The Bozhong Depression, located along the Tan-Lu Fault Zone in eastern China, represents the largest offshore Cenozoic depocenter in the Bohai Bay Basin. Although its characteristic alternating uplift-and-depression pattern strongly influenced Cenozoic sedimentation and hydrocarbon accumulation, its underlying Mesozoic–Cenozoic tectonic evolution and formation mechanisms remain incompletely resolved. By integrating drill-core data with high-resolution 3D seismic data, we reconstruct the structural framework and polyphase tectonic evolution of the western Bozhong Depression. Seven regional unconformities bound seven distinct tectono-stratigraphic units, while balanced cross-section restorations define five broad geological periods comprising eight evolutionary stages. Contractional deformation during the Late Triassic produced a maximum shortening of ca. 6.1 km, establishing a deeply rooted fold-thrust basement architecture. During the Early Cretaceous, intense extension produced ca. 17.7 km of horizontal stretching. Subsequently, during the Late Cretaceous, flat-slab subduction of the Izanagi Plate led to structural inversion and widespread regional denudation, forming a basin-wide angular unconformity at the top of the Lower Cretaceous (T8). Paleogene extensional overprinting caused negative inversion of some pre-existing contractional structures, reactivating them as normal faults. Our structural restorations indicate that the Cenozoic structural partitioning was dictated primarily by the inheritance and reactivation of Mesozoic contractional structures rather than uniform lithospheric extension. This inherited tectonic framework, together with spatial variations in crustal rheology, exerted a first-order control on the petroleum system. Rheologically driven block tilting partitioned the basin into confined, deep-water depocenters favorable for source-rock preservation, whereas long-lived, rigid paleo-uplifts, such as the Shaleitian uplift, supplied coarse clastic sediment to high-quality reservoirs. These findings provide an updated geodynamic model and a predictive structural framework for deep hydrocarbon exploration in superimposed intracratonic basins.

Transitions within the syn-rift stage provide a key window for examining sediment-routing changes and associated sedimentary responses in lacustrine rift basins. In the Bohai Bay Basin, the interval from the third member (Es3) to the second member (Es2) of the Eocene Shahejie Formation records a transition from early strong rifting toward relatively stable rifting. The Qinan Sag, a secondary sag along the Qikou Sag margin, was sensitive to this transition. Using cores, well logs, three-dimensional (3D) seismic data, and heavy-mineral data, this study reconstructs the source configuration, palaeogeomorphology, depositional-system evolution, and Es3-Es2 source-related sediment-dispersal domains. The results show that the supply pattern shifted from coeval supply by a southern regional source and northern and western local sources during Es3 to southern regional-source dominance during Es2. Accordingly, Es3 contains strongly differentiated braided-delta, fan-delta, and subaqueous-fan assemblages. Es2 contains weakly differentiated shallow-water delta and beach-bar assemblages. Three source-related sediment-dispersal domains coexisted during Es3. During Es2, the northern domain was no longer identified, and the western gentle-slope belt evolved into a high-sand-ratio beach-bar belt. This reorganization was mainly controlled by the combined effects of source-configuration changes, geomorphic segmentation, and contrasting slope-A/S conditions (A/S = accommodation/sediment supply). Supply-pattern simplification and weakened geomorphic segmentation shifted sediment routing after basin entry from multiple, dispersed pathways to dominant-source-controlled focused routing. Moderate-to-steep slopes and higher relative A/S proxy values during Es3 favoured discrete, segmented sandy-deposit preservation; gentle slopes and lower relative A/S proxy values during Es2 promoted focused routing and preservation of sandy deposits along the dominant direction, with local shallow-water enrichment. Across the Es3-Es2 syn-rift stage transition, regional-source-related sediment routing showed stronger persistence; local-source-related routing more often weakened or terminated, with corresponding areas tending to show shallow-water redistribution and enrichment signals.

