Element mapping the Merensky Reef of the Bushveld Complex  

作　　者：William Smith Wolfgang Maier Stephen Barnes Gareth Moorhead David Reid Bartosz Karykowski 

机构地区：[1]School of Earth and Ocean Sciences,Cardiff University,Cardiff CF240DE,United Kingdom [2]CSIRO Mineral Resources,Perth 6160,Australia [3]CSIRO,Clayton,Victoria,Australia [4]University of Cape Town,South Africa [5]Fugro Germany Land GmbH,12555 Berlin,Germany

出　　处：《Geoscience Frontiers》2021年第3期259-278,共20页地学前缘（英文版）

摘　　要：The Merensky Reef hosts one of the largest PGE resources globally.It has been exploited for nearly 100 years,yet its origin remains unresolved.In the present study,we characterised eight samples of the reef at four localities in the western Bushveld Complex using micro-X-ray fluorescence and field emission scanning electron microscopy.Our results indicate that the Merensky Reef formed through a range of diverse processes.Textures exhibited by chromite grains at the base of the reef are consistent with supercooling and in situ growth.The local thickening of the Merensky chromitite layers within troughs in the floor rocks is most readily explained by granular flow.Annealing and deformation textures in pyroxenes of the Merensky pegmatoid bear testament to recrystallisation and deformation.The footwall rocks to the reef contain disseminations of PGE rich sulphides as well as olivine grains with peritectic reaction rims along their upper margins suggesting reactive downward flow of silicate and sulphide melts.Olivine-hosted melt inclusions containing Cl-rich apatite,sodic plagioclase,and phlogopite suggest the presence of highly evolved,volatile-rich melts.Pervasive reverse zonation of cumulus plagioclase in the footwall of the reef indicates dissolution or partial melting of plagioclase,possibly triggered by flux of heat,acidic fluids,or hydrous melt.Together,these data suggest that the reef formed through a combination of magmatic,hydrodynamic and hydromagmatic processes.

关 键 词：Merensky Reef Bushveld Complex Magmatic sulphide Platinum-group elements PGE ANORTHOSITE 

分 类 号：P612[天文地球—矿床学]