摘要
公婆泉铜矿位于甘肃-蒙古-北山斑岩铜矿成矿带公婆泉岛弧区,为典型的斑岩型铜矿,赋矿围岩主要为英安斑岩、花岗闪长斑岩和石英闪长玢岩。矿石矿物主要有黄铜矿和斑铜矿,其次有少量的黄铁矿、闪锌矿、方铅矿以及蓝辉铜矿等。对含矿石英脉中流体包裹体研究表明,公婆泉铜矿主要有4类流体包裹体：纯气相包裹体（Ⅰ型）、纯液相包裹体（Ⅱ型）、原生富液相气液两相包裹体（Ⅲa型）以及次生富液相气液两相包裹体（Ⅲb型）。其中与成矿密切相关的为原生富液相气液两相包裹体（Ⅲa型）。该类包裹体的均一温度集中在100～260℃,盐度在0.18%～9.98%（NaCleq）,密度为0.75～1.0g/cm3;激光拉曼探针分析表明,液相成分以H2O为主,气相成分以H2、N2以及CH4为主。成矿流体具有中低温、低盐度以及低密度的流体特征。斑岩的上升侵位为矿床的形成奠定了物质基础——Cu、S。斑岩分异出成矿流体沿早期断裂系统向上运移发生减压沸腾导致相态分离,从而造成Cu发生沉淀。因此,减压沸腾可能是导致流体中金属卸载的主要原因。
Gongpoquan copper deposit is a typical porphyry copper deposit located in the quan island arc zone of Gansu-Mongolia-Beishan porphyry copper metallogenic belt. Gongpo The host rocks are characterized by dacite porphyry, granodiorite porphyry and quartz diorite porphyrite. The ore minerals mainly consist of chalcopyrites and bornites, with few pyrites, sphalerites, ga lenas and dige types of fluid type）, nature gas-liquid two nites etc. The study of fluid inclusions in the ore-bearing vein-quartz concludes four inclusions namely pure vapor inclusions （Ⅰ-type）, pure aqueous inclusions （Ⅱ aqueous-rich gas-liquid two phase inclusions （Ⅲ a-type） and secondary aqueous-rich phase inclusions （Ⅲ b type）. The mineralization is closely related to nature aque ous-rich gas-liquid two phase inclusions, i. e. IIIa-type. This kind of fluid inclusions have horn- ogenization temperature of 103- 250℃, salinity of 0.18%-9. 98% （NaCleq）, and density of 0.75 - 1.0g/cm3 , which shows that the ore-forming fluid is mesothermal, with low salinity and low density. Laser-Raman microspectroscopy analyses reveal that the liquid phase is mainly com- posed of H2O, and the vapor phase of H2, N2 and CO2. The rising and emplacement of porphyry provided ore-forming materials such as Cu and S for the formation of the copper deposit. Due to late tectonic activity, the porphyry became mobilized and generated ore-forming fluid through dif- ferentiation, the decompressing boiling of which resulted in separation of phases while migrating upward, and then Cu precipitated. Therefore, the decompressing boiling might be mainly respon- sible for the precipitation of metal in fluid.
出处
《西北地质》
CAS
CSCD
2015年第1期91-100,共10页
Northwestern Geology
基金
青年基金项目"中天山构造带阿拉塔格环状杂岩体成因研究"(41202045)
牛圈子等6幅1:5万区域地质调查项目(12120113046400)联合资助
关键词
矿床地质
流体包裹体
公婆泉铜矿
甘肃北山
ore geology
fluid inclusions
Gongpoquan copper deposit
Beishan of Gansu
