末次冰期以来南极斯科舍海东南部沉积物来源与环境变化  

Sediment provenances and environmental changes in the southeastern Scotia Sea,Antarctica,since the Last Glaciation

作　　者：冯宗保 陈志华 杨春丽 黄元辉 崔迎春 唐正 刘焱光 Feng Zongbao;Chen Zhihua;Yang Chunli;Huang Yuanhui;Cui Yingchun;Tang Zheng;Liu Yanguang(Key Laboratory of Marine Geology and Metallogeny,First Institute of Oceanography,Ministry of Natural Resources,Qingdao 266061,China;Laboratory for Marine Geology,Pilot National Laboratory of Marine Science and Technology(Qingdao),Qingdao 266061,China;First Exploration Team of Shandong Coalfield Geology Bureau,Qingdao 266500,China;China Polar Research Center,Shanghai 200136,China)

机构地区：[1]自然资源部第一海洋研究所自然资源部海洋地质与成矿作用重点实验室,山东青岛266061 [2]青岛海洋科学与技术试点国家实验室海洋地质过程与环境功能实验室,山东青岛266061 [3]山东省煤田地质局第一勘探队,山东青岛266500 [4]中国极地研究中心,上海200136

出　　处：《海洋学报》2023年第7期56-68,共13页

基　　金：南极重点海域对气候变化的响应与影响(IRASCC2020-2022-01-03,02-03);国家自然科学基金(41676191)。

摘　　要：本文通过南极斯科舍海东南部海域DC-11岩芯稀土元素(REE)特征及其与生源硅(BSiO_(2))、磁化率、Al_(2)O_(3)、Fe_(2)O_(3)的耦合关系,深入探讨了34 ka BP以来研究区沉积物的来源及冰山−海流−大气搬运历史。结果表明,DC-11岩芯沉积物REE含量变化与Al_(2)O_(3)相似,主要赋存于陆源碎屑之中,BSiO_(2)对其有明显稀释效应。末次冰期REE含量高,页岩标准化模式平坦,Eu正异常弱,LaN/YbN比值较大,沉积物主要来源于地壳相对较老的威德尔海周边地区,磁化率、ΔAl_(2)O_(3)、TFe_(2)O_(3)/Eu比值证实该时期沉积物中南美风尘物质多。冰消期早期(19.6~14.1 ka BP)气候快速回暖,西风带与海洋锋面南移,南美风尘输入迅速减弱,南极绕极流南部分支增强,导致南设德兰群岛−南极半岛的冰山及沉积物向东搬运至研究区,沉积物Eu正异常明显,LaN/YbN比值小,磁化率、ΔAl_(2)O_(3)、TFe_(2)O_(3)/Eu比值降低。南极冷倒转期(14.1~12.9 ka BP),南极气温明显下降,海洋锋面小幅北移,来自南设德兰群岛−南极半岛沉积物减少,威德尔海沉积物在岩芯中占主导,沉积物Eu正异常弱,LaN/YbN比值接近于1,冰筏碎屑含量高;冰消期晚期(12.9~11.7 ka BP)海洋锋面再次南移,南设德兰群岛−南极半岛海域南极绕极流分量增强,对DC-11岩芯沉积物贡献加大;全新世(11.7~0 ka BP)气候温暖,南设德兰群岛−南极半岛海域南极绕极流分量总体增强,对岩芯沉积物贡献加大,与来自威德尔海的沉积物量大体相当。Rare earth elements(REE)and their relationships with biogenic silica(BSiO_(2)),magnetic susceptibility,Al_(2)O_(3)and Fe_(2)O_(3)in Core DC-11 were analyzed to reveal sediment provenances and transport history by iceberg-current-atmosphere since 34 ka BP in the southeastern Scotia Sea,Antarctica.Temporal variation of REE is similar to that of Al_(2)O_(3),indicating they mainly occur in terrigenous detritus and BSiO_(2)has obvious dilution effect on them.Sediments with high REE concentration,flat shale-normalized pattern,weak positive Eu anomaly,and high LaN/YbN ratio during the last glacial period indicated they are transferred from the Weddell Sea and eroded from the bordering lands with relatively old crust.The increases in magnetic susceptibility,ΔAl_(2)O_(3),TFe_(2)O_(3)/Eu ratio indicated an enhanced input of dust from South America during this period.In early Deglaciation(19.6−14.1 ka BP),increasing Eu positive anomaly and lower LaN/YbN ratio indicated the southern branch of Antarctic Circumpolar Current(ACC)strengthened and contributed more sediments from the South Shetland Islands and Antarctic Peninsula due to the southward shifts of oceanic fronts,while decreasing magnetic susceptibility,ΔAl_(2)O_(3),TFe_(2)O_(3)/Eu ratios showed rapid decrease in dust supply from South America.During the Antarctic Cold Reversal period(ACR,14.1−12.9 ka BP),sediments from the South Shetland Islands and Antarctic Peninsula decreased sharply due to cold condition and weakened ACC branch,the weakest Eu positive anomaly and highest LaN/YbN ratio indicated that the sediments from the Weddell Sea dominated in the core again,and the peak of ice raft debris indicated ice rafting is vital or dominant agent.In the late Deglaciation(12.9−11.7 ka BP),the return of ACC branch to the South Shetland Islands and Antarctic Peninsula contributed more to the sediments in Core DC-11;in Holocene(11.7−0 ka BP),the ACC branch in the area between the South Shetland Islands and Antarctic Peninsula was generally enhanced,and its contrib

关 键 词：南极 斯科舍海 稀土元素 沉积物来源 环境变化 

分 类 号：P728.2[天文地球—海洋科学] P736.212