燕山中晚期的中国东部高原:埃达克岩的启示

AN EAST CHINA PLATEAU IN MID-LATE YANSHANIAN PERIOD: IMPLICATION FROM ADAKITES

中国东部燕山期岩浆岩广泛发育 ,其中有一类具埃达克岩的特征 ,并根据埃达克岩的成因提出中国东部在燕山中晚期可能为一个高原。本文就中国东部高原的范围、高原存在的依据、高原隆升和减薄的机制进行了讨论 ,指出中国东部高原大规模的抬升事件大约发生在中 -晚侏罗世期间 ,在早白垩世之后塌陷。高原的隆升与板块消减作用无关 ,是陆内事件的产物。高原的塌陷是下地壳拆沉作用的结果。拆沉作用不仅可以解释高原的减薄 ,而且可以解释新生代玄武岩喷发和中国东部盆地的形成。

It is reported that some of the felsic igneous rocks of Yanshanian period from the eastern part of China are geochemically analogous to adakites. Based on the genesis of adakites, as well as other geological evidences, the paper is proposing that in Mid Late Yanshanian period the eastern part of China continent was probably a plateau, which was uplifted in Mid Late Jurassic and thinned after Early Cretaceous. The covered areas, mechanism of uplifting and thinning of the plateau are discussed, and it is considered that uplifting and thinning of the plateau were due to intra continental orogenic events and delamination of lower continental crust, respectively. The delamination may be also responsible for the eruption of basalts and formation of basins in the eastern part of China during Cenozoic.