南极半岛Bransfield海峡约6000年以来的陆源组分记录及其古环境意义  

A 6000-YEAR RECORD OF TERRIGENEOUS COMPONENTS FROM THE BRANSFIELD STRAIT,ANTARCTIC PENINSULA:RESPONSES TO CLIMATE CHANGE

作　　者：聂森艳 王汝建[1] 肖文申[1] 

机构地区：[1]同济大学海洋地质国家重点实验室,上海200092

出　　处：《第四纪研究》2014年第3期590-599,共10页Quaternary Sciences

基　　金：国家自然科学基金项目"南北极环境综合考察与评估"专项项目(批准号:CHINARE2014-01-02和CHINARE2014-04-01);中国地质调查局项目(批准号:水[2013]02-013-012)共同资助

摘　　要：通过对中国第28次南极科学考察在南极半岛Bransfield海峡采集的D1-7钻孔样品粘土矿物组合、粗颗粒组分、火山灰丰度及AMS^(14)C测年分析,建立了该钻孔5.83ka以来的地层年代框架。该区域有机碳测年中老碳污染年龄约为2.1ka。该孔中7个火山灰层及其年龄(0.33ka、2.12ka、2.82~2.94ka、3.34ka、3.96ka、4.76ka和5.57ka)与附近的地质记录有很好的对应关系。该区域粘土矿物主要为蒙脱石(>60%),绿泥石和伊利石次之,高岭石最少(<6%);蒙脱石相对含量在火山灰层增高。研究表明,这些粘土矿物主要来源于南极半岛火山岩及火山灰的化学风化作用,且深度风化矿物相对含量很低,4种组分基本稳定,反映了南极半岛火山岩及火山灰化学风化作用较弱的区域特征。晚全新世增多的冰筏碎屑(IRD)事件与附近的地质记录相符,反映了晚全新世以来受ENSO和季节性太阳辐射量变化的影响,南极半岛区域气候变冷,冰架崩塌增多。The climate change of Antarctic Peninsula is particularly sensitive to global warming, thus representing one of the hotspot of the recent climate study. Holocene climate changes in this region provide insights of the future development of the recent rapid warming. Terrigeneous components including clay minerals and coarse fractions in the sediment document direct information of the surrounding environment changes related to climate oscillations and ice-sheet instability. Terrigeneous components are investigated on gravity core D1-7（62°16.163＇S, 56°35.457＇W; l l00m water depth） collected from the Bransfield Strait, Antarctic Peninsula region, during the 28th Chinese National Antarctic Expedition. The core mainly consists of silty clay, with coarse megascopic black ash layer at 214-222cm. A total of 154 samples were taken at 2-cm intervals over the total core length of 307cm. AMS 14C dating was performed in Beta Analytic Inc., Miami, on organic carbon in 8 bulk samples and benthic foraminifera （Bulimina aculeata）in l sample. Other analyses were carried out in State Key Laboratory of Marine Geology, Tongji University. The core covers the period of 0.28-5.83ka. The organic carbon based 14C age is biased by the fossil carbon contamination of about 2.1ka. 7 layers containing abundant tephra were identified （0.33ka, 2.12ka, 2.82-2.94ka, 3.34ka, 3.96ka, 4.76ka and 5.57ka） , which can be regionally correlated. Clay mineral composition in the core is rather stable, mainly consists of smectite （〉60%）, chlorite （24%） and illite （9%）, kaolinite is generally less than 6%. Smectite remarkably increases in the major tephra layer （3.96ka）. The clay mineral composition suggests the volcanic origin as the major source in this region. The low abundance of deep weathering minerals reflects the weak weathering intensity in the cold Antarctic region. Frequent ice rafted debris （IRD） events are recognized in the Late Holocene interval and consistent with the adjacent marine and ice core records su

关 键 词：南极半岛 粘土矿物 火山灰层 IRD事件 冰川排泄 

分 类 号：P619.231[天文地球—矿床学] P575.5[天文地球—地质学]