First Record of the Belemnite Genus Hibolithes from Late Jurassic–Early Cretaceous Turbidites from Malaysia

Discovery of the remains of belemnites referred to the Hibolithes sp.from the Jurassic–Cretaceous Pedawan Formation in Sarawak,on the island of Borneo(Malaysia)comprises four fragments of belemnite rostra.The specimens are characterized by multiple fractures and vein filling.Two fragments measuring about 130 mm are relatively intact,with only part of the alveolar region missing;a third piece represents the middle part of a rostrum,and the fourth specimen is too fragmentary to be assigned to any specific part of the rostrum.Based on specimen characteristics,a Tithonian–Hauterivian age is plausible.The sedimentary succession that yielded the belemnite material comprises thick shale that reflects the Te division of Bouma sequence.The occurrence of a Hibolithes taxon in the uppermost Jurassic to lowermost Cretaceous Pedawan Formation sediments in Borneo reflects a near to global palaeobiogeographic distribution of this genus.

Formation of Hengchun Accretionary Prism Turbidites and Implications for Deep-water Transport Processes in the Northern South China Sea

Located at the end of the northern Manila Trench,the Hengchun Peninsula is the latest exposed part of Taiwan Island,and preserves a complete sequence of accretionary deep-sea turbidite sandstones.Combined with extensive field observations,a’source-to-sink’approach was employed to systematically analyze the formation and evolutionary process of the accretionary prism turbidites on the Hengchun Peninsula.Lying at the base of the Hengchun turbidites are abundant mafic normal oceanic crust gravels with a certain degree of roundness.The gravels with U-Pb ages ranging from 25.4 to23.6 Ma are underlain by hundreds-of-meters thickness of younger deep-sea sandstone turbidites with interbedded gravels.This indicates that large amounts of terrigenous materials from both the’Kontum-Ying-Qiong’River of Indochina and the Pearl River of South China were transported into the deep-water areas of the northern South China Sea during the late Miocene and further eastward in the form of turbidity currents.The turbidity flow drastically eroded and snatched mafic materials from the normal South China Sea oceanic crust along the way,and subsequently unloaded large bodies of basic gravel-bearing sandstones to form turbidites near the northern Manila Trench.With the Philippine Sea Plate drifting clockwise to the northwest,these turbidite successions eventually migrated and,since the Middle Pleistocene,were exposed as an accretionary prism on the Hengchun Peninsula.

Turbidite Dynamics and Hydrocarbon Reservoir Formation in the Tano Basin: A Coastal West African Perspective

This study examines the turbidite dynamics and hydrocarbon reservoir formation in Ghana’s Tano Basin, which is located in coastal West Africa. Through an exploration of geological processes spanning millions of years, we uncover key factors shaping hydrocarbon accumulation, including source rock richness, temperature, pressure, and geological structures. The research offers valuable insights applicable to exploration, management, and sustainable resource exploitation in coastal West Africa. It facilitates the identification of exploration targets with higher hydrocarbon potential, enables the anticipation of reservoir potential within the Tano Basin, and assists in tailoring exploration and management strategies to specific geological conditions of the Tano Basin. Analysis of fluvial channels sheds light on their impact on landscape formation and hydrocarbon exploration. The investigation into turbidite systems unveils intricate interactions involving tectonics, sea-level fluctuations, and sedimentation patterns, influencing the development of reservoirs. An understanding of sediment transport and depositional settings is essential for efficient reservoir management. Geomorphological features, such as channels, submarine canyons, and distinct channel types, are essential in this situation. A detailed examination of turbidite channel structures, encompassing canyons, channel complexes, convex channels, and U-shaped channels, provides valuable insights and aids in identifying exploration targets like basal lag, channel levees, and lobes. These findings underscore the enduring significance of turbidite systems as conduits for sediment transport, contributing to enhanced reservoir management and efficient hydrocarbon production. The study also highlights how important it is to examine the configuration of sedimentary layers, stacking patterns, and angular laminated facies to identify turbidites, understand reservoir distribution, and improve well design. The dynamic nature of turbidite systems, influenced by basin characteristics such as shape and slope, is highlighted. The research provides valuable insights essential for successful hydrocarbon exploration, reservoir management, and sustainable resource exploitation in coastal West Africa.

