Pub Date : 2025-10-09DOI: 10.1016/j.marpetgeo.2025.107614
C.K. Mishra , P. Dewangan , G. Sriram , P.A. Mohammed Masood , S.K. Arun
Gas hydrates have been identified in the Cauvery-Mannar Basin, a passive rift setting largely devoid of recent tectonic activity as evidenced by seismic data. This study provides novel insights into gas migration pathways from deep-seated reservoirs to the shallow subsurface, with particular emphasis on the role of seismic chimneys as focused conduits for fluid and gas transport. The Bottom Simulating Reflector (BSR), a key seismic indicator of gas hydrates, is observed intermittently across multiple seismic profiles, underlain by extensive gas-charged sediments. A prominent feature in one of the seismic profile is a chimney-like structure, ∼650 m tall and 1000 m wide, originating from deeper gas-rich strata at depth. Formed through overpressure-induced hydrofracturing, the chimney acts as a conduit for vertical gas migration from deep-seated gas reservoirs to the Gas Hydrate Stability Zone (GHSZ). At the base of GHSZ, hydrates form impermeable layers that restrict vertical migration of free gas and promote lateral migration. Amplitude variation with angle (AVA) analysis reveals strong Class III anomalies in the updip direction of BSR, indicating preferential lateral gas migration along the base of GHSZ. Class IV anomalies observed in the updip region may signify high-concentration gas hydrates or fracture-filled deposits formed through focused gas accumulation. In this tectonically quiescent setting, hydrostatic pressure gradient drives both vertical and lateral gas migration, transporting gas from deep reservoirs to the shallow subsurface in the Mannar basin. These findings have important implications for understanding gas hydrate systems in other passive continental margin environments.
{"title":"Seismic chimneys as gas migration pathways and their role in hydrate accumulation: AVA insights from the Cauvery-mannar basin","authors":"C.K. Mishra , P. Dewangan , G. Sriram , P.A. Mohammed Masood , S.K. Arun","doi":"10.1016/j.marpetgeo.2025.107614","DOIUrl":"10.1016/j.marpetgeo.2025.107614","url":null,"abstract":"<div><div>Gas hydrates have been identified in the Cauvery-Mannar Basin, a passive rift setting largely devoid of recent tectonic activity as evidenced by seismic data. This study provides novel insights into gas migration pathways from deep-seated reservoirs to the shallow subsurface, with particular emphasis on the role of seismic chimneys as focused conduits for fluid and gas transport. The Bottom Simulating Reflector (BSR), a key seismic indicator of gas hydrates, is observed intermittently across multiple seismic profiles, underlain by extensive gas-charged sediments. A prominent feature in one of the seismic profile is a chimney-like structure, ∼650 m tall and 1000 m wide, originating from deeper gas-rich strata at depth. Formed through overpressure-induced hydrofracturing, the chimney acts as a conduit for vertical gas migration from deep-seated gas reservoirs to the Gas Hydrate Stability Zone (GHSZ). At the base of GHSZ, hydrates form impermeable layers that restrict vertical migration of free gas and promote lateral migration. Amplitude variation with angle (AVA) analysis reveals strong Class III anomalies in the updip direction of BSR, indicating preferential lateral gas migration along the base of GHSZ. Class IV anomalies observed in the updip region may signify high-concentration gas hydrates or fracture-filled deposits formed through focused gas accumulation. In this tectonically quiescent setting, hydrostatic pressure gradient drives both vertical and lateral gas migration, transporting gas from deep reservoirs to the shallow subsurface in the Mannar basin. These findings have important implications for understanding gas hydrate systems in other passive continental margin environments.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"183 ","pages":"Article 107614"},"PeriodicalIF":3.6,"publicationDate":"2025-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145322817","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}
Pub Date : 2025-10-09DOI: 10.1016/j.marpetgeo.2025.107637
Jochen Knies , Stephen Killops , Trond Brekke , Kari Grøsfjeld , Kasia K. Sliwinska , Sverre Planke , Carmen Gaina , Giuliana Panieri , Claudio Argentino , Ute Mann , Wiktor Bönke , Tomas Kjennerud , Rune Mattingsdal
This study evaluates the source rock potential, organic matter input, and depositional environments of Miocene-aged sediments in the eastern Nordic Seas. It focuses on ODP/IODP Sites 909, 985, and U1572, two exploration wells (7316/5-1 and 6608/10-1), and oil seeps offshore western Svalbard. Integrated marine palynological, biomarker, and geochemical analyses indicate a mainly Early to Middle Miocene age and a mixed terrestrial-marine origin of the sedimentary organic matter and associated oil seeps. Angiosperm-derived biomarkers, especially triterpenoids like oleananes and oleanenes, are abundant and help link seeping oils to deltaic terrestrial sources. Depositional settings ranged from oxic in the Fram Strait (Hole 909C) to dysoxic or anoxic in southern Sites (Holes 985A and U1572B), influenced by the semi-enclosed Nordic Seas. Geochemical indicators such as sulfur content, TOC/S ratios, and Pr/Ph values reflect variations in bottom water oxygenation and sediment conditions. Terrestrial organic input is linked to Miocene deltaic systems, likely formed by tectonic uplift in East Greenland, the Barents Sea, and central Norway.
