山西支家地银矿地质特征及矿床成因

GEOLOGICAL CHARACTERISTICS AND GENESIS OF THE ZHIJIADI SILVER DEPOSIT,SHANXI PROVINCE

支家地银矿系产于火山岩-次火山岩中,属浅成中低温热液型银矿床。研究了银矿的地质特征、微量元素、稳定同位素和包裹体地球化学特征,探讨了成矿的控制因素和物理化学条件及矿床成因,建立了成矿模式。

The Zhijiadi silver deposit is a large-sized deposit present in the cryptoexplosive breccia rimming the neck facies quartz porphyry, with orebodies in veinlike and lenticular forms.Silver minerals are mainly native silver and argentite, making up disseminated and brecciated ores.The ore-forming process might be divided into three stages, with strong wall rock alteration.Minor element geochemistry of rocks and sulfides suggests that the ore-forming fluids are endogenic hydrothermal solutions, and stable isotope studies reveal the enrichment of ^(34)S which shows relatively small positive values and obvious tower effect.Ore lead and dolomite lead (Changcheng System) have similar and relatively stable composition, implying that they might both have been derived from the lower crust with the entry of some mantle materials.Carbon and oxygen isotopic composition exhibits the feature of magmatic hydrothermal solutions.Inclusion thermometry gives ore-forming temperatures of 130～335℃;salinity is 0.97%.It is considered that the Zhijiadi silver deposit is a shallow-seated mesothermal-epithermal deposit related to volcanic-subvolcanic rocks.A metallogenic model has been established in this paper.