In shallow-water lacustrine basins characterized by gentle slopes, it remains unclear whether delta-front and beach-bar sands form independently or whether beach-bar sands are derived from wave reworking of contemporaneous deltaic deposits. Resolving this relationship is critical for reconstructing sediment dispersal and predicting sandbody connectivity and reservoir heterogeneity. Here, we define a Delta–Beach Bar Composite System (DBCS) in Members 1–2 of the Eocene Shahejie Formation in the northwestern Bozhong Depression, China. Integrated analyses of well logs, cores and thin sections, grain-size analyses and 3D seismic data identify six sedimentary elements: subaqueous distributary channels, sandy beach bars, mixed beach bars, bioclastic shoals, interdistributary-bay mudflats, and shallow-lacustrine mudflats. The DBCS is characterized by high-frequency vertical interbedding of delta-front and beach-bar sands, systematic lateral partitioning of sedimentary elements, and the derivation of beach-bar sands through wave reworking of contemporaneous deltaic deposits. Quantitative grain-size analysis identifies four hydrodynamic patterns recording the transition from fluvial traction transport to wave reworking and mixed accumulation. Integration with paleogeomorphic reconstruction supports two genetic depositional models. Model A develops on broad gentle slopes, where high-frequency lake-level oscillations generate 2–5 m sandstone layers with rhythmic sand–mud interbedding and good lateral continuity. Model B develops in restricted lowlands, where rapid sediment unloading forms thick channel sands capped by wave-reworked deposits. Paleogeomorphology and climate-driven high-frequency lake-level fluctuations jointly govern the coupling between fluvial sediment supply and wave reworking. The DBCS provides a predictive framework for reservoir connectivity and heterogeneity in analogous intracontinental rift basins.

Reservoirs within carbonate platforms are governed by complex variations in facies zones,exhibiting a wide range of sedimentary microfacies,including tidal channels and reef shoals.Since the sedimentary microfacies interbed with each other,carbonate platform reservoirs feature diverse architectural styles and complex macroscopic structures.Consequently,conventional individual modeling techniques are often inadequate to effectively characterize the reservoir structures of carbonate platforms that experienced rapid facies transitions under differential sedimentary settings.Therefore,it is necessary to develop quantitative characterization and modeling strategies for the architectural units of reservoirs tailored to different microfacies.By integrating core observations,logs,and seismic data,this study presents a hierarchical analysis of architectural units of carbonate reservoirs in the H oilfield in Iraq.As a result,two types of sedimentary architectural unit assemblages are identified within the carbonate platforms:tidal channel-bioclastic shoal complexes and tidal bioclastic delta complexes.Based on seismic response characteristics,the interface morphologies and spatial distribution patterns of these architectural units are delineated.Accordingly,for microfacies within these architectural units,we systematically analyze their differential overlapping styles in both plane and cross-section views based on their scales and evolution patterns.Furthermore,a layered and segmented modeling strategy is established for carbonate platform reservoirs.The analytical results indicate that tidal channel-bioclastic shoal complexes primarily occur within the MB1-2 layers.These architectural units exhibit roughly uniform thicknesses(average single-stage thickness of approximately 15 m)and high width-to-thickness ratios.Based on variations in architectural style,these complexes can be subdivided into three segments:meandering,aggradational,and migratory segments.Within each segment,distinct interfaces of tidal channel-bioclastic shoal complexes are identified.The primary differences among the three segments arise from tidal channels in different migration directions,which result in varying degrees of erosion and incision of bioclastic shoals under the influence of the meandering of single-stage tidal channels.Consequently,the shoal bodies show mutual truncation and stacking.Based on these findings,a multi-level architectural modeling strategy is proposed for tidal channel-bioclastic shoal complexes.Specifically,the 5th-level architectural model is established using a deterministic modeling method with deterministic interfaces as constraints.Then,the 4th-level architectural model is constructed within the framework of the 5th-level architectural model using the object-based modeling(OBM)method,with modeling parameters set based on the statistical geometric features of architectures.On the other hand,tidal bioclastic delta complexes are predominantly identified within the MB2 layer.These architectural units pinch out from the center toward both sides,featuring relatively large average single-stage thicknesses(approximately 30 m)and low width-to-thickness ratios.Based on variations in architectural style,these complexes can also be further subdivided into three segments:distal progradational delta,incised valley,and proximal retrogradational delta.Under the constraint of the 5th-level deterministic architectural interfaces,the 4th-level architectural models of tidal bioclastic delta complexes are established through multi-point statistics(MPS)simulation.During the modeling process,the progradational pattern of tidal deltas is incorporated for image training and modeling parameter setting.This study systematically reveals the architectural types and their geometric features within carbonate platforms and establishes modeling workflows based on geometric features,providing a reference for geological modeling of similar reservoirs.