Basin modeling in the southwestern Barents Sea, using seismic and well data, shows that Miocene source rocks have reached maturity levels sufficient for hydrocarbon generation, especially beneath thick Plio-Pleistocene glacial overburden. The presence of oleanene and oleanane in both boreholes and oil seeps supports the conclusion that these Miocene source rocks are regionally widespread and part of an active petroleum system.
{"title":"A prolific Tertiary source rock of terrestrial origin in the eastern Nordic Seas","authors":"Jochen Knies , Stephen Killops , Trond Brekke , Kari Grøsfjeld , Kasia K. Sliwinska , Sverre Planke , Carmen Gaina , Giuliana Panieri , Claudio Argentino , Ute Mann , Wiktor Bönke , Tomas Kjennerud , Rune Mattingsdal","doi":"10.1016/j.marpetgeo.2025.107637","DOIUrl":"10.1016/j.marpetgeo.2025.107637","url":null,"abstract":"<div><div>This study evaluates the source rock potential, organic matter input, and depositional environments of Miocene-aged sediments in the eastern Nordic Seas. It focuses on ODP/IODP Sites 909, 985, and U1572, two exploration wells (7316/5-1 and 6608/10-1), and oil seeps offshore western Svalbard. Integrated marine palynological, biomarker, and geochemical analyses indicate a mainly Early to Middle Miocene age and a mixed terrestrial-marine origin of the sedimentary organic matter and associated oil seeps. Angiosperm-derived biomarkers, especially triterpenoids like oleananes and oleanenes, are abundant and help link seeping oils to deltaic terrestrial sources. Depositional settings ranged from oxic in the Fram Strait (Hole 909C) to dysoxic or anoxic in southern Sites (Holes 985A and U1572B), influenced by the semi-enclosed Nordic Seas. Geochemical indicators such as sulfur content, TOC/S ratios, and Pr/Ph values reflect variations in bottom water oxygenation and sediment conditions. Terrestrial organic input is linked to Miocene deltaic systems, likely formed by tectonic uplift in East Greenland, the Barents Sea, and central Norway.</div><div>Basin modeling in the southwestern Barents Sea, using seismic and well data, shows that Miocene source rocks have reached maturity levels sufficient for hydrocarbon generation, especially beneath thick Plio-Pleistocene glacial overburden. The presence of oleanene and oleanane in both boreholes and oil seeps supports the conclusion that these Miocene source rocks are regionally widespread and part of an active petroleum system.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"183 ","pages":"Article 107637"},"PeriodicalIF":3.6,"publicationDate":"2025-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145733504","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}
Pub Date : 2025-10-09DOI: 10.1016/j.marpetgeo.2025.107619
Yaxin Shang , Keyu Liu , Ziyi Wang , Bo Zhang
Chlorite can strongly affect the quality of clastic sandstone reservoirs and may also impact the potential of geologic sequestration of CO2 in deep saline aquifers. However, there is a lack of quantitative evaluation of the effect of chlorite on CO2 sequestration in sandstones to date. Here we applied a suite of analytical techniques including petrographic and petrological analysis, X-ray diffraction measurement, petrophysical analysis, and CO2-fluid-rock reactive-transport simulations to investigate the impact of chlorite on both reservoir quality and CO2 geological sequestration in the Upper Permian sandstones in the northeastern Ordos Basin, China. Three types of chlorite are present in the reservoir sandstone: grain-coating, pore-throat-blocking, and pore-filling. Grain-coating chlorite sandstones feature thin chlorite wrapping on sand grain surfaces that effectively prevent quartz cementation, thus preserving good reservoir porosity and permeability. Pore-throat-blocking chlorite sandstones generally exhibit high porosity but low permeability with the thick chlorite coatings inhibiting quartz cement growth and preserving porosity while blocking pore throats and reducing permeability. Pore-filling chlorite sandstones are characterized by both low porosity and low permeability due to extensive chlorite filling of the pore spaces as matrix. Reactive transport simulations demonstrate that high-porosity and -permeability reservoir sandstones may not always be the most favorable sandstone type for CO2 geological sequestration when considering the key geochemical sequestration mechanisms (i.e. dissolution and mineral trapping). When disregarding the impact of chlorite on reservoir quality, pore-filling chlorite sandstones, with their high chlorite content, are most suitable for CO2 sequestration due to their greater capacity for trapping CO2 via mineralization. However, when both chlorite abundance and reservoir quality factors are considered, pore-throat-blocking chlorite sandstones would possess the largest total CO2 sequestration capacity.
