澜沧老厂矿田滑脱构造及其控矿特征

GEOLOGIC CHARACTERISTICS OF DETACHMENT FAULT AND ITS RELATIONSHIP TO MINERALIZATION IN LAOCHANG ORE FIELD, LANCANG, YUNNAN PROVINCE

澜沧老厂超大型银铅多金属矿床是产在晚古生代裂谷火山岩中的多因复成矿床，本文通过对老厂矿田滑脱构造的研究，指出了滑脱构造普遍存在于该区中上石炭统一下二叠统巨厚层状灰岩和下石炭统火山岩之间，它是大陆地壳伸展构造的一种类型，具有其独特的地质特征，其形成与裂谷演化后期区域伸展作用和深部岩浆物质底辟作用有关。老厂矿田的银铅多金属成矿作用与滑脱构造有密切的成因联系，滑脱构造带直接控制了重要工业矿体的产出。

The Laochang superlarge Ag-Pb-polymetallic depsoit is a polygenetic compound deposit which occurred in the rift-type volcanic rocks formed in the Late Paleozoic era. Based on the study of the detachment faults in this area, this paper points out that the detachment faults generally exist between the volcanic rocks (C1) and limestones (C2P1 ) which have huge thickness. The detachment faults with their special geological characteristics are also a special type of extensional structures.Their formation are related to both regional extension during the later evolutional period of the rift and diapirism of magma from the deep depth of the earth. The mineralization of the Ag-Pb-polymetallic deposit may have a close relation ship to the detachment faults. The occurence of the economic orebodies is directly controlled by the detachment faults.