Despite the documentation of compound clinoform morphology in modern deltas over the past two decades, there is still a scarce recognition of these in the stratigraphic record. Among the ancient cases that have been recognized, tide-and wave-dominated compound clinoforms have been documented. Here we present a fluvial-and wave-dominated compound clinoform delta in the Pliocene Orinoco Moruga Delta on Trinidad. The outcrops exhibit lateral variation with wave-dominated and mixed-influence deltaic clinothems preserved in the proximal (i.e., upstream) part (SSW) of the compound system and wave-dominated deltaic clinothems in the distal (i.e., downstream) part (NNE). The shoreline clinothems are 5-15 m thick, sandy coarsening-upward units, and they commonly comprise HCS/SCS and wave-rippled sandstones generated by storm wave processes in both upstream and downstream parts. In the upstream part where the deposition location was close to main sediment supply, the shoreline clinothems comprise an upper unit of fluvial-dominated mouth bar and channel deposits overlying a lower unit of mixed-influence mouth bars and wave-to tide-influenced channel deposits. The subaqueous clinothems are 30-50 m thick and are characterized by coarsening-upward units changing from thick, bioturbated siltstones and mudstones at lower levels, through interbedded siltstones/mudstones and thin hummocky/swaley cross-stratified (HCS/SCS) sets, to occasional amalgamated HCS/SCS beds. The subaqueous clinothems in these proximal and upstream parts are somewhat sandy and notably influenced by wave processes. In contrast, the distal parts of the subaqueous clinothems are muddy with repetitive, frequent thin beds of both HCS or wave-rippled beds and especially wave-enhanced sediment gravity flow deposits. The compound clinoform delta in the Moruga Formation thus exhibits a spectrum of fluvial, tidal, and storm-wave signals, along with diverse channel types. This variability provides a valuable opportunity to document the interactions among river, tidal, and storm-wave processes as well as delta building processes driven by the various types of channels within the compound clinoform delta.

The rapidly accumulating alluvial fans are important archives of tectonic and climatic processes. However, deciphering how alluvial fans respond to orbital-scale climate fluctuations remains unclear. While some alluvial fans exhibit a distinct response to glacial-interglacial cycles, others do not. This detailed outcrop study of the late Quaternary Bantanzi alluvial fan in the Daihai Lake Basin, northern China, reveals two stratigraphic intervals with distinct facies, where a lower stratigraphic succession is dominated by debris flow deposits and palaeosols and a higher stratigraphic unit by flash-flood deposits and loess. Physical correlations to well-dated successions on the Chinese Loess Plateau provide a chronological framework. The palaeosols and the elevated values in magnetic susceptibility of the debris flow-dominated interval, dated 88.1 to 73.4 ka (the last interglacial period MIS5, 130 to 70 ka), indicate a climate with intense seasonal monsoon rainfall, which facilitated chemical weathering and saturation of clay-rich sediments on hillslopes triggering debris flows. The wind-blown loess deposits together with regional data in the flash flood-dominated interval, dated 58.5 to 22.1 ka (the last glacial period MIS 2 to 4, 70 to 14 ka), indicate an arid climate with highly intermittent and short-duration rainfall. Such rainfall conditions tend to promote rapid run-off and generate flash floods, as well as hinder hillslope saturation and chemical weathering resulting in a regolith with higher permeability and erodibility, hindering high pore pressures from building up and promoting erosion by run-off. These distinct climatic conditions between interglacial and glacial periods were controlled by the latitudinal shift of the margin of the East Asian Monsoon. The Bantanzi fan's position at this climatic boundary, coupled with its small size, made it highly sensitive to glacial-interglacial cycles. Comparison with other fan systems suggests that the position of alluvial fans at distinct climate boundaries, rather than within the climate zones, is an important control on their sensitivity to climate changes and their potential as climate-change archives.