Comprehensive constraint on the tectono-sedimentary setting of Late Paleozoic turbidites of the Kamuste area, eastern Junggar,Xinjiang

Petrography and geochemistry, combined with sedimentation analyses allow for a thorough evaluation of the tectono-sedimentary setting of late Paleozoic turbidites of the Kamuste area eastern Junggar. Sandstones of the Alabiye1) Formation are composed mostly of volcanic and sedimentary detritus with lesser amounts of plagioclase and quartz. They were derived from an undissected magmatic-arc provenance. The geochemistry of sandstone-mudrock suites indicates a fesic-intermediate igneous provenance, and constrains the Alabiye Formation to have derived from a differentiated oceanic-continental margin island-arc tectonic setting. Likewise, geochemistry and sandstone petrography of the Kamuste Formation reflect a mixed provenance signature dominated by magmatic arc, basement uplift, and subduction-complex sources of a differentiated continental-island arc. Sedimentation analysis indicates that the Alabiye and Kamuste formations are two sets of turbidite sequences deposited on a submarine slope and a submarine fan and basin plain respectively. In conclusion, submarine slope turbidite deposition of the Alabiye Formation records the main sedimentary response to the development of early Devonian back-arc basins of the northern Junggar tectonic belt. Submarine fan and basin plain turbidite and background hemipelagic deposition of the Kamuste Formation record the main sedimentary response to the late Early Carboniferous development of an inter-arc relict ocean basin of the eastern Junggar composite terrane.

Structural characteristics and deep-water hydrocarbon accumulation model of the Scotian Basin, Eastern Canada

Commercial hydrocarbon reservoirs have been discovered in shallow-water areas of the Scotian Basin, Eastern Canada. However, knowledge about the structure and hydrocarbon accumulation characteristics of the basin is still insufficient, which constrains the oil and gas exploration in deep-water areas. Based on comprehensive data of magnetic anomalies, seismic survey, and drilling, this study determines the structure characteristics of the Scotian Basin and its hydrocarbon accumulation conditions in deep waters and evaluates the deep-water hydrocarbon exploration potential. The transform faults and basement structures in the northern basin control the sedimentary framework showing thick strata in east and thin strata in west of the basin. The bowl-shaped depression formed by thermal subsidence during the transitional phase and the confined environment (micro basins) caused by salt tectonics provide favorable conditions for the development of source rocks during the depression stage (also referred to as the depression period sequence) of the basin. The progradation of large shelf-margin deltas during the drift phase and steep continental slope provide favorable conditions for the deposition of slope-floor fans on continental margins of the basin. Moreover, the source-reservoir assemblage comprising the source rocks within the depression stage and the turbidite sandstones on the continental margin in the deep waters may form large deep-water turbidite sandstone reservoirs. This study will provide a valuable reference for the deep-water hydrocarbon exploration in the Scotian Basin.

北吕宋岛菲律宾活动带蛇绿岩及其上覆浊积岩的放射虫研究新进展(英文)

The basement of the Philippine Mobile Belt (PMB) is mainly composed of ophiolites that are mostly overlain by Paleogene to Miocene turbidites in central Luzon.To clarify the geological development of the PMB with respect to the initial stage of the arc volcanism(eg.Yumul et al.,2003,2008;

Sediment Deformations Due to Paleoseismic Events

There are many different processes generating soft-sediment deformation. This paper is confined to deformations generated by paleoseismic events in Sweden. The Paleoseismic Catalogue of Sweden includes 66 events. The structural characteristics and driving forces of liquefaction are discussed in details. “Crypto-deformations” refer to a special type of fluidization not affecting the sedimentary bedding itself, but the internal orientation of the ChRM and AMS carrying particles. Extensive turbidites are formed at some events. They constitute useful “marker-varves”. Out of the 66 paleoseismic events, 31 are dated by varves as to a single year (in one case even to the season of a year). Tsunamites are recorded from 19 of the paleoseismic events;some with wave-heights up to 15 - 20 m.

