Marine and Petroleum Geology最新文献

{"title":"Shallow gas accumulation mechanism in the Qiongdongnan Basin, South China Sea","authors":"Junfeng Zhang ,&nbsp;Detian Yan ,&nbsp;Jianxiang Pei ,&nbsp;Wei Luo ,&nbsp;Entao Liu ,&nbsp;Peng Song ,&nbsp;Tong Li ,&nbsp;Zeyu Lu ,&nbsp;Xudong Lin","doi":"10.1016/j.marpetgeo.2025.107389","DOIUrl":"10.1016/j.marpetgeo.2025.107389","url":null,"abstract":"<div><div>The Qiongdongnan Basin is one of the most important oil and gas basins in the South China Sea. Previous studies primarily focused on the middle strata around 3000–4000 m. In recent years, abundant shallow oil and gas resources have been discovered in the shallow Ledong Formation of the Qiongdongnan Basin. Previous researchers believed that these shallow accumulations originated from deep strata and that the shallow strata could not serve as effective source rocks. There was a lack of relevant studies on how deep gas sources transport gas to shallow areas, where gas was accumulated in shallow layers, how the cap rock was distributed, and how the transport system, reservoir, and cap rock matched. This research aimed to clarify the types and spatial distribution of transport systems in the study area using 3D seismic data, combined with methods such as root mean square amplitude attributes and variance cube slicing. Simultaneously, it sought to identify the development types and sizes of reservoirs and cap rocks and elucidated the relationships among these three influencing factors, clarifying the process of deep natural gas accumulation in shallow reservoirs. Six transport systems, including diapiric gas chimneys, fracture-type gas chimneys, polygonal faults and fractures, large faults, submarine slump, and multi-stage channels, were identified in this study, along with their distributions. The main reservoirs in the Ledong Formation were submarine fans, slope fans, and shoreland sandbars, with their upper portions predominantly capped by mass transport deposits and mudstone layers. Based on these findings, the spatial matching of transport systems and reservoirs was conducted to clarify the process of gas migration, transport, and accumulation from deep to shallow strata, summarizing corresponding accumulation models. Gas chimneys and faults were considered the primary transport systems, while submarine fans were identified as the highest-quality reservoirs, and mass transport deposits were effective cap rocks. The accumulation model formed by the combination of these three elements represented the primary accumulation mode in the study area. The results of this study will provide guidance for the development of shallow resources in the South China Sea.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"177 ","pages":"Article 107389"},"PeriodicalIF":3.7,"publicationDate":"2025-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143681236","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":"Spatiotemporal hierarchy of fault systems and associated syn-rift stratigraphic sequences across the Santos Basin, offshore SE Brazil","authors":"Peryclys Raynyere de Oliveira Andrade ,&nbsp;Tiago M. Alves ,&nbsp;Mário Neto Cavalcanti de Araújo ,&nbsp;Renata da Silva Schmitt ,&nbsp;Daniel Galvão Carnier Fragoso ,&nbsp;Anderson Henrique de Melo","doi":"10.1016/j.marpetgeo.2025.107384","DOIUrl":"10.1016/j.marpetgeo.2025.107384","url":null,"abstract":"<div><div>This paper uses high-resolution 2D and 3D seismic surveys tied to stratigraphic data from 155 boreholes in the mapping and hierarchization of 1551 extensional faults across the Santos Basin and its Outer High. These faults were able to control deposition in extensional basins with different ages – they are thus classified into three (3) main systems with the aim of understanding their geodynamic significance. Fault system 1 (FS1) controlled the oldest syn-rift sequence and delimits the very first half-graben basins developed during an Early Rift stage. Fault System 2 (FS2) was formed in response to crustal thinning during an Intermediate rifting stage. Fault System 3 (FS3) responded to the migration of the rift axis towards the distal margin in a Late Rift stage. Strikingly, fault reactivation occurred throughout the entirety of the proximal domain of the Santos