The complex plate collision process led the South Yellow Sea Basin （SYSB） to go through an intensity tectonic inversion during the early Cenozoic， leading to a regional unconformity surface development. As a petroliferous basin， SYSB saw intense denudation and deposition processes， making it hard to characterize their source-to-sink system（S2S）， and this study provided a new way to reveal them quantitatively. According to the seismic interpretation， it was found that two types of tectonic inversion led to the strata shortening process， which was classified according to their difference in planar movements: dip-slip faults and strike-slip ones. As for dip-slip faults， the inversion structure was primarily formed by the dip-slip movement， and many fault-related folds developed， which developed in the North Depression Zone of the SYSB. The strike-slip ones， accompanied by some negative flower structures， dominate the South Depression Zone of the SYSB. To reveal its source-to-sink（S2S） system in the tectonic inversion basin， we rebuild the provenance area with detrital zircon U-Pb data and heavy mineral assemblage. The results show， during the Eocene（tectonic inversion stage）， the proximal slump or fan delta from the Central Uplift Zone was prominently developed in the North Depression Zone， and the South Depression Zone is filled by sediments from the proximal area （Central Uplift Zone in SYSB and Wunansha Uplift） and the prograding delta long-axis parallel to the boundary faults. Then， calculations were conducted on the coarse sediment content， fault displacements， catchment relief， sediment migration distance， and discussions about the impact factors of the S2S system developed in various strata shortening patterns with a statistical method. It was found that， within the dip-slip faults-dominated zone， the volume of the sediment routing system and the ratio of coarse-grained sediments merely have a relationship with the amount of sediment supply and average faults break displacement. Compared with the strike-slip faults-dominated zone， the source-to-sink system shows a lower level of sandy sediment influx， and its coarse-grained content is mainly determined by the average faults broken displacement.

Many modern paralic depositional systems are characterized by complicated morphologies mixed with the river, tide, and wave processes. However, the prediction of hydrodynamic processes within their ancient counterparts is challenging from the subsurface data due to the limitation of resolution and coverage. This study illustrates an integrated work on the mixed-energy paralic deposits of the lower Miocene Zhujiang Formation in the western shelf of the Pearl River Mouth Basin, northern South China Sea. Through a synthesis of grain size and heavy mineral analysis, well-based facies interpretation, and seismic stratigraphic study, it generally shows a vertical change from the dominance of tidal strait deltas and tide-influenced deltas to a river-dominated delta with the wave-dominated shelf throughout three members, in response to the evolution from semi-closed to open marine settings. Tidal, river, and wave signals were recognized from the mixed-energy paralic deposits, albeit with alternative interpretations and non-negligible limitations. Tidal processes, which were interpreted from grain size distribution unmixing and statistical heavy mineral comparison, intensified towards the distal reach in the Member 2, and they generally declined after the drowning of paleo-Highs in the Member 1-2. Fluvial processes, which were reflected by heavy mineral evidence and sedimentary response, significantly enhanced from Member 2 to Member 1-1 with more extensive drainages and increased sediment supply, despite the long-term transgression. The presence of large-scale shoreline-parallel shelf sand ridges in the Member 1-1 was mostly controlled by the wind-driven Guangdong Coast Currents and intrusion of the South China Sea Branch of Kuroshio Current, which were coupled with the maximum East Asian Monson intensity and the Indonesian Seaway shoaling before the final closure. We demonstrated that a multidisciplinary approach presented can be effectively used to assess the changes in hydrodynamic processes of mixed-energy depositional systems, which unravel more paleogeographic, paleoclimatic, and paleoceanographic information from depositional records.

Ephemeral streams are rivers with high values of annual peak discharge variability. Therefore, the ephemeral rivers are often catastrophic, yet represent an important sediment routing system from source to sink that show unique bedding structures and internal architectures. The rivers surrounding the rifted Daihai Lake in a semi-arid area are mostly ephemeral streams with high inter-annual peak discharge variation, which document sedimentary architectures and reveal sedimentary processes of fluvial to deltaic system with strongly peaked discharge. This field trip describes sedimentary structures in alluvial fan to river to delta deposits, and investigates that how the structures and the morphodynamics change from the mountainous rivers to their delta fronts. Clinoforms with different geometries are examined in deltaic deposits, which reflect the controls of relative lake-level changes, paleobathymetry, and sediment supply.

