东太平洋克拉里昂-克里帕顿断裂带WPC1101沉积柱样磁性地层及沉积环境  

A Preliminary Study on Magnetostratigraphy and Sedimentary Environment of Piston Core WPC1101 from ClarionClipperton Fractrue Zone,Eastern Pacific

作　　者：王海峰[1] 韩玉林[2] 朱克超[1] 易亮[3] 邓希光[1] 刘广虎[1] 任江波[1] 

机构地区：[1]国土资源部海底矿产资源重点实验室/广州海洋地质调查局,广州510075 [2]中国科学院南海海洋研究所,广州510301 [3]中国科学院地质与地球物理研究所,北京100029

出　　处：《吉林大学学报（地球科学版）》2014年第6期1892-1905,共14页Journal of Jilin University：Earth Science Edition

基　　金：国土资源部国家专项(GZH201100303);国际海域资源调查与开发"十二.五"课题(DY125-14-R-01);国土资源部海底矿产资源重点实验室开放基金(KLMMR-2013-A-04)

摘　　要：对采自东太平洋 CC 区西部的 WPC1101重力活塞柱样进行了岩石磁学、古地磁极性地层及古生物地层年代学研究工作。等温剩余磁化强度（IRM）、磁滞回线和反向场退磁曲线测试结果表明，沉积物中的磁性矿物主要为磁铁矿，仅在柱状样底部存在少量赤铁矿/针铁矿。340~350 cm 发育的埋藏结核层，标志着一处沉积间断的存在；60~336 cm 发育上新世晚期的硅藻化石 Cosinodiscus nodulifer ，但古地磁极性地层缺失上新世第四纪的2r 反极性时；0~60 cm 见第四纪标准化石 Pseudoenuotia doliolus 、Spongaster tetras ，且顶部缺失1正极性时。综合对比古生物地层学、磁性地层学以及邻近区域地层学特征，认为该柱状样记录了从晚渐新世至第四纪的沉积历史，期间存在晚渐新世至早上新世、上新世晚期至第四纪早期及第四纪晚期3个时期的沉积间断，上述沉积间断的形成可能是南极底流的形成与增强、CCD 界面抬升及海底侵蚀作用增强共同控制的结果。The piston core WPC1 101 collected from western Clarion-Clipperton fracture zone,Eastern Pacific, was studied by the methods of rock magnetism, magnetostatigraphy and biogeochronology.The results of rock magnetic measurements,which include isothermal remanent magnetization （IRM）,IRM acquisition curves and hysteresis loops showed that most of subsamples contain magnetite as the magnetic minerals and only a few subsamples at the bottom of the core contain minor hematite and/or goethite.Buried polymetallic nodule layer between 340 350 cm was the symbol of a sedimentary gap;Species of diatom fossil Cosinodiscus nodulifer in 60 336 cm indicated the stratum was deposited in the Late Pliocene,but the 2r reversal was missed;Species of P seudoenuotia doliolus ,Spongaster tetras were found in the top 60 cm,meanwhile,the uppermost 1 normal epoch was missed.After comparing with previous studies nearby,we inferred that the sedimentary history from Late Oligocene till now was recorded in the core,and there are three sedimentary gaps within the Late Oligocene and Early Pliocene,Late Pliocene and Early Quaternary and the Late Quaternary.Those sedimentary gaps might be related to the formation and enhancement of the Antarctic bottom water, rising of calcite compensation depth and enhancement of the marine floor erosion.

关 键 词：磁性地层 沉积间断 南极底流 磁铁矿 东太平洋 

分 类 号：P736.45[天文地球—海洋地质]