南海变质基底基本轮廓及其构造演化

BASIC OUTLINE AND TECTONIC EVOLUTION OF THE METAMORPHIC BASEMENT IN THE SOUTH CHINA SEA

南海变质基底基本轮廓是由中央向周缘自老变新的拼盘式褶皱基底，南海中央西沙群岛海域为前寒武纪变质基底，围绕该古陆周缘发育有加里东期、海西期和印支期褶皱变质基底。南海构造演化十分复杂，经历元古代至古生代的华南地块与印支地块多次张裂与聚敛，形成晋宁期、加里东期和海西－印支期褶皱变质带；中生代又经历库拉－太平洋板块俯冲消减，形成“安第斯型大陆边缘”，新生代又经历陆缘扩张作用的演化才形成现今的构造格局。

The basic outline of the metamorphic basement in South China Sea is a mosaic folding basement with thefeature of senile basement located in the center and neobasement to the periphery of South China Sea,The Precambrianmetamorphic basement was found in waters of the Xisha Isles in central South China Sea Surrounding this paleoland-mass , the Caledonian , Hercynian,and Indo- Chinese epoch folding basements were developed in the periphery area. Thetectonic cvolution in South China is considered to be significantly complicated.The area experienced divergence and con-vergence of South China and Indo- Chinese massifs many times,forming the Jinning,Caledonian , Hercynian,Indo-Chi-nese folding metamorphic zones from the Proterozoic to the Paleozoic era and further exporienced the subduction of theKula-Pacific plate,forming the “Andes continental margin”in the Mesozoic,and later experienced the continental margin-spreading,forming the modern tectonic framework in the Cenozoic.