Deltaic sedimentary systems form the most favorable hydrocarbon reservoirs in continental faulted lacustrine basins, and their types and controlling factors directly affect the distribution of hydrocarbons. The systematic study of typical modern delta deposition provides significant guidance regarding the distribution of oil and gas reservoirs in the subsurface. For this reason, the Heima River delta in Qinghai Lake, which features multiple sediment sources and clear sedimentary evolution stages, was selected for this research. A detailed study of the sedimentology and architectural characteristics of the Heimahe delta in Qinghai Lake was conducted. A total of 4 types of gravel facies, 4 types of sand facies, and 2 types of mud facies were identified. This study also focuses on recognizing the architectural elements within channels and bars. The delta plain features debris-flow, switched, and migrated channels and vertical and bilateral aggradation bars. The delta front features migrated and filled channels and bilateral and lateral aggradation bars. Twenty-two representative outcrop sections were selected. Detailed observation and analysis of these sections revealed three stages: the progradation to aggradation (PA) stage, in which the deposits show evidence of sigmoid-type and coarse-grained sedimentation; the retrogradation (R) stage, which is characterized by imbricated regression; and the aggradation to progradation and degradation (APD) stage, which is characterized by a terraced-stepping, progression stacking pattern. Based on the integrated analysis of the sedimentary environment, outcrop lithofacies associations, architecture stacking patterns, fossils and bioclasts, we identified diverse depositional associations and constructed a sedimentary evolution model of the depositional system in this area. We suggest that the depositional system transitioned from an early single-provenance gravel-rich fan delta to a multi-provenance mud-rich delta and that two factors mainly controlled the transition: the southern boundary fault activity and lake level variations. The contemporaneous activity of the fault increased the accommodation in the low-stand systems tract, which resulted in continuous coarse-sediment deposition.

The Mesozoic fan deltas in the north-west margin of the Junggar Basin, as important petroleum reservoirs, exhibited complex facies change and internal structures with strong heterogeneity which were controlled by the transformation of slope-patterns, bringing great challenges to the study of sedimentary characteristics. The Upper Karamay Formation at north-west margin of the Junggar Basin was the objective in this paper which attempts to clarify the mechanism of sedimentary response and sand-body distribution of fan delta systems under the control of slope-pattern change. Based on a data set of cores, well logs and seismic, two types of slope-pattern were identified in the study area, which include steep-to-gentle in the south and gentle-to-steep in the north. The control of difference slope-patterns on the sand-body distribution was clarified based on the analysis of the sedimentary dynamics, facies characteristics, and depositional evolution of the fan deltas. The study shows that the transport mechanism of sediments on the steep-slope was dominated by debris flows, developing coarse-grained, thick-bedded lobes with poor structural maturity of clasts. On the gentle-slope, the deposition was dominated by hyperconcentrated-traction currents, forming relatively fine-grained, thin-bedded lobes with increased sandy matrix. The sand-bodies show frequent bar-channel transformation and channel down-cutting under the steep slope setting, which exhibit migration of isolated river channels on the gentle slopes. Under the steep-to-gentle pattern, the coase-grained sediments were mainly accumulated at slope toe, generally developed equiaxial lobes. However, the coarse-grained clasts were preserved both at proximal and distal lobes on the gentle-to-steep slopes, showing obvious lateral extension of the fan delta. The slope patterns controlled sedimentary respond rates of the fan deltas during lake level change. By comparing the modern cases of fan systems worldwide, the control of slope patterns on deposition of coarse-grained fans was clarified, providing insight into hydrocarbon exploration on basin margins.

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. (c) 2024 Elsevier B.V. All rights reserved.

