甘肃省肃北县二口井金矿床地质特征

肃北县二口井金矿位于天山—内蒙褶皱系,北山褶皱带的南带大奇山复式向斜带中,严格受NW向次级断裂构造控制,均产于华力西晚期花岗闪长岩体中,属岩浆热液型矿床。通过地表地质调查和深部工程验证圈定金矿体4条,矿体长60~251m,矿体真厚度0.3~2.8m,矿体倾向215°,倾角33°~80°;矿体呈透镜状、细脉状。矿石类型主要为含金石英脉型,次为破碎蚀变岩型。金主要为银金矿,次为金银矿,呈浅黄—金黄色,主要以游离金形式产出,往往多赋存于"层"间或者石英脉内部裂隙中;少量为包裹金出现,包裹金分布于黄铁矿或褐铁矿颗粒和碳酸盐及石英当中。本文通过分析和总结矿床地质特征,为寻找该类型矿床提供更多的依据。

Geologic Features of Erkoujing Gold Deposit in Subei County of Gansu Province

Erkoujing gold deposit which is administratively subordinate to Subei Mongolian autonomous county is located in Tianshan-Inner Mongolia Fold System and south of Daqishan duplicate syncline belt. Erkoujing occurred in the Late Variscian Epoch granodiorite and constrained by the NE-SW trending secondary faults being defined as a magmatic hydrothermal type gold deposit. Four gold ore bodies with lenticular and veinlet shape have been targeted based on the geological surficial research and the deep prospecting projects. Morphologically, they are 60m to 251m long and 0.3m to 2.8m thick with the attitude of 215? tendency and 30? to 80? dip angle. The quartz-vein gold ore is the predominant type while crushed alteration-type gold ore is subordinate. Gold in Erkoujing mainly formed electrum (AgAu) and crystallized to kustelite secondarily with pale yellow to golden yellow color, and it usually deposited as dissociated gold mainly at the stratigraphic gap and fractures of the quartz-vein. There are also a few gold inclusions dispersing in the grains of pyrite, limonite, carbonate and quartz. This paper aims at exploring this type gold deposits by analyzing and summarizing geological features of Erkoujing gold deposit.