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The role of fluid-induced partial melting in magmatic crystal mush in the origin of stratiform chromite deposits of the Bushveld Complex, South Africa

流体引起的部分熔融在南非布什维尔德杂岩层状铬铁矿矿床成因中岩浆晶体糊中的作用

基本信息

批准号：
391702990
负责人：
Dr. Ilya Veksler, Ph.D.
金额：
--
依托单位：
Department of Earth Sciences
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2018
资助国家：
德国
起止时间：
2017-12-31 至 2021-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/391702990?language=en
关键词：
role fluid induced partial melting

项目摘要

This project aims at addressing unresolved key questions about the origin of layers chiefly composed of Cr-spinel in mafic-ultramafic layered rocks of the Bushveld intrusive complex in South Africa. In terms of economic geology, the layers are synonymous with stratiform chromite deposits and constitute the greatest world reserve of metallurgical chromium and platinum-group elements. The project aims at testing a working hypothesis that chromitite layers of the Bushveld Complex formed in situ by partial melting and replacement reactions at the floor of the magma chamber. Partial melting and replacement of silicate minerals by chromite at the top of the earlier formed crystal mush is proposed to be triggered by additions of volatile components to the resident mama. It is assumed in the working hypothesis that the volatiles were introduced by crustal fluids generated by dehydration of Transvaal sediments below the Bushveld magma chamber. The research program is a combination of petrographic, geochemical, experimental and structural studies. It includes experimental study of the effects of H2O on the crystallisation of the Bushveld parental magma; experimental modelling of replacement reactions involving Cr-spinel; documentation of disturbances and subsequent chemical and textural equilibration in natural rock samples of the chromite layers and silicate rocks immediately below and above them. Special attention in the study of natural samples will be given to equilibration temperature estimations based on trace elements and oxygen isotope distribution between minerals.

本项目旨在解决有关南非Bushveld侵入杂岩中镁铁质-超镁铁质层状岩石中主要由铬尖晶石组成的地层起源的未解决的关键问题。在经济地质学方面，这些层是层状铬铁矿矿床的代名词，构成了世界上最大的冶金铬和铂族元素储量。该项目的目的是测试一个可行的假设，即布什维尔德复合体的铬铁矿层是由岩浆库底部的部分熔化和置换反应在原地形成的。在早期形成的晶体糊状顶部，铬铁矿的部分熔融和硅酸盐矿物的替代被认为是由挥发性组分的添加引起的。在工作假设中假定挥发物是由Bushveld岩浆库下面的德兰士瓦沉积物脱水产生的地壳流体引入的。该研究项目是岩石学、地球化学、实验和构造研究的结合。它包括H2O对Bushveld母岩浆结晶影响的实验研究；cr尖晶石置换反应的实验模拟；铬铁矿层和硅酸盐层的天然岩石样品的扰动和随后的化学和结构平衡的记录。在自然样品的研究中将特别注意基于微量元素和矿物间氧同位素分布的平衡温度估计。

项目成果

期刊论文数量（6）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Chemical and Textural Re-equilibration in the UG2 Chromitite Layer of the Bushveld Complex, South Africa

南非 Bushveld 杂岩体 UG2 铬铁矿层的化学和结构再平衡

DOI：
10.1093/petrology/egy058
发表时间：
2018
期刊：
Journal of Petrology
影响因子：
3.9
作者：
Veksler I.V;Sedunova A.P;Darin A.V;Anosova M.O;Reid D.L;Kaufmann F;Hecht L;Trumbull R.B.
通讯作者：
Trumbull R.B.

Experimental study on the effects of H2O upon crystallization in the Lower and Critical Zones of the Bushveld Complex with an emphasis on chromitite formation

H2O 对 Bushveld 杂岩下区和临界区结晶影响的实验研究，重点是铬铁矿的形成