秦岭造山带柞水-山阳矿集区斑岩型铜矿成矿规律及找矿方向分析

柞水-山阳矿集区为秦岭造山带内一晚古生代构造-裂陷沉降带和热水沉积盆地,是秦岭造山带内重要的矿集区之一。盆地内燕山期中酸性小岩体较为发育,且围绕小岩体的铜矿化作用较强。以往的找矿工作中,由于找矿思路等方面的束缚,对区内小岩体的深入工作较少。近年来,对区内一些小岩体的野外地质特征、成矿特点等方面进行了勘查、评价工作,取得了突破性进展,在池沟地区和冷水沟地区均发现了厚大铜矿体,矿体多赋存于斑岩体与围岩的接触带附近,蚀变强烈,主要发育钾硅酸盐化、青磐岩化、绢英岩化,其中钾硅酸盐化与青磐岩化叠加部位铜矿化尤为强烈,具有典型的斑岩型矿化特征,认为区内铜矿化作用与燕山期小岩体关系密切。本文在分析区内现有斑岩型铜矿床成矿地质特征及找矿潜力的基础上,总结成矿规律,提出找矿方向,认为围绕燕山期斑岩体寻找斑岩型铜矿可作为本区寻找铜矿的一个突破口。

Metallogenic regularities of porphyry copper deposits and prospecting direction in the Zhashui-Shanyang ore concentration area, Qin Ling orogenic belt

The Zhashui-Shanyang ore concentrating area in the Qin Ling orogenic belt is a hydrothermal sedimentary basin in a late-Paleozoic rifting subsidence zone. Within this basin, there are a mass of Yanshanian small-sized intermediate-acid rock bodies, which are surrounded by strong copper mineralization. Previous prospecting work conducted few studies on these small rock bodies due to the limitation of prospecting concepts and others. In recent years, exploration and evaluation work on geological features and metallogenic characteristics of some small rock bodies in this area have made great progress, and have discovered big copper ore bodies in the Chigou and Lengshuigou areas. These ore bodies mainly occur in the contact zone between porphyry and surrounding rocks with strong alteration that led to transform into potassium silicate, propylite and sericite. The copper mineralization is particularly intense in the superposition area of potassium silicate alteration and propylitization, which is a typical characteristic of the porphyry type mineralization. This work suggests that the copper mineralization in this area is closely related with the Yanshanian small rock bodies. Based on the analysis of the geological characteristics and prospecting potential, this paper summarizes the metallogenic regularities of the porphyry copper orebodies, puts forward the prospecting direction, and considers that the Yanshanian porphyries as a potential breakthrough in efforts of searching for porphyry copper deposits in this region.