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The West Bogda Mountains separate the two largest petroliferous sedimentary basins in Northwest (NW) China and may record the evolution history of the Central Asian Orogenic Belt (CAOB). The timing of the initial uplift of the West Bogda Mountains is debated, which may provide the robust constraint on the CAOB evolution. Here we present an integrated study of sedimentology, geochemistry, and detrital zircon geochronology to constrain the timing of the initial uplift of the West Bogda Mountains. The late Lower Permian Lucaogou Formation in the West Bogda Mountains is dominated by organic-rich laminated shale, gravity flow deposits and dolomite without shallow-water sedimentary structures, suggesting a deep-water lacustrine depositional environment. The Middle Permian Quanzijie Formation is mainly composed of poorly sorted and sub-rounded conglomerate, which indicates that the depositional environment changed to an alluvial fan. The depositional environment changed to a meandering river system in the early Upper Permian Wutonggou Formation, with evidence from the widely developed cross-bedding in its sandstone and the typical 'dual structure'. The compositions of immobile elements and detrital zircon U-Pb geochronology reveal changes in sediment sources from the early to late Permian. The sediments of the late Lower Permian Lucaogou Formation were mainly sourced from the North Tianshan, while the sediments in the Middle Permian were mostly locally derived. Combining these evidences, we infer that the initial uplift of the West Bogda Mountains likely occurred in the period from the late Lower to Middle Permian (~289.8 Ma to ~265.7 Ma), and was probably caused by the intracontinental collision between Junggar Block in the north and the Tarim Block in the south. [ABSTRACT FROM AUTHOR]

The formation of vertical sedimentary succession of a delta in the arid and semi-arid basin-margin progradation dramatically depends on the variation of sediment flux and accommodation, but the discontiguous record of signals tends to exist enormously variable, which renders the bulk record of microfacies difficult to quantify from the vertical sedimentary succession. We analyzed the 18 vertical sedimentary successions collected from 18 field trenches of a lake delta by the cusp-catastrophe model, allowing detailed mapping of microfacies. The present detailed study indicates the suitability of cusp-catastrophe theory for explaining vertical sedimentary succession in the BWH (Bawanghe) delta. Three equilibrium states of processes responsible for the deposition of the BWH delta's evolution were established: sandy-dominated upper leaves primarily exhibit the delta plain; sandy/muddy-dominated lower leaves present the delta plain and pro-delta; and sandy-dominated middle leaves which commonly developed the delta front. The result of analysis shows that the reliability of the cusp-catastrophe model to identity mutation of vertical sedimentary succession exceeds 50 %, and to identity microfacies transitions with a precipitation periodicity exceeds 70 %. These cognitions support the previous view that changing precipitation results in an abrupt change in margin progradation. Simultaneously, the study gives new insights into the microfacies quantification of lake deltas and reveals the influence of crest value changes of precipitation on vertical sedimentary succession can be understood from the dependence of microfacies distribution on the change of sediment flux and accommodation. [ABSTRACT FROM AUTHOR]

Although volcanism is an important process in the evolution of rift basins, current tectono‐sedimentary models largely neglect its impact on sediment supply, transport pathways, and depositional systems. In this paper, we integrate core, well logs, and 3D seismic data from the Palaeogene‐Neogene Shaleitian (SLT) uplift and surrounding sub‐basins, Bohai Bay Basin, China, to investigate the sedimentology and geomorphology of a volcanic rift basin. Results of this study show that the spatial distribution of extrusive centres was strongly controlled by basement‐involved intra‐basin normal faults. During the early part of the syn‐rift stage, the SLT uplift supplied sediments to transverse fan deltas and braided‐river deltas that fringed the adjacent syn‐rift depocentres. Volcanic deposits mainly occurred as relatively thin lava flow and pyroclastic facies that partially filled fault‐controlled topographic lows, reducing topographic rugosity, and enhanced breaching of basement highs between syn‐rift depocentres. Integration of drainage to the syn‐rift depocentres and development of through‐flowing axial depositional systems was enhanced. During the later part of syn‐rift and in early post‐rift stages, the SLT uplift was progressively inundated, reducing sediment supply to the fringing transverse depositional systems. In contrast, axial braided‐river deltas became the main depositional systems, sourced by large hinterland drainage from the Yanshan fold‐belt to the northwest. Volcanism in the late syn‐rift and early post‐rift occurs as thick lava flow and pyroclastic facies that infill rift topographic lows and locally blocked axial fluvial systems creating isolated lakes. Within hanging wall depocentres, volcanic topographic highs split and diverted axial fluvial and deltaic systems. Furthermore, volcanism supplied large volumes of volcanic sediment to the rift resulting in increased sedimentation rates, and the development of unstable subaerial and subaqueous slopes and deposits, increasing the occurrence of landslides. Based on the observations of this study we update tectono‐sedimentary models for rift basins to include volcanism. [ABSTRACT FROM AUTHOR]

