Marine and Petroleum Geology最新文献

{"title":"Integrated sedimentological and geochemical characterization of the Silurian Qalibah Formation in central Saudi Arabia: Implications to paleoenvironmental reconstruction and organic richness evaluation","authors":"Mutasim Osman ,&nbsp;Korhan Ayranci ,&nbsp;Khairul Azlan Mustapha ,&nbsp;Eduardo Gramajo ,&nbsp;Rached Maurice Rached ,&nbsp;Thomas Finkbeiner ,&nbsp;Mahmoud Mowafi","doi":"10.1016/j.marpetgeo.2025.107498","DOIUrl":"10.1016/j.marpetgeo.2025.107498","url":null,"abstract":"<div><div>Unconventional hydrocarbon reservoirs are challenging due to their vertical and lateral heterogeneities. The Silurian Qalibah Formation in Saudi Arabia comprising of the Qusaiba and Sharawra members, serves as a prime example. This study investigates reservoir heterogeneity and variations in depositional conditions to produce a high-resolution chemozonation of the Qalibah Formation. Mineralogical and elemental compositions were determined using X-ray fluorescence (XRF) and X-ray diffraction (XRD), while organic matter characterization was performed using Rock-Eval pyrolysis. Three facies were identified: laminated grey-red mudstones in the Qusaiba Member, heterolithic sandstone-mudstone alternation in the lower Sharawra Member, and thickening upward fine sandstones in the upper Sharawra Member. Clay minerals dominate the Qusaiba Member (50 %), while quartz, mica, and K-feldspars prevail in the Sharawra Member. Organic matter is in early maturation stage with poor-to-fair total organic carbon (TOC) content, averaging 0.2 wt% in the Qusaiba Member and 0.05 wt% in the Sharawra Member. Detrital influx proxies indicate higher sedimentation rates in the Sharawra Member compared to the Qusaiba Member. Paleoclimatic proxies suggest humid to semi-arid conditions in the Qusaiba Member and semi-arid to arid conditions in the Sharawra Member. Paleomarine proxies consistently reveal brackish to saline and suboxic to oxic conditions. Five chemozones were established: three in the Qusaiba Member (Q-1: Ti/P depletion; Q-2: elevated TOC; Q-3: spiking Sr/Ba) and two in the Sharawra Member (S-1: lower Zr/Al and Sr/Cu than S-2). This chemozonation highlights spatial-temporal geochemical variability, offering insights into depositional dynamics and reservoir heterogeneity. The framework supports chemo-steering applications to optimize drilling, enhance reservoir targeting, and improve hydrocarbon recovery in analogous unconventional systems.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"181 ","pages":"Article 107498"},"PeriodicalIF":3.7,"publicationDate":"2025-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144272235","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Bimodal volcanism during the Early Cretaceous in Santos Basin, Brazil: Mantle-crust interaction, thermal regimes, CO2 influx and coeval magma generation onshore and offshore the South Atlantic volcanic rifted margins","authors":"Bárbara Santos Queiroz ,&nbsp;Sergio de Castro Valente ,&nbsp;Anderson Costa dos Santos ,&nbsp;Monica Heilbron","doi":"10.1016/j.marpetgeo.2025.107495","DOIUrl":"10.1016/j.marpetgeo.2025.107495","url":null,"abstract":"<div><div>There are many sedimentary basins along the South Atlantic rifted margins with voluminous hydrocarbon reservoirs. It evolves from rift to drift tectonic stages give rise to geological processes that control part of their petroleum systems. Some of these processes are related to changes in thermal regimes due to long-standing tectono-magmatic events associated to mantle-crust interactions. The Santos Basin, offshore southeast Brazil, contains the country's largest oil and gas reservoirs. Its origin is related to the rift process that led to the Gondwana breakup during the Early Cretaceous. This paper presents wellbore, petrographic, geochemical, isotopic and geochronological data obtained for an 800m-tick magmatic section recorded along the so-called pre-salt sedimentary sequence in the well 6-BG-6P-SPS in the Santos Basin. This magmatic section comprises effusive mafic and composite felsic rocks associated with long-standing bimodal volcanism (135-122 Ma). The geochemical models allowed to propose that the basic mafic and acid felsic rocks are no-cogenetic by differentiation processes, although some of the basic and intermediate liquids can be linked by AFC within the upper continental crust. The enriched isotope signature of the basic rocks can be explained by geodynamic processes involving the Tristan da Cunha plume and enriched portions of the SCLM (EMII-like mantle reservoir). The data were used to propose conceptual models for the mantle geodynamics and the tectono-magmatic settings from the Hauterivian to Aptian. These models show how mantle-crust tectonic and magmatic interactions imposed thermal regimes that may have controlled geological processes, hydrothermalism and CO₂ influx recorded in the pre-salt petroleum systems in the Santos Basin.