The biogenic silica of sediment samples from Core CJ01-185 which is collected from the eastern India Ocean off the Sunda Strait is analyzed to evaluate the impact of the opening of the Sunda Strait on a paleoproductiv...The biogenic silica of sediment samples from Core CJ01-185 which is collected from the eastern India Ocean off the Sunda Strait is analyzed to evaluate the impact of the opening of the Sunda Strait on a paleoproductivity evolution. The new results indicate that the biogenic silica mass values of Core CJ01-185 show the lowest 0.86% in the last glacial period, and reach its maxima of 1.89% in the late Holocene. Furthermore, the biogenic silica mass accumulation rate(MARBSi) values also vary with much higher during the late Holocene than during the last glaciation. The input of additional terrigenous materials from the Java Sea has enhanced the paleoproductivity and increased the biogenic silica mass and MARBSi values after the opening of the Sunda Strait. It is suggested that the paleoproductivity in the study area is mainly influenced by the southeast monsoon and upwelling before the opening of the Sunda Strait. However, the paleoproductivity is dominated by the terrigenous materials input other than by the southeast monsoon or upwelling in the Holocene.展开更多
Ridges are common features found on continental shelves and understanding their formation processes is crucial for sedimentology,stratigraphy,and geological engineering.This study investigates the development of ridge...Ridges are common features found on continental shelves and understanding their formation processes is crucial for sedimentology,stratigraphy,and geological engineering.This study investigates the development of ridges on the broad shelf of the East China Sea using a core(DH03)and associated seismic profile.Lithology analysis of the core revealed a 50 m thick shallow sandy sequence which consisted mainly of silty fine sands with intercalations of mud beds composed of sand-mud couplets.Benthic foraminifera examination indicated the offshore species were dominant.The seismic profile indicated that the ridges were separated from the older delta layers due to a boundary formed by river erosion during the last glacial maximum.Radiocarbon dating of the sandy sequence revealed an irregular chronological sequence,with most age ranges falling within the past 3 ka.Based on the chronological data from DH03 and other cores,we propose that the ridges,which were formed during the early Holocene transgression,have been active on a shelf scale in the recent 3-2 ka.Synthetic analysis of the shelf-scale ridge formation processes indicates that the sea-level fluctuations during the mid-late Holocene sea-level highstand triggered the ridge activities.A center for ridge activity developed in the southern shelf,facilitated by thicker ridge deposits in the paleo-Changjiang River Estuary and stronger currents(tidal currents and possibly internal waves)induced by the remaining funnel-shaped estuary topography.Based on these findings,we propose a conceptual model for ridge development,which includes a ridge formation stage during the early Holocene transgression and a ridge activation stage during the mid-late Holocene sea-level highstand.展开更多
The ocean is the largest active carbon reservoir on Earth. Organic carbon(OC), as the primary species of carbon sequestration in the ocean, plays an important role in the global carbon cycle through its deposition and...The ocean is the largest active carbon reservoir on Earth. Organic carbon(OC), as the primary species of carbon sequestration in the ocean, plays an important role in the global carbon cycle through its deposition and burial. In this study,sedimentary OC data from 5796 stations, together with relevant geochemical and sedimentological parameters in the Bohai Sea,Yellow Sea, and East China Sea(BYES) were used to summarize and elucidate the distribution and burial patterns of sedimentary OC, and assess carbon sink effect of sedimentary OC burial. The results show that the OC content in the sediments of the BYES ranges from 0.00% to 2.12%, with an average content of 0.47%±0.26%. OC content is significantly correlated with finegrained sediments, with an average OC content in mud areas being 39% higher than that in non-mud areas. Modern OC buried in the BYES are mainly deposited in 7 major mud areas, with a total sedimentary OC burial flux of approximately 8.20 Mt C yr^(–1).Among them, the burial flux of biospheric OC is 6.92 Mt C yr^(–1), equivalent to the OC consumption amount of silicate weathering of the 9 major river basins in the eastern China. In its natural state, the annually sequestered OC in the sediments of the eastern China seas is equivalent to 25.37 Mt of atmospheric CO_(2), indicating a significant carbon sink effect. The distribution and burial of terrigenous OC in the BYES are mainly influenced by the large river inputs and complex marine hydrodynamic environment,while human activities such as dam construction have significantly altered the OC burial in these coastal mud areas.展开更多
基金The National Programme on Global Change and Air-sea Interaction under contract Nos GASI-GEOGE-06-03 and GASI-02-IND-CJ01the China-Indonesia Joint Project under contract No."BENTHIC"the Third Institute of Oceanography,Ministry of Natural Resources Research Grant under contract No.2015015
文摘The biogenic silica of sediment samples from Core CJ01-185 which is collected from the eastern India Ocean off the Sunda Strait is analyzed to evaluate the impact of the opening of the Sunda Strait on a paleoproductivity evolution. The new results indicate that the biogenic silica mass values of Core CJ01-185 show the lowest 0.86% in the last glacial period, and reach its maxima of 1.89% in the late Holocene. Furthermore, the biogenic silica mass accumulation rate(MARBSi) values also vary with much higher during the late Holocene than during the last glaciation. The input of additional terrigenous materials from the Java Sea has enhanced the paleoproductivity and increased the biogenic silica mass and MARBSi values after the opening of the Sunda Strait. It is suggested that the paleoproductivity in the study area is mainly influenced by the southeast monsoon and upwelling before the opening of the Sunda Strait. However, the paleoproductivity is dominated by the terrigenous materials input other than by the southeast monsoon or upwelling in the Holocene.
