-arc extensional basin of the CEIM, facing the Neotethys to the south. Compared to the thick Jurassic, the post-Jurassic strata are relatively thin and played a limited role in the thermal history of the coal in the northern Tabas Block. A relatively high geothermal gradient in the tectonically highly mobile area of the northern Tabas Block and/or heating by regionally widespread Palaeogene intrusions were most probably the key drivers of the thermal maturation of the Middle Jurassic coals. [ABSTRACT FROM AUTHOR]

Sandbody distribution patterns and controls are the most important foundation for petroleum exploration and development, particularly in a lacustrine basin with rapid changes in the sedimentary environment. To provide sedimentologists and petroleum geologists around the world with an analogue for sandstone reservoir prediction, the sedimentary facies of the fourth member of the Shahejie Formation (Sha-4 Member) in the Huimin Depression of the Bohai Bay Basin were analyzed, and the sequence stratigraphic framework was established based on characteristics of spontaneous potential logs and lithology. According to the findings of this study, the Sha-4 Member's sedimentary environment was dominated by delta front and shallow lake facies. Delta front sandbodies were discovered to retrograde before prograding again throughout the established profile. The Sha-4 Member in the Huimin Depression is divided into a third-order sequence (LSC1), which can be further divided into four fourth-order sequences (MSC1 to MSC4), corresponding to the four sub-members (S4-1 to S4-4). During the development of the MSC1 to MSC4 sequences, the delta depositional scale first decreased and then increased with the changing base level. The maximum flooding surface developed within the MSC3 sequence. The Sha-4 Member sequence model reveals that the deltas in the study area exhibit self-similarity, and delta sandbodies are primarily developed in the MSC1, MSC2, and MSC4, whereas mudstone is largely developed in the MSC3. [ABSTRACT FROM AUTHOR]

Sediments from the mountain are transported downstream and accumulate in basins by river systems. Sediments routing through the network of rivers display downstream grain size fining due to sorting and abrasion. The riverbed sediments rapidly change from gravel to sand over a short downstream distance, the grain size transition from gravel to sand along rivers is termed the gravel-sand transition (GST). GST is preserved in the stratigraphy as the conglomerate-sandstone transition. Previous studies demonstrate that GST is a universal sedimentary facies symbol in spatial and temporal evolution of sedimentary basins, and it has tectonic and climatic implications. The controlling factors of the positions of GST and their geological implications from the existing related studies were summarized and reviewed. The reconstruction of the spatial and temporal evolutionary history of GST within the sedimentary basins reflects that the position of GST in a sedimentary basin succession is determined by basin subsidence rate, sediment supply flux, and grain size distribution of sediment supply, and the geological implications of GST in different basin-mountain backgrounds are entirely different. The horizontal migration of GST relative to the basin reflects the changes in basin subsidence rate or sediment supply flux decided by tectonic or climate changes, when the basin is fixed relative to the mountain. The migrations of GST within the convergent foreland basin-orogen systems reveal the convergence processes between the basins and orogens, and the migration rates of GST provide a potential proxy for long-term crustal shortening rates in the systems. [ABSTRACT FROM AUTHOR]

Turbidity currents commonly bypass sediment in submarine channels on the continental slope, and deposit sediment lobes farther down-dip on the flat and unconfined abyssal plain. Seafloor and outcrop data have shown that the transition from bypass to deposition usually occurs over complex zones referred to as channel–lobe transition zones (CLTZs). Recognition of these zones in cores and outcrop remains challenging due to a lack of characteristic sedimentary facies and structures. This paper focuses on Unit E of the Permian Fort Brown Formation in the Karoo Basin, South Africa, in the Slagtersfontein outcrop complex, which has previously been interpreted as a CLTZ. This study integrates thin-section micrographs, sedimentary facies, bed-set and stratigraphic architecture, and palaeoflow directions to achieve a multiscale analysis of CLTZ features. A novel process-based facies scheme is developed to evaluate deposits in terms of the depositional or erosional tendencies of the flows that formed them. This scheme allows bypass to be distinguished from depositional zones by the spatial distribution of certain sediment facies. Areas of net sediment bypass were predominantly marked by erosive sediment facies and a larger variability in palaeoflow direction while depositional areas showed a lower variability in palaeoflow directions. Metre-scale structures in the bypass-dominated area reveal seafloor erosion and scour formation. Field relations suggest the presence of a ∼500 m long mega-scour in the CLTZ. The characteristic structures documented here are applicable for identifying CLTZs in sparse datasets such as outcrops with limited palaeogeographical context and sediment cores obtained from subsurface systems. [ABSTRACT FROM AUTHOR]

Copyright of BSGF: Earth Sciences Bulletin is the property of EDP Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)