云南个旧锡多金属矿田构造岩相成矿规律与西区找矿研究

A study of the tectono-lithofacies mineralization regularities of the Gejiu tinpolymetallic orefield,Yunnan,and prospecting in its western part

云南个旧超大型锡多金属矿田研究成果很多,但是西区找矿一直没有取得突破。本文以建造构造成矿综合研究为基本思路,综合前人的大量资料,重点为西区建立了新的构造岩相找矿模型。以中三叠统个旧组为沉积建造基础,晚白垩世发育花岗杂岩体建造。中生代晚期经历了大规模的岩浆热液成矿过程,成矿时代覆盖了70-90Ma,集中在80Ma左右,形成最主要的成矿岩相。通过矿田构造岩相成矿图的编制,发现成矿阶段处于挤压-伸展构造转换体制,认为原始的个旧断裂两盘成矿是一致的,西区与东区的成矿模型是相同的。构造岩相的界面成为构造岩浆热液流体充填和交代蚀变两种主要矿床类型的有利空间。矿田构造地层岩浆即构造岩相成矿模型显示,由于个旧断裂垂直和水平方向多期次、规模性活动的改造,西区表现为高隆起、复杂错动的构造特点,因而成矿构造岩相具有残留性、复杂性、低位性等特征。依据上述研究成果,结合地物化信息,指出了西区找矿方向和有利区段。

The superlarge Gejiu tin-polymetallie orefield has been explored and studied for more than 1000 years, but its western part has long been a blind area for prospecting. Taking the synthetic study of formatiow tectonics-mineralization as the basic way of thinking, the paper is focused on establishing a new teetonolithofacies prospecting model for the western part. With the Gejiu group of middle Trassic series as the sedimentary formational basis, the granitoid complex was developed in the late Cretaceous epoch. In the late stage of the Mesozoic Era, the orefidd underwent largescale magmatic hydrothermal metallogenie processes, probably lasting 70 - 90 Ma （mainly in 80 Ma）, which formed the most important mineralization lithofacies. By the compilation of the tectono-lithofacies map of the orefield, the authors have figured out that the mineralization took place in the compression-extension transforming tectonic regime, and the original metallogenic model in both sides of the Gejiu fault zone should be consistent. The tectono-lithofacies interfaces became favorable spaces for the two major mineralization types, i. e. , the tectono-magmatic-hydrothemal fluid filling and the metasomatic alteration types. The tectonism-stratigraphymagmatism, i. e. tectono-lithofacies metallogenetic model has shown that because of the reformation caused by multi-stage and large scale activation of the Geiiu fault both in vertical and horizontal directions, the western part displayed the significant tectonic features of high upheaval and complicated disturbances. As a result, the mineralization of the western part demonstrates the characteristics of residue, complexity and deep levels. On the basis of above mentioned results combined with geological-geochemical-geophysical information, the prospecting direction and favorable segments for prospecting in the western part can be proposed.