Liaodong Bay Depression is a strike‐slip basin with complex tectonic movement that lead the source‐to‐sink (S2S) systems evolution vary greatly in temporal and spatial characteristics. This study explored the sedimentary characteristics, dispersal patterns, and pathway formation in Liaodong Bay Depression, as well as their controlling factors. We selected more than 10 pathways with north‐west and north‐east directions in Liaoxi Sag in the western part of Liaodong Bay Depression, a typical strike‐slip bet controlled graben, to investigate their S2S system distribution. By combining seismic data, we divided the strike‐slip fault bends into three stress setting parts, namely, a central restraining bend, which is the fault translation part, and two releasing bends in the southern and northern of fault terminals. As the heavy mineral assemblage and clay content in the west side of Liaoxi Sag differs from that in the east side, we put forward an S2S index to show the sediment transport distance according to the data we have obtained. Using this index, we recovered the dispersal pattern and pathway development and speculated on the sedimentary provenance. In the restraining bend, we recognized that the pathways mainly show a symmetrical "V" or "W" shape with unclear erosion boundaries and were dominated by filling processes. Considering the heavy mineral assemblage data, we also found that the sediment provenance area decreased and the sediment provided direction transferred from the two‐side provenance to one. Combining the fast sedimentary rate calculated with clay content data, the S2S systems in this area were steep–wide–deep systems and a wide and shallow system. In the releasing bend, the pathways show an asymmetrical "V" or "W" shape and a clear erosional boundary. As shown by the heavy mineral assemblage data, the sediments from these areas mainly have a west side provenance and were deposited in the proximal area. Thus, the S2S system in this area is a kind of steep–deep system. Then, the investigation by integrated of tectonic movement and S2S geomorphic statistical parameters revealed that the elevation height of the S2S is a key factor in control pattern development. The various evolution patterns within the two different stress settings provide insights into the formation process of the S2S developed in a strike‐slip tectonic belt. [ABSTRACT FROM AUTHOR]

This paper investigates the reservoir characteristics of deep-water lacustrine-delta sandstones in the Upper Triassic Yanchang Formation in the western Ordos Basin, north-central China. The Yanchang Formation has previously been interpreted as a shallow-water lacustrine deltaic succession, and this interpretation has been used to guide petroleum exploration activities which have however met with only limited success. The present study integrates thin-section, wireline log, X-ray diffraction and SEM data from wells in the western Ordos Basin to determine the sedimentary and diagenetic characteristics of sandstones in the C6 and C4+5 sub-members of the Yanchang Formation, and to interpret the units' depositional environment. The C6 and C4+5 sub-members in the study area are composed of: mudstones and fine-grained sandstones, which are interpreted as deep-water pro-delta deposits; laterally-extensive sand sheets (outer delta-front deposits); and small-scale distributary channel and mouth bar sandbodies (inner delta-front deposits). The sandstones have reservoir potential but diagenesis has had a range of effects on reservoir quality. Compaction together with cementation by calcite and clay minerals including chlorite and kaolinite may have affected pore throat geometry and permeability adversely. However dissolution of feldspars and calcite cement created secondary porosity. Hydrocarbon accumulations may occur in delta-front channel and mouth bar sandbodies. Core studies show that some sandstone intervals have relatively good reservoir properties with porosity up to 15% and permeability up to 9mD. [ABSTRACT FROM AUTHOR]

