西藏八宿侏罗纪花岗岩的岩石学特征及找矿意义

探讨西藏八宿地区侏罗纪花岗岩的岩石学特征,为找矿提供理论依据.通过对花岗岩类岩体的地质、地球化学、成分演化程度、分异程度和氧化状态的分析,结果表明区内侏罗纪花岗岩大量分布,反映了一次大规模岩浆事件.花岗岩由北西—南东向的断裂控制.岩石组合为黑云角闪石英二长闪长岩-黑云母花岗闪长岩-花岗闪长斑岩-黑云母二长花岗岩,为过铝...

Petrologic characteristics and prospecting significance of Jurassic granites in Basu of Tibet, China

The petrologic characteristics of the Jurassic granites in the Basu area of Tibet are systematically studied to provide a theoretic basis that there are volumes of Jurassic granites in the Anglong Gangri-Bange subzone in the tectonic-magmatic zone-Basu site.This reflects a large-scale magmatic event.There,the distribution of the granites is controlled by NW-SE fractures.And the rock assemblages are biotite hornblende quarts monzogranite,biotite granodiorite,porphyritic granodiorite and biotite hornblende monzonite diorite.They are metaluminous-peraluminous and most of high-K calc alkaline series.The geological and chemical characteristics show that most are I-type and S-type.In general,there is an enrichment of LREE,and a depletion of HREE,with a medium-strong negative Eu-anomaly and rich Rb,Th,Ce,but depletion of Ba,Nb,Sr.This shows that the tectonic setting is mainly volcanic island arc and collision environment.Many minerals,such as W,Sn,Cu,Pb,Au,Ag,and Pb-polymetallic and so on,are prominently correlated to Jurassic granites,and the distribution of the ore deposits(spots) is banded,similar to the granites.The characteristics of the oxidation state,alteration,stratum and tectonic evolution are beneficial to metallization.