旬阳地区志留系铅锌矿成矿时代探讨

THE METALLOGENETIC EPOCH OF SILURIAN LEAD-ZINC MINERALIZATION IN XUNYANG DISTRICT

陕西旬阳地区志留系铅锌矿位于南秦岭-大别构造带中部，镇（安）旬（阳）古生代沉积盆地的南缘。铅锌矿带东西长约100km，南北宽10～50km。已初步查明区内铅锌矿有中志留统双河镇组和下志留统梅子垭组含矿层位并划分为泗人沟-南沙沟、杨柳-任家沟-小沟、长沙-西营-黄石板铅锌（铜）矿带。在矿带内发现20余处铅锌（铜）矿床（点），已获铅锌资源量10×10^5t以上。志留纪为本区志留系铅锌矿成矿期的沉积期；华力西运动中期（铅模式年龄为320Ma）为本区志留系铅锌矿成矿期改造阶段的石英阶段，华力西运动晚期（Rb—Sr等时线年龄为260Ma4-7Ma）为主要铅锌矿改造阶段，印支运动和燕山运动为改造阶段的碳酸盐化阶段。

The Silurian lead-zinc mineralized zone is located in the Xunyang district, tectonically in the middle of the southern Qinling-Dabieshan structural zone and the southern margin of a Paleozoic sedimentary basin in Zhen＇an-Xunyang area, Shaanxi province. It has a length of 100km from east to west and width 10-50km from south to north. Two ore-bearing horizons have been preliminarily found in the Middle Silurian Shuanghezhen Formation and the Lower Silurian Meiziya Formation. They can be divided into three lead-zinc （copper） mineralized belts in Sirengou-Nanshagou, Yangliu-Renjiagou-Xiaogou, Changsha-Xiying- Huangshiban respectively, from which 20 lead-zinc （copper） deposits （occurrences） have been found containing lead-zinc resources over 10 × 10^5t. The Silurian epoch was the sedir mentary stage for lead-zinc mineralization; the middle stage of the Variscan orogeny （lead model age 320Ma） was a quartzification stage for reformation of the Silurian lead-zinc mineralization in this area; the late stage of the Variscan orogeny （Rb-Sr isochron dating 260Ma± 7Ma） was the major reformation phase for the lead-zinc mineralization; the indosinian movement and the Yenshan movement were the carbonation phase of the reformation.