兰坪—思茅盆地红层铜矿成矿规律

METALLOGENIC LAW OF RED-BED COPPER DEPOSITS OF THE LANPING-SIMAO BASIN, YUNNAN, CHINA

兰坪—思茅地洼盆地中新生代红层铜矿可分为三个成因类型:沉积型,沉积-改造型和改造型。它们呈“层—梯”式产出。在成因上与热卤水活动有关。在分布上受澜沧江断裂和中轴断裂控制。微量和稀土元素及同位素地球化学研究表明,成矿物质以壳源为主。成矿热动力与成矿期区域性幔热异常和强烈的构造活动有关。矿床形成于两个时期,即地洼初动期的沉积—成岩矿化期(T_3-E_1)和地洼激烈期的改造成矿期(E_2)。其中,改造成矿是本区铜矿最重要的成矿过程。

The red-bed copper deposits in Mesozoic-Cenozoic strata of Lanping-Simao di-wa basin can be divided into three origin types: sedimentary (diagenetic) , sedimentary-transformed and transformed types. They have character of 'layer-ladder' model in occurence, con- stitute a metallogenic series relating closely to activity of middle-low temperature hot brine, and are controlled by Lan-cangjiang and central axis large fractures. Many evidences of trace element, REE and isotope geochemistry show that ore-forming materials of the all deposits were mainly derived from crustal sources. But the thermal and dynamic source related to the regional thermal anomaly of upper mantle and intensive tectonic movements during the mineralization epoch. The deposits underwent two formation stages, i. e. , the formation of sedimentary-diagenetic mineralization in diwa initial-mobility period (T3-E1) and the formation of the transformed mineralization in diwa maximum-mobility period (E2). The latter is the most important ore-forming process of the copper deposits in the region.