我国的南海是世界著名的边缘海之一,也是地质上争执最大的弧后盆地,由于地质情况复杂,研究程度又低,很多问题没有得到澄清,西沙礁灰岩之下基底的时代和成因问题就是其中之一.1973年12月-1974年4月石油部南海石油勘探指挥部在西沙群岛的永兴岛施工的西永1井孔深1384.60m,是西沙地区到目前为止唯-钻透礁灰岩达到基底的钻井.该井上部1251m为礁灰岩,1251-1384.60m为风化层及基底岩石.用Rb-Sr法测得基底片麻岩 Due to complicated geological conditions and low degree of research, many problems have not been clarified. The era and genesis of the basement under the Xisha reef limestone are the major causes of the geological problems in the South China Sea. Is one of them.December 1973-April 1974 the Ministry of Petroleum South China Sea Oil Exploration Command in Yongxing Island, Xisha Islands, the construction of the West Wing 1 hole depth of 1384.60m, is the only so far in Xisha region - through the reef gray The rock reaches the basement of the wellbore where 1251 m of reef limestone and 1251-1384.60 m of weathering and basement rocks are measured.The basement gneiss