Basin during the Late Rift Stage. This work is important as each interpreted fault system is understood to have controlled the availability of accommodation space during its peak activity, thereby shaping the inner proximal, outer proximal, and distal domains of the Santos Basin. The evolution of these fault systems also resulted in the deposition of syn-rift sequences that obey a specific order, or ranking. By correlating fault systems with their adjacent syn-rift strata, we propose 1^st-order sequence boundaries that are associated with each stage of the development of the Santos Basin, formed as a consequence of changes in thermo-mechanical conditions during the evolution of rifted margins. Identified 2^nd-order sequences are attributed to tectonic movements at the crustal-block scale. In contrast, stratigraphic sequences of the 3^rd- and 4^th-orders are associated with localised tectonic inputs. Within this framework, we use stratigraphic surfaces as structural markers across multiple observational scales. Consequently, sequence 1SEQ1 corresponds to the stretching phase, standing for the initial stages of rifting within an intraplate setting. Sequence 1SEQ2 relates to the necking stage and formation of the outer proximal domain, whereas sequence 1SEQ3 accompanied the development of the distal domain in the so-called hyperextension and continental-breakup stages. Ultimately, this work demonstrates that the tectono-stratigraphic evolution of continental margins, from the onset of rifting to continental breakup, is documented by a clear, diachronic tectono-stratigraphic record. Such a record varies along and across hierarchized fault systems that are developed at multiple scales of observation.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"177 ","pages":"Article 107384"},"PeriodicalIF":3.7,"publicationDate":"2025-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143740010","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":"Tectono-stratigraphy of the Shushan Basin, Western Desert, Egypt: A window into the evolution of the SE Mediterranean province","authors":"Ahmed I. Albrkawy ,&nbsp;Tiago M. Alves ,&nbsp;Thomas Blenkinsop","doi":"10.1016/j.marpetgeo.2025.107387","DOIUrl":"10.1016/j.marpetgeo.2025.107387","url":null,"abstract":"<div><div>The SE Mediterranean is a key region documenting the geological history of the Mesozoic Tethys Ocean while comprising one of the most promising provinces in the world in terms of energy resources. Using 2D seismic reflection data tied to exploration wells, this work analyses the Shushan Basin of northern Egypt within a context dominated by continental rifting, ocean propagation, and closure of the Tethys Ocean. Nine (9) seismic megasequences and four (4) major structural trends are identified in the Shushan Basin. In the centre of the basin, the interpreted megasequences document four (4) major tectonic episodes: i) a Paleozoic early-rift stage, ii) a syn-rift stage lasting from the Early Jurassic to the Early Cretaceous, iii) an Aptian-Cenomanian post-rift stage, and iv) a syn-compressional phase that started in the Late Cretaceous and ended in the Miocene. Importantly, the data in this work suggest the presence of up to 1.6 km of Upper Paleozoic-Triassic strata below the Lower Jurassic Ras Qattara Formation. Widespread extension occurred from the Late Triassic to the Early Cretaceous, a period of time in which graben and half-graben basins were formed and delimited by E-W and NW-SE striking faults. Later in the basin's evolution, mild tectonic reactivation predominated and was accompanied by a (post-rift) thermal episode in Northern Egypt. As a corollary, we show that the tectonic episodes interpreted in this work reflect the position of the Shushan Basin near the junction between the southern margin of the Tethys Ocean, the Syrian Arc system, and the Red Sea continental rift. Consequently, regional faults interpreted in this work are grouped into four families with distinct trends: i) Red Sea, ii) Tethyan, iii) Syrian Arc, and iv) Aqaba.