巍山-漾濞锑汞砷金多金属矿带包裹体研究

A STUDY ON INCLUSIONS OF THE Sb-Hg-As-Au MULTIMETALLIC DEPOSIT ZONE IN WEISHAN-YANGBI

巍山-漾濞多金属矿带位于兰坪-思茅裂谷地堑带北段的东南部,为一北北西向展布(与裂谷地堑带一致)的复背斜构造。矿带长约50余千米,宽6—8千米。复背斜轴部主要为三叠系上统歪古村组砂泥质板岩和三合洞组下段灰岩,翼部依次出露三叠系上统三合洞组上段黑色页岩、麦初箐组砂泥岩和侏罗系下统漾江组砂泥质碎屑岩。区内北北西向、东西向断裂组发育,形成格状构造。早期为断块下陷的张性断裂(即北北西向纵断层),成矿期则受近东西向的(?)平挤压(转为压扭性),它们控制着锑、汞、砷、金矿的展布。

The multimetallic deposits in this area occur in the axis and limb of the Shejie-Zijinshan anticlinorium. The inclusions in the multimetallic deposits are well developed. The types of the inclusions are many and varied, and the major ones are gaseous and irregular shape inclusions. The organic and CO_2 inclusions in the Sb-Hg-Au deposit show that the organic matters have played an important role in the migration of Sb, Hg, Au. The inclusions in the Sb-Hg deposit are relatively large, mainly with irregular shapes, more gaseou constituent and distributed in groups or sparsely, which shows that they are formed in a relatively open environment with low-pressure, low-temperature and longer metallogenetic epoch. And they are contrary to the inclusions in the AuAs deposit. The multimetallic deposits are of medium saltness (5--13.5％ wt) and medium-low temperature (290--120℃) hydrothermal metallogenesis which can be divided into 2 stages. In the Au-As-Sb-Hg metallogenetic process, the metallogenetic temperature and pressure gradually decreased, whereas the density of the metallogenetic fluid increased step by step. The metallogenetic fluid of each deposit (or prospect) basically possesses the same salthess, which displays that the origin and the property of their metallogenetic fluid are similar to one another. The saltness of the metallogenetic fluid decreases with the decrease of the temperature, which shows that the decrease of the temperature and pressure is an important factor causing the metallogenetic precipitation. The analysis of the composition of the liquid of the inclusions confirms that the metallogenetic liquid in this area is Na-Ca-S-Cl type hydrothermal brine, and characteristic of middle-low temperature primary formation water (preserved water) and supergenous hydrothermal solution.