Abstract: Although there are widespread indications of oil and gas in the Chang 6–4+5 layer of western Mahuang Mountian, well test proves that there is more water and less oil with the distribution and continuity of sand being not yet clear. To understand the distribution and evolution of sedimentary microfacies in the area, six kinds of sedimentary microfacies and ten kinds of sedimentary structures were identified, and ten patterns of contact between microfacies and five kinds of sedimentary sequence model were summarized through detailed observation and description of the core of rock and logging data. Each model represents different sedimentary facies. Reversed cycle is dominant and normal short-term cycle also exists in the vertical direction; Mouth bar and subaqueous distributary channel developed alternately in the lateral direction. The lower channel sand is “large in quantity but small in size with the layer narrow and thin”, whereas the upper sand is “few in quantity but large in size with a wide and thick layer”. The “single-factor analysis and multifactor comprehensive” research method was used to divide this area into three phase belts—delta inner front, delta outer front, and predelta. Subaqueous distributary channel, distributary mouth bar, and interdistributary deposits are prevailing in the delta inner front. Distal bar and sand sheet are dominant in the delta outer front, and predelta mud is dominant in the predelta. According to modern sedimentary facies model, the area is a constructive braided river-lake delta. Three stages appeared in its evolution: the initial development period (Chang 63), in which the predelta and the delta outer front are the main facies belts; the early-middle development period (Chang 62–Chang 61), in which the inner delta front and the delta outer front dominates and each micro-facies is a single phase and is deposited alternately; the middle-late development period (Chang 4 +52–Chang 4 +51), in which the delta inner front dominates and subaqueous distributary channel shows multiphase stacking pattern. [Copyright &y& Elsevier]

The article presents a study which aims to determine the Cretaceous shallow- water delta in the Songliao Basin, China. The study suggests that the shallow-water deltas were developed commonly in lake basins under a comparatively stable tectonic setting, shallow water depth, gentle slope having low subsidence rate, a frequently fluctuating lake level, open lake basin characteristics and sufficient sediment supply.

With the aid of modern sedimentology, seismic geomorphology, and the comprehensive analysis of geophysical data and core data from more than 10 wells, the Qingshankou Formation has been divided into 3 long-term cycles and further into 6 medium-term cycles in the Qijia area, Songliao Basin. The 3 long-term cycles, SQ1, SQ2 and SQ3 correspond to the members Qing I, Qing II and Qing III of the Qingshankou Formation, spanning 11.5 Ma during the Late Cretaceous. The time scale of the medium-term cycles, which are subunits of the long-term cycles, is approximately 0.5–1.5 Ma with thicknesses ranging from 45 m to 116 m. A shallow-water delta that consists of high-maturity fine-grained sandstone developed in the Qingshankou Formation. The scour surfaces reflect strong flow action, and the parallel bedding and large-scale cross bedding are well developed. Distributary channel sandstones are well developed in the shallow-water delta depositional system, in which a single channel can be several meters thick. The cumulative thickness of the distributary channels can reach tens of meters across a large area, extending tens of kilometers to the center of the lacustrine basin. The development of the subaqueous distributary channel of the shallow-water delta is closely related to base level (lake level) changes. In the early stage of a rising half-cycle and the late stage of a falling half-cycle, the fluviation is significant and the well-developed channel sandstone can extend towards the center of the lacustrine basin more than 50 km, with large cumulative thicknesses of compound sandbodies (17–28 m) and high sandstone-to-strata ratios (78–88%). In the late stage of a rising half-cycle and the early stage of a falling half-cycle, the lake level is high and the fluviation is weak, resulting in a distributary channel extent of less than 30 km, small cumulative thicknesses of compound sandbodies (5–12 m) and low sandstone-to-strata ratios (22–45%). The delta front can be divided into the inner front and the outer front. The subaqueous distributary channels in the inner front have good continuity and extend further, whereas the subaqueous distributary channels in the outer front have poor continuity, and sheet sand is well developed. Therefore, a shallow-water delta generally shows features including (1) sedimentary structures formed by strong currents, (2) stacked fining upward rhythm, (3) subaqueous distributary channels well developed, (4) delta front divided further into an inner and an outer front. There was a relatively good linear relationship between the thickness of the sandbody based on the well data and the maximum amplitude of the seismic trace next to the well. The reddish amplitude of the seismic attribution suggests thicker channel sandbodies (4–9 m), whereas the light amplitude of the seismic attribution indicates thinner channel sandbody (1–4 m). Of the two typical sedimentary models for shallow-water deltas, delta plains develop well in humid climates and delta fronts develop well in arid climates, both of which are found in the Qijia area, Songliao Basin. Stratal slices from seismic geomorphology are applied to display the branchlike sandstone dispersal patterns of the shallow-water delta and the broad distribution characteristics. This study also notes that the delta front distributary channel sandstone, which is near an oil source and faults, would be a favorable exploration target. [ABSTRACT FROM AUTHOR]