基金The National Natural Science Foundation of China under contract No.T2192951the Basic Scientific Fund for National Public Research Institutes of China under contract Nos 2021Q09 and 2021S01。
文摘Ridges are common features found on continental shelves and understanding their formation processes is crucial for sedimentology,stratigraphy,and geological engineering.This study investigates the development of ridges on the broad shelf of the East China Sea using a core(DH03)and associated seismic profile.Lithology analysis of the core revealed a 50 m thick shallow sandy sequence which consisted mainly of silty fine sands with intercalations of mud beds composed of sand-mud couplets.Benthic foraminifera examination indicated the offshore species were dominant.The seismic profile indicated that the ridges were separated from the older delta layers due to a boundary formed by river erosion during the last glacial maximum.Radiocarbon dating of the sandy sequence revealed an irregular chronological sequence,with most age ranges falling within the past 3 ka.Based on the chronological data from DH03 and other cores,we propose that the ridges,which were formed during the early Holocene transgression,have been active on a shelf scale in the recent 3-2 ka.Synthetic analysis of the shelf-scale ridge formation processes indicates that the sea-level fluctuations during the mid-late Holocene sea-level highstand triggered the ridge activities.A center for ridge activity developed in the southern shelf,facilitated by thicker ridge deposits in the paleo-Changjiang River Estuary and stronger currents(tidal currents and possibly internal waves)induced by the remaining funnel-shaped estuary topography.Based on these findings,we propose a conceptual model for ridge development,which includes a ridge formation stage during the early Holocene transgression and a ridge activation stage during the mid-late Holocene sea-level highstand.
基金supported by the Laoshan Laboratory (Grant No.LSKJ202204200)the Chinese Offshore Investigation and Assessment Project (Grant No.908~ZC~I~05)+2 种基金the National Natural Science Foundation of China-Shandong Joint Fund for Marine Science Research Centers (Grant No.U1606401)the National Natural Science Foundation of China Shiptime Sharing Project (Grant Nos.42049902,42149902)the Taishan Scholar Program of Shandong (Grant No.tspd20181216)。
文摘The ocean is the largest active carbon reservoir on Earth. Organic carbon(OC), as the primary species of carbon sequestration in the ocean, plays an important role in the global carbon cycle through its deposition and burial. In this study,sedimentary OC data from 5796 stations, together with relevant geochemical and sedimentological parameters in the Bohai Sea,Yellow Sea, and East China Sea(BYES) were used to summarize and elucidate the distribution and burial patterns of sedimentary OC, and assess carbon sink effect of sedimentary OC burial. The results show that the OC content in the sediments of the BYES ranges from 0.00% to 2.12%, with an average content of 0.47%±0.26%. OC content is significantly correlated with finegrained sediments, with an average OC content in mud areas being 39% higher than that in non-mud areas. Modern OC buried in the BYES are mainly deposited in 7 major mud areas, with a total sedimentary OC burial flux of approximately 8.20 Mt C yr^(–1).Among them, the burial flux of biospheric OC is 6.92 Mt C yr^(–1), equivalent to the OC consumption amount of silicate weathering of the 9 major river basins in the eastern China. In its natural state, the annually sequestered OC in the sediments of the eastern China seas is equivalent to 25.37 Mt of atmospheric CO_(2), indicating a significant carbon sink effect. The distribution and burial of terrigenous OC in the BYES are mainly influenced by the large river inputs and complex marine hydrodynamic environment,while human activities such as dam construction have significantly altered the OC burial in these coastal mud areas.