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"181 ","pages":"Article 107495"},"PeriodicalIF":3.7,"publicationDate":"2025-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144290493","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The evolution of organic matter sources and sedimentary environments in lakes during the Eocene Climatic Optimum","authors":"Chuan Xu ,&nbsp;Guangrong Peng ,&nbsp;Pei Liu ,&nbsp;Ye He ,&nbsp;Peimeng Jia ,&nbsp;Xuanlong Shan ,&nbsp;Guoli Hao ,&nbsp;Mengrong Shen ,&nbsp;Kang Li","doi":"10.1016/j.marpetgeo.2025.107496","DOIUrl":"10.1016/j.marpetgeo.2025.107496","url":null,"abstract":"<div><div>The global climate experienced many rapid and long-term warming events during the early–middle Eocene, and these warming events had a significant impact on the evolution of the global paleoecosystem and led to the widespread development of organic-rich fine-grained sediments worldwide during the same period. To elucidate the regulatory effects of early–middle Eocene warming events on the organic matter (OM) sources and sedimentary environments of paleolakes, in this study, which is based on a detailed analysis of organic petrology, mineralogy, bulk geochemistry and biomarkers of typical wells, combined with a previous understanding of paleoclimate and hydrothermal activities, the influences of warming events on the OM sources and sedimentary environments of early–middle Eocene lakes were systematically investigated. The results demonstrate that units I and III, which were deposited under warm and humid climates, experienced massive freshwater influxes, highstand lacustrine conditions, and dysoxic–anoxic bottom waters, fostering the codominance of algae and terrestrial vascular plants. In contrast, units II and IV record lacustrine salinization events under warm semiarid–semihumid climates and synsedimentary hydrothermal activity, marked by increased salt-tolerant/thiophilic bacteria and euxinic bottom conditions linked to salinity stratification and hydrothermal sulfur cycling. The climatic transition from warm–humid to hyperthermic and semihumid–semiarid conditions during deposition of the Wenchang Formation triggered the amplification of lacustrine biodiversity and expansion of the oxygen minimum zone. Salinization-driven ecosystem restructuring, coupled with elevated primary productivity and exceptional preservation, resulted in organic-rich mudstones with high hydrocarbon generation potential. This study fully reveals the effects of paleoclimate fluctuations during warm periods on the evolution of the ecological environment of paleolakes, thus providing key geological information for deciphering the OM enrichment mechanism in early–middle Eocene paleolakes.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"181 ","pages":"Article 107496"},"PeriodicalIF":3.7,"publicationDate":"2025-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144231618","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Impact of burrows on electrical resistivity: Example from the Jurassic Hanifa Formation, Saudi Arabia","authors":"Ahmed Nagy ,&nbsp;Hassan A. Eltom ,&nbsp;Ammar El-Husseiny ,&nbsp;John D. Humphrey ,&nbsp;Mohammed Al Hamad","doi":"10.1016/j.marpetgeo.2025.107497","DOIUrl":"10.1016/j.marpetgeo.2025.107497","url":null,"abstract":"&lt;div&gt;&lt;div&gt;Although the influence of burrows on porosity and permeability is well documented, their impact on electrical properties remains poorly understood. The study addresses this gap by employing an integrated methodology, focusing primarily on high-resolution imaging to facilitate digital rock analysis, and customized resistivity setups developed for analyzing 4-inch diameter core samples from the Hanifa Formation in central Saudi Arabia. The setups allow for detailed analysis of the cores on a 4-inch diameter scale, alongside field observations, petrography, and petrophysical measurements. The primary objective is to test the hypothesis that the resistivity of sedimentary strata characterized by passively