Ca-Enrichment Characteristics of Parental Magmas of Chromitite in Ophiolite:Inference from Mineral Inclusions
Liu Xia
Su Benxun
Bai Yang
Chen Chen
Xiao Yan
Liang Zi
Yang Saihong
Peng Qingshan
Su Bencan
Liu Bin
Abstract：The origin and mechanisms involved in the formation of chromitite deposit in ophiolites remain a controversial subject of continuous debate.One of the important ways to address this issue is to investigate the nature and composition of parental magmas of chromitite,which may be revealed by mineral inclusions in chromite interpreted to have crystallized contemporane-ously with or earlier than the host chromite.Various types of inclusions have been found in chromite ores with different tex-tures in the