西菲律宾海GX149柱状样沉积物磁学性质及其环境意义  

Magnetic properties of core GX149 sediments from the West Philippine Sea and their environmental implications

作　　者：李波[1,2] 石显耀[3] 王艳 李顺[2] 张江勇[2] 田成静[2] 李学杰[2] 钟和贤[2] 

机构地区：[1]国土资源部海底矿产资源重点实验室,广东广州510075 [2]中国地质调查局广州海洋地质调查局,广东广州510075 [3]中国地质调查局,北京100037 [4]广东省有色地质勘查院,广东广州510080

出　　处：《地学前缘》2017年第3期341-349,共9页Earth Science Frontiers

基　　金：国土资源部海底矿产资源重点实验室开放基金课题(KLMMR-2014-A-12);国家自然科学基金项目(41306042;41272384);中国地质调查局地质调查项目(GZH201300502;GZH201500202)

摘　　要：对取自西菲律宾海西部的GX149柱状样沉积物进行详细的环境磁学研究,揭示其蕴含的环境意义和物源信息。岩石磁学结果表明,GX149柱状样沉积物中携磁矿物以低矫顽力磁铁矿为主;反映磁性颗粒粒径的King图与Day图显示沉积物中磁性矿物以准单畴(PSD)为主。剖面上磁学参数变化明显,以磁性矿物粒径参数(χARM/χ)作为替代指标反演古气候变化结果显示:冷期沉积物中磁性矿物含量相对更高,粒径更粗,高矫顽力矿物含量增加;而暖期沉积物中磁性矿物含量相对较低,粒径更细,高矫顽力矿物含量降低。干燥、寒冷、风大的冷期气候下,东亚季风携带的粉尘输入增加导致沉积物中高矫顽力矿物含量增多;而温暖湿润的暖期,沉积物中风成粉尘输入减少,高矫顽力矿物含量降低。GX149柱状样沉积物与西菲律宾海其他区域以及南海沉积物相似的磁学特征,相同的冰期-间冰期旋回趋势说明沉积物磁学特征对气候变化的响应在东亚地区具有共性。The sediment core GX149 collected from the western West Philippine Sea was selected for environmental magnetic studies to reconstruct paleoenvironment and trace the provenance of sediments. Rock magnetic results indicate that the low-eoercivity magnetite is the dominant magnetic mineral in the sediments. The King Plot and Day Plot, which reflect the magnetic particle size, show that pseudo-single-domain （PSD） phase magnetic particles are predominant magnetic minerals in the sediments. The variation in magnetic parameters on the profile is obvious. Climate change indicated by the parameter of magnetic particle size （χARM/χ） shows that high magnetic concentrations in sediments are related to cold periods, in which the amount of high coercivity minerals increased, and the grain size is coarser, while during warm periods the sediments are characterized by low magnetic concentrations, decreased amount of high coercivity minerals, and finer-grain size. Eolian transport by Asian monsoon is inferred to deliver increasing amounts of high coercivity minerals into the sediments during a colder, windier, and more arid condition. On the contrary, a decreasing amount of high coercivity minerals were delivered to sediments during a warmer and humid condition. The similar magnetic properties and the same glacial-interglacial cycles in magnetic profile between West Philippine Sea and South China Sea imply similar magnetic response to regional climate changes in East Asia.

关 键 词：西菲律宾海 磁学特征 粒径 古气候 

分 类 号：P736.2[天文地球—海洋地质] P539.3[天文地球—海洋科学]