地学前缘 ›› 2011, Vol. 18 ›› Issue (5): 147-158.

• 论文 • 上一篇    下一篇

青海德合龙洼铜（金）矿流体包裹体特征及成矿作用分析

曹勇华，赖健清，康亚龙，樊俊昌   

  1. 1. 中南大学 有色金属成矿预测教育部重点实验室； 地球科学与信息物理学院， 湖南 长沙410083
    2. 青海西部矿业地质勘查有限公司， 青海 西宁810016
  • 收稿日期:2011-08-09 修回日期:2011-09-10 出版日期:2011-09-18 发布日期:2011-09-18
  • 作者简介:曹勇华（1987—），男，博士研究生，矿产普查与勘探专业。E-mail：cyh0422@yahoo.cn
  • 基金资助:

    国家“十一五”科技支撑计划重大项目“柴达木南北缘铜铅锌矿成矿规律及大型资源基地评价技术示范研究”课题（2006BAA01B06）

Characteristics of fluid inclusions and mineralization of the Dehelongwa copper（gold） deposit, Qinghai Province.

  1. 1. Key Laboratory of Metallogenic Prediction of Nonferrous Metals, Ministry of Education；School of Geosciences and InfoPhysics, Central South University, Changsha 410083, China
    2. Qinghai Ltd. of Western Mining Geological Prospecting and Survey， Xining 810016， China
  • Received:2011-08-09 Revised:2011-09-10 Online:2011-09-18 Published:2011-09-18

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摘要：

德合龙洼铜（金）矿床为青藏高原北东端的一个岩浆热液型矿床。研究发现矿石中石英发育富液相水溶液（Ⅰ型）、富气相水溶液（Ⅱ型）和含子矿物水溶液（Ⅲ型）3种类型的流体包裹体。Ⅰ型包裹体呈均一至液相，均一温度为187～413 ℃，盐度值（NaClequiv.，质量分数）则为2.0%～19.0%。Ⅱ型包裹体呈均一至气相，均一温度为350～413 ℃，盐度值为5.3%～9.8%。Ⅲ型包裹体根据升温过程中子矿物先于或晚于气泡消失的情况，可进一步分为Ⅲa（子矿物先消失）、Ⅲb（气泡先消失）两亚类：其中Ⅲa类包裹体子矿物熔化温度为192～491 ℃，均一温度为276～520 ℃，盐度值在31.5%～57.1%;Ⅲb类包裹体子矿物熔化温度为250～500 ℃，气液均一温度为195～325 ℃，盐度值则为33.0%～59.8%。分析认为矿区存在3种不同性质的成矿流体：强超压的高盐度岩浆热液流体A、中高盐度沸腾流体B和中低盐度混合流体C。3种流体均为岩浆期后残余原始流体不同阶段演化的产物。依据沸腾流体B停止沸腾温度上限350 ℃计算的成矿压力值为160 bar（1 bar=105Pa），推断德合龙洼铜（金）矿成矿作用的深度为1.6 km，为中深环境。根据以上研究推断岩浆出溶形成高盐度流体迁移了大量成矿物质，其中铜在流体中主要以CuCl2(aq)、CuCl-等氯络合物形式存在和迁移，而金主要以硫砷络合物形式迁移。由于后期流体的不断演化，包括沸腾作用、流体混合及盐度、温度以及压力的不断降低，导致成矿元素Cu、Au沉淀。

关键词: 流体包裹体, 成矿流体, 铜金矿, 德合龙洼

Abstract:

The Dehelongwa copper (gold) deposit, located in the northeast part of QinghaiTibet Plateau, is a magmatic hydrothermal deposit. Three types of inclusions hosted in quartz are found in the orebodies, i.e., liquidrich twophased aqueous inclusions (type Ⅰ), vaporrich aqueous inclusions (type Ⅱ), and aqueous inclusions with daughter mineral(s) (type Ⅲ). Inclusions of type Ⅰ homogenize to liquid at temperatures of 187413 ℃ and have salinities from 2.0% to 19.0% (NaClequiv.). Inclusions of type Ⅱ homogenize to vapor at temperatures from 350 ℃ to 413 ℃ and the salinities are 5.3% to 9.8% (NaClequiv.). Inclusions of type Ⅲ can be further classified into two subtypes (Ⅲa,Ⅲb) depending on dissolution of daughter minerals before or after the disappearance of the gas bubbles during the heating processes. Inclusions of subtype Ⅲa have liquidvapor homogenization temperatures of 276 ℃ to 520 ℃，with daughter minerals melting temperatures from 192 ℃ to 491 ℃ and corresponding salinities from 31.5% to 57.1% NaClequiv.. Inclusions of subtype Ⅲb have homogenization temperatures (daughter minerals melting temperatures) from 250 ℃ to 500 ℃, with corresponding salinities from 33.0% to 59.8% (NaClequiv.), and liquidvapor homogenization temperatures of 195325 ℃. Based on the fluid inclusion data, three types of oreforming fluids are deduced, they are strongly overpressured and high salinity magmatic hydrothermal fluid A, mediumhigh salinity boiling hydrothermal fluid B, and lowmedium salinity fluid C. These fluids were all originated from different evolutional stages of the primitive fluids derived from the magmatic intrusion. Based on the highest boiling ceasing temperature of fluid B (350 ℃) and calculated pressure (160 bar), the mineralization depth is interpreted to be 1.6 km. It is suggested that oreforming elements were transported by high salinity magmatic fluids, with Cu mainly as chlorocomplex such as CuCl2(aq) and CuCl- and Au mainly as sulfurarsenic complex. The oreforming components were precipitated due to boiling and fluid mixing as well as the decrease in salinity, temperature, and pressure of the fluids.

Key words: fluid inclusion, oreforming fluid, coppergold deposit, Dehelongwa

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