湖南省花岗岩成因类型及其与金矿的关系

湖南省花岗岩主要形成于加里东期、印支期和燕山期,分为"I"型和"S"型两个成因类型。其中"I"型花岗岩主要为角闪(或含角闪)石英闪长岩-花岗闪长岩-二长花岗岩,Mf值(铁镁比值)多小于0.78;"S"型花岗岩主要为黑云母(或二云母)二长花岗岩-钾长花岗岩,Mf值多大于0.78."I"型花岗岩与金矿的关系更为密切,于该类岩体内或其周围形成岩浆热液型或混合热液型多金属共生金及钨锑-金矿床。根据"I"型花岗岩与金矿关系的不同特点,将其划分为自源型金成矿"I"型花岗岩带和它源型金成矿"I"型花岗岩带。"S"型花岗岩与金矿的关系仅表现为部分岩体周围发育一定程度的金矿化。

RELATIONS WITH GOLD AND GENETIC TYPES OF THE GRANITES IN HUNAN PROVINCE

The granites in Hunan province were mainly formed in Caledouian，Indosinian and Yan-shanian period，which could be divided into two types according to their petrology and geo-chemistry. Those are＂I＂type and＂S＂type. The＂I＂type granites include amphibole－quartzdiorite， granodiorite and monzonite， Mf＜0．78；The＂S＂type granites are mainly biotite（or muscovite ）monzonite and k－feldspar granite，Mf＞0．78．The ＂I＂type shows more rela-tions with gold deposits， in or around which magmatic hydrothermal and mixed hydrothermalpolymetallic－gold or W－Sb－Au ore deposits were formed．Two kinds of gold－forming＂I＂type granite－belts are divided， those are in NE and EW direction， In those two kinds belts the gold was manily from granites and gold－containing strata respectivihy. Relations be-tween＂S＂type granites and gold are no more than ＂I＂type granites， only some small scalegold mineraeization can be found around them.