The grain size distribution of bulk sediment samples was decomposed in a core to reconstruct paleoceanographic evolution over the past 60 ka in the northern Norwegian Sea.The results show that sediments consisted of 3...The grain size distribution of bulk sediment samples was decomposed in a core to reconstruct paleoceanographic evolution over the past 60 ka in the northern Norwegian Sea.The results show that sediments consisted of 3–4 grain populations derived from the North Atlantic Current(NAC)and Barents Ice Sheet(BIS).The grain size data suggest three palaeoceanographic evolution stages:(1)an environment affected by BIS and NAC and changed with the interstadial/stadial transition in phase with the Greenland ice-core record at 60–31 ka BP,during which discharge of icebergs and the content of the coarsest population containing ice-rafted debris(IRD)in the sediments increased significantly during stadial,while the fine silt population containing volcanic glasses increased with the enhancement of NAC during the interstadial;(2)an extreme environment controlled by BIS at31–13 ka BP.BIS reached to its maximum at about 31 ka BP and the turbid plumes that formed at the leading edge of BIS contributed to a significant increase in the clayey population in sediments.Icebergs drained into the northern Norwegian Sea with periodical calving of the BIS at 31–19 ka BP.Subsequently,the ablation of the BIS discharged massive floods with clayey sediments and icebergs into the Norwegian Sea at 19–13 ka BP,resulting in a constant increase in clay and IRD in sediments;and(3)a marine environment similar to the present one under the strong influence of NAC following the complete melting of the BIS after 13 ka BP,NAC is the dominant transport agent and no IRD occurred in sediments.The fine silt populations containing volcanic glasses transported by NAC significantly increased.展开更多
A new approach was taken to investigate the crustal stucture of the Kane transform and its aseismic extension, using high quality bathymetry and gravity data. The gravity signatures associated with variations in crust...A new approach was taken to investigate the crustal stucture of the Kane transform and its aseismic extension, using high quality bathymetry and gravity data. The gravity signatures associated with variations in crustal thickness of the transform were isolated from the observed free air anomaly, was continued downward to the mean depth of the crust/mantle interface and converted onto the relief on that surface. The crustal thickness of the transform was then calculated by subtracting seawater depth from the depth of the gravity inferred crust/mantle interface.3 D gravity investigation results indicate that the Kane transform and adjacent areas are associated with a crust thinner than normal oceanic crust. The transform trough is largely underlain by a crust less than 4.5km thick and in the nodal basins the crust may be as thin as 3 km. The crust beneath the fracture zone valley is 4-5.5 km thick. The rift valleys on the spreading segments are also characterized by thin crust (4-5 km thick). Thin oceanic crust extends to 20-30 km from the transform axis,except for some localized places such as the inside corner highs adjoining the ridge transform intersections. These gravity inferred results match fairly well with limited published seismic results. Thinning of the crust is mainly attributable to a thin layer 3, which in turn may be explained by the combined effects of reduced magma supply at the ends of the spreading segments and tectonic activities in the region.展开更多
Using a 34 years database consisting of sea level pressure and sea iceconcentration, the relationship between Antarctic Oscillation (AAO) and Antarctic Sea-iceOscillation (ASO) was investigated. Firstly, Empirical Ort...Using a 34 years database consisting of sea level pressure and sea iceconcentration, the relationship between Antarctic Oscillation (AAO) and Antarctic Sea-iceOscillation (ASO) was investigated. Firstly, Empirical Orthogonal Function (EOF) analysis depictsthe spatial variability of AAO and ASO and Antarctic Sea-ice Oscillation Index (ASOI) was definedfor the first time. Secondly, power spectrum and head-lag correlation analysis show that ASO and AAOhave the same periods of quasi-three years, quasi-one year and quasi-half a year. Corresponding toAAO, ASO has an evident anti-oscillation after one and half a year.展开更多
基金The Basic Scientific Research Operation Fee of the Third Institute of Oceanography,the Ministry of Natural Resources under contract No.2018006the project of the Chinese Arctic and Antarctic Administration of the State Oceanic Administration under contract No.CHINARE2016-03-02the Shandong Provincial Natural Science Foundation under contract No.ZR2019BD054。
文摘The grain size distribution of bulk sediment samples was decomposed in a core to reconstruct paleoceanographic evolution over the past 60 ka in the northern Norwegian Sea.The results show that sediments consisted of 3–4 grain populations derived from the North Atlantic Current(NAC)and Barents Ice Sheet(BIS).The grain size data suggest three palaeoceanographic evolution stages:(1)an environment affected by BIS and NAC and changed with the interstadial/stadial transition in phase with the Greenland ice-core record at 60–31 ka BP,during which discharge of icebergs and the content of the coarsest population containing ice-rafted debris(IRD)in the sediments increased significantly during stadial,while the fine silt population containing volcanic glasses increased with the enhancement of NAC during the interstadial;(2)an extreme environment controlled by BIS at31–13 ka BP.BIS reached to its maximum at about 31 ka BP and the turbid plumes that formed at the leading edge of BIS contributed to a significant increase in the clayey population in sediments.Icebergs drained into the northern Norwegian Sea with periodical calving of the BIS at 31–19 ka BP.Subsequently,the ablation of the BIS discharged massive floods with clayey sediments and icebergs into the Norwegian Sea at 19–13 ka BP,resulting in a constant increase in clay and IRD in sediments;and(3)a marine environment similar to the present one under the strong influence of NAC following the complete melting of the BIS after 13 ka BP,NAC is the dominant transport agent and no IRD occurred in sediments.The fine silt populations containing volcanic glasses transported by NAC significantly increased.
文摘A new approach was taken to investigate the crustal stucture of the Kane transform and its aseismic extension, using high quality bathymetry and gravity data. The gravity signatures associated with variations in crustal thickness of the transform were isolated from the observed free air anomaly, was continued downward to the mean depth of the crust/mantle interface and converted onto the relief on that surface. The crustal thickness of the transform was then calculated by subtracting seawater depth from the depth of the gravity inferred crust/mantle interface.3 D gravity investigation results indicate that the Kane transform and adjacent areas are associated with a crust thinner than normal oceanic crust. The transform trough is largely underlain by a crust less than 4.5km thick and in the nodal basins the crust may be as thin as 3 km. The crust beneath the fracture zone valley is 4-5.5 km thick. The rift valleys on the spreading segments are also characterized by thin crust (4-5 km thick). Thin oceanic crust extends to 20-30 km from the transform axis,except for some localized places such as the inside corner highs adjoining the ridge transform intersections. These gravity inferred results match fairly well with limited published seismic results. Thinning of the crust is mainly attributable to a thin layer 3, which in turn may be explained by the combined effects of reduced magma supply at the ends of the spreading segments and tectonic activities in the region.
文摘Using a 34 years database consisting of sea level pressure and sea iceconcentration, the relationship between Antarctic Oscillation (AAO) and Antarctic Sea-iceOscillation (ASO) was investigated. Firstly, Empirical Orthogonal Function (EOF) analysis depictsthe spatial variability of AAO and ASO and Antarctic Sea-ice Oscillation Index (ASOI) was definedfor the first time. Secondly, power spectrum and head-lag correlation analysis show that ASO and AAOhave the same periods of quasi-three years, quasi-one year and quasi-half a year. Corresponding toAAO, ASO has an evident anti-oscillation after one and half a year.