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"177 ","pages":"Article 107387"},"PeriodicalIF":3.7,"publicationDate":"2025-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143681240","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Asymmetric oceanic crustal accretion and mantle serpentinization in the southwestern propagator tip of the South China Sea basin","authors":"Jialing Zhang ,&nbsp;Chun-Feng Li ,&nbsp;Zhaocai Wu ,&nbsp;Yuhan Li ,&nbsp;Yinxia Fang ,&nbsp;Chongzhi Dong ,&nbsp;He Li","doi":"10.1016/j.marpetgeo.2025.107380","DOIUrl":"10.1016/j.marpetgeo.2025.107380","url":null,"abstract":"<div><div>A multi-channel seismic profile crossing the conjugate continental margins at the southwestern propagator tip of the South China Sea unveils asymmetric crustal structures. The southern margin exhibits rapid necking of the continental crust, while the northern margin features hyper-thinned crust controlled by detachment faults. The northern margin has thicker syn-rift deposits, while in the most distal parts of the southern margin, these deposits become thin or vanish entirely. Notably, the oceanic crustal structure is also asymmetric with respect to the spreading center. North of the spreading center, the oceanic crust is only 2–3 km thick, whereas to the south it is ∼5 km thick. Two sub-horizontal intra-basement reflections are identified in the northern oceanic domain, one representing the interface between basaltic oceanic crust and serpentinized mantle, and the second from gabbroic intrusions. Joint inversion of gravity, magnetic, and seismic data supports the presence of a highly serpentinized mantle beneath the thin oceanic crust. The reduced melting at the ridge-segment end may explain the observed asymmetrical rifting and seafloor spreading.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"177 ","pages":"Article 107380"},"PeriodicalIF":3.7,"publicationDate":"2025-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143680744","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":"Deciphering hydrocarbon evolution history of the Cambrian shales in tectonically complex basins: Constraints from calcite U-Pb dating and low-temperature thermochronology","authors":"Qingqing Fan ,&nbsp;Dadong Liu ,&nbsp;Hui Tian ,&nbsp;Xuesong Lu ,&nbsp;Yi Chen ,&nbsp;Xia Feng ,&nbsp;Wei Du ,&nbsp;Mingyang Xu ,&nbsp;Xiaoting Pang ,&nbsp;Zijun Tang","doi":"10.1016/j.marpetgeo.2025.107386","DOIUrl":"10.1016/j.marpetgeo.2025.107386","url":null,"abstract":"<div><div>Assessing hydrocarbon evolution of organic-rich shales in tectonically complex basins is critical for shale gas resource evaluation. A major obstacle is the difficulty in precisely constraining the timing of hydrocarbon migration and leakage events. Here, fluid inclusion microthermometry, calcite U-Pb and detrital zircon (U-Th)/He dating were integrated to reconstruct the hydrocarbon evolution history of the Cambrian organic-rich shales in the southeastern margin of the Upper Yangtze Platform. We assessed the dynamic evolution of shale gas content over time by methane isothermal adsorption coupled with geothermometry and geobarometry. The calcite veins yield U-Pb ages of 113.5–108.9 Ma (C1 calcite) and 65.5–65.2 Ma (C2 calcite), with fluid inclusion trapping temperatures of 186.2 °C and 74.8 °C, respectively. Detrital zircon (U-Th)/He dating indicate that the basin inversion started at the Middle Triassic (ca. 241 Ma), leading to a cooling in the shales. The onset of intense exhumation and folding deformation occurred at ca. 113Ma, which corresponds to the Yanshanian Orogeny. This tectonic deformation event triggered the opening of fractures (as indicated by the formation of the C1 calcite veins with ages of ca. 114–109 Ma), facilitating shale gas migration and leakage, with a shale gas loss of at least 0.75 cm³/g. These results demonstrate that combination of fluid inclusion and geochronological data can provide accurate geochronological constraints on shale gas migration and leakage associated with tectonic uplifts, which can be an effective approach to decipher hydrocarbon evolution history of shales in tectonically complex basins worldwide.