Alluvial fans in the piedmont zones of mountains respond most rapidly to tectonic activity, base-level conditions, and climate changes. These allogenic signals are effectively recorded by the external morphology and internal sedimentary characteristics of the fan. Based on field survey interpretation and integrated optically stimulated luminescence (OSL) chronology, we selected a case study of the modern Xiangpi Fan on the south bank of Lake Qinghai, NE Tibetan Plateau, and built a three-stage alluvial fan pattern since Marine isotope stages 3 (MIS3), namely, the debris flow lobe building stage (DFLBS), aeolian building stage (ABS), and streamflow reworking stage (SRS). The climatic indicators, such as the total organic carbon (TOC) flux, precipitation, and sediment particle size flux, are highly correlated with the above stages, indicating that the sedimentary process and changes in fan morphology effectively record orbital climate changes in the Lake Qinghai basin. During the DFLBS, the cold-dry climate accelerated the sediment yield sufficiently, leading to many coarse-grained sediments and low TOC flux being imported into the basin through debris flow processes. During the ABS, the extreme dry-cold climate caused the stagnation of fan development, and aeolian processes dominated the transport of fine sediment. In the SRS, warm-humid conditions led to limited sediment yield and perennial stream power, which promoted the transport of fine-grained material and TOC to the basin by braided–meandering channels. This study provides an excellent case showing how an alluvial fan responds to climate oscillations through changes in sedimentology and geomorphology.

鄂尔多斯盆地上古生界本溪组历经多次海侵,发育广阔陆表海沉积,其东南部地区碎屑障壁体系的展布特征和控制因素尚不明确.基于现场岩心、电测井等资料,研究建立障壁体系的沉积序列,恢复宏观古地貌特征,并刻画障壁砂体的平面展布,明确本溪组障壁体系的迁移样式和控制因素.研究识别出障壁海岸沉积体系中的障壁岛—冲溢扇、潮汐水道—三角洲、潮坪—潟湖和沼泽4类沉积序列,刻画本1段底部台阶式陡坡地形和本2段底部连续性缓坡地形2类古地貌特征.障壁沿多期平行岸线方向展布,沿岸线方向砂体连续性高,垂直岸线方向呈现多期迁移特征.障壁体系表现出2类平面迁移模式,本1段以滚动连续式迁移为主,垂向叠置程度低,横向连续性较强;本2段以跳跃间隔式迁移为主,叠置程度高,横向连续性较弱.海侵过程促进了障壁体系的保存,但其展布和迁移主要受古地貌控制,其中岸线轨迹控制障壁的优势长轴展布方向,陡缓坡分别主导障壁的迁移样式差异.研究同时强调海平面上升、古地形在建立古代障壁体系演化模式中的重要性.

Late Paleozoic strata in the southeastern Ordos Basin comprise targeted reservoirs for tight gas exploration. As a typical intracratonic basin, the Ordos Basin is characterized by low-accommodation space and a complex sediment infilling process, which attracts much attention. During the early Permian, the southeast area was fed by sediments from multiple sediment sources, which makes it difficult to identify the pinch-out of the sand bodies and reconstruct the sediment routing system. In this study, we reconstruct the paleo-topography of the late Paleozoic setting using high-resolution 2D and 3D seismic data. Thus, we identify two types of topography: the eastern block is presented as a semiclosed depression, and the western block is observed as a flat platform. Based on detrital zircon U–Pb data and heavy mineral assemblages, we reconstruct the provenance area and show that early Permian sediments originate from the northern margin of the Ordos Basin and from the northern Qinling orogenic belt in the south. By integrating the trace element contents, carbon and oxygen isotope data and sedimentary structure from core samples, we can observe the paleoenvironment and the corresponding facies associations in these blocks. The eastern block was infilled by a prograding delta; the western block was infilled by a tide-dominated delta or a wavy-dominated delta. By using stratigraphic forward modelling, we find that most sediments in the semiclosed setting are progradational and intensely interacted. In contrast, the sediments in the western block present an open setting, infilled and gently interacted. The fine-grained deposits were not easily preserved due to tidal or wave reworking processes in the shallow-water marine setting, and they were transported into deep-water areas. Furthermore, to explore the dominant factors in a pattern of fluvial–deltaic sand bodies formed in the low-accommodation basin, we rebuild the sediment routing system parameters and plot them on a bubble chart. According to the fitness between the depositional volume and the above parameters, we determine the key factors in the routing systems that formed. The results show that the sediment supply has a high relevance to the depositional volume in a semiclosed setting, such as the eastern block, while the terrain height may drive sedimentation in an open marine setting, such as the western block. We demonstrate that two different infill patterns and different sand-body stacking patterns with multiple sediment sources in a low-accommodation basin may serve as a model for similar settings.