{"title":"Quantifying the effect of chlorite on reservoir quality and CO2 sequestration in deep saline aquifers from the permian tight sandstone reservoir in the ordos basin, China","authors":"Yaxin Shang , Keyu Liu , Ziyi Wang , Bo Zhang","doi":"10.1016/j.marpetgeo.2025.107619","DOIUrl":"10.1016/j.marpetgeo.2025.107619","url":null,"abstract":"<div><div>Chlorite can strongly affect the quality of clastic sandstone reservoirs and may also impact the potential of geologic sequestration of CO<sub>2</sub> in deep saline aquifers. However, there is a lack of quantitative evaluation of the effect of chlorite on CO<sub>2</sub> sequestration in sandstones to date. Here we applied a suite of analytical techniques including petrographic and petrological analysis, X-ray diffraction measurement, petrophysical analysis, and CO<sub>2</sub>-fluid-rock reactive-transport simulations to investigate the impact of chlorite on both reservoir quality and CO<sub>2</sub> geological sequestration in the Upper Permian sandstones in the northeastern Ordos Basin, China. Three types of chlorite are present in the reservoir sandstone: grain-coating, pore-throat-blocking, and pore-filling. Grain-coating chlorite sandstones feature thin chlorite wrapping on sand grain surfaces that effectively prevent quartz cementation, thus preserving good reservoir porosity and permeability. Pore-throat-blocking chlorite sandstones generally exhibit high porosity but low permeability with the thick chlorite coatings inhibiting quartz cement growth and preserving porosity while blocking pore throats and reducing permeability. Pore-filling chlorite sandstones are characterized by both low porosity and low permeability due to extensive chlorite filling of the pore spaces as matrix. Reactive transport simulations demonstrate that high-porosity and -permeability reservoir sandstones may not always be the most favorable sandstone type for CO<sub>2</sub> geological sequestration when considering the key geochemical sequestration mechanisms (<em>i.e.</em> dissolution and mineral trapping). When disregarding the impact of chlorite on reservoir quality, pore-filling chlorite sandstones, with their high chlorite content, are most suitable for CO<sub>2</sub> sequestration due to their greater capacity for trapping CO<sub>2</sub> via mineralization. However, when both chlorite abundance and reservoir quality factors are considered, pore-throat-blocking chlorite sandstones would possess the largest total CO<sub>2</sub> sequestration capacity.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"183 ","pages":"Article 107619"},"PeriodicalIF":3.6,"publicationDate":"2025-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145270613","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}
Pub Date : 2025-10-08DOI: 10.1016/j.marpetgeo.2025.107632
Hugh Daigle , Eli Cable , Carlos Figueroa-Diaz , Jordan Jee , Aidan Pyrcz
Scientific ocean drilling has provided a significant amount of information about the marine subsurface over the last 57 years, including samples and data pertaining to physical properties, geochemistry, microbiology, lithology, stratigraphy, and structural geology. Our understanding of subsurface mass transport has benefited from many hundreds of permeability measurements performed on scientific ocean drilling samples. We assembled a database of 836 permeability measurements along with other physical properties measured shipboard, including determinations of porosity and grain density from moisture and density (MAD) measurements, natural gamma radiation and magnetic susceptibility from multisensory core logger (MSCL) measurements, total carbonate content, and lithological description, silt percentage, and clay percentage from smear slides. The goals of our study were assessing the state of our understanding of marine sediment permeability, assessing processes that control permeability, and the best ways to leverage legacy ocean drilling samples and datasets to improve our understanding of the subsurface. We found that the majority of permeability samples (71 %) come from the Pacific Ocean, particularly its active margins; that clays and silts are the most frequently tested lithologies; that the depth distribution of samples is similar to the overall depth distribution of drilled holes, indicating that the data are not biased towards particular depth ranges; and that the permeabilities obtained span nearly 11 orders of magnitude. We observed weak to no correlation between permeability and the physical properties we considered, but we were able to train a random forest regression model to predict permeability within about half an order of magnitude based on measurements that were performed previously or can be obtained from unpreserved, legacy cores. This presents an opportunity to be able to predict permeability in more locations globally and answer research questions about fluid flow and pore pressure.
