熊耳山地区槐树坪金矿床黄铁矿特征及其地质意义

Characteristics of Pyrite from Huaishuping Gold Deposit in Xiong' ershan District and Its Geological Significance

熊耳山地区槐树坪金矿床位于华北克拉通南缘,矿体赋存于中元古界熊耳群火山岩地层中,受断裂控制。矿石类型为蚀变岩型和石英脉型,主要的金属矿物有黄铁矿、方铅矿、闪锌矿和黄铜矿。热液成矿过程划分为早、中、晚3个阶段,分别形成石英—黄铁矿脉、石英—多金属硫化物脉和石英—方解石脉。早阶段黄铁矿为自形粒状,粒径为0.8~2.0 mm;中阶段黄铁矿为半自形、他形粒状,粒径为0.30~0.45 mm;晚阶段黄铁矿为自形—半自形粒状,粒径为0.1~3.0 mm。电子探针分析结果表明:该矿区黄铁矿S元素质量分数为51.25%~52.71%,Fe元素质量分数为45.78%~48.11%。其中,成矿阶段黄铁矿的Cu、Zn、Sb元素质量分数分别为0.11%、0.13%和0.12%。Co/Ni比值为0.57~0.60;黄铁矿的δFe-δS主量元素投图和Co-Ni-As质量分数三角图研究表明,槐树坪金矿床成矿流体来源为中低温变质热液。

Huaishuping gold deposit is located in the Xiong’ershan district,southern margin of the North China Craton.It is hosted by the Mesoproterozoic volcanic rocks of Xiong’er Group.The occurrence of gold orebodies is controlled by faults.Its ore types are altered rock and quartz vein,and the major metal minerals are pyrite,galena,sphalerite and chalcopyrite.The hydrothermal ore-forming process can be divided into three stages:quartz-pyrite vein(early),quartz-polymetallic vein(middle)and quartz-calcite vein(late).In the early stage,pyrites are euhedral granular,with size of 0.8~2.0 mm;in the middle stage,they are subhedral and xenomorphic granular of 0.30~0.45 mm;and in the late stage,pyrite is euhedral-subhedral granular,and the particle size is 0.1~3.0 mm.The electron microprobe analysis showed that S element content in the pyrite was 51.25%~52.71%,and Fe element content was 45.78%~48.11%.The Cu,Zn and Sb elements content of pyrites in the middle stage were 0.108%,0.131%and 0.115%respectively.TheδFe andδS plot of major elements and the Co-Ni-As triangular diagram of pyrites study shows that the source of ore-forming fluid in Huaishuping gold deposit is medium-low temperature metamorphic hydrothermal fluid.