Sedimentary Patterns and Stratigraphic Trap Models of Deeply Buried Intervals in the Baxian Depression, North China

The Baxian depression is a typical half-graben located in the Jizhong sub-basin, north China. Commercial petroleum traps have been discovered in the Jizhong sub-basin. However, the 3^(rd) and 4^(th) members of the Shahejie Formation in this sub-basin have been poorly explored. These two members, belonging to the Lower Paleogene age, are buried deeply in the depression. Favorable petroleum reservoir conditions exist in such deep intervals of the half-graben due to the presence of different types and extent of deltas and turbidity fans in various areas. In fact, three types of turbidite fans are developed in the sag below the transitional belt on the eastern gentle slope. This work summarized three stratigraphic trap belts, i.e., the steep slope, gentle slope, and sag. On the steep slope, structuralstratigraphic traps with small-scale delta fronts and turbidite sandbodies are well developed. On the gentle slope, hydrocarbons generally accumulate in the large-scale delta front, onlapping beds and those sandbodies adjacent to unconformities. In the sag, petroleum trap models are typically characterized by pinched-out turbidite sandbodies. Stratigraphic traps were easily formed in turbidite fans below the eastern transitional belt. The petroleum traps that have already been discovered or predicted in the study area indicate that stratigraphic traps have favorable petroleum exploration potential in deeply buried areas(depth >5000 m) in a half-graben basin or depression.

CHARACTERIZATION OF FINE-GRAINED TURBIDITE DEPOSITS FROM THE SOUTH CHINA SEA SEDIMENT CORES

Two depositional processes controlled the muddy sediments in the South China Sea Basin. Bathyal sediments depositional rate was 7.66 cm/la in the northern continental slope of the Basin where turbidity current was almost nonexistent. In the northern margin of the Basin, abyssal sediment depositional rate was 5.05cm/ka and turbidity current occurrence averaged 0.22 per 1000 years. Turbidite was found in the middle of the Basin. Over half of the muddy sediments in the deep sea basin were deposited by turbidity currents, and had typically graded bedding, and contents of organic matter, calcareous material and micropaleontologic species inconsistent with the environment.

3D modeling of deepwater turbidite lobes:a review of the research status and progress

Deepwater turbidite lobe reservoirs have massive hydrocarbon potential and represent one of the most promising exploration targets for hydrocarbon industry.Key elements of turbidite lobes internal heterogeneity include the architectural hierarchy and complex amalgamations at each hierarchical level leading to the complex distribution of shale drapes.Due to limitation of data,to build models realistically honoring the reservoir architecture provides an effective way to reduce risk and improve hydrocarbon recovery.A variety of modeling techniques on turbidite lobes exist and can be broadly grouped into pixel-based,process-based,process-oriented,surface-based,object-based and a hybrid approach of two or more of these methods.The rationale and working process of methods is reviewed,along with their pros and cons.In terms of geological realism,object-based models can capture the most realistic architectures,including the multiple hierarchy and the amalgamations at different hierarchical levels.In terms of data conditioning,pixel-based and multiple-point statistics methods could honor the input data to the best degree.In practical,dif?ferent methods should be adopted depending on the goal of the project.Such a review could improve the understanding of existing modeling methods on turbidite lobes and could benefit the hydrocarbon exploration activities of such reservoirs in offshore China.

Turbidite Reservoirs in the Dongying Sag,Bohai Bay Basin:Interactions between Carbonate Cementation and Hydrocarbon Charge

Turbidite sandstones have become increasingly significant in hydrocarbon exploration.Carbonate cementation occur commonly in turbidite reservoirs developing within the Paleocene lacustrine basins,Northeastern China.This study utilizes core data,thin section data and production data to investigate the interaction between the carbonate cementation and hydrocarbon charge within turbidite reservoirs in the Niuzhuang Sub-sag of the Dongying Sag,Bohai Bay Basin,East China.The results reveal that the carbonate cementation is mainly developed at the top and bottom of the turbidite sandbodies,and even forms carbonate cement shells.Three stages of hydrocarbon accumulation are identified based on fluid inclusion analysis:stage I(27.5–24.6 Ma),stage II(14.0–5.0 Ma),and stage III(5.0–0 Ma).The interaction between the carbonate cementation and hydrocarbon charge has significant controls on the formation of a turbidite reservoir.The temporal relations and intensity relations between the two factors should be considered significantly.Moreover,hydrocarbon charge during the early stage can inhibit the carbonate cementation,favoring the hydrocarbon accumulation in turbidite reservoirs.Many deep-lacustrine turbidite sandbodies surrounded by source rocks with abnormal high pressure,are also favorable for hydrocarbon accumulation.These results suggest that some deeply buried turbidite sandbodies with similar geological settings have high potential for hydrocarbon exploration.