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.

珠江口盆地珠三坳陷是中国南海北部大陆地区的主要产油区之一,储层物性差异较大,油气不集中.根据珠三坳陷珠海组岩心、钻井、测井和岩石薄片等资料,结合扫描电镜和常规物性分析,分析珠三坳陷珠海组沉积微相类型及储层特征,明确储层物性的控制因素.结果表明:受潮汐作用控制,珠三坳陷珠海组发育扇三角洲、辫状河三角洲和潮坪沉积体系,沉积微相以水下分流河道、河口坝、分流河道间及混合坪为主,其中河口坝物性最好,混合坪和水下分流河道物性次之,分流河道间物性最差.沉积微相的砂岩厚度、岩石粒度及沉积构造不同,储层孔隙度和渗透率也存在差异;成岩作用决定储层后期改造,珠海组以压实作用、胶结作用和溶蚀作用为主,其中压实作用和胶结作用为破坏性成岩作用,溶蚀作用为建设性成岩作用.该研究结果对珠江口盆地珠三坳陷后续勘探具有指导意义.

鄂尔多斯盆地东南部作为我国重要的煤炭和煤层气产地,其较为复杂的沉积环境演化过程为陆表海背景下聚煤环境研究提供了良好的研究对象.以鄂尔多斯东部晚古生代沉积为例,建立统一标准的层序地层格架,并且提出对应的层序叠置样式;在此基础上结合陆表海聚煤规律,揭示不同层系间聚煤范围的差异,厘清垂向上的层序叠加样式和平面含煤沉积体展布规律之间的关系.从井—震精细解释出发,定量刻画出不同平面范围内沉积物供给量(S)与可容纳空间变化量(A).最终归纳出三种短期层序的叠加演化样式:持续进积型层序,持续暴露型层序,沉积转化型层序.其中,持续进积型层序主要发育中厚煤层,受地形影响较大;持续暴露型层序发育煤层较薄,分布范围有限;沉积转化型层序,沉积供给方向不断变化,导致泥炭局部聚集为厚煤层,但是平面发育范围有限.针对上述三种层序样式,结合成煤环境确定对应主控因素,提出持续进积型层序与持续暴露型层序主要受控于可容纳空间变化,而沉积转化型层序受控于沉积供给速率影响.

碎屑岩沉积体系的三维展布特征及其成因机制是建立沉积模式与预测其砂体分布的关键,更是沉积学研究的关键性科学问题.国内外绝大多数学者认为其平面形态和剖面充填型式均与其沉积的地形坡度、粒度粗细有密切的联系,但其定量关系并不清楚.建立不同类型沉积体中粒度和坡度之间的定量关系,对于预测沉积体中不同颗粒的运动方式及其分布至关重要.应用"源-汇"系统研究的思路,分析了供源区、搬运(输送)区及汇积区各自的地质特点,从单向水流对不同质量颗粒在静止/运动中的受力分析与沉积前总体地形斜坡设定2个角度,系统分析、推导并模拟了不同碎屑颗粒在纵向剖面上的运动轨迹,其表现为随着设定的坡型呈抛物线变化,反映出沉积物输送营力的变换及其随坡度变化的响应特征.建立了陆相碎屑岩沉积体系纵向剖面的流速与坡度的计算方程,明确指出沉积物的流速或流态决定其沉积方式,阐述了汇积区碎屑颗粒的加积型式与沉积物分布上的总体规律,由此提出碎屑岩沉积体系的"物-坡"耦合效应及其主要内涵,并从多个维度与源-汇的各区段,阐述了"物-坡"耦合效应在各种沉积体系的沉积物类型及其空间形态特征上的地质响应.