谢丁, 吴世敏, 孙萍. 南海北缘中段近岸陆区晚中生代以来构造应力场反演——以广东樟木头地区为例[J]. 海洋地质与第四纪地质, 2016, 36(3): 91-102. DOI: 10.16562/j.cnki.0256-1492.2016.03.009
引用本文: 谢丁, 吴世敏, 孙萍. 南海北缘中段近岸陆区晚中生代以来构造应力场反演——以广东樟木头地区为例[J]. 海洋地质与第四纪地质, 2016, 36(3): 91-102. DOI: 10.16562/j.cnki.0256-1492.2016.03.009
XIE Ding, WU Shimin, SUN Ping. PALEOSTRESS INVERSION FOR THE ONSHORE NORTH MARGIN OF SOUTH CHINA SEA SINCE LATE MESOZOIC:TAKING ZHANGMUTOU,GUANGDONG PROVINCE AS A CASE[J]. Marine Geology & Quaternary Geology, 2016, 36(3): 91-102. DOI: 10.16562/j.cnki.0256-1492.2016.03.009
Citation: XIE Ding, WU Shimin, SUN Ping. PALEOSTRESS INVERSION FOR THE ONSHORE NORTH MARGIN OF SOUTH CHINA SEA SINCE LATE MESOZOIC:TAKING ZHANGMUTOU,GUANGDONG PROVINCE AS A CASE[J]. Marine Geology & Quaternary Geology, 2016, 36(3): 91-102. DOI: 10.16562/j.cnki.0256-1492.2016.03.009

南海北缘中段近岸陆区晚中生代以来构造应力场反演——以广东樟木头地区为例

PALEOSTRESS INVERSION FOR THE ONSHORE NORTH MARGIN OF SOUTH CHINA SEA SINCE LATE MESOZOIC:TAKING ZHANGMUTOU,GUANGDONG PROVINCE AS A CASE

  • 摘要: 利用樟木头及其邻区断层擦痕数据,采用"多重逆解法"反演该区晚中生代以来的构造应力场,为华南陆缘地区晚中生代以来构造演化过程的研究提供参考。通过5个野外断层擦痕测点观察与数据测量,采集了125组有效断层滑动数据,反演得到八种应力状态,进一步区分了晚中生代以来该区4个期次的构造应力场,即①NNW-SSE方向(254.9°~355.7°)的拉张应力体制;②ENE-WSW方向(64.9°)的拉张应力体制:③最大主应力优势方位为NE-SW向(约46.8°~59.9°)的走滑应力体制;④最大主应力优势方位NW-SE向(约329.5°~339.7°)的走滑应力体制。应力场的变化反映出控制该区不同时期的大地构造背景差异,即由早期的太平洋板块的俯冲带后撤、古太平洋俯冲方向的改变,之后的印度-澳大利亚板块与欧亚板块碰撞及印支块体顺时针旋转,最后,菲律宾海板块俯冲方向以及强度的变化。

     

    Abstract: Widely spreaded in the upper-crust, brittle fractures are one of the most important forms of rock deformation. They are very useful for paleostress inversion in certain areas. We made a paleostress field reconstruction in the area of the Zhangmutou Town and adjacent areas, applying the Multiple Inverse Method developed by Yamaji. We obtained 125 valid fault-slip data at 5 valid measurement sites, and got inversion results-the orientation of principal axis of stress and φ, a parameter representing the shape of stress ellipsoid-with Multiple Inverse Method software package. Based on our field observation and the inversion results, combined with tectonic analysis, four stages of paleostress were subdivided since Late Mesozoic in the research area:①the stress regime which led to NNW-SSE extension,within which the principal axis of σ1was nearly vertical, and the azimuth of σ3 diverted from 254.9° to 355.7°; ②the stress regime which led to ENE-WSW extension, within which the principal axis of σ1was nearly vertical and the azimuth of σ3was around 64.9°; ③strike-slip type stress regime within which the azimuth of σ1is NE-SW(46.8°~59.9°); ④strike-slip type stress regime within which the azimuth of σ1 is NW-SE(329.5°~340°). The tectonic implications of the paleostress regime are discussed at the same time. 1) the first stage of extension(NNW-SSE) had same mechanism as the rifting of South China Sea. It belongs to the continental margin extension in East Asia which resulted from the rollback of paleo-Pacific plate; 2) the second stage of extension(NNW-SSE) was associated with the clockwise rotation of the Indochina Block during the late stage of its extrusion; 3)the third stage of strike-slip (NE-SW) stress regime might subject to the convergence of India-Australia Plate and Eurasian Plate; 4) the last stage of strike-slip (NW-SE) stress regime may controlled by the subduction of the Philippine Sea Plate beneath the Eurasian Plate.

     

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