对下扬子与华南边界结合带东延问题的地球物理探讨
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摘要
以江山—绍兴、铅山—宜春等断裂带作为华南与扬子块体之间的边界结合带 ,这种认识目前已基本为大家所接受 .但是 ,这条边界结合带向东延伸入海之后的位置与去向一直是多年来研究的热点 .本文基于黄、东海研究区的地球物理数据 (空间重力数据、布格重力数据和地震层析成像结果 ) ,利用方向导数等处理方法 ,对研究区的地球物理数据进行处理 ,并对研究区的地球物理场进行了分析 ,划分出不同的区块 .结合研究区的磁力与地质资料 ,利用各种成图、成像技术 ,形成一系列分析图件 .在此基础上对华南与扬子块体之间的边界结合带进行了追踪 .研究结果认为 :该结合带的位置有可能比传统认识中自长江口至大黑山群岛的位置更向南一些 ,在杭州湾—长崎、对马海峡一线 ,并呈现向北略微凸出的弓形 .边界结合带在深度上属于深大断裂带 ,一直可以追索到上地幔的顶部 .与中朝与扬子块体之间的边界结合带相比较 ,本条结合带的踪迹不是十分清晰 .表明加里东运动之后 ,该结合带的运动明显减弱 .
It is known that Jiangshan-Shanxing, Qianshan-Yichun faults etc., are the boundary belt between Yangtze and Huanan blocks in East China area, but extension of this belt in sea areas was not so clear. In light with Free-air and Bouguer gravity data and tomography result in Yellow Sea and East China Sea, various information on faults were obtained after the processing (upward, arbitrary horizontal direction derivative, wavelet transform etc,.) and geophysical features of research region were analysis. It can be divided into different small areas according to geophysical feature differences. The geophysical evidences on the boundary belt between Yangtze and Huanan Blocks are shown after comprehensive analysis on gravity, magnetic, tomography result and geological information. It is believed that the boundary combine belt is possibly from Hangzhou Bay extending to round Nagasaki, Tsushima strait. It shows arc sharp to the north. The tomography result shows that geophysical evidences of the boundary belt can be found in the depth of upper mantle. Geophysical traces of this belt were not clear comparing with the boundary combine belt between Sino-korea and Yangtze Blocks. We believe that the tectonic movement of this combine belt became weaken after Caledonian movement.
It is known that Jiangshan-Shanxing, Qianshan-Yichun faults etc., are the boundary belt between Yangtze and Huanan blocks in East China area, but extension of this belt in sea areas was not so clear. In light with Free-air and Bouguer gravity data and tomography result in Yellow Sea and East China Sea, various information on faults were obtained after the processing (upward, arbitrary horizontal direction derivative, wavelet transform etc,.) and geophysical features of research region were analysis. It can be divided into different small areas according to geophysical feature differences. The geophysical evidences on the boundary belt between Yangtze and Huanan Blocks are shown after comprehensive analysis on gravity, magnetic, tomography result and geological information. It is believed that the boundary combine belt is possibly from Hangzhou Bay extending to round Nagasaki, Tsushima strait. It shows arc sharp to the north. The tomography result shows that geophysical evidences of the boundary belt can be found in the depth of upper mantle. Geophysical traces of this belt were not clear comparing with the boundary combine belt between Sino-korea and Yangtze Blocks. We believe that the tectonic movement of this combine belt became weaken after Caledonian movement.
引文
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[2] 朱炳泉,王慧芬,邹丽萍,等.浙闽地幔地球化学与华南—扬子地幔边界划分讨论[A].见:李继亮主编:东南大陆岩石圈结构与地质演化[C].北京:科学出版社,1993,60～68.
[3] 冯志强,姚永坚,曾祥辉,等.对黄海中、古生界地质构造特征及油气远景的新认识[J].海洋地质动态,2002,18(11):17～20.
[4] 刘光鼎主编.中国海区及邻域地质地球物理系列图集[M].北京:科学出版社.1992.
[5] 蔡乾忠.黄海含油气盆地区域地质与大地构造环境[J].海洋地质动态.18(11):8—12,2002.
[6] 郝天珧,SuhMancheol,王谦身,等.根据重力数据研究黄海周边断裂带在海区的延伸[J].地球物理学报,2002,45(3):385～397.
[7] JohnM .Wageman,ThomsWC ,Hilde,KOEmery.StructuralframeworkofEastChinaSeaandYellowSea[J].TheAmericanAsso ciationofPetroleumGeologistsBulletin,1970,54(9):1611～1643.
[8] 袁学诚,左愚,蔡学林,等.华南板块岩石圈构造与地球物理[A].见:八十年代中国地球物理进展[C].北京:学术书刊出版社,1989,234～249.
[9] 周新民,朱云鹤.中国东南部晚元古代碰撞造山带与地缝合带的岩石学证据[A].见:李继亮主编:东南大陆岩石圈结构与地质演化[C].北京:科学出版社,1993,87～97.
[10] 郝天珧,刘建华,宋海斌,等.华南及其相邻边缘海域一些重要断裂带的地球物理证据[J].地球物理学进展.2002,17(1):13～23.
[11] 刘建华,吴华,刘福田.华南及其海域三维速度分布特征[J].地球物理学报.1996,39(4):483～492.
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