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| 安徽铜陵新桥Cu-Au-S矿床黄铁矿微量元素LA-ICP-MS原位测定及其对矿床成因的制约 | |
| 引用本文： | 周涛发,张乐骏,袁峰,范裕,David R.Cooke.安徽铜陵新桥Cu-Au-S矿床黄铁矿微量元素LA-ICP-MS原位测定及其对矿床成因的制约[J].地学前缘,2010,17(2):306. |
| 作者姓名： | 周涛发 张乐骏 袁峰 范裕 David R.Cooke |
| 作者单位： | 1. 合肥工业大学,资源与环境工程学院,安徽,合肥,230009;Centre of Excellence in Ore Deposits, University of Tasmania, Private Bag 79, Hobart, Tasmania 7001, Australia 2. 合肥工业大学,资源与环境工程学院,安徽,合肥,230009 3. Centre of Excellence in Ore Deposits, University of Tasmania, Private Bag 79, Hobart, Tasmania 7001, Australia |
| 基金项目： | 国家自然科学基金，科技部科研项目，新世纪优秀人才支持计划，澳大利亚塔斯马尼亚大学国家优秀矿床研究中心科研基金，安徽省优秀青年科技基金 |
| 摘 要： | 激光剥蚀电感耦合等离子体质谱(LA-ICP-MS)是一种固体微区分析新技术。用该技术来分析矿床中硫化物的微量元素组成可以为研究成矿流体特征、矿床成因及找矿勘探提供有关的科学信息。文中以安徽铜陵矿集区内新桥Cu-Au-S矿床中的黄铁矿为研究对象,在详细的野外观察和室内鉴定的基础上,将矿床中的黄铁矿分为具有沉积特征的胶状黄铁矿(PyⅠ)、具有变形重结晶和热液叠加作用特征的细粒他形黄铁矿(PyⅡ)和具热液成因特征的中—粗粒自形黄铁矿(PyⅢ)3种类型。LA-ICP-MS原位微量元素测定结果显示,PyⅠ中相对富含Ti、Co、Ni、As、Se、Te;PyⅡ继承了PyⅠ中富含Ti、Co、Ni、As、Se、Te、Bi的特征,同时还含有不均匀分布的少量成矿元素(Cu、Pb、Zn、Au、Ag);PyⅢ中成矿元素Cu、Pb、Zn、Ag、Au以及Bi元素的含量较高,Co、Ni、As的含量较低。在元素赋存状态方面,Co、Ni、As、Se和Te均以类质同象的形式进入到了黄铁矿的晶格中;Bi在PyⅡ中主要以含Bi矿物的微细包裹体形式存在,而在PyⅢ中的Bi还部分取代了Fe而占据了晶格;Cu、Pb、Zn、Au、Ag这些成矿元素中,Cu和Zn分别以黄铜矿和闪锌矿的矿物包裹体存在于黄铁矿中;PyⅡ中所含的少量Au、Ag,可能分别以自然金和自然银的形式存在,而在PyⅢ中Au可能主要以银金矿的形式存在,Ag除了以银金矿的形式存在以外还可能赋存于黄铁矿中含铋的矿物包裹体内;Pb主要赋存于黄铁矿中的方铅矿或含铋矿物的包裹体中。在综合分析黄铁矿的结构形态和微量元素组成特征的基础上认为,PyⅠ型黄铁矿可能形成于前人提出的晚古生代海底沉积或喷流沉积环境,PyⅡ和PyⅢ型黄铁矿分别形成于中生代区域构造变形-热液叠加改造的过渡环境和热液环境,PyⅡ和PyⅢ的形成时间相近。新桥矿床的形成可能经历了晚古生代海底沉积或喷流沉积期和燕山期热液期,胶黄铁矿主要形成于沉积成矿期,而矿床中成矿物质Cu、Pb、Zn、Au、Ag等主要来自燕山期岩浆侵入作用形成的热液成矿系统。 |
| 关 键 词： | LA-ICP-MS 黄铁矿 微量元素 新桥 铜陵 |
LA-ICP-MS in situ trace element analysis of pyrite from the Xinqiao Cu-Au-S Deposit in Tongling, Anhui, and its constraints on the ore genesis |
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| Zhou Taofa,Zhang Lejun,Yuan Feng,Fan Yu,David R.Cooke.LA-ICP-MS in situ trace element analysis of pyrite from the Xinqiao Cu-Au-S Deposit in Tongling, Anhui, and its constraints on the ore genesis[J].Earth Science Frontiers,2010,17(2):306. | |
| Authors: | Zhou Taofa Zhang Lejun Yuan Feng Fan Yu David RCooke |
| Abstract: | As a newly-developed micro-analytic technique, Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) of sulfide minerals can provide us important informations regarding the nature of ore-forming fluids, ore genesis and their implications on mineral exploration. Pyrites from Xinqiao Cu-Au-S deposit in the Tongling mineralization belt, Anhui Province, China, have been selected for detailed study in this paper. Three types of pyrite were recognized through detailed field work and paragenetic studies, among which the earliest colloform pyrite, termed PyI, is interpreted as sedimentary in origin, whereas PyII is mainly composed of fine grained, anhedral crystals with some characteristics of deformation and recrystallization. Medium-coarse grained and euhedral PyIII is inferred to be the result of hydrothermal activities and associated with mineralization. The LA-ICP-MS analyses of three types of pyrite indicate that the sedimentary PyI contains the highest values of Ti, Co, Ni, As, Se, Te. PyII pyrite also is rich in Ti, Co, Ni, As, Se, Te,with variable content of ore-forming elements such as Cu, Pb, Zn, Au and Ag. PyIII shows distinguished composition compared to other two types of pyrite. Cu, Pb, Zn, Au, Ag and Bi give much higher ranges in PyIII but Co, Ni and As are relatively lower. Evidences show that Co, Ni, As, Se and Te are contained in pyrite as isomorphous solid solution. Bi occurs as Bi-containing minerals which are commonly small inclusions in PyII pyrite, however, in PyIII, Bi partially replaced Fe in lattice. The ore-forming elements, e.g. Cu, Pb, Zn, Au and Ag in Xinqiao deposit mainly occurred in PyIII. Cu and Zn are mainly represented by chalcopyrite and sphalerite inclusions enclosed in pyrite. Au and Ag in PyII, albeit with low content, probably occur as inclusions of free-gold and free-silver. However, in PyIII, electrum is the major mineral containing Au and Ag, which is also possibly in bismuth minerals. Pb occurs in both galena and bismuth minerals inclusions in pyrite. Textures, paragenesis and trace element geochemistry of pyrite indicate that PyI was formed in the process of the Late Paleozoic submarine-exhalative sedimentation, which was supported by other studies, whereas PyII and PyIII pyrite may occur during the Mesozoic tectonic transition-deformation and subsequent hydrothermal superimposition, respectively. Therefore, the formation of Xinqiao Cu-Au-S deposit may have recorded both the late Paleozoic submarine or exhalation sedimentation and hydrothermal telescoping in the Mesozoic. Colloform pyrite with rare Cu and Au mineralization deposited during sedimentation, while most of economic metals, e.g., Cu, Pb, Zn, Au and Ag, were introduced through hydrothermal fluids during emplacement of the Yanshanian dioritic intrusions. |
| Keywords: | LA-ICP-MS LA-ICP-MS pyrite trace element Xinqiao Tongling |
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