Organic mudstone can be a high-quality source rock in petroleum basins. The accumulation patterns of various types of mudstone can also serve as a useful record of paleogeography. Due to the impact of tectonic movements, the East China Sea Basin (ECSB) saw its deposition setting transform from closed-lacustrine to open marine settings. This provides an opportunity to explore organic matter accumulation patterns within such a transformation setting. This study classified the constituent mudstones according to their differences in composition and sedimentary structure as follows: coaly mudstone or carbonaceous mudstone, calcareous mudstone, clayey mudstone, and siliceous mudstone. Considering the different sedimentary structures, siliceous mudstone can be subdivided into laminated, wavy, and slumped mudstones. Using integrated multiple indices of the paleo-environment, which includes clay mineral content, trace mineral content, and micro-paleontology assemblages, we reconstructed the paleography setting during the Paleocene and inferred that during this time, the ECSB was characterized by sedimentary differentiation. We discerned two different organic mudstone accumulation patterns by combining the results from rock-eval pyrolysis and paleo-environmental indices: 1) A closed-lacustrine mudstone accumulation pattern characterized by abundant sediment supply and dominated by allogenous mudstone formation by the flocculation process. The fresh to slightly salty water environment provided adequate nutrition to microorganisms and an appropriate temperature led to the increased accumulation of type II 1 and II 2 kerogen. 2) An open-marine mudstone accumulation pattern which revealed a sediment-starved setting. The flocculation process and fine-graded turbidities were the main processes leading to mudstone accumulation. More plants were concentrated in shallow water with declining salinity, leading to peat and mass carbon mudstone accumulation. • Classified the mudstone into six types according to its genesis difference. • Build the relationship between the paleo-environment and the abundance/types of organic matters. • Restore the mudstone distribution and the sedimentary facies association evolution process. • Put out the organic matter accumulation pattern in the transition setting. [ABSTRACT FROM AUTHOR]