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"177 ","pages":"Article 107386"},"PeriodicalIF":3.7,"publicationDate":"2025-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143681238","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":"Astronomical forcing of lake-level and environmental changes in saline-alkaline lakes during the Late Paleozoic Ice Age","authors":"Dadong Liu ,&nbsp;Mingyang Xu ,&nbsp;Qian Cao ,&nbsp;Qingqing Fan ,&nbsp;Hui Chen ,&nbsp;Chen Zhang","doi":"10.1016/j.marpetgeo.2025.107383","DOIUrl":"10.1016/j.marpetgeo.2025.107383","url":null,"abstract":"<div><div>The Late Paleozoic Ice Age (LPIA) records Earth's latest icehouse-greenhouse transition, which offers a deep-time perspective for future climatic and environmental predictions. Astronomical cycles are believed to play a key role in the evolution of climatic and environmental changes during the LPIA. However, the interactions among the astronomical forcing, climatic conditions, sea-level and lake-level changes remain ambiguous. Here, we conducted a cyclostratigraphic analysis of gamma ray (GR) and paleo-water depth (WD) data of the upper Carboniferous–lower Permian Fengcheng and Lucaogou formations in the Junggar Basin, NW China. A floating astronomical time scale of <em>∼</em>3.4 Myr for the Fengcheng Formation and <em>∼</em>5 Myr for the Lucaogou Formation are established by astronomical tuning of GR data to the robust 405 kyr eccentricity cycle. The lake-level changes of the two formations are recovered based on the sedimentary noise model, which both show antiphase relationship with relative sea-level fluctuations, however different phase relationship with obliquity amplitude variations. The <em>∼</em>1.2 Myr (s₄–s₃) obliquity amplitude modulation cycle was the main driving force of lake levels in the Northern Hemisphere during the LPIA. In addition, the <em>∼</em>170 kyr cycles regulates the lake-level fluctuations and affect the development of saline-alkaline minerals in the closed lake basins. The cyclical growth and retreat of extensive ice sheets was an important factor that influence the hydrological response to the same obliquity cycle, which reflect the nonlinear response of Earth's climate system to changes in astronomical orbital parameters. We conclude that the combination of climatic background and astronomical forcing cannot be generalized, as they have a more complex superposition mechanism. Our study demonstrates the important role of the termination of icehouse climate in lake evolution and supports the existence of the 'nonlinear response process' across different time scales.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"177 ","pages":"Article 107383"},"PeriodicalIF":3.7,"publicationDate":"2025-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143642754","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":"Tectono-stratigraphic evolution of multiphase rifts in a hangingwall dip-slope setting: A case study in Eocene western slope, Xihu Sag of East China Sea Shelf Basin","authors":"Xuesong Zhou ,&nbsp;Xiaoming Zhao ,&nbsp;Jiawang Ge ,&nbsp;Massine Bouchakour ,&nbsp;Guofeng Yin ,&nbsp;Jianwei Wang ,&nbsp;Shumei Yan ,&nbsp;Xian Liu","doi":"10.1016/j.marpetgeo.2025.107382","DOIUrl":"10.1016/j.marpetgeo.2025.107382","url":null,"abstract":"<div><div>The hangingwall dip-slope settings are important components of rift basins, being able to influence offshore sedimentation, but a few studies have examined their properties. Their reactivation of growth faults can contribute to re-shape basin geometry influencing the associated stratigraphic successions. This paper investigates the structural evolution of a hangingwall dip-slope setting to explore the development of multiphase rifts that imprint tectonic properties and stress field migration by utilizing seismic, well-log, and core data from the Xihu Sag, East China Sea Shelf Basin. Three composite sequences (CS1-3) are defined within the Eocene syn-rift deposits, along with three third-order sequences in CS3. We have reconstructed the evolution of two tectonic phases: rift phase 1 and rift phase 2. Furthermore, we identified two stages within each phase: rift initiation and rift development 1 for rift phase 1, and rift development 2 and rift termination for rift phase 2. However, an immediate decrease in fault activity was recorded in the rift phase 2. Alterations in the stress field throughout intermittent rift phases led to differences in tectono-stratigraphic structures. In rift phase 1, expansion occurred from small isolated depocenters to larger systems, while rift phase 2 experienced contraction. Concurrently, basin geometry evolved from wedge-shaped half-grabens to dish-like geometries. The tectonic change caused sediment overfilling to starvation in rift phase 1 and sediment starvation to balance filling in rift phase 2. This contribution provides insights into hangingwall dip-slope dynamics and rift basin depositional systems.