Magnetic minerals in sediments of the continental shelf are sensitive to environmental changes.Therefore,to determine the exact phases of magnetic minerals is the prerequisite to investigate the paleoenvironmental sig...Magnetic minerals in sediments of the continental shelf are sensitive to environmental changes.Therefore,to determine the exact phases of magnetic minerals is the prerequisite to investigate the paleoenvironmental significances.In this study,a comprehensive rock magnetic investigation,coupled with mineralogical studies,was carried out on the long core NHH01(with a length of 125.64 m)from the central continental shelf of the South Yellow Sea.Single-domain greigite was identified as the dominant magnetic carrier in sediments between44.90 and 51.80 m,and terrigenous magnetite is the major magnetic phase in the adjacent layers.The existence of greigite unambiguously indicates an anoxic environment.We tentatively interpreted that such an environment could be formed by the fast sea level changes,long-existing of the cold eddies during warm stages,or in a lake which might be related to locally tectonic uplifting.Therefore,the occurrence of the thick-layer greigite could supply a new perspective to paleoenvironmental or even tectonic studies.展开更多
A total of six d13C minimum events,i.e.,VI,V,IV,III,II,and I,were observed via a stable carbon and oxygen isotope analysis of infaunal benthic foraminifera Uvigerina spp.in gravity core OS03-1 in the southeastern Okho...A total of six d13C minimum events,i.e.,VI,V,IV,III,II,and I,were observed via a stable carbon and oxygen isotope analysis of infaunal benthic foraminifera Uvigerina spp.in gravity core OS03-1 in the southeastern Okhotsk Sea over the last 180 ka.These events occurred at112–109,102–90,85–76,57–54,44–40,and 17–10 ka BP.The largest negative excursions reached 2.5%in event V and were greater than 1%in the other events.We proposed that all d13C minimum events were caused by the increase in sea surface water productivity,the weakened formation of Okhotsk Sea intermediate water,and the enhancement of the oxygen minimum zone.The negative excursions were unaffected by methane hydrate destabilization and subsequent methane release based on the results obtained by using archaeal lipid markers.展开更多
基金supported by the Project of State Oceanic Administration, China (908-01-BC15)the National Natural Science Foundation of China (41374073, 41025013 and40821091)
文摘Magnetic minerals in sediments of the continental shelf are sensitive to environmental changes.Therefore,to determine the exact phases of magnetic minerals is the prerequisite to investigate the paleoenvironmental significances.In this study,a comprehensive rock magnetic investigation,coupled with mineralogical studies,was carried out on the long core NHH01(with a length of 125.64 m)from the central continental shelf of the South Yellow Sea.Single-domain greigite was identified as the dominant magnetic carrier in sediments between44.90 and 51.80 m,and terrigenous magnetite is the major magnetic phase in the adjacent layers.The existence of greigite unambiguously indicates an anoxic environment.We tentatively interpreted that such an environment could be formed by the fast sea level changes,long-existing of the cold eddies during warm stages,or in a lake which might be related to locally tectonic uplifting.Therefore,the occurrence of the thick-layer greigite could supply a new perspective to paleoenvironmental or even tectonic studies.
基金supported by the National Basic Research Program of China (2013CB429700)the Basic Scientific Fund for the National Public Research Institutes of China (2012G07, 2013G38)+1 种基金the National Natural Science Foundation of China (40431002, 4071006900 and 40906035)the Youth Marine Science Foundation of the State Oceanic Administration (2013313)
文摘A total of six d13C minimum events,i.e.,VI,V,IV,III,II,and I,were observed via a stable carbon and oxygen isotope analysis of infaunal benthic foraminifera Uvigerina spp.in gravity core OS03-1 in the southeastern Okhotsk Sea over the last 180 ka.These events occurred at112–109,102–90,85–76,57–54,44–40,and 17–10 ka BP.The largest negative excursions reached 2.5%in event V and were greater than 1%in the other events.We proposed that all d13C minimum events were caused by the increase in sea surface water productivity,the weakened formation of Okhotsk Sea intermediate water,and the enhancement of the oxygen minimum zone.The negative excursions were unaffected by methane hydrate destabilization and subsequent methane release based on the results obtained by using archaeal lipid markers.