Developed on the North China Craton, the intracratonic Ordos Basin contains a complete Paleozoic-to-Cenozoic sediment record, allowing for long-term paleoenvironmental and climate change investigation. During the Carboniferous–Permian period, convergence between the North China block and the paleo-Yangtze plate to the south resulted in a general marine regression characterized by a series of second-order transgression/regression cycles diachronous along the eastern margin of the Ordos. However, the detailed mechanisms that induced these cycles, as well as the associated paleoecological changes, remain unknown. In this study, we integrate multiple indices, including δ18O and δ13C, rare earth element (REE), paleontological assemblages, and clay content (w (chlorite + kaolinite)/ w ((Illite) ratio) planar distribution, to restore the paleo-water depth distribution. These parameters are then used to reconstruct the paleo-sea level from the Pennsylvanian to the middle Permian. We conclude that the direction of second-order transgression/regression was mainly toward the east during the Pennsylvanian–early Permian and switched clockwise toward the north during the middle Permian. We suggest that the second-order cycles, diachronous in space and time, are mainly linked to local variations in sediment supply and regional uplift. Using detrital zircon U–Pb data and the REE and trace element content and heavy mineral assemblages (HMA), we estimate the sediment provenance area. The sediment volumes deposited in the basin through time are obtained using 2D seismic data. During the Carboniferous, the coarse-grained sediments deposited in the eastern Ordos were derived from the uplifting Helan Mountain (Qiandam–Qilian orogenic belt). By the middle Permian, the detrital material became multi-sourced, thus issuing the Yinshan range to the north and the Qinling range to the south. We then integrate the description of numerous core samples with electric log and 2D seismic data to reconstruct the sediment facies associations across the first-order regression from the Carboniferous tidal flat depositional system to the middle Permian prograding fluvial delta system. According to the transfer of the glacial epoch, the sedimentation rate, and the transgression/regression rate above, we classify the evolution process into three patterns: low-transgression rate and less-sediment supply pattern (the late Carboniferous), high regression rate and mass sediment supply pattern (the north block during the early Permian), and low regression rate and mass sediment supply pattern (the south block during the Sakmarian stage). Lastly, with the quantitative calculation of the source-to-sink (S2S) parameters, including the S2S system volume and the elevated height of regional uplift with the 2D seismic data, we propose the mechanism of transgression/regression in the Ordos Basin, responding to the above three pattern s. The first pattern was controlled by regional uplift, whereas the second pattern was controlled by sediment supply. As to the third one, uplift and sediment supply could affect the transgression/regression process. • Identified provenance area of the eastern margin of the Ordos Basin during the Pennsylvanian to the early Permian. • Reconstructed the clockwise evolution process of the relative sea level in the study area. • Identified different types of source-to-sink systems insight from the sea level and sediment supply. • Proposed an integrated method to determine the dominating factors influencing the relative sea level. [ABSTRACT FROM AUTHOR]

Sedimentary features of a source-to-sink (S2S) system produce distinct responses to diverse bedrock types (i.e., silicate and carbonate rocks) in the catchment; these majorly influence the sediment flux, volume, and grain size in the sink area. By comparing a modern S2S system of Holocene Erhai Lake Basin (ELB) (in southwestern China) and an ancient S2S of Eocene western Offshore Bohai Bay Basin (OBBB) (in eastern China), we investigated the differences and proportional ranges among sandy sediment flux (Q f) and sediment discharge (Q s) from catchment associated with diverse bedrock types in a humid and subtropical lacustrine rift basin by combining with the Google-topographic-map, BQART-model, and seismic-geomorphology analysis. Based on geomorphological and 3D visualization analysis, we identified the differences among multiscale catchment-fluvial segments and their sedimentary responses in S2S systems, and then extracted parameters of catchment-unit area (A), catchment relief (R), and total sediment discharge (Q s , calculated by BQART model). Furthermore, we analyzed sediment-dispersal patterns and sandy sediment fluxes in the nearshore (Q f) using regional geologic data, outcrops and the Google Earth database in the Holocene ELB, and using seismic geomorphology in the Eocene western OBBB. Finally, quantitative analysis of the modern and ancient S2S segments was used to investigate the total sandy sediment flux (Q f), which is supplied by >60% of the entire sediment discharge (Q s) for catchments with silicate bedrocks (e.g., metamorphic rock and granite), while the ratio Q f /Q s corresponding to carbonate bedrocks is less than 30%. Additionally, the ratio Q f /Q s for catchments with mixed silicate carbonate bedrocks ranges between 30% and 60%. These results not only provide a new perspective for investigating sandy sediments in a subtropical lacustrine rift basin, but also yield implications for better understanding of continental S2S system theory for diverse bedrock types. • Divide the modern and ancient source-to-sink (S2S) segments into multi-order catchment units and fan-lobes. • Extract the kernel parameters of sediment discharge from catchments and sediment flux of proximal fans. • Discuss the proportional range between sandy sediment flux and sediment discharge associated with diverse bedrock types. • Establish a flux model of source-to-sink segments with diverse bedrock types in subtropical lacustrine rift basins. [ABSTRACT FROM AUTHOR]

