Magnetic recording of the Cenozoic oceanic crustal accretion and evolution of the South China Sea basin

被引:79
|
作者
Li ChunFeng [1 ]
Song TaoRan [1 ]
机构
[1] Tongji Univ, State Key Lab Marine Geol, Shanghai 200092, Peoples R China
来源
CHINESE SCIENCE BULLETIN | 2012年 / 57卷 / 24期
基金
中国国家自然科学基金;
关键词
South China Sea magnetic anomalies; continent-ocean boundary; Zhongnan Fault; seafloor spreading; Curie-point depth; magnetic layer; filtering; GEOPHYSICAL RESEARCH; NORTHEASTERN MARGIN; ANOMALIES; FIELD; BOTTOM; MODEL; LAYER;
D O I
10.1007/s11434-012-5063-9
中图分类号
O [数理科学和化学]; P [天文学、地球科学]; Q [生物科学]; N [自然科学总论];
学科分类号
07 ; 0710 ; 09 ;
摘要
We review and discuss some of the recent scientific findings made on magnetic data in the South China Sea (SCS). Magnetic anomalies bear extremely rich information on Mesozoic and Cenozoic tectonic evolution. 3D analytical signal amplitudes computed from magnetic anomalies reveal very precisely relict distributions of Mesozoic sedimentary sequences on the two conjugate continental margins, and they are also found very effective in depicting later-stage magmatism and tectonic transitions and zonation within the SCS oceanic crust. Through integrated analyses of magnetic, gravity and reflection seismic data, we define the continent-ocean boundary (COB) around the South China Sea continental margin, and find that the COB coincides very well with a transition zone from mostly positive to negative free-air gravity anomalies. This accurate outlining of the COB is critical for better tracing magnetic anomalies induced by the oceanic crust. The geometrically complex COB and inner magnetic zonation require the introduction of an episodic opening model, as well as a transform fault (here coined as Zhongnan Fault) between the East and Southwest Sub-basins, while within the East and Southwest Sub-basins, magnetic anomalies are rather continuous laterally, indicating nonexistence of large transform faults within these sub-basins. We enhance magnetic anomalies caused by the shallow basaltic layer via a band-pass filter, and recognize that the likely oldest magnetic anomaly near the northern continental margin is C12 according to the magnetic time scale CK95. Near the southern continental margin, magnetic anomalies are less recognizable and the anomaly C12 appears to be missing. These differences show an asymmetrical opening style with respect to the relict spreading center, and the northern part appears to have slightly faster spreading rates than to the south. The magnetic anomalies C8 (M1 and M2, similar to 26 Ma) represent important magnetic boundaries within the oceanic basin, and are possibly related to changes in spreading rates and magmatic intensities. The magnetic evidence for a previously proposed ridge jump after the anomaly C7 is not clear. The age of the Southwest Sub-basin has yet to be further examined, most favorably with deep-tow magnetic surveys and ocean drilling. Our magnetic spectral study shows that the shallowest Curie points are located around the eastern part of the Southwestern Sub-basin, whereas within the East Sub-basin Curie depths are smaller to the north of the relict spreading center than to the south. This pattern of Curie depths is consistent to regional heat flow measurements and later-stage volcanic seamount distributions, and we therefore reason that Curie-depth variations are closely associated with later-stage magmatism, rather than with crustal ages. Although magnetic anomalies located around the northern continent-ocean transition zone (COT) are relatively quiet, this area is not a typical magnetic quiet zone since conceptually it differs markedly from an oceanic magnetic quiet zone. The relatively quiet magnetic anomalies are seemingly associated with a shallowing in Curie isotherm and thinning in magnetic layer, but our comprehensive observations suggest that the well-preserved thick Mesozoic sedimentary rocks are major causes for the magnetically quiet zone. The high similarities between various low-pass filtered marine and air-borne magnetic anomalies and satellite magnetic anomalies clearly confirm that deeper magnetic sources (in the lower crust and the uppermost mantle) have contributions to long-wavelength surface magnetic anomalies in the area, as already inferred from magnetically inversed Curie depths. The offshore south China magnetic anomaly (SCMA) becomes more prominent on low-pass filtered marine and air-borne magnetic anomalies and satellite magnetic anomalies, indicating very deeply-buried magnetic sources beneath it.
引用
收藏
页码:3165 / 3181
页数:17
相关论文
共 50 条
  • [1] Magnetic recording of the Cenozoic oceanic crustal accretion and evolution of the South China Sea basin
    LI ChunFeng SONG TaoRan State Key Laboratory of Marine Geology Tongji University Shanghai China
    [J]. Chinese Science Bulletin., 2012, 57 (24) - 3181
  • [2] Magnetic recording of the Cenozoic oceanic crustal accretion and evolution of the South China Sea basin
    LI ChunFeng & SONG TaoRan State Key Laboratory of Marine Geology
    [J]. Science Bulletin, 2012, (24) : 3165 - 3181
  • [3] The oceanic crustal structure and the magmatic accretion history of the South China Sea
    Zeng, Chenghui
    Sun, Zhen
    Yao, Yongjian
    Zhang, Cuimei
    Xu, Xing
    [J]. EARTH AND PLANETARY SCIENCE LETTERS, 2024, 637
  • [4] Characteristics and evolution of Cenozoic sediments in the Liyue Basin, SE South China Sea
    Yao, Yongjian
    Liu, Hailing
    Yang, Chupeng
    Han, Bing
    Tian, Jijun
    Yin, Zhengxin
    Gong, Junli
    Xu, Qiaoyue
    [J]. JOURNAL OF ASIAN EARTH SCIENCES, 2012, 60 : 114 - 129
  • [5] CRUSTAL STRUCTURE OF THE SOUTH CHINA SEA BASIN
    YAO, B
    WANG, GG
    [J]. SCIENTIA SINICA SERIES B-CHEMICAL BIOLOGICAL AGRICULTURAL MEDICAL & EARTH SCIENCES, 1983, 26 (06) : 648 - 661
  • [6] CRUSTAL STRUCTURE OF THE SOUTH CHINA SEA BASIN
    姚伯初
    王光宇
    [J]. Science China Chemistry, 1983, Ser.B.1983 (06) : 648 - 661
  • [7] Asymmetry in oceanic crustal structure of the South China Sea basin and its implications on mantle geodynamics
    Zhang, Fan
    Lin, Jian
    Zhang, Xubo
    Ding, Weiwei
    Wang, Tingting
    Zhu, Jian
    [J]. INTERNATIONAL GEOLOGY REVIEW, 2020, 62 (7-8) : 840 - 858
  • [8] Tectonic cycle of marginal oceanic basin: A new evolution model of the South China Sea
    Zhang, Gongcheng
    Wang, Pujun
    Wu, Jingfu
    Liu, Shixiang
    Xie, Xiaojun
    [J]. Earth Science Frontiers, 2015, 22 (03) : 27 - 37
  • [9] CHARACTERISTICS OF MAGNETIC LINEATIONS AND TECTONIC EVOLUTION OF THE SOUTH CHINA SEA BASIN
    吕文正
    柯长志
    吴声迪
    刘建华
    林长松
    [J]. Acta Oceanologica Sinica, 1987, (04) : 577 - 588
  • [10] The Cenozoic sedimentary environment and sedimentary filling evolution of Wan'an Basin in the western South China Sea
    Wang, Yibo
    Zhao, Zhigang
    Xie, Xiaojun
    Yang, Huaizhong
    Song, Shuang
    [J]. Petroleum Research, 2019, 4 (03) : 257 - 267