西藏甲玛斑岩矿床是冈底斯成矿带上具有重大经济意义和科学研究意义的超大型矿床,近年来,取得了重大的找矿突破,现已累计查明和控制铜金属资源储量超过700万吨,共伴生钼、铅+锌、金、银资源储量均达到大型以上规模。笔者在充分收集、整理甲玛矿床最新勘查、研究成果的基础上,对矿区386个钻孔样品化学分析数据进行了系统梳理和分析,按一般工业指标边界品位圈定矽卡岩型铜钼矿体、矽卡岩型铅锌矿体,对厚大矽卡岩型矿体在平面上、剖面上的分布及产出特征进行了全面、系统的分析。研究发现,甲玛矿区厚大矽卡岩矿体主要分布于3个区域:1矿区中部斑岩接触带;2矿区南部铜山滑覆体内;3矿区北西部牛马塘一带。对于不同部位的厚大矿体,其控矿因素各不相同,按主要制约因素,可以概括为:岩体接触带控矿、滑覆体构造控矿和背斜核部构造控矿。文章通过对矿区厚大矽卡岩矿体控矿因素的探讨,建立了相应的岩浆-构造控矿模式,对于完善甲玛斑岩成矿系统模型及矿山开采具有重大意义。
A great breakthrough was achieved by the authors in the exploration of the Jima porphyry deposit in the Gangdise metallogenic belt which is a superlarge deposit with remarkable economic and scientific significance. Its proved reserves have achieved more than 7 million tons of copper resources, which, together with associated molybdenum, lead and zinc, gold, silver resources, have attained the scale of a large deposit. The previous re-searchers have conducted a lot of research work on this deposit in the aspects of geological and geochemical char- acteristics and obtained fruitful research results; nevertheless, the study of thick and large skarn orebodies of the porphyry metallogenic system and their ore-controlling factors remains very insufficient. Based on fully collecting and sorting the latest exploration and research results of the Jima porphyry deposit, the authors systematically arranged and analyzed chemical analytical data from 386 drill hole samples. According to the general industrial index marginal grade, the authors delineated skarn type copper-molybdenum orebodies and skarn type lead-zinc orebodies. Then the distribution and occurrence characteristics of thick and large orebodies were analyzed com- prehensively and systematically in the plane and along the section. The results achieved show that the thick and large skarn orebodies are mainly distributed in three areas in Jiama: (2) the exocontact zone of the porphyry in the central mining area; (2) Tongshan gliding nappe in the southern mining area; (3) Niumatang area in the northwest mining area. The ore-controlling factors are different in different parts of the thick and large skarn orebody and the main factors can be summarized as follows: porphyry contact zone ore-controlling action, gliding nappe ore-controlling action and anticlinal core ore-controlling action. On such a basis, a corresponding magma- tectonic ore-controlling model has been established, which is of great significance for improving the model of the Jiama porphy