海南岛后地台造山-造盆模型:火成岩地球化学制约

POST-PLATFORM OROGENY AND BASIN-MAKING MODEL IN THE HAINAN ISLAND OF CHINA: GEOCHEMICAL CONSTRAINTS FROM IGNEOUS ROCKS

海南岛自海西运动晚幕之后进入后地台活化或地洼阶段，并经历了晚海西-印支期挤压（碰撞）造山、地壳隆起和燕山期以来的块断型造山-造盆作用的过程。火成岩研究资料表明，海南岛地区在晚海西-印支运动期间曾形成一个具有加厚陆壳的后地台造山带；燕山晚期开始出现的裂陷作用是在仍有山根（约60km厚的陆壳）存在的条件下造山带拉伸塌陷阶段的产物；岩石圈底层剥离与地壳山根的去除并最终导致了海南及其邻区从大陆型壳体向陆缘扩张带型壳体的转化。

Since the late Hercynian episode the crust of Hainan has entered the stage of post-platfom activation or the diwa stage in which it has undergone a process from compressive (collision) orogeny and uplifting during the late Hercynian-Indosinlan movements to block-faulting type mountain-building and basin-making during the Yanshan-Himalayan movements. It has been shown by the researches of igneous rocks that a post-platform orogenic zone being of a greatly thickened continental crust was once formed in the Hainan area during the late Hercynian-Indosinian cycle; the taphrogeny starting in the late Yanshan episode was a product at the stage of late orogenic extension under coTlclitions of the mountain root with a thickness of about 60 km retained; at last, the lower lithospheric delamiTlation .and the crustal derooting of the orogens caused Hainan and its neighborillg areas to transform from the continental type crustobody to the continental-margin-spreading- type crustobody.