南海北部陆缘东部的地壳结构
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摘要
本文利用中、美联合调查南海海洋地质项目所采集的双船地震扩展排列剖面资料，研究了南海北部陆缘的地壳结构．其特征为：从陆架到深海平原，地壳呈阶梯状减薄，地壳厚度分别为２６—２８ｋｍ，２３—２４ｋｍ，１３—１５ｋｍ，以及南海洋盆中５—７ｋｍ厚的洋壳，反映了地壳在新生代早期是幕式拉张的．地壳底部存在高速地壳层，地震波速度为７．１—７．４ｋｍ／ｓ．它是在地壳被拉张后，上地幔熔融物质上涌到地壳底部冷却而形成的．
North continental margin of South China Sea was passive in Cenozoic which developed 60 Ma B.P.The margin is a ideal one in the world for study of tectonic evolution of passive continental margin.The crustal structure is studied by using the data of two-ship seismic extended spread profiles acquired in project"USA-China Joint Investigation on Marine Geology of South Chine Sea". The crustal structure is featured by four-terrace thinned crust from continental shelf to deep sea plain. Crust thicknesses of the four terraces are 26-28 km,23-24km,13-15km and 5-7 km (oceanic crust)in South Chins Sea basin. This shows that it was episodic extensional in early Cenozoic. High-velocity layer with seismic velocity of 7.1-7.4 km/s is found on the bottom of the crust. The layer was brought about by the process that melted materals from upper mantle cooled on the bottom of the crust after extension of the crust.
North continental margin of South China Sea was passive in Cenozoic which developed 60 Ma B.P.The margin is a ideal one in the world for study of tectonic evolution of passive continental margin.The crustal structure is studied by using the data of two-ship seismic extended spread profiles acquired in project"USA-China Joint Investigation on Marine Geology of South Chine Sea". The crustal structure is featured by four-terrace thinned crust from continental shelf to deep sea plain. Crust thicknesses of the four terraces are 26-28 km,23-24km,13-15km and 5-7 km (oceanic crust)in South Chins Sea basin. This shows that it was episodic extensional in early Cenozoic. High-velocity layer with seismic velocity of 7.1-7.4 km/s is found on the bottom of the crust. The layer was brought about by the process that melted materals from upper mantle cooled on the bottom of the crust after extension of the crust.
引文
［1］滕吉文、玉谦身、魏斯禹，中国地壳构造的基本轮廓，IUGG第17届年会，14－30，1979．［2］邵学钟、张家茹、李振江等，广东大亚湾周围地区地壳和上地幔结构的初步研究，地震地质，5（4），39—50，1983．［3］廖其林、王振明、玉屏路等，福州—泉州—汕头地区地壳结构的爆炸地震研究，地球物理学报，3，270—280，1986．［4］刘昭蜀、黄滋流、杨树康等，南海地质构造与陆缘扩张，科学出版社，1988．［5］金庆焕、陈邦彦、姚伯初等，南海地质与油气资源，地质出版社，1989．［6］姚伯初、王光宇，南海海盆的地壳结构，中国科学，B辑，2，177—186，1983．图4南海北部大陆张裂及高速地壳层的产生模式［7］姚伯初、何廉声，南海北部大陆边缘上的声纳浮标测量（一），海洋地质研究，2（3），11—23，1982．［8］姚伯初，南海海盆在新生代的构造演化，南海地质研究，广东科技出版社，3，9—23，1991．［9］曾维军，广州—巴拉望地学断面综合研究，南海地质研究，广东科技出版社，3，36—64，1991．［10］Bally，A．W．，Atlantic－TypeMaryins，GeologyofPassiveContinentalMargins，AAPGEducationCourseNoteSeries19，1—48，1981．［11］Diebold，J．B．，Stoffa，P．L．，Puhl，P．，Venzuelabasincrustalstructure，J．Geophys．Res．，86（B9），7901—7923，1981．［12］Diebold．J．B．，Stoffa，P．L．，ALargeApertureSeismicExperimentintheBaltimoreCanyonTrough，PersonalCommunication，1987．［13］Grow，J．A．，DeepStructureandEvolutionoftheBaltimoreCanyonTroughintheVisinityofCOSTNo．B－3Well，U．S．GeologicalSurveyCircular833，117—126，1980．［14］Grow，J．A．，StructureoftheAtlanticMarginoftheUnitedStates，GeologyofPassiveContinentalMargins，AAPGEducationCourseNoteSeries19，3—40，1981．
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