河南内乡县银洞沟银多金属矿床碳-氢-氧同位素地球化学

Zhang J,Yan GP,Ye L,Li GP,Li ZL and Wang ZG.2005.The C-H-O isotope systematics of the Yindonggou Ag-dominated poly-metals deposit in the Neixiang county,Henan province.

河南内乡银洞沟银多金属矿床赋存于东秦岭北坡的二郎坪群,属于断裂构造控制的脉状造山型银多金属矿床成矿流体δ^(18)O 值为2.7～9.6‰,δD 值为-95～-73‰,δ^(13)C 值为0.1～0.9‰。早阶段流体为源于含海相碳酸盐的岩石组合的变质脱水,晚期流体来自大气降水的循环。矿区南侧含大理岩的秦岭群符合早阶段变质流体的源区岩性特征,因此认为,在中生代扬子与中朝大陆碰撞过程中,秦岭群板片沿朱夏断裂向北陆内俯冲到二郎坪地体之下,在二郎坪地体之下变质脱水,导致造山型银/金矿床成矿流体系统发育,流体在赋矿构造的韧脆性转变带或韧脆性转变期卸载成矿物质,形成银洞沟大型银多金属矿床。

The Yindonggou Ag-dominated poly-metals deposit is a fault-controlled lode deposit hosted in the Erlangping Terrane, northern East Qinling Orogen. The δ^18O, δD and δ^13CPDB values of its ore-fluids range 2.7～9.6‰, -95～-73‰, and 0.1～0.9‰, respectively. This implies that the fluids in the early stage are sourced from the metamorphic devolatilization of marine carbonate-containing lithologies, and in the late stage from meteoric water circulation. The marble-containing Qinling Group in the south of the Yindonggou deposit can match up with the lithologic source of the early stage ore-fluids. Hence we think that the Qinling Group underthrusted northward beneath the Erlangping Terrane along the Zhu-Xia fauh during Mesozoic collision between the Yangtze and Sino-Korea continents; the underthrusted slab metamorphically devolatilized, resulting development of the orogenic-type Au/Ag ore-forming fluid-systems; and then the ore-fluids discharged ore-forming metals at the ductile-to-brittle transition stage or/and position of the ore-hosting structures, causing the formation of the Yindonggou large-sized Ag-dominated poly-metals deposit.