Distribution Patterns of Calcite Cement in the Turbidite Sandstones of the Shahejie Formation in the Dongying Depression,Eastern China

Calcite cements are volumetrically dominant among the most diagenetic constituents in turbidite sandstones of the Paleogene Shahejie Formation in the Dongying Depression.The results show carbonate cements mainly occur in three phases:Calcite I(pre-compaction),Calcite II(post-compaction)and ankerite in the turbidite sandstone.The isotopic composition of Calcite I and Calcite II range from−4.3‰to 4.4‰,−3.5‰to 4.3‰PDB,respectively,suggesting that the calcite cements are mainly derived from the interbedded shales.The early calcite cement precipitated from the mixing of lacustrine and meteoric waters at 38-69℃.The late-phase calcite precipitated from pore waters modified by water-rock interactions at 64-126℃.Two distribution patterns of calcite cements can be identified,depending on their position within the sandstone.The peripheral cementation of the sandstones is near the sand-shale contact.The development of cement is controlled by sandstone thickness and the properties of the interbedded shale.For scattered cementation,the distribution of the calcite cement is not controlled by the sand-shale contact.Calcite cement was preferentially distributed in coarse-grained sandstones,indicating that sandstones with high original permeability are the preferred pathway for the migration of early diagenetic fluids.

Cambrian- Ordovician Deep - Water Deposits in Southwest Jiangxi, China

The Cambrian-Ordovician rocks in southwestern Jiangxi are mainly composed of deep-water deposits, in which 5 facies have been recognized: sandstone facies, sandstone-mudstone facies, siltstone-mudstone facies, mudstone (slate)facies, and chert facies. They are of turbidity current origin and are related to pelagic and hemipelagic deposits. In the light of facies distribution, the Cambrian-Ordovician deposits can be classified into 3 facies associations formed in middle fan, outer fan and deep-sea plain environments respectively. The 3 different orders of vertical cycles in the stratigraphic sequence are considered to be controlled by factors such as sea-level fluctuation, basin subsidence and submarine fan progradation. The tectonic setting of the sedimentary basin is interpreted as passive continental margin based on the chemical composition analysis of the sandstone.

Bed type and flow mechanism of deep water sub-lacustrine fan fringe facies:an example from the Middle Permian Lucaogou Formation in Southern Junggar Basin of NW China

Submarine or sub-lacustrine lobe deposits are important reservoirs,but the fan fringe deposits form heterogeneities within deep water fan deposits.Fan fringe facies records the complex sediment gravity flow types.By understanding of the bed types and flow mechanisms,we can identify the fan fringe deposit,which aids in the reconstruction of deep water fan and reservoir evaluations.The Jiucaiyuanzi and Dalongkou sections in the West Bogda Mountains preserve well-exposed 536-m and 171-m thick successions,respectively,of a deep water lacustrine depositional system from the Middle Permian Lucaogou Formation.Bed types of the Lucaogou Formation include high-density turbidite,low-density turbidite,incomplete Bouma-type turbidite,hybrid event beds,and slump deposits.The Lucaogou Formation is interpreted here as a fan fringe facies due to the thin bed thickness that characterize turbidites and hybrid event beds,as well as the predominance of the isolated sheet architecture.Previous studies suggest that these deposits were considered as deposited in a deep water setting due to the absence of wave-related structures.The presence of abundant mud clasts in massive medium-coarse grained sandstone beds reflects the significant erosional capability and interactions between high-density turbidity currents and lake floor.The fan fringe facies here contains amalgamated and thick-bedded homolithic facies(~30%)and thin-bedded heterolithic facies(~70%).The examination of the bed type is of wider significance for facies prediction and reservoir heterogeneity in the sub-lacustrine fan fringe facies.

