A number of cold seeps have been discovered in the northern South China Sea(SCS) including the Haiyang 4 cold-seep area where Core 973-5 was collected. Intact polar lipids(IPLs) and core lipids(CLs) were analyzed sepa...A number of cold seeps have been discovered in the northern South China Sea(SCS) including the Haiyang 4 cold-seep area where Core 973-5 was collected. Intact polar lipids(IPLs) and core lipids(CLs) were analyzed separately in sediments from Core 973-5. The most abundant lipid biomarkers were isoprenoidal GDGTs(iso GDGTs), with Crenarchaeol and GDGT-0 predominating. IPL-iso GDGTs and CL-iso GDGTs were mainly derived from Thaumarchaeota. IPL-iso GDGTs were mainly produced and retained in situ thus containing most of the in situ microbiological information. Branched GDGTs were predominantly derived from generated in marine production, and mixed with some terrestrial inputs. All IPLs groups presented a high value in the sulfate-methane transition zone(SMTZ). Furthermore, IPL and CL-MI, IPL-R;showed the highest values within the SMTZ, while IPL and CL-R;had the lowest values at the SMTZ, suggesting that the contribution of Methanophila and methanogenic to GDGTs increased, while the contribution of ammonia-oxidizing Archaea to GDGTs decreased at the SMTZ.展开更多
The biological removal of CH4 by methanotrophic(CH4-oxidizing)archaea always occurs at a distinct zone which is known as sulfate-methane transition zone(SMTZ).It is an important indication for high methane flux and ga...The biological removal of CH4 by methanotrophic(CH4-oxidizing)archaea always occurs at a distinct zone which is known as sulfate-methane transition zone(SMTZ).It is an important indication for high methane flux and gas hydrate occurrence.In this study,we collected pore-water data from South China Sea,Carolina Rise and Blake Ridge to analyze the relationship between CH4,SO42−concentration and depth.We found that below the SMTZ,the methane concentration increases continuously with depth and sulfate concentration decrease linearly to zero.In addition,the geochemical data taken from all these sites show that SMTZ is relatively shallow(less than 20 m),which may indicate that these areas have high methane flux.展开更多
Carbonate deposits related to active seeps are documented along most continental margins and are characterized by peculiar seep-related facies and by chemical(isotope signature),paleontological and mineralogical marke...Carbonate deposits related to active seeps are documented along most continental margins and are characterized by peculiar seep-related facies and by chemical(isotope signature),paleontological and mineralogical markers.Their fossil analogues are recognized all over the world by the same features and occurred since the beginning of Phanerozoic.In this paper,we present a new seep outcrop(Castagneto village,Reggio Emilia,northern Italy)belonging to the late Eocene Loiano Formation which,to our knowledge,is in Italy the most ancient seep deposit with not-reworked chemosymbiotic fauna.The outcrop can be roughly divided into two portions,a northern part showing abundant presence of macrofossils in silty carbonate matrix and subhorizontal subdivisions,and a southern part,where macrofossils are almost absent,characterized by sub-vertical internal subdivisions and a clear vertical structure consisting of the rhythmic alternation of light and dark mineralization.Detailed analysis of samples from the southern portion showed the occurrence of authigenic calcite and pyrite,the latter with a peculiar framboidal texture.This feature,together with the occurrence of chemosymbiotic species and~(13)C isotope depletion,suggests possible hydrocarbon-rich fluid-related genesis and provides useful criteria for identifying hydrocarbon-rich fluid-related deposits in geologic units.展开更多
基金supported by the Natural Science Foundation of China(Grant Nos.40672005 and 41776066)。
文摘A number of cold seeps have been discovered in the northern South China Sea(SCS) including the Haiyang 4 cold-seep area where Core 973-5 was collected. Intact polar lipids(IPLs) and core lipids(CLs) were analyzed separately in sediments from Core 973-5. The most abundant lipid biomarkers were isoprenoidal GDGTs(iso GDGTs), with Crenarchaeol and GDGT-0 predominating. IPL-iso GDGTs and CL-iso GDGTs were mainly derived from Thaumarchaeota. IPL-iso GDGTs were mainly produced and retained in situ thus containing most of the in situ microbiological information. Branched GDGTs were predominantly derived from generated in marine production, and mixed with some terrestrial inputs. All IPLs groups presented a high value in the sulfate-methane transition zone(SMTZ). Furthermore, IPL and CL-MI, IPL-R;showed the highest values within the SMTZ, while IPL and CL-R;had the lowest values at the SMTZ, suggesting that the contribution of Methanophila and methanogenic to GDGTs increased, while the contribution of ammonia-oxidizing Archaea to GDGTs decreased at the SMTZ.
基金the Key Geological Issues in China Sea,the China Geological Survey(Nos.DD20160147 and GZH201100202)the Taishan Scholar Project Grant to Guangxue Li.
文摘The biological removal of CH4 by methanotrophic(CH4-oxidizing)archaea always occurs at a distinct zone which is known as sulfate-methane transition zone(SMTZ).It is an important indication for high methane flux and gas hydrate occurrence.In this study,we collected pore-water data from South China Sea,Carolina Rise and Blake Ridge to analyze the relationship between CH4,SO42−concentration and depth.We found that below the SMTZ,the methane concentration increases continuously with depth and sulfate concentration decrease linearly to zero.In addition,the geochemical data taken from all these sites show that SMTZ is relatively shallow(less than 20 m),which may indicate that these areas have high methane flux.
文摘Carbonate deposits related to active seeps are documented along most continental margins and are characterized by peculiar seep-related facies and by chemical(isotope signature),paleontological and mineralogical markers.Their fossil analogues are recognized all over the world by the same features and occurred since the beginning of Phanerozoic.In this paper,we present a new seep outcrop(Castagneto village,Reggio Emilia,northern Italy)belonging to the late Eocene Loiano Formation which,to our knowledge,is in Italy the most ancient seep deposit with not-reworked chemosymbiotic fauna.The outcrop can be roughly divided into two portions,a northern part showing abundant presence of macrofossils in silty carbonate matrix and subhorizontal subdivisions,and a southern part,where macrofossils are almost absent,characterized by sub-vertical internal subdivisions and a clear vertical structure consisting of the rhythmic alternation of light and dark mineralization.Detailed analysis of samples from the southern portion showed the occurrence of authigenic calcite and pyrite,the latter with a peculiar framboidal texture.This feature,together with the occurrence of chemosymbiotic species and~(13)C isotope depletion,suggests possible hydrocarbon-rich fluid-related genesis and provides useful criteria for identifying hydrocarbon-rich fluid-related deposits in geologic units.
