Platinum-group elements geochemistry of chromite from Kondyor ultramafic intrusion, Siberia: Re-evaluation of factors controlling PGE content of intrusive chromite

IF 3.6 2区地球科学 Q1 GEOCHEMISTRY & GEOPHYSICS

Chemical Geology Pub Date : 2025-05-23 DOI:10.1016/j.chemgeo.2025.122871

Irina A. Zhukova , Aleksandr S. Stepanov , Shao-Yong Jiang , Fedor I. Zhimulev , Dmitry V. Gurevich , Alexander A. Polonyankin , Andrey V. Lavrenchuk , Alexey Kotlyarov

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引用次数: 0

Abstract

Platinum-group elements (PGE) concentrations in chromite could be sensitive to crystallisation conditions and potentially are a useful petrologic and exploration indicator. Chromite from certain volcanic rocks is enriched in PGE, occurring as lattice-hosted forms and microinclusions of platinum group minerals (PGM), whereas chromite from many intrusive complexes has insignificant PGE content. We report new in situ data on PGE concentrations in chromite from platiniferous Kondyor intrusion in Siberia obtained by laser-ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Investigated samples included dunites and chromitites from unmetasomatised and metasomatised domains. Kondyor chromite is enriched in IPGE (iridium-group PGE: 2–51 ppb Ir, 29–147 ppb Ru and 2–23 ppb Os), Rh (36–96 ppb) and has less than detection levels Pt and Pd. Chromite from two petrological domains was compared: relatively unmetasomatised dunite core (Verhniy) and metasomatized dunite (Anomalniy). Chromite from the metasomatic domain is enriched in Fe, Al, Ti, Mn and Zn, relative to dunite core, however, IPGE and Rh content remains similar. The presence of IPGE and Rh in Kondyor chromite shows that IPGE could have significant concentrations in chromite from some intrusions. We discuss various factors affecting PGE content in chromite and conclude that a relatively high cooling rate, high fO₂, the low abundance of sulfides in dunite and chromitites and the low activity of Al in Kondyor rocks, all favored concentration and preservation of IPGE and Rh in chromite. Our results suggest that in some intrusions, chromite could be a significant host for PGE and represent a useful tool for understanding of mafic-ultramafic intrusions and exploration for PGE deposits.

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西伯利亚Kondyor超镁质侵入岩铬铁矿铂族元素地球化学特征：侵入铬铁矿PGE含量控制因素的再评价

铬铁矿中的铂族元素（PGE）浓度对结晶条件敏感，可能是一个有用的岩石学和勘探指标。来自某些火山岩的铬铁矿富含铂族矿物（PGM），以晶格形式和微包裹体的形式存在，而来自许多侵入杂岩体的铬铁矿的PGE含量不高。本文报道了用激光烧蚀电感耦合等离子体质谱法（LA-ICP-MS）原位测定西伯利亚含铂的Kondyor岩体中铬铁矿中PGE浓度的新数据。所调查的样品包括来自未交代和交代区域的铁榴石和铁榴石。Kondyor铬铁矿富含IPGE（铱族PGE: Ir 2-51 ppb， Ru 29-147 ppb, Os 2-23 ppb）， Rh (36-96 ppb)， Pt和Pd低于检测水平。比较了两个岩石学域的铬铁矿：相对未交代的泥质岩心（Verhniy）和交代的泥质岩心（anomaly）。交代域铬铁矿相对于泥质岩心富集Fe、Al、Ti、Mn和Zn，而IPGE和Rh含量基本一致。在Kondyor铬铁矿中IPGE和Rh的存在表明，IPGE在某些侵入体的铬铁矿中可能具有显著的浓度。分析了影响铬铁矿中PGE含量的各种因素，认为较高的冷却速率、较高的fO2、低丰度的硫化物以及低活度的Al在Kondyor岩石中有利于IPGE和Rh在铬铁矿中的富集和保存。我们的研究结果表明，在某些侵入岩中，铬铁矿可能是PGE的重要寄主，是了解基性-超基性侵入岩和寻找PGE矿床的有用工具。

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来源期刊

Chemical Geology 地学-地球化学与地球物理

CiteScore

7.20

自引率

10.30%

发文量

374

审稿时长

3.6 months

期刊介绍： Chemical Geology is an international journal that publishes original research papers on isotopic and elemental geochemistry, geochronology and cosmochemistry. The Journal focuses on chemical processes in igneous, metamorphic, and sedimentary petrology, low- and high-temperature aqueous solutions, biogeochemistry, the environment and cosmochemistry. Papers that are field, experimentally, or computationally based are appropriate if they are of broad international interest. The Journal generally does not publish papers that are primarily of regional or local interest, or which are primarily focused on remediation and applied geochemistry. The Journal also welcomes innovative papers dealing with significant analytical advances that are of wide interest in the community and extend significantly beyond the scope of what would be included in the methods section of a standard research paper.