filled burrows varies inversely with the percentage and connectivity of burrows, particularly where the burrows are connected along the core from bottom to top. CT scans provided detailed insights into burrow connectivity and pore structures within the burrow fillings, enabling quantification of burrow percentages. Surprisingly, the burrow percentage exhibited a strong positive correlation with bulk resistivity measurements (p-value &lt;0.05, r&lt;sup&gt;2&lt;/sup&gt; = 0.98), contradicting the initial expectation that increasing burrow percentages, resulting in connected burrow networks saturated with brine, would lead to reduced resistivity. Further investigation with high-resolution radial resistivity measurements at a centimeter scale revealed a similar positive correlation between resistivity and burrow percentage (p-value &lt;0.05, r&lt;sup&gt;2&lt;/sup&gt; = 0.86). To explain these unexpected results, petrographic analysis and CT imaging were used to examine the rock texture of the studied cores. Micro CT scans revealed that what appeared to be connected interparticle and moldic pores in the petrographic data were, in fact, isolated in three dimensions, preventing the formation of permeability pathways within the burrow fillings. As a result, the burrow networks did not hold connected fluid phase or contribute to electrical current transmission, likely explaining the positive correlation between burrow percentage and resistivity. Further core flooding results confirm what has been observed in CT scan data by yielding very low permeability (∼3 mD) in cores with a connected burrow network. Additionally, porosity measurements indicated that the surrounding burrow matrix is highly porous, with microporosity accounting for more than 70 % of total porosity. The microporosity acted as the primary conductor of electrical current, creating a short-circuiting effect that dominated the resistivity readings. The study suggests that for burrows to affect resistivity inversely, they must be both connected and permeable. When burrows do not form permeability pathways in a microporous matrix, resistivity may vary proportionally with their presence. These findings provide valuable insights into the relationship between burrows and electrical resistivity in sedimentary stra","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"181 ","pages":"Article 107497"},"PeriodicalIF":3.7,"publicationDate":"2025-06-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144279756","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Characterization of the Miocene Castellón Sandstones Formation in the Western Mediterranean as a potential geological carbon storage site","authors":"Marc Gil-Ortiz ,&nbsp;Enrique Gomez-Rivas ,&nbsp;Juan Alcalde ,&nbsp;Patricia Cabello ,&nbsp;Luis Miguel Yeste ,&nbsp;Gonzalo Zamora ,&nbsp;Ángel Carrasco ,&nbsp;David García Fernández-Valderrama ,&nbsp;Antonio Martín-Monge ,&nbsp;Marta Mañas ,&nbsp;María Victoria Olgado Azpiazu ,&nbsp;Manuel Ron Martín ,&nbsp;Pujianto Lukito ,&nbsp;Francisco Pángaro","doi":"10.1016/j.marpetgeo.2025.107493","DOIUrl":"10.1016/j.marpetgeo.2025.107493","url":null,"abstract":"<div><div>In response to the growing interest in decarbonizing Europe's industrial hubs, this study examines the potential of the Miocene Castellón Sandstones Formation in the Valencia Trough for geological carbon storage. The proposed storage unit is represented by a siliciclastic succession formed mainly by sandstones and sandy heterolithics, in the Ebro Delta offshore area of the Valencia Trough. The sedimentological characterization of this succession, based on the study of a cored section from Amposta Marino C-2 well, has allowed to identify up to eleven lithofacies, comprising sandstones, heterolithics, calcarenites and carbonate breccias. These lithofacies can be grouped in six facies associations, including: 1) fluvial channel, 2) delta front proximal mouth bar, 3) delta front distal mouth bar, 4) proximal prodelta, 5) distal prodelta and 6) shelfal lag. The seismic stratigraphic analysis carried out throughout the study area points out to the additional presence of delta plain deposits in the northeastern sector of the study area, approximately at 30 km from the present-day Ebro delta shoreline. Based on the interpretation of these facies and seismic facies associations, the proposed depositional model consists of a river dominated, wave-influenced delta for the proto-Ebro deltaic system during the Late Miocene in the Valencia Trough. This study proposes that this sand-prone succession is presented as a good candidate for geological carbon storage in the study area, considering its proximity to the onshore Tarragona's industrial complex and its optimal reservoir characteristics. Additionally, the thick succession of the Ebro Shales also shows great potential as a vertical and lateral seal of the underlying Castellón Sandstones Formation.