地学前缘 ›› 2022, Vol. 29 ›› Issue (5): 23-34.DOI: 10.13745/j.esf.sf.2020.5.55

• 物理海洋与气候变化 • 上一篇    下一篇

热带西太平洋沉积物的环境磁学特征对东亚冬季风的响应

侯啸林1,2(), 徐继尚1,2,3,*(), 姜兆霞1,2,3, 曹立华1,2,3, 张强4, 李广雪1,2,3, 王双5, 翟科6   

  1. 1.中国海洋大学 海底科学与探测技术教育部重点实验室, 山东 青岛 266100
    2.中国海洋大学 海洋地球科学学院, 山东 青岛 266100
    3.中国海洋大学 海洋油气开发与安全保障教育部工程研究中心, 山东 青岛 266100
    4.中国科学院 地质与地球物理研究所, 北京 100029
    5.中国地质调查局 青岛海洋地质研究所, 山东 青岛 266071
    6.青岛海大海洋能源工程技术股份有限公司, 山东 青岛 266073
  • 收稿日期:2020-03-11 修回日期:2020-05-27 出版日期:2022-09-25 发布日期:2022-08-24
  • 通讯作者: 徐继尚
  • 作者简介:侯啸林(1993—),男,硕士研究生,主要从事海洋沉积与地质工程研究工作。E-mail: 1324819353@qq.com
  • 基金资助:
    国家自然科学基金项目(91858203);国家自然科学基金项目(41976198);国家自然科学基金项目(41030856);自然资源部全球变化与海气相互作用专项(GASI-02-PAC-CJ15)

Environmental magnetic characteristics of sediments of the western tropical Pacific: Response to the East Asian Winter Monsoon

HOU Xiaolin1,2(), XU Jishang1,2,3,*(), JIANG Zhaoxia1,2,3, CAO Lihua1,2,3, ZHANG Qiang4, LI Guangxue1,2,3, WANG Shuang5, ZHAI Ke6   

  1. 1. Key Lab of Submarine Geosciences and Prospecting Techniques, MOE, Ocean University of China, Qingdao 266100, China
    2. College of Marine Geosciences, Ocean University of China, Qingdao 266100, China
    3. Engineering Research Center of Marine Petroleum Development and Security Safeguard, MOE, Ocean University of China, Qingdao 266100, China
    4. Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China
    5. Qingdao Institute of Marine Geology, China Geological Survey, Qingdao 266071, China
    6. Qingdao Haida Ocean Energy Engineering Technology Co. Ltd,Qingdao 266073, China
  • Received:2020-03-11 Revised:2020-05-27 Online:2022-09-25 Published:2022-08-24
  • Contact: XU Jishang

摘要:

西太平洋暖池(Western Pacific Warm Pool,WPWP)指位于热带太平洋中、西部(包括南海南部和苏禄海)年平均水温超过 28 ℃的广大海域。由于巨厚的表层暖水覆盖,西太平洋暖池成为全球热量和水汽交互的重要源区,对驱动温盐环流、调节全球气候变化具有重要作用。东亚冬季风(EAWM)是全球气候系统中最活跃的组成部分之一,它可能会通过寒潮侵入热带地区,引起深层对流,以此加强暖池区的对流活动和降水异常,从而影响赤道地区的潜热释放。但地质历史时期西太平洋暖池与东亚冬季风的相互作用关系尚不明确。由于东亚冬季风携带的风尘中往往包含有大颗粒的高矫顽力磁性矿物,我们可以通过沉积物中磁性矿物的组合、含量、颗粒大小和形态变化,分析不同时间尺度上气候环境变化和风尘物质的输入情况,进而反演东亚冬季风的强度变化。本文对取自热带西太平洋B10钻孔的岩心样品进行了环境磁学测试,以揭示地质历史时期西太平洋暖池沉积物环境磁学特征对东亚冬季风的响应。实验结果表明,沉积物中的主要载磁矿物为低矫顽力的磁铁矿,属于亚铁磁性矿物,并含有少量高矫顽力磁性矿物。沉积物中的磁性颗粒以准单畴(PSD)颗粒为主。高矫顽力的磁性矿物含量和细颗粒磁铁矿相对含量在冰期和间冰期呈现出显著相对变化,对东亚冬季风的变化有敏感响应:冰期沉积物中高矫顽力矿物含量增多,磁性颗粒粒径变大;间冰期沉积物中高矫顽力矿物含量降低,磁性颗粒粒径变细。在干燥、寒冷的冰期,由风尘携带而来的高矫顽力磁性矿物相对含量增加,沉积物中的磁性颗粒粒径变大,反映冰期东亚冬季风强度增大;在气候温暖湿润的间冰期,风尘的输入量较小,由风尘携带的高矫顽力磁性矿物含量相对较低,沉积物中的磁性颗粒粒径变小,反映间冰期东亚冬季风的强度减弱。

关键词: 西太平洋, 东亚冬季风, 环境磁学, 磁铁矿

Abstract:

The Western Pacific Warm Pool (WPWP) refers to a vast sea area located in the middle and west of the tropical Pacific Ocean (including the southern South China Sea and the Sulu Sea) with an average annual water temperature of over 28 ℃. Covered by the ultra thick layer of warm surface water, with increasing prominence as a global heat source and site of water-vapor exchange, the WPWP plays an important role in driving the thermohaline circulation and regulating global climate change. The East Asian Winter Monsoon (EAWM), on the other hand, is one of the most active components of the global climate system. It can cause deep convection in tropical regions through cold waves, thereby strengthening convective activities and abnormal precipitation in the warm pool area. However, the historical interaction between WPWP and EAWM is still unclear. As aeolian dust carried by the EAWM usually contains large high-coercivity magnetic mineral particles, and these particles can cause fluctuations in environmental magnetic parameters, such as changing the mineralogy, concentration, grain size and morphology of magnetic minerals in sediments, one can assess the historical aeolian mineral inputs and EAWM intensity variations by analyzing the changes of environmental magnetic parameters of pelagic sediments in the WPWP. In this paper, we carried out environmental magnetic measurements on the B10 borehole sediments to reveal the response of the environmental magnetic characteristics of the WPWP sediments to the EAWM. We found the dominant magnetic minerals in the sediments were pseudo-single-domain (PSD) low-coercivity ferrimagnetic magnetite; and some high-coercivity magnetic minerals were also present. We also found the variabilities of high-coercive magnetic mineral content and relative content of fine-grained magnetite were highly correlated during the glacial and interglacial periods and sensitive to the EAWM intensity change: Both high-coercive magnetic mineral content and magnetic grain size increased during the glacial period and decreased during the interglacial period, in accordance with the strengthening and wakening of EAWM intensities during the respective periods.

Key words: western Pacific, East Asian Winter Monsoon, environmental magnetism, magnetite

中图分类号: