滇西北保山核桃坪铅锌矿床铅同位素和成矿过程对比研究

A Comparative Study on Lead Isotope and Mineralization of Hetaoping Pb-Zn Ore Deposit,Baoshan

滇西北核桃坪铅锌矿是保山地块内沿澜沧江断裂带发育的一个大型铅锌多金属矿床。矿体赋存于上寒武统核桃坪组和沙河厂组大理岩化灰岩及矽卡岩中,严格受近SN向的断裂带及层间破碎带控制。在分析矿床地质特征的基础上,通过与澜沧江老厂铅锌矿进行对比,对核桃坪铅锌矿形成的大地构造成因进行研究。大地构造位置,主成矿期铅同位素比值、物质来源等证据显示核桃坪矿床与老厂矿床具有相同的成因。根据老厂矿床的前人研究得出核桃坪铅锌矿床形成的机制为青藏高原的主碰撞期末,大规模走滑断裂的形成导致地壳重融、减薄,幔源岩浆沿走滑断裂侵入地壳与围岩交代蚀变成矿。

Hetaoping lead zinc ore deposit is a large-sized polymetallic deposit that developed along the Lancang River fault zone,Baoshan block,northwest Yunnan.Occurring in marbleization-limestone and skarn of the Hetaoping Group and the Shahechang Group of the Upper Cambrian Series,this deposit is firmly controlled by the nearly N-S trending fault-rupture and the interlayer fracture zone.The tectonic origin of Hetaoping Lead Zinc Deposit is analyzed by comparing that of Laochang Lead Zinc Deposit based on the researches of geological characteristics of mineral deposits.ectonic positions,Pb isotopic ratios of main metallogenic period and material sources all indicate that the causes of formation of these two deposits are alike.Hetaoping Lead Zinc Ore deposit is a large-sized polymetallic deposit that developed along the Lancang River Fault Zone,Baoshan Block,northwest Yunnan.Occurring in marbleization-limestone and skarn of the Hetaoping Group and the Shahechang Group of the Upper Cambrian Series,this deposit is firmly controlled by the nearly N-S trending fault-rupture and the interlayer fracture zone.Comparing with previous studies on Laochang deposit,crustal re-melting and thinning was induced by the occurrence of the large-sized strike-slip faults that formed in the late stage of the main collisional period of the Qinghai-Tibet Plateau.Therefore,the mantle derived magma intruded along strike-slip faults into the mantle crust and then metasomatic altered with surrounding rocks that became the formative mechanism of Hetaoping Lead Zinc Deposit.