投稿时间：2015-06-27
修订日期：2016-03-14
网络发布日期：2016-08-25
中文摘要:硫同位素示踪是矿床研究的重要手段之一，它在示踪成矿物质来源方面具有极其重要的作用。由于阳山金矿床的载金黄铁矿普遍发育环带结构，显示多期热液活动的特点，而前人研究往往得到整颗粒黄铁矿硫同位素的混和值，因而无法将不同阶段的硫同位素来源区分清楚。本次研究采用纳米二次离子质谱分析技术（Nano-SIMS）对不同阶段的黄铁矿的不同部位进行了原位硫同位素分析。结果表明，斜长花岗斑岩脉中载金黄铁矿的硫同位素分布基本表现为核部高、环带低的特点，其中，黄铁矿核部的δ34S值为0~1.3‰，显示硫来自于深源岩浆，而环带的δ34S值为-4.5‰~-1.3‰，表明成矿过程中的硫主要来源于岩浆硫，同时可能还有部分沉积硫的混入；千枚岩中草莓状黄铁矿和自形黄铁矿核部的δ34S值均较低（平均值分别为-22.2‰和-26.5‰），显示细菌还原海水硫酸盐过程所产生的硫同位素特征，而自形黄铁矿环带的δ34S值为-5.1‰~1.3‰，同样显示硫来源于岩浆硫与一定程度沉积硫的混合。笔者综合研究区内岩浆活动与成矿的关系后认为，岩浆活动与成矿关系密切，岩浆活动的频发不仅为流体运移提供了足够的热源，同时还带来了丰富的成矿物质。
中文关键词:地球化学 Nano-SIMS原位分析 成矿物质 岩浆活动 阳山金矿床
Abstract:Sulfur isotope plays an important role in the study of sulfide deposits in that it always provides useful information for tracing the origin of ore-forming materials. The Au-bearing pyrites in the Yangshan gold deposit exhibit zonal textures, which reflects multiple episodes of hydrothermal activities. However, based on the bulk analyses of pyrites, previous researches fail to identify different sulfur sources during the formation of pyrites, leading to an ambiguous understanding for ore fluids origin. This paper gives in situ sulfur isotopic data based on Nano-SIMS. The results reveal that the distribution of sulfur isotope in plagiogranite porphyry related to ore formation is characterized by high δ34S values of cores relative to rims. Cores of pyrites in plagiogranite porphyry have a magmatic origin with δ34S values ranging from 0 to 1.3‰ and δ34S values of rims varying from -4.5‰ to -1.3‰, suggesting that sulfur in rims is derived from the magma with contamination by sulfur in sedimentary rocks. The sulfur isotopic compositions of framboidal pyrites and cores of euhedral pyrites in phyllites are characterized by high negative values, mainly due to the process of bacteria sulfate reduction (BSR) in ancient sea water. δ34S values of rims in pyrites from phyllite, ranging from -5.1‰ to 1.3‰, are similar to those of granite, which suggests that both of them had the same source of sulfur. Combined with a discussion on the relationship between the magma and mineralization, the authors hold that the regional magmatism contributed greatly to the formation of the Yangshan gold deposit. The magma not only offered enough heat for migration of Au-rich fluid but also provided a lot of ore-forming materials.
文章编号：
中图分类号：P597+.2
文献标志码：
基金项目:本文得到了中国地调局地调科研项目《西南地区主要成矿带铜铁金多金属找矿模式与勘探技术方法综合研究》（项目编号：12120113095500）和国家自然科学基金项目（编号：41273031）的联合资助
引用文本：
赵静,梁金龙,倪师军,向启荣.2016.甘肃阳山金矿载金黄铁矿硫同位素Nano-SIMS原位分析[J].矿床地质,35(4):653~662ZHAO Jing,LIANG JinLong,NI ShiJun,XIANG QiRong.2016.In situ sulfur isotopic composition analysis of Au-bearing pyrites by using Nano-SIMS in Yangshan gold deposit, Gansu Province[J].Mineral Deposits35(4):653~662
图/表
