四川宁南跑马铅锌矿床的成矿时代及其地质意义

Rb-Sr isotopic age of sphalerite from the Paoma lead-zinc deposit in Sichuan Province and its implications

摘要: 提要：四川省宁南县跑马铅锌矿床是产于下寒武统麦地坪段白云岩中的层控矿床，主要受层间破碎带控制，有两个含矿层。该矿床是沉积改造型铅锌矿床，Pb+Zn的品位6%～9%，富矿可达30%以上。笔者利用TIMS测试技术获得闪锌矿的Rb-Sr同位素年龄值，结果表明跑马铅锌矿化等时线年龄为（200.1±4.0）Ma，属印支晚期—燕山早期。由于该矿床与云南会泽铅锌矿年龄相近，推断为同一构造－岩浆活动的产物。

Abstract: Abstract：Located in Nanning County of Sichuan Province, the Paoma lead-zinc deposit is a stratabound deposit in a cataclastic zone of Lower Cambrian Maidiping dolomite. Being a reworked sedimentary stratoid (irregular) lead-zinc deposit, it includes two ore horizons. Pb and Zn in the ore deposit are economic elements possessing an average grade of 6%～9%, with the grade of rich ore in excess of 30%. The sphalerite Rb-Sr isochron age of 200±1Ma by TIMS method suggests an age of Late Indosinian-Early Yanshanian. This ore deposit has the same age as the Huize lead-zinc deposit in Yunnan Province, and therefore it is inferred that they had the same ore-forming setting.