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"177 ","pages":"Article 107382"},"PeriodicalIF":3.7,"publicationDate":"2025-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143681237","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":"Delving into the Jurassic sediments of the Matruh basin, Northwestern Desert, Egypt: A multidisciplinary approach using seismic data, stratigraphic analysis, and 3D facies modeling","authors":"Amr M. Eid,&nbsp;Mohammed Amer,&nbsp;Walid M. Mabrouk,&nbsp;Ahmed El-khteeb,&nbsp;Ahmed Metwally","doi":"10.1016/j.marpetgeo.2025.107376","DOIUrl":"10.1016/j.marpetgeo.2025.107376","url":null,"abstract":"<div><div>This study integrates multiscale datasets, including seismic interpretation, well-log analysis, and sequence stratigraphy, to evaluate reservoir potential and spatial distribution within the Khatatba Formation of the Obayied Oilfields, Northwestern Desert, Egypt. Seismic interpretation reveals NE-SW trending horsts, grabens, and step faults, segmenting the study area into eleven structural blocks. Structural cross-sections highlight lateral extensions, thickness variations, and fault-controlled reservoir compartmentalization. The Khatatba Formation is analyzed within the Masajid-Khatatba sequence (M.K. SQ), exhibiting mixed siliciclastic and carbonate lithofacies, distinct wireline-log signatures, and seismic reflections. Petrophysical analysis identifies the sandstone-rich LST-1 as a key reservoir zone, while the Masajid Formation offers limited potential. Advanced 3D facies models of the Upper and Lower Safa Members enhance insights into structuration and facies distribution. The Upper Safa Member exhibits porosity of 10–18 %, shale volume of 15–24 %, and water saturation of 18–53 %, while the Lower Safa Member shows porosity of 10–16 %, shale volume of 17–28 %, and water saturation of 15–47 %, with improved reservoir quality in the northeast and southeast, respectively. Geochemical analysis indicates Total Organic Carbon (TOC) values of 1–5 % in Jurassic formations, confirming moderate to good source rock potential. The Upper Jurassic Masajid Formation, with substantial carbonate content, serves as an effective seal rock, while faults from Late Cretaceous to Early Miocene inversion structures influence hydrocarbon migration and reservoir compartmentalization. These findings enhance understanding of hydrocarbon prospectivity, providing a foundation for optimized exploration and development strategies in the Obayied Field and the broader Matruh-Shushan Basin.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"177 ","pages":"Article 107376"},"PeriodicalIF":3.7,"publicationDate":"2025-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143629477","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":"Carbonate cement genesis and links to siliciclastic environments of deposition: Hibernia Formation, Jeanne d’Arc basin, offshore Newfoundland","authors":"Mateo Acuna-Uribe,&nbsp;David Lowe,&nbsp;Karem Azmy","doi":"10.1016/j.marpetgeo.2025.107379","DOIUrl":"10.1016/j.marpetgeo.2025.107379","url":null,"abstract":"<div><div>Carbonate cements filling intergranular pores in siliciclastic reservoirs dramatically reduce porosity and permeability, creating baffles and flow barriers that impact reservoir performance and drilling. Understanding the origin and controls of carbonate cementation aids in identifying and predicting carbonate-cemented intervals in reservoir stratigraphy. Sedimentologic and diagenetic studies of the Lower Cretaceous Hibernia Formation in the Jeanne d’Arc basin, Newfoundland, Canada, were conducted to explore links between carbonate cements, facies associations and sea-level fluctuations. The Lower Hibernia zone records the transition from a deltaic to an estuarine environment, characterized by two regressive sequence boundaries and comprising