The magnetic susceptibility measurements of turbidity current sediments from Fuxian Lake of Yunnan Province and their correlations with earthquakes

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Earthquake Recurrences Since Late Pleistocene in Nankai Trough of Kumano

The Nankai Trough has a 1300-year record of generating large earthquakes(M_w】8)with a recurrence time of～100-200 a,but unfortunately,we don’t know the frequency of earthquakes before.Results from recent expeditions of NanTroSEIZE Stage 1 IODP 314/315/316 recovered many cycles of turbidites since late Pleistocene,which are triggered during the past earthquake shaking.Our purpose is

Controls on the Gas Hydrate Occurrence in Lower Slope to Basin-Floor,Northeastern Bay of Bengal

High resolution seismic data and newly acquired logging data reveal the presence of gas hydrates in the deep-water area in the northeastern Bay of Bengal.Bottom Simulating Reflectors(BSRs)appear at 430 ms beneath the seafloor,with the features of typical gas hydrates reported elsewhere except for some discontinuity.The BSR distribution is closely related to the position of anticline structures and turbidite channels.Anticlines provide conduits for the upward migration of gases from deeper intervals,while the turbidite sands within channels act as reservoirs for gas hydrate accumulation.High sedimentation rates in the Bengal Fan were ge-nerally favorable to produce a great amount of methane gas,providing favorable preconditions for the formation of gas hydrates.The discovery of gases in adjacent area indicates the contribution of the biogenic gas to the formation of gas hydrates.Meanwhile,seismic sections provide the evidence for the potential thermogenic gas kitchen in deep intervals.The anticline structures and the associated vertical fractures may constitute vertical fluid flowing conduits,which hydraulically connect the two deeper thermogenic petroleum systems(i.e.,rifting and Eocene-Oligocene source rocks)with the turbidite reservoirs and thus facilitate the fluid migration from the sources to the reservoirs,generating favorable conditions for gas-hydrate accumulation in such foreland setting.

A training image optimization method in multiple-point geostatistics and its application in geological modeling

Based on the analysis of the high-order compatibility optimization method proposed by predecessors, a new training image optimization method based on data event repetition probability is proposed. The basic idea is to extract the data event contained in the condition data and calculate the number of repetitions of the extracted data events and their repetition probability in the training image to obtain two statistical indicators, unmatched ratio and repeated probability variance of data events. The two statistical indicators are used to characterize the diversity and stability of the sedimentary model in the training image and evaluate the matching of the geological volume spatial structure contained in data of the well block to be modeled. The unmatched ratio reflects the completeness of geological model in training image, which is the first choice index. The repeated probability variance reflects the stationarity index of geological model of each training image, and is an auxiliary index. Then, we can integrate the above two indexes to achieve the optimization of training image. Multiple sets of theoretical model tests show that the training image with small variance and low no-matching ratio is the optimal training image. The method is used to optimize the training image of turbidite channel in Plutonio oilfield in Angola. The geological model established by this method is in good agreement with the seismic attributes and can better reproduce the morphological characteristics of the channels and distribution pattern of sands.

Architecture of deepwater turbidite lobes: A case study of Carboniferous turbidite outcrop in the Clare Basin, Ireland

Through lithofacies analysis and architecture anatomy of the Carboniferous Ross Sandstone turbidites outcropped at western Ireland,the depositional model of deepwater turbidite lobes is established.Seven types of lithofacies are recognized including goniatites-rich shale,laminated shale,laminated siltstone,massive sandstone,fine-medium sandstone with mud-clast,basal gravel,and chaotic mudstone,which can be subdivided into units of three origins,turbidite lobe,turbidite channel,and slide-slump;and four hierarchical levels,lobe complex,lobe,lobe element and single sandstone layer.The lobes show apparent compensational stacking pattern,lobe elements display typical thickening-upward cycles on vertical profile,and the higher the hierarchical level,the better the preservation of the hierarchical boundary is.In general,turbidite lobe deposits appear as tabular,parallel/sub-parallel sandstone and mudstone interbeds,and change from thick,massive sandstone in the proximal end to thinner sandstone and mudstone interbeds from axis to fringe,with the sand-shale ratio and degree of sandstone amalgamation decreasing.

Turbidite-hosted Gold, Silver and Polymetallic Ore Deposits in eastern Liaoning

There exist a large area of turbidites in eastern Liaoning occurred lead-zinc deposits. During the past years, large -scaled Au, Ag deposits were found near the lead-zinc deposits. The paper preliminarily studied the typical Au, Ag and Pb-Zn deposits and summarized the genesis of turbidite-hosted deposits. The area where turbidite is deposited in Liaohe group was thought as a good place to find Au, Ag polymetallic ore deposits.