摘要
中国东南部福州复式岩体主要由两个岩套构成:(1)钙碱性岩套(丹阳岩体、福州岩体)侵位于约105—100Ma前(Rb-Sr年龄)。这些花岗岩显示了有斜长石和角闪石分离的分异作用。Sr和Nd同位素证据说明老地壳物质在岩浆形成中起了重要作用。(2)碱性岩套(魁岐岩体、笔架山岩体)侵位于90Ma前。这个岩套主要由超溶线过碱性花岗岩组成。这些过碱性花岗岩的岩浆分异作用很微弱,特征是稀土含量高。Sr和Nd同位素资料表明,在岩浆形成过程中地壳物质带入未起重要作用。 由岩石成因研究可见,福州复式岩体是逐渐连续侵位于地壳上部。钙碱性岩套是侵位于俯冲带的典型岩套,而碱性岩套则与较大的地壳深断裂有关。
In SE China the Fuzhou plutonic complex is made up of two major suites:a) A calc-alkaline suite (Danyang, Fuzhou) emplaced about 105-100 Ma ago (Rb-Sr ages). These granitic rocks show a calc-alkaline differentiation trend, with fractionation of plagioclase and hornblende. Sr and Nd isotopic evidence suggests that ancient crustal material has played an important role in the magma genesis.b) An alkaline suite intruded about 90 Ma ago (Kuiqi, Bijiashan). It is composed of hypersolvus per-alkaline granites, which show little magmatic differentiation. These rocks are characterized by high abundances of REE. Sr and Nd isotopic data indicate that crust involvement was not significant.The petrogenetic study suggests that the successive intrusions of that complex were emplaced progressively at higher crustal levels. The calc-alkaline suite is typical of those emplaced in subduction-zone environments, whereas the hyperalkaline suite is associated with major deep crustal faults.
出处
《地球化学》
CAS
CSCD
北大核心
1991年第2期101-111,共11页
Geochimica