fluvial, tidal-fluvial, and tidal facies associations. Petrographic analyses revealed three main pervasive carbonate cements: early calcite, early dolomite and late ferroan calcite. The δ¹⁸O (δ¹⁸O_calcite = −7.6 to −4.2 ‰ VPDB; δ¹⁸O_dolomite = −4.1 to −1.6 ‰ VPDB) and trace element geochemistry of calcite and dolomite suggest that parent fluids were influenced by mixing of marine-meteoric water under relatively reducing conditions at shallow depths. Dolomite cementation is linked with seawater retention within sediments during sea level regressions and fluid expulsion due to compaction of the underlying shales. Conversely, calcite cements are associated with transgressions and an increased marine water flux into the recently deposited sediments. Acidic pore water dissolved early carbonate cements, developing secondary porosity predating ferroan calcite cementation. The wide distribution of ferroan calcite in the overall stratigraphy, its depleted δ¹⁸O composition (δ¹⁸O_{ferroancalcite} = −10.2 to −9.1 ‰ VPDB) and high Fe and Mn concentrations suggest that ferroan calcite cementation occurred during early burial.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"177 ","pages":"Article 107379"},"PeriodicalIF":3.7,"publicationDate":"2025-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143681239","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":"Petrologic and geochemical evolution of carbonates of South Bruce region, Southwest Ontario: Dolomite petrogenesis and fluid flow evolution","authors":"Ihsan S. Al-Aasm ,&nbsp;Richard Crowe ,&nbsp;Marco Tortola","doi":"10.1016/j.marpetgeo.2025.107377","DOIUrl":"10.1016/j.marpetgeo.2025.107377","url":null,"abstract":"<div><div>Cored samples from two deep boreholes in the South Bruce Region, Ontario, Canada were analyzed to assess the dolomitization process and other diagenetic features of rocks spanning from the Ordovician to Devonian periods. These samples, including dolomitized limestone, dolostones, and evaporites, were compared with previous results from the Bruce Nuclear site and adjacent areas. The analyses focused on mineralogy, stable isotope composition, geochemistry, fluid inclusions microthermometry, and Sr-isotopic ratios, offering insights into source fluids and the timing of dolomitization. Dolomitization in the region is characterized by two main generations: non-stoichiometric replacive dolomite and saddle dolomite cement. The replacive dolomite includes microcrystalline matrix dolomite (D1) that replaces wackestone, packstone, and occasionally grainstone facies. A later formed medium to coarse crystalline dolomite (D2) replaces grainstone facies and is associated with dissolution seams, stylolites, and recrystallized dolomite. Both dolomites formed from warm, saline basinal fluids. Saddle dolomite (SD) is found in minor vugs and fractures in Ordovician and Silurian strata, postdating D1 and D2. Isotopic and microthermometric data indicate multiple diagenetic fluid events with the formation of D1 at shallow burial depth followed by the formation of D2 and SD at an intermediate burial depth likely occurred during Taconian and Acadian orogenies. The negative δ¹⁸O values, enriched ⁸⁷Sr/⁸⁶Sr ratios, and high homogenization temperatures for D2, and SD dolomites suggest formation from connate fluids influenced by basinal brines and hydrothermal fluids. In contrast, Devonian dolomite and blocky calcite exhibit lower salinity and higher homogenization temperatures, reflecting fluid evolution linked to the Alleghenian Orogeny. Geochemical similarities between the Bruce Nuclear site and South Bruce region highlight their geographic proximity, with variations due to different depositional settings, diagenetic fluid compositions and the presence of hydrothermal fluids.</div><div>The integration of the petrographic, isotopic and geochemical data in this study reveals the connection between fluid flux history and diagenetic processes, highlighting their role in the regional tectonic evolution of the Michigan Basin.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"177 ","pages":"Article 107377"},"PeriodicalIF":3.7,"publicationDate":"2025-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143629476","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}