吉林大学学报(地球科学版)

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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

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   

  1. 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
  • 收稿日期:2014-03-18 出版日期:2014-11-26 发布日期:2014-11-26
  • 作者简介:王海峰(1986-),男,助理工程师,硕士,主要从事海洋地质研究,E-mail:wanghaifeng112@163.com
  • 基金资助:

    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)

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

Wang Haifeng1, Han Yulin2, Zhu Kechao1, Yi Liang3, Deng Xiguang1, Liu Guanghu1, Ren Jiangbo1   

  1. 1.MLR Key Laboratory of Marine Mineral Resources/Guangzhou Marine Geological Survey, Guangzhou510075, China;
    2.South China Sea Institute of Oceanology, Chinese Academy of Science, Guangzhou510301, China;
    3.Institute of Geology and Geophysics, Chinese Academy of Science, Beijing100029, China
  • Received:2014-03-18 Online:2014-11-26 Published:2014-11-26

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。

关键词: 磁性地层, 沉积间断, 南极底流, 磁铁矿, 东太平洋

Abstract:

The piston core WPC1101 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 Pseudoenuotia 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.

Key words: magnetostratigraphy, sedimentary gap, Antarctic bottom water, magnetite, Eastern Pacific

中图分类号: 

  • P736.45
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