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"181 ","pages":"Article 107493"},"PeriodicalIF":3.7,"publicationDate":"2025-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144231765","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Coalification patterns and thermal-depositional history of the Upper Cretaceous-Paleogene coal in the Eastern Cordillera Basin, Colombian Andes","authors":"Juan Sebastian Gomez-Neita ,&nbsp;Ana Maria Pimentel Mizusaki ,&nbsp;Taís Freitas da Silva ,&nbsp;Sandra Rocio Manosalva-Sánchez ,&nbsp;Jorge Eliecer Mariño-Martínez ,&nbsp;César Augusto Mora-Hernández ,&nbsp;Gleubis Belén Silveira-Moreno ,&nbsp;Mauricio Alberto Bermúdez-Cella ,&nbsp;Lady Alejandra Barrera-Chaparro ,&nbsp;Marcos Müller Bicca ,&nbsp;Simone Patricia Aranha da Paz","doi":"10.1016/j.marpetgeo.2025.107489","DOIUrl":"10.1016/j.marpetgeo.2025.107489","url":null,"abstract":"<div><div>Understanding coalification patterns and thermal history in coal-bearing sequences is critical for basin analysis. In most basins, coalification is linked to maximum burial temperatures. However, syn/post-deformational thermal overprinting may occur in tectonically active settings. This study evaluates the coalification history of the Cretaceous-Paleogene Guaduas Formation in the Colombian Andes, a 1000 m thick sequence with extensive coal seams and significant gas generation potential. A comprehensive methodology was applied, including a geological survey, open system pyrolysis (Hawk), organic petrology, and thermal history modeling of 118 coal samples. The gas content was also determined using the desorption method. Total Organic Carbon (TOC) varied from 19.29 wt% to 82.73 wt%, with Tmax values between 430 °C and 494 °C. The random vitrinite reflectance (VRr%) ranged from 0.46 % to 1.65 %, indicating coal rank from Sub-bituminous A to Bituminous A (ISO 11760 classification). Paleotemperatures ranged from 72.5 °C to 175.9 °C, with gas content varying between 6.01 ft³/ton and 55.23 ft³/ton. Paleogeothermal gradients ranged from 63.4 °C/km to 94.9 °C/km. Coal rank generally increases with depth, highlighting burial as the primary coalification driver. However, variations in VRr% within individual seams suggest irregular coalification linked to multiple deformation phases. An increase in paleotemperature toward the northern sector correlates with enhanced tectonic activity. Burial modeling indicates over 4100 m of sedimentary overburden, followed by significant Cenozoic erosion after the Andean uplift. The organic matter (type II-III) and the combined influence of burial and tectonic processes played a fundamental role in organic matter maturation and the development of gas generation potential.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"180 ","pages":"Article 107489"},"PeriodicalIF":3.7,"publicationDate":"2025-05-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144212941","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Understanding the relationship between shale gas potential and depositional environment in the Duvernay Formation, Kaybob area, Canada: Implications for lithofacies identification of shale gas reservoir","authors":"Sung Kyung Hong ,&nbsp;Hyun Suk Lee ,&nbsp;Jiyoung Choi ,&nbsp;Hyojong Lee ,&nbsp;Carl Ozyer","doi":"10.1016/j.marpetgeo.2025.107491","DOIUrl":"10.1016/j.marpetgeo.2025.107491","url":null,"abstract":"<div><div>The lithofacies of hydrocarbon-bearing stratigraphy possess distinct physical and chemical properties that are directly related to their hydrocarbon generation potential and brittleness. Systematically studying the lithofacies and their depositional environments therefore facilitates a more accurate evaluation of shale gas reservoir characteristics. In this study, an attempt was made to identify suitable lithofacies for efficient shale gas extraction through a comprehensive evaluation of the hydrocarbon generation capacity and brittleness index (BI) and reveal their depositional conditions of the Duvernay Formation in the Kaybob area. The hydrocarbon generation