热带海洋学报 ›› 2020, Vol. 39 ›› Issue (4): 100-115.doi: 10.11978/2019116

• 海洋地球物理学 • 上一篇    下一篇

全球三大洋底高原重力异常与地壳厚度特征及对比研究*

罗怡鸣1,2,3,4,6(), 张锦昌1,2,3, 林间1,2,3,5,6()   

  1. 1.中国科学院边缘海与大洋地质重点实验室, 南海海洋研究所, 南海生态环境工程创新研究院, 广东 广州 510301
    2.中国-巴基斯坦地球科学研究中心, 广东 广州 510301
    3.南方海洋科学与工程广东省实验室(广州), 广东 广州 511458
    4.中国科学院大学, 北京 100049
    5.Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA
    6.南方科技大学海洋科学与工程系, 广东 深圳 518055
  • 收稿日期:2019-11-13 修回日期:2019-12-25 出版日期:2020-07-20 发布日期:2020-07-27
  • 通讯作者: 林间
  • 作者简介:罗怡鸣(1993—), 女, 广东省河源市人, 博士研究生, 从事海洋地质与地球物理研究。E-mail: ymluo@scsio.ac.cn
  • 基金资助:
    国家重点研发计划(2018YFC0309800);南方海洋科学与工程广东省实验室(广州)人才团队引进重大专项(GML2019ZD0205);国家自然科学基金项目(41776058);国家自然科学基金项目(41890813);国家自然科学基金项目(91628301);国家自然科学基金项目(U1606401);国家自然科学基金项目(41706056);国家自然科学基金项目(41976066);广东省自然科学基金项目(2017A030313243);中国科学院项目(QYZDY-SSW-DQC005);中国科学院项目(133244KYSB20180029);中国科学院项目(Y4SL021001)

Characteristics of gravity anomaly and crustal thickness of three largest oceanic plateaus

Yiming LUO1,2,3,4,6(), Jinchang ZHANG1,2,3, Jian LIN1,2,3,5,6()   

  1. 1.Key Laboratory of Ocean and Marginal Sea Geology, South China Sea Institute of Oceanology, Innovation Academy of South China Sea Ecology and Environmental Engineering, Chinese Academy of Sciences, Guangzhou 510301, China
    2.China-Pakistan Joint Research Center on Earth Sciences, Guangzhou 510301, China
    3.Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou 511458, China
    4.University of Chinese Academy of Sciences, Beijing 100049, China
    5.Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA
    6.Department of Ocean Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, China
  • Received:2019-11-13 Revised:2019-12-25 Online:2020-07-20 Published:2020-07-27
  • Contact: Jian LIN
  • Supported by:
    Foundation item: National Key Research and Development Program of China(2018YFC0309800);Key Special Project for Introduced Talents Team of Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou)(GML2019ZD0205);National Natural Science Foundation of China(41776058);National Natural Science Foundation of China(41890813);National Natural Science Foundation of China(91628301);National Natural Science Foundation of China(U1606401);National Natural Science Foundation of China(41706056);National Natural Science Foundation of China(41976066);Natural Science Foundation of Guangdong Province(2017A030313243);Chinese Academy of Sciences Project(QYZDY-SSW-DQC005);Chinese Academy of Sciences Project(133244KYSB20180029);Chinese Academy of Sciences Project(Y4SL021001)

摘要:

翁通爪哇高原、凯尔盖朗高原与沙茨基海隆是全球三大洋底高原, 是大量岩浆喷发到地表的结果, 火山面积分别达1.90×106、1.25×106、0.53×106km2。本文详细分析了该三大洋底高原的地形、剩余地幔布格重力异常(residual mantle Bouguer anomaly, RMBA)与重力反演的相对地壳厚度, 并结合地质与地球化学特征约束进行对比研究。结果显示, 翁通爪哇高原、凯尔盖朗高原与沙茨基海隆分别高出周围海底约4.3、5、4km, 相应的地幔布格重力异常最大变化值分别为250、330、200mGal, 以及相应的相对地壳厚度变化分别为11、13、9km, 表明形成三大洋底高原的岩浆量远远大于正常洋中脊的岩浆量。此外, 三大洋底高原皆形成于洋中脊附近。Nd、Pb、Hf同位素比值分析表明, 翁通爪哇高原的玄武岩组分为洋岛玄武岩; 凯尔盖朗高原大部分类似于洋岛玄武岩, 并含有洋中脊玄武岩组分; 沙茨基海隆的玄武岩组分主要为东太平洋海隆正常洋中脊玄武岩, 却又存在少量位于全球洋岛玄武岩范围内。这些特征揭示了三大洋底高原可能形成于“地幔柱-洋中脊相互作用”。对此本文提出了两种模式: 一为洋中脊被地幔柱拖拽至其上方; 二为洋中脊之下的软流圈受到地幔柱影响, 从而产生超常熔融与超厚地壳。

关键词: 翁通爪哇高原, 凯尔盖朗高原, 沙茨基海隆, 重力异常, 地壳厚度, 地幔柱-洋中脊相互作用

Abstract:

The Ontong Java Plateau, Kerguelen Plateau, and Shatsky Rise are the three largest oceanic plateaus on Earth, exhibiting voluminous magmatism with areas of 1.90×106, 1.25×106, and 0.53×106 km2, respectively. In this study, we conducted a detailed comparative analysis of bathymetry, residual mantle Bouguer anomaly (RMBA), and gravity-derived relative crustal thickness of the three plateaus, correlating results with geological and geochemical constraints. Relative to adjacent normal seafloors, the Ontong Java Plateau is elevated by 4.3 km; the Kerguelen Plateau, by 5 km; and the Shatsky Rise, by 4 km. The corresponding peak-to-trough amplitudes in RMBA are about 250, 330, and 200 mGal, while the relative crustal thickness variations are of 11, 13, and 9 km, respectively, implying that the magma output forming these three oceanic plateaus is far more than that generated by a normal mid-ocean ridge. Moreover, all three plateaus were formed near mid-ocean ridge or ridge triple junction settings. Isotopic analyses of Nd, Pb, and Hf reveal that the Ontong Java Plateau is characterized by ocean island basalts (OIB); most of the Kerguelen Plateau is predominantly OIB, but is mixed with some mid-ocean ridge basalts (MORB); and most of the Shatsky Rise volcanism shows East Pacific Rise-type MORB, with a few exceptions of OIB-like components. These features imply that these oceanic plateaus were probably formed by “plume-ridge interaction”. Two models are proposed herein: (1) the peripheral mid-ocean ridge is dragged onto the top of the mantle plume, and/or (2) the asthenosphere is fed by plume material nearby, resulting in melting anomalies and the resultant thickened crust along the mid-ocean ridge.

Key words: Ontong Java Plateau, Kerguelen Plateau, Shatsky Rise, gravity anomaly, crustal thickness, plume-ridge interaction

中图分类号: 

  • P738.2