安徽省绩溪县际下钨(铜)矿床地质特征及成矿条件分析

GEOLOGICAL FEATURES AND ANALYSIS OF OREFORMING CONDITIONS OF THE JIXIA TUNGSTEN(COPPER) ORE DEPOSIT IN JIXI COUNTY, ANHUI

绩溪县际下钨(钼)矿区位于扬子陆块,江南古隆起带北东倾伏端,宁国墩—五城边界断裂从矿区南侧通过,矿区位于仁里复向斜中的际下村轴隆部位。矿体赋存于震旦纪蓝田组及南华纪南沱组中,呈层状、似层状及透镜状。矿石类型:透闪石—硫化物型、细脉型、含砾凝灰质板岩—石英细脉型和石英脉硫化物型。矿床具层控式矽卡岩型矿床特征。燕山时期,江南陆内造山带形成于壳―幔相互作用等深部过程,随着宁国墩—五城深大断裂伸展、冲断等转变,岩石圈减薄发生减压熔融,基性岩浆底侵在壳幔边界并使下地壳局部熔融产生中酸性岩浆。岩浆演化分异,钨在岩浆热液中富集,最终演化为含矿热液。随着应力转变,矿质析出,沉淀成矿。

The Jixia tungsten（copper） ore district, Jixi County is situated in the Yangtze landmass, in the northeastern plunging crown of the Jiangnan old land uplifting belt, where the Ningguodun-Wucheng border fault passes by to the south of it, which lies at the axial uplift in Jixia village of the Renli synclinore. The ore body is hosted in the Lantian Formation of Sinian Period and the Nantuo Formation of Nanhua Period, bedded, stratoid and lenticular in form. Ore types are tremolite-sulfide, veinlet, gravel tuffaceous slate-quartz veinlet and quartz vein sulfide. It shows the features of strata-bound skarn deposit. In the Yanshanian period, the Jiangnan intraland orogen formed in the depth where the crust interacts with the mantle, with the extending and thrusting of the Ningguodun-Wucheng deep fault, lithosphere thinned and melted with decompression, basic magma underplated at the crust-mantle border and partly melted lower crust to produce intermediate-acid magma. With magmatic evolution and differentiation, tungsten enriched in magmatic hydrothermal fluid and finally developed into orebearing hydrothermal solution. With the change of stress, mineral separated out and deposited.