potential was inferred from the original generative organic carbon (GOCo) content, and the BI was calculated based on the mineral composition. Based on the sedimentary characteristics, the Duvernay mudstones were classified into four lithofacies: white laminated mudstone, Mlw; crudely stratified mudstone, Mc; laminated mudstone, Ml; and papery fractured mudstone, Mpf. Mlw has a high GOCo content and BI, indicating that it can generate significant volumes of hydrocarbons and form a clean fracture under stress. Based on geochemical proxies, variations in shale gas potential according to lithofacies were found to be related to the interplay of primary productivity in the surface water (excess-SiO₂ and P₂O₅), clastic sediment input (Al₂O₃, TiO₂, and Hf), and redox conditions in the bottom water (Th/U, EF_U, and EF_Mo). The Mlw, with excellent shale gas potential, was deposited in association with enhanced primary productivity within surface water, diminished clastic sediment input, and reducing conditions in the bottom water, which led to an enrichment of organic matter and biogenic silica in the mudstones. The Upper Duvernay Formation, mainly composed of Mlw with a minor amount of Mc, is considered a primary target for shale gas exploration.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"180 ","pages":"Article 107491"},"PeriodicalIF":3.7,"publicationDate":"2025-05-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144203270","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Paleoenvironment and source rock potential within the Jurassic-Cretaceous succession of the Nile Delta Basin, Egypt: Insights from palynology and organic geochemistry","authors":"Haytham El Atfy ,&nbsp;Bandar I. Ghassal ,&nbsp;Ali Soliman ,&nbsp;Hans Kerp ,&nbsp;Leon Richtscheid ,&nbsp;Benjamin Bomfleur","doi":"10.1016/j.marpetgeo.2025.107492","DOIUrl":"10.1016/j.marpetgeo.2025.107492","url":null,"abstract":"<div><div>Despite decades of active exploration in the Nile Delta, particularly in the offshore Mediterranean, the depositional settings and source rock potential of the Mesozoic strata remain unclear, primarily due to the limited number of drill cores. With its comprehensive approach, this study aims to fill gaps in our understanding of the Jurassic-Cretaceous paleoenvironments and source rock potential in one of the largest petroleum basins in Egypt and the Mediterranean region. The investigated successions are from the Abu Hammad-1 well in the onshore Nile Delta Basin, the only well that penetrated the Jurassic-Cretaceous in the basin. Our study presents an integrated palynological and organic geochemical approach, offering a comprehensive and reliable method for gaining precise insights and linking age dating to depositional environments, kerogen types, and thermal maturity. Palynological data are supplemented with organic geochemical analyses, comprising total organic carbon, Rock-Eval pyrolysis, biomarker, and elemental data. The obtained palynological results reveal two distinct assemblages, from younger to older, dated as Barremian-Aptian and Bathonian-Kimmeridgian, respectively. The studied sediments are derived from nearshore marine environments characterized by stable, oxygen-rich, suboxic bottom waters. This specific setting and proximity to the shoreline contribute to minimal preservation of organic matter. The organic content is dominated by Type III and Type IV kerogen, indicating a gas-prone source derived from terrestrial plant material and amorphous organic matter. Source rock characterization shows low thermal maturity. The study provides valuable insights into the Upper Jurassic and Lower Cretaceous geology of the Nile Delta Basin, facilitating the prediction of depositional environments and source rocks.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"181 ","pages":"Article 107492"},"PeriodicalIF":3.7,"publicationDate":"2025-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144231764","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Tectonic and climatic interplay controls organic matter enrichment in Eocene low-latitude rift lakes: Insights from the Asian continental margin","authors":"Zixuan Liu ,&nbsp;Detian Yan ,&nbsp;Xiaosong Wei ,&nbsp;Jianxin Yu ,&nbsp;Shangbin Chen ,&nbsp;Yong Deng ,&nbsp;Yunlong He","doi":"10.1016/j.marpetgeo.2025.107486","DOIUrl":"10.1016/j.marpetgeo.2025.107486","url":null,"abstract":"<div><div>Organic matter enrichment in lacustrine rift basins remains enigmatic compared to marine