{"title":"What scientific ocean drilling has taught us about the permeability of marine sediments","authors":"Hugh Daigle , Eli Cable , Carlos Figueroa-Diaz , Jordan Jee , Aidan Pyrcz","doi":"10.1016/j.marpetgeo.2025.107632","DOIUrl":"10.1016/j.marpetgeo.2025.107632","url":null,"abstract":"<div><div>Scientific ocean drilling has provided a significant amount of information about the marine subsurface over the last 57 years, including samples and data pertaining to physical properties, geochemistry, microbiology, lithology, stratigraphy, and structural geology. Our understanding of subsurface mass transport has benefited from many hundreds of permeability measurements performed on scientific ocean drilling samples. We assembled a database of 836 permeability measurements along with other physical properties measured shipboard, including determinations of porosity and grain density from moisture and density (MAD) measurements, natural gamma radiation and magnetic susceptibility from multisensory core logger (MSCL) measurements, total carbonate content, and lithological description, silt percentage, and clay percentage from smear slides. The goals of our study were assessing the state of our understanding of marine sediment permeability, assessing processes that control permeability, and the best ways to leverage legacy ocean drilling samples and datasets to improve our understanding of the subsurface. We found that the majority of permeability samples (71 %) come from the Pacific Ocean, particularly its active margins; that clays and silts are the most frequently tested lithologies; that the depth distribution of samples is similar to the overall depth distribution of drilled holes, indicating that the data are not biased towards particular depth ranges; and that the permeabilities obtained span nearly 11 orders of magnitude. We observed weak to no correlation between permeability and the physical properties we considered, but we were able to train a random forest regression model to predict permeability within about half an order of magnitude based on measurements that were performed previously or can be obtained from unpreserved, legacy cores. This presents an opportunity to be able to predict permeability in more locations globally and answer research questions about fluid flow and pore pressure.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"183 ","pages":"Article 107632"},"PeriodicalIF":3.6,"publicationDate":"2025-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145270562","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}
Submarine mud volcanoes (MVs) are seafloor features commonly found in tectonically active margins with high sedimentation and compressional regimes. This study reports the first discovery of a prominent crater-like mud volcano on the Chilean margin, named the Cucao Mud Volcano (CMV), located ∼86 km offshore Chiloé Island (∼42°S) at a depth of 1800 m. Multichannel seismic data reveal that the CMV is structurally emplaced along the crest of a faulted anticline within a transpressional setting, indicating that tectonic deformation governs both its morphology and fluid pathways. A strong, continuous Bottom Simulating Reflector (BSR), seismic blanking, bright spots, and chaotic facies in the shallow subsurface suggest the presence of gas hydrates, free gas, and active fluid migration. High-resolution multibeam bathymetry and backscatter mosaics show a caldera-like edifice with a central crater, dome-shaped flanks, and surrounding depressions. Comparative data from 2012 to 2018 indicate reduced surface activity, possibly reflecting a transition to a quiescent phase. Additionally, dome-shaped reflectors above the BSR suggest diapir-like intrusions and vertical conduits associated with gas hydrate dissociation and overpressure. These findings underscore the complex interplay between tectonics, gas hydrate systems, and mud volcanism, positioning the CMV as a key site for understanding fluid dynamics along convergent continental margins.