During the Eocene, the western Shaleitian Uplift and its adjacent sags constituted a source-to-sink (S2S) system on an active lacustrine basin margin with a steeply dipping boundary fault. We integrated a range of data types with subsurface observations from the western offshore Bohai Bay Basin (OBBB) that allowed us to quantify the size and classification of catchment-fluvial segments, and analyze the sedimentary architecture and sediment fluxes of the proximal fan-delta system. We then discovered quantitative coupling relationships among the parameters of ancient source-to-sink segments. Results show that in the study area the bedrock of the western Shaleitian Uplift is composed of Proterozoic migmatized granites or granites. On the basis of paleogeomorphology reconstruction, we established classification standards for multi-scale catchment units, divided the provenance into four third-order catchment units, obtained quantitative parameters of the catchment-unit area (A), catchment relief (R), and total sediment discharge (Q s , calculated by BQART model) and then confirmed the scales and distribution (cross-sectional area, S cs) of sediment-transport pathways. Furthermore, we analyzed tectonic subsidence, sediment-dispersal patterns, and sediment fluxes of fan-delta systems (Q f) using seismic sedimentology in the third member of the Eocene Shahejie Formation (Es 3). Finally, we used quantitative, multivariate, statistical analysis of the parameters involved in the source-to-sink segments to (1) show the proportional range between total sediment fluxes of fan delta (Q f) and sediment discharge (Q s) from catchment (largest rate of Q f /Q s in the lower part of Es 3 , smallest rate of Q f /Q s in the middle part of Es 3 , and the range from 30% to 70%) and (2) arrange the mainly controlled parameters in terms of their importance (i.e., rate of tectonic subsidence, catchment area, catchment relief, and cross-sectional area of sediment-transport pathway are listed in order of importance). This study can provide an effective way of quantifying and ordering the parameters important in that controlling a complex ancient source-to-sink system, thus helping to achieve an understanding of the process of tectono-sedimentary evolution on a rifted, lacustrine-basin margin. • Divide the catchment segment into different orders and pick up the main parameters. • Indicate the sediment-dispersal patterns and sediment flux of fan-deltas in an active extensional setting. • Reveal the correlation and ordering of multiple important parameters of ancient source-to-sink in a rift basin margin. [ABSTRACT FROM AUTHOR]

In multi-phase rift basins, the links between fault activities and sequence stratigraphic architectures are still poorly understood compared to single-rift basins. The purpose of this work is to give implications for tectono-stratigraphic signatures in multiphase rifts based on seismic data from the Zhu-3 Depression in the Pearl River Mouth Basin, China. Stratigraphically, three composite sequences (CS1-3) defined by major unconformities in the Paleogene successions of the Zhu-3 Depression are interpreted, with each one subdivided into two or three third-order sequences. Regional unconformities and basin configurations indicate two episodic rift phases, termed rift phase 1 (formed CS1), and rift phase 2 (formed CS2) followed by a lithospheric breakup phase (formed CS3). From rift phase 1 to rift phase 2, the basin evolved from small-sized, independent half-grabens into relatively large-scale grabens and finally a dish-like basin configuration. Fault displacement and stratigraphic stacking patterns revealed three distinctive structural stages of rift phase 1: rift initiation (WC-SQ1), rift development (WC-SQ2), and rift termination (WC-SQ3) stages. However, an immediate decrease in fault activity was recorded in the rift phase 2. Immediate strain localization under rotated extension fields during episodic rift phases led to variabilities in tectono-stratigraphic architectures. In turn, this transition may likely contribute to interpreting the depositional pattern from balanced infill during rift phase 1 to an overfilled pattern during rift phase 2 as well as the breakup stage in response to possible enhanced sediment supply. This work enhanced our understanding of additional hydrocarbon evaluations in the Zhu-3 Depression, South China Sea. • The Eocene-Oligocene sequence framework in the Zhu-3 rift are systematically reported. • Fault pattern, basin geometry and drainages basin in episodic rift phases are illustrated. • Tectono-stratigraphic signatures of three rift cycles in the Zhu-3 rift are proposed. • Controls of boundary fault arrays evolution on two-phase rift development are discussed. [ABSTRACT FROM AUTHOR]