systems, despite their significant role in global carbon cycling. The Eocene Liushagang Formation (South China Sea) provides valuable insight into how tectonic-climatic interactions control organic matter accumulation during active rifting. While conventional models emphasize productivity-anoxia interplay, the role of tectonic-climatic controls on organic matter deposition was less discussed. By integrating sedimentology, petrology, organic geochemistry, palynology, and elemental geochemistry, this multidisciplinary dataset seeks to elucidate the relationships between regional tectonism, climate change, and lake environment. Our results suggest that: (1) Intense rift activity, warm-humid climate, and moderate chemical weathering promoted a deep and stratified lake with high productivity and anoxia; (2) A distinct vertical variation in organic matter enrichment, with exceptional TOC contents in lower E₂l² shales contrasting sharply with diminished accumulation in upper E₂l² due to climate cooling and nutrient depletion; (3) Three predictive models of organic matter enrichment that correlate specific depositional conditions with accumulation efficiency. These results fundamentally advance our understanding of rift lake organic matter enrichment by highlighting tectonic accommodation space and Early Eocene Climatic Optimum (EECO) perturbations as primary drivers. The established models provide a valuable framework for evaluating lacustrine source rocks potential in Cenozoic basins worldwide, with particular relevance for low-latitude rift systems.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"180 ","pages":"Article 107486"},"PeriodicalIF":3.7,"publicationDate":"2025-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144185090","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Distribution patterns of storage space and diagenesis in lacustrine shale controlled by laminae combinations—A case study from Jiyang depression","authors":"Yuegang Wang ,&nbsp;Chao Liang ,&nbsp;Yingchang Cao ,&nbsp;Zhouhai Xiong ,&nbsp;Wanlu Han ,&nbsp;Huimin Liu ,&nbsp;Junran Wang","doi":"10.1016/j.marpetgeo.2025.107488","DOIUrl":"10.1016/j.marpetgeo.2025.107488","url":null,"abstract":"<div><div>Well–developed laminae are a prominent feature of lacustrine shale systems. Elucidating the reservoir space architecture and formation mechanisms associated with distinct laminae assemblages is critical for advancing the understanding of hydrocarbon accumulation processes in lacustrine shale oil reservoirs. In this study, reservoir space development model, diagenesis and controlling factors of different laminae combinations were analyzed in the shale of Paleogene shale (Upper Member 4 to Lower Member 3, UM4–LM3) in the Jiyang Depression. Through integrated thin–section, field emission scanning electron microscopy (FE–SEM), X–ray diffraction (XRD) analysis, physical property testing, and geochemical analysis, four diagnostic laminae assemblages were identified: (1) sparry calcite and clay laminae (LC1), (2) micritic calcite and clay laminae (LC2), (3) clay and organic laminae (LC3), and (4) organic–rich clay and silty laminae (LC4). In LC1, the calcite–associated pores are the most developed, followed by clay mineral–associated pores. By contrast, in the LC2, clay mineral–associated pores are the most developed, accounting for 27.33 % of the total areal porosity. In LC3, the clay mineral–associated pores are the most developed. In LC4, the most developed pore type is felsic–associated pore, which accounts for about 50 %. The laminar fractures in LC1 are well developed, with better fracture extensibility than others. The development and distribution of the storage space are predominantly governed by lithofacies and lamina combinations, while temperature and pressure exhibit fundamental controls on fracture network evolution. Furthermore, interlaminal fluid flux and reactive mass transfer play a crucial role in authigenic mineral paragenesis and pore network evolution. The degree of lamina development exerts a significant influence on hydrocarbon generation, migration, and accumulation processes. In organic–rich mudstones, enhanced lamination intensity exhibits a positive correlation with elevated values of S1/TOC.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"180 ","pages":"Article 107488"},"PeriodicalIF":3.7,"publicationDate":"2025-05-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144185091","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}