{"title":"Discovery of an active crater-like mud volcano at ∼42°S on the Chilean margin: structural controls and gas hydrate associations","authors":"Cristian Rodrigo, Fernanda Ruiz, Nitza Garrido, Ximena Contardo","doi":"10.1016/j.marpetgeo.2025.107618","DOIUrl":"10.1016/j.marpetgeo.2025.107618","url":null,"abstract":"<div><div>Submarine mud volcanoes (MVs) are seafloor features commonly found in tectonically active margins with high sedimentation and compressional regimes. This study reports the first discovery of a prominent crater-like mud volcano on the Chilean margin, named the Cucao Mud Volcano (CMV), located ∼86 km offshore Chiloé Island (∼42°S) at a depth of 1800 m. Multichannel seismic data reveal that the CMV is structurally emplaced along the crest of a faulted anticline within a transpressional setting, indicating that tectonic deformation governs both its morphology and fluid pathways. A strong, continuous Bottom Simulating Reflector (BSR), seismic blanking, bright spots, and chaotic facies in the shallow subsurface suggest the presence of gas hydrates, free gas, and active fluid migration. High-resolution multibeam bathymetry and backscatter mosaics show a caldera-like edifice with a central crater, dome-shaped flanks, and surrounding depressions. Comparative data from 2012 to 2018 indicate reduced surface activity, possibly reflecting a transition to a quiescent phase. Additionally, dome-shaped reflectors above the BSR suggest diapir-like intrusions and vertical conduits associated with gas hydrate dissociation and overpressure. These findings underscore the complex interplay between tectonics, gas hydrate systems, and mud volcanism, positioning the CMV as a key site for understanding fluid dynamics along convergent continental margins.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"182 ","pages":"Article 107618"},"PeriodicalIF":3.6,"publicationDate":"2025-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145219115","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}
Pub Date : 2025-09-29DOI: 10.1016/j.marpetgeo.2025.107615
Jin Qian , Xiujuan Wang , Jiapeng Jin , Maheswar Ojha , Nengyou Wu , Ranjana Ghosh , Kalachand Sain , Zhen Liu
In the Krishna-Godavari (K-G) offshore basin, India, a 130 m thick fracture-filling gas hydrate-bearing layer (GHBL), associated with near-seafloor paleo-cold seep activity, was identified during drilling and coring at Site NGHP-01-10 (Site 10). Our new analyses of drilling cores and pore-water show that authigenic carbonates and shells are present throughout the upper 200 mbsf at Site 10, with two separate intervals of high chloride concentrations up to 663 mM. It indicates a periodically active cold seep and relatively young hydrate system. This study combines core, well log and seismic data to gain insight into the fine characteristics and detailed formation process of such a thick paleo-cold seep and hydrate system. Seismic imaging of newly interpreted chimney-like structures, growth faults and multiple stacked mass transport deposits (MTDs) illustrates that the system is located within a geologically disturbed sediment zone. Synthetic seismogram-derived time-depth relationship between seismic and core data shows that multiple MTDs repeatedly control the paleo-cold seeps and further influence the hydrate. A new paleo-cold seep and hydrate system is identified southeast of Site 10, where seismic data reveal a buried vent characterized by a high amplitude reflection consistent with seafloor polarity, along with high density and velocity indicative of authigenic carbonates. These two thick systems probably formed in stages due to the clear stratifications on the seismic data, 2D anisotropic saturations and internal chimney-like structures. They are originated from diapirism and growth faulting, and their lateral extent depends on the fracture zone width within the anticline ridge. After formation, the process of hydrate recycling is triggered by the sedimentation and has led to the upward shift of the system. Our findings indicate that there exists a periodically active cold seep and gas hydrate system at Site 10. The activity of this periodic system can account for the formation of the multilayered or thick GHBL, and facilitate an understanding of the evolution of the paleo-cold seep found around the world. Although the cold seep at Site 10 is not active and the hydrate is currently only in the chloride diffusion stage, the underlying gas accumulation means that new cold seep and hydrate systems may form in the future.
