摘要
世界上的含金夕卡岩大多属钙夕卡岩型，镁夕卡岩金矿床十分稀少。本文介绍我国安徽北部三铺地区镁夕卡岩金（铜、铁）矿床的地质地球化学特征。该区含金（铜、铁）镁夕卡岩主要产于地台断拗区燕山期石英二长闪长玢岩与中上寒武统白云质大理岩外接触带。岩体内接触带发育钙夕卡岩和钾长石化，局部有辉钼矿化产出。金矿化与铜的硫化物密切共生，属于镁夕卡岩的退化热液交代作用产物。金属矿化分带序列自蚀变石英二长闪长玢岩到镁夕卡岩、蛇纹石化白云质大理岩依次为：Ｍｏ→Ｆｅ→Ｃｕ（Ａｕ）→Ａｕ（Ｃｕ）。矿物共生组合和流体包裹体研究表明，交代成矿作用的演化可分为３个阶段：①镁（钙）夕卡岩阶段；②铁（镁）氧化物阶段；③碳酸盐（石英）－硫化物和金矿化阶段。
Abstract
Magnesian skarns consist of diopside,forsterite,phlogopite,chondrodite,clinohumite,and have
been subjected to strong serpentinization.clinochloritization and carbonitization associated with
iron,gold and copper sulfide mineralization.In the endocontact zones,there are diopside garnet
epidote calcic skarns associated with K feldspathization of adjacent quartz monzodiroite
porphyry.Locally,molybdenite mineraization occurs in the fractural zones of the K feldspathized
quartz monzodiorite porphyry. The mineralization zoning in some depsoits is very clear.The
zonal sequence from altered quartz monzodiorite porphyry through magnesian skarn to
serpentinized dolomitic marble is Mo→Fe→Cu(Au)→Au(Cu). Studies of the mineral
paragenesis and fluid inclusions suggest that the metasomatic mineralization may be divided
into three stages:①magnesian(calcic)skarn stage;②iron(magnesian)oxide stage forming
magnetitie,magnesiomagnetite and magnesioferrrite;③carbonate(quartz)sulfide and gold
mineralization stage.The formation temperature of magnesian skarn stage is 400℃～625℃
with salinites of 38 4￣59 7%NaCl.The last two stages correspond to the retrograde
hydrothermal metasomatic stage of the early magnesian skarns.The formation temperatures of
these two stages are 180℃～450℃ with slainities of 17 8￣31wt% NaCl.The pressure of the
petrogenesis and metallization is from 23 6 MPa to 612 9MPa.
出处
《矿床地质》
CAS
CSCD
北大核心
1999年第1期1-10,共10页
Mineral Deposits
基金
国家自然科学基金
