藏北尼雄地区燕山期岩浆流体系统与成矿

Spatio-temporal framework and mineralization of the Yanshanian magmatic fluid systems in the Nyixung region, northern Xizang

关键词:  尼雄地区  流体系统  燕山期  铜矿  铁矿

Key words:  Nyixung region  fluid system  Yanshanian  copper deposit  iron deposit

摘要:

在野外调查并综合前人资料的基础上,初步建立了藏北尼雄地区燕山期岩浆流体系统的时空格架及其与矿产的关系。将尼雄地区的岩浆流体系统分为两类3个子系统,一类是与早白垩世早期侵入体有关的流体系统,依据其活动时间和流体活动特征,可进一步划分为早、晚两个子流体系统,早期的流体活动与尼雄铁矿关系密切,晚期的流体活动与沙松南铁矿关系密切;另一类是与花岗斑岩体(90Ma±)有关的流体系统,其与日阿斑岩铜矿关系密切。

Abstract:

The present paper deals, on the basis of field investigation and previous data, with the spatio-temporal framework of the Yanshanian magmatic fluid systems, and the relationship between the magmatic activity and mineral resources in the Nyixung region, northern Xizang. The Yanshanian magmatic fluid systems in the Nyixung region may be classified into two categories covering three subsystems. One of fluid systems is associated with the early Early Cretaceous intrusions, i. e. the arc granitic complexes caused by the closure of the Shiquanhe ocean. The fluid systems may further be subdivided, according to the ages of magmatic intrusion and features of fluid activity, into two subsystems, including the early fluid activity associated with the Nyixung iron deposit, and the later fluid activity associated with the southern Shasong iron deposit. The other is associated with granite porphyry dated about 90 Ma and closely related to the Ri'a porphyry copper deposit. The magmatic hydrothermal solution contains plenty of mineral elements in itself. The heat energy released by boiling magmas not only caused the formation water to be activiated, but also made the mineralization fluids to extract the mineral elements from the Xiala and Dibuco Formations, and thus resulting in the formation of rich contents of ores and larger sizes of ore bodies.