{"title":"Characteristics of periodically active cold seep and gas hydrate systems in Krishna-Godavari offshore basin, India","authors":"Jin Qian , Xiujuan Wang , Jiapeng Jin , Maheswar Ojha , Nengyou Wu , Ranjana Ghosh , Kalachand Sain , Zhen Liu","doi":"10.1016/j.marpetgeo.2025.107615","DOIUrl":"10.1016/j.marpetgeo.2025.107615","url":null,"abstract":"<div><div>In the Krishna-Godavari (K-G) offshore basin, India, a 130 m thick fracture-filling gas hydrate-bearing layer (GHBL), associated with near-seafloor paleo-cold seep activity, was identified during drilling and coring at Site NGHP-01-10 (Site 10). Our new analyses of drilling cores and pore-water show that authigenic carbonates and shells are present throughout the upper 200 mbsf at Site 10, with two separate intervals of high chloride concentrations up to 663 mM. It indicates a periodically active cold seep and relatively young hydrate system. This study combines core, well log and seismic data to gain insight into the fine characteristics and detailed formation process of such a thick paleo-cold seep and hydrate system. Seismic imaging of newly interpreted chimney-like structures, growth faults and multiple stacked mass transport deposits (MTDs) illustrates that the system is located within a geologically disturbed sediment zone. Synthetic seismogram-derived time-depth relationship between seismic and core data shows that multiple MTDs repeatedly control the paleo-cold seeps and further influence the hydrate. A new paleo-cold seep and hydrate system is identified southeast of Site 10, where seismic data reveal a buried vent characterized by a high amplitude reflection consistent with seafloor polarity, along with high density and velocity indicative of authigenic carbonates. These two thick systems probably formed in stages due to the clear stratifications on the seismic data, 2D anisotropic saturations and internal chimney-like structures. They are originated from diapirism and growth faulting, and their lateral extent depends on the fracture zone width within the anticline ridge. After formation, the process of hydrate recycling is triggered by the sedimentation and has led to the upward shift of the system. Our findings indicate that there exists a periodically active cold seep and gas hydrate system at Site 10. The activity of this periodic system can account for the formation of the multilayered or thick GHBL, and facilitate an understanding of the evolution of the paleo-cold seep found around the world. Although the cold seep at Site 10 is not active and the hydrate is currently only in the chloride diffusion stage, the underlying gas accumulation means that new cold seep and hydrate systems may form in the future.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"182 ","pages":"Article 107615"},"PeriodicalIF":3.6,"publicationDate":"2025-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145219114","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}
Pub Date : 2025-09-29DOI: 10.1016/j.marpetgeo.2025.107613
E. Luzzi , M. D'Emidio , L. Macelloni
Brine pools are underwater hypersaline and often anoxic lakes, which occur abundantly in the Gulf of America (Gulf) due to its complex geological and structural setting, particularly because of the presence of the buried Louann salt deposit. Fluids migrating upward dissolve this salt, and the resulting brine ascends until it is expelled at the seafloor through cold seeps. In instances where the brine accumulates without significant overflow, brine pools are formed. These extreme environments host interconnected communities of bacteria and archaea, and at their edges, chemosynthetic communities thrive, forming extensive mussel beds. By studying the variable geochemical gradients and biological settings of the Gulf brine pools, researchers have significantly advanced our understanding of these extreme environments. However, due to the limited accessibility of these sites, brine pools remain understudied compared to more accessible locations, leaving many questions unanswered. This review synthesizes current knowledge of Gulf brine pools, providing a standardized foundation for future exploration, assessments of critical minerals, and research efforts, which could shed light on the habitability limits on our planet and inform the search for life in similar environments within our solar system.
{"title":"Brine pools in the Gulf of America: A review","authors":"E. Luzzi , M. D'Emidio , L. Macelloni","doi":"10.1016/j.marpetgeo.2025.107613","DOIUrl":"10.1016/j.marpetgeo.2025.107613","url":null,"abstract":"<div><div>Brine pools are underwater hypersaline and often anoxic lakes, which occur abundantly in the Gulf of America (Gulf) due to its complex geological and structural setting, particularly because of the presence of the buried Louann salt deposit. Fluids migrating upward dissolve this salt, and the resulting brine ascends until it is expelled at the seafloor through cold seeps. In instances where the brine accumulates without significant overflow, brine pools are formed. These extreme environments host interconnected communities of bacteria and archaea, and at their edges, chemosynthetic communities thrive, forming extensive mussel beds. By studying the variable geochemical gradients and biological settings of the Gulf brine pools, researchers have significantly advanced our understanding of these extreme environments. However, due to the limited accessibility of these sites, brine pools remain understudied compared to more accessible locations, leaving many questions unanswered. This review synthesizes current knowledge of Gulf brine pools, providing a standardized foundation for future exploration, assessments of critical minerals, and research efforts, which could shed light on the habitability limits on our planet and inform the search for life in similar environments within our solar system.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"183 ","pages":"Article 107613"},"PeriodicalIF":3.6,"publicationDate":"2025-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145322769","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}
Pub Date : 2025-09-29DOI: 10.1016/j.marpetgeo.2025.107608
Suyane Gonçalves de Campos , Marcus Vinicius Dorneles Remus , Bruno Rafael de Barros Pereira , Cristiano de Carvalho Lana , Marcia Boscato Gomes , Susan Drago Martins , Norberto Dani , Emilson Fernandes Soares , Diogo Andre Buck
Sedimentary provenance analysis based on the major element composition of detrital garnet and tourmaline is a conventional and widely used method. However, overlapping compositional fields in standard garnet classification diagrams often hinder the accurate identification of source areas. To overcome such ambiguities, this study applies an integrated analytical approach. The methodology involved the compositional analysis of major and trace elements (Zn, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) in 1043 garnet grains, major elements in 1493 tourmaline grains, and multivariate statistical analysis to refine the provenance of sandstones from the Pendência, Alagamar and Açu formations (Potiguar Basin, NE Brazil). Initial classification using major elements suggested a significant contribution from felsic igneous sources (Bi-type). However, trace-element geochemistry revealed that a significant portion of these garnets ( of the original Bi type) shows an affinity with amphibolite and granulite-facies metapelites. This reclassification is corroborated by the predominance of tourmalines derived from metapelites and by the statistical analysis of the major elements of the garnets in the investigated samples. Therefore, the results indicate that the sediment supply for the studied formations has a more significant metasedimentary contribution than suggested by conventional methods alone. The integrated data point to the Seridó Terrane and the Caicó Complex, within the Borborema Province, as the most likely source areas, with a predominance of amphibolite-facies and, secondarily, granulite-facies metasedimentary rocks. The participation of igneous sources was more evident in the pre-rift phase due to precursor and contemporaneous Cretaceous magmatic activity. A mixed supply, with an expressive contribution from igneous and metamorphic basement sources, characterized the rift phase (Pendência Formation). The post-rift (Alagamar Formation) and drift (Açu Formation) phases maintained this mixed pattern, with a predominance of metasedimentary sources from the basement, but with the addition of new magmatic pulses and the reworking of preexisting volcaniclastic materials during the drift phase.
{"title":"Identifying source-rocks using trace-elements and garnet discrimination diagrams: Example from Potiguar Basin, equatorial margin, NE Brazil","authors":"Suyane Gonçalves de Campos , Marcus Vinicius Dorneles Remus , Bruno Rafael de Barros Pereira , Cristiano de Carvalho Lana , Marcia Boscato Gomes , Susan Drago Martins , Norberto Dani , Emilson Fernandes Soares , Diogo Andre Buck","doi":"10.1016/j.marpetgeo.2025.107608","DOIUrl":"10.1016/j.marpetgeo.2025.107608","url":null,"abstract":"<div><div>Sedimentary provenance analysis based on the major element composition of detrital garnet and tourmaline is a conventional and widely used method. However, overlapping compositional fields in standard garnet classification diagrams often hinder the accurate identification of source areas. To overcome such ambiguities, this study applies an integrated analytical approach. The methodology involved the compositional analysis of major and trace elements (Zn, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) in 1043 garnet grains, major elements in 1493 tourmaline grains, and multivariate statistical analysis to refine the provenance of sandstones from the Pendência, Alagamar and Açu formations (Potiguar Basin, NE Brazil). Initial classification using major elements suggested a significant contribution from felsic igneous sources (Bi-type). However, trace-element geochemistry revealed that a significant portion of these garnets (<span><math><mrow><mo>≈</mo><mn>79</mn><mtext>%</mtext></mrow></math></span> of the original Bi type) shows an affinity with amphibolite and granulite-facies metapelites. This reclassification is corroborated by the predominance of tourmalines derived from metapelites and by the statistical analysis of the major elements of the garnets in the investigated samples. Therefore, the results indicate that the sediment supply for the studied formations has a more significant metasedimentary contribution than suggested by conventional methods alone. The integrated data point to the Seridó Terrane and the Caicó Complex, within the Borborema Province, as the most likely source areas, with a predominance of amphibolite-facies and, secondarily, granulite-facies metasedimentary rocks. The participation of igneous sources was more evident in the pre-rift phase due to precursor and contemporaneous Cretaceous magmatic activity. A mixed supply, with an expressive contribution from igneous and metamorphic basement sources, characterized the rift phase (Pendência Formation). The post-rift (Alagamar Formation) and drift (Açu Formation) phases maintained this mixed pattern, with a predominance of metasedimentary sources from the basement, but with the addition of new magmatic pulses and the reworking of preexisting volcaniclastic materials during the drift phase.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"182 ","pages":"Article 107608"},"PeriodicalIF":3.6,"publicationDate":"2025-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145265000","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}
Pub Date : 2025-09-29DOI: 10.1016/j.marpetgeo.2025.107616
Yong Cheng , Jia-Xi Zhou , Yuzhao Hu , Saihua Xu , Shengbao Shi , Yiming Wen , Qi Nie , Ye Zhou , Kai Luo , Xiaolin Tan , Liang Zhou , Yadong Li , Yang Liu , Xiaoliang Zhang
The Niujiaotang Mississippi Valley-Type (MVT) Pb–Zn deposit (SW China) hosts 0.35 Mt Zn (5.85–24.48 wt%) and 5.3 kt Cd (0.04–1.43 wt%). Although previous inorganic geochemical studies have indicated a significant role of organic matter in mineralization, critical organic geochemical evidence is still lacking. This study presents the first integrated biomarker investigation of solid bitumen derived from the host rock of the deposit, clarifying the sources of organic matter, its thermal evolution, and metallogenic implications. Hydrothermal alteration assessments reveal that biomarker distributions have undergone only mild biodegradation and reliably preserved source and maturity information. Multiple maturity proxies indicate an over-mature stage (>150 °C), which meets the thermal requirement for thermochemical sulfate reduction (TSR). Saturated and aromatic hydrocarbon fingerprints, combined with carbon-isotope data, demonstrate derivation from Lower Cambrian source rocks dominated by marine algal/bacterial organic matter with minor terrestrial higher-plant input. The relative abundances of dibenzothiophene series compounds (5.84–9.54 %, mean 7.27 %) versus biphenyls (1.77–7.01 %, mean 4.62 %) provide robust molecular evidence for extensive TSR reactions. This study strengthens the interpretation that sulfur-rich hydrocarbons act as the principal reductant in TSR, facilitating the conversion of stratal sulfate to H2S and thereby establishing the reduced sulfur reservoir essential for Pb–Zn precipitation. Macroscopic intergrowths of solid bitumen with sulfide and carbonate gangue, alongside microscopic hydrocarbon inclusions in sphalerite and dolomite, corroborate this model. These organic-geochemical constraints refine genetic concepts for MVT deposits and emphasize the value of integrating petroleum system analysis into exploration workflows for analogous Pb–Zn systems.
{"title":"The biomarker signatures in the Niujiaotang sulfide ore field: Exploring the role of organic matter in ore formation","authors":"Yong Cheng , Jia-Xi Zhou , Yuzhao Hu , Saihua Xu , Shengbao Shi , Yiming Wen , Qi Nie , Ye Zhou , Kai Luo , Xiaolin Tan , Liang Zhou , Yadong Li , Yang Liu , Xiaoliang Zhang","doi":"10.1016/j.marpetgeo.2025.107616","DOIUrl":"10.1016/j.marpetgeo.2025.107616","url":null,"abstract":"<div><div>The Niujiaotang Mississippi Valley-Type (MVT) Pb–Zn deposit (SW China) hosts 0.35 Mt Zn (5.85–24.48 wt%) and 5.3 kt Cd (0.04–1.43 wt%). Although previous inorganic geochemical studies have indicated a significant role of organic matter in mineralization, critical organic geochemical evidence is still lacking. This study presents the first integrated biomarker investigation of solid bitumen derived from the host rock of the deposit, clarifying the sources of organic matter, its thermal evolution, and metallogenic implications. Hydrothermal alteration assessments reveal that biomarker distributions have undergone only mild biodegradation and reliably preserved source and maturity information. Multiple maturity proxies indicate an over-mature stage (>150 °C), which meets the thermal requirement for thermochemical sulfate reduction (TSR). Saturated and aromatic hydrocarbon fingerprints, combined with carbon-isotope data, demonstrate derivation from Lower Cambrian source rocks dominated by marine algal/bacterial organic matter with minor terrestrial higher-plant input. The relative abundances of dibenzothiophene series compounds (5.84–9.54 %, mean 7.27 %) versus biphenyls (1.77–7.01 %, mean 4.62 %) provide robust molecular evidence for extensive TSR reactions. This study strengthens the interpretation that sulfur-rich hydrocarbons act as the principal reductant in TSR, facilitating the conversion of stratal sulfate to H<sub>2</sub>S and thereby establishing the reduced sulfur reservoir essential for Pb–Zn precipitation. Macroscopic intergrowths of solid bitumen with sulfide and carbonate gangue, alongside microscopic hydrocarbon inclusions in sphalerite and dolomite, corroborate this model. These organic-geochemical constraints refine genetic concepts for MVT deposits and emphasize the value of integrating petroleum system analysis into exploration workflows for analogous Pb–Zn systems.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"183 ","pages":"Article 107616"},"PeriodicalIF":3.6,"publicationDate":"2025-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145227566","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}
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