摘要
长江中下游的岩浆岩在某些地区表现为由酸性→中性→基性的演化顺序,我们称之为岩浆的逆向演化.本文讨论了岩浆逆向演化的地质、地球化学背景及其产生机制,同时也论证了岩浆逆向演化与内生成矿作用的关系.
Magmatic activity in the lower-middle reaches of Yangtze River during Yenshanian stage is cheracterized by strong multistage magmatism, and the genetic type of granite belongs to syntexis magma (I -type). A reversed evolution type of magma is proposed as magmatic evolution and rock intrusive sequence are from acidic, intermediate to basic in Ning-Zhen, Ning-Wu and Lu-Zhong districts, and large amount of geological evidences are given in this paper. High pressure and high temperature experimental melting of granodiorite-porphyry confirms that liquid magma rich in volatiles and alkli metals in high pressure give vise to a vertical liquid zoning, layered liquid immiscible, where the upper layer is acidic, the middle one intermediate and the lower basic. Geochemical mechanism of reversed evolution type magma is the existence of immiscible liquid magma in magmatic chamber. It is unique to mineralization of intermediate-basic magma at later stage of reversed evolution, which is characterized mainly by gold and uranium mineralizations.
出处
《火山地质与矿产》
1992年第3期15-24,共10页
Volcanology & Mineral Resources
关键词
成矿作用
岩浆岩
逆向演化
Magma reversed evolution type mineralization.
