| 朱金初,王新光,殷成玉.个旧锡矿区不同岩石中锡的富集特征及成矿模式[J].地质找矿论丛,1991,(2):11-17 |
| 个旧锡矿区不同岩石中锡的富集特征及成矿模式 |
| EXISTING FORMS OF TIN IN DIFFERENT ROCKS AND METALLOGENETIC MODEL OF GEJIU TIN FIELD |
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| DOI：10.6053/j.issn.1001-1412.1991.2. 002 |
| 中文关键词: 锡含量 锡的赋存形式 成矿模式 个旧锡矿 |
| 英文关键词: |
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| 中文摘要: |
| 花岗岩及其造岩矿物以及副矿物中锡含量及其赋存形式的研究表明,个旧花岗岩中的锡主要赋存于黑云母等造岩矿物中。对个旧马松岩体的分析还表明,除造岩矿物外,尚有一部分锡赋存于榍石等副矿物中。黑云母和矽卡岩中锡主要呈类质同象置换形式存在,因而很容易受后期交代作用的影响而释放出来,参与成矿。基于此,可以得出本区锡矿的成矿模式:来自花岗岩浆的演化热液,通过交代蚀变作用摄取了花岗岩中主要赋存于造岩矿物中的锡,在运移过程中又使早期矽卡岩矿物如钙铁榴石等发生分解,汲取部分锡,最终在外接触带以及地层中有利的地质构造环境下,沉淀出有价值的工业矿体。 |
| 英文摘要: |
| It can be seen from this study that tin in Gejiu granites is mainly concentrated in rock-forming minerals, especially in biotite, in which tin occurs chiefly as isomorphic replacement of Fe3+, Ti4+ by the substitution:Sn4+→Fe3++Li+ and Sn4+→Ti4+.Large quantity of tin may be brought into ore-forming solution when biotite decomposes (e.g.muscovitization of biotite).As for the Mashong granite, tin may partly exist in accessory minerals such as sphene by the substitution:Sn4+→Ti4+.Tin in this form cannot be easily remobilized for sphene is comparatively stable.Some early skarn minerals such as andradite have high tin contents (mostly higher than 450ppm).Mossbauer spectroscopy study shows that tin in andradite occurs as isomorphic substitution:Sn4++Fe2+→2Fe3+.By contrast, later skarn minerals, which are the products of replacement of earlier ones, have low tin contents (from 14 to 75ppm, much lower than the early skarn minerals).This indicates that the tin in early skarn min-erals can be remobilized into the ore-forming solution when they are replaced by the late hydroxyl skarn minerals.Based on these materials, a metallogenetic model of Gejiu tin field can be set up as follows:tin-bearing ore-forming solution derived from granite magama leaches quantity of tin from biotite and other rock-forming minerals by replacement of hydrothermal alteration.This tin-enriched solution can collect more tin when it replaces the early tin-bearing skarn minerals in contact zone, thus concentrating tin in the solution.During the mineralization period, cassiterites can be deposited from the solution in the outer contact zone and certain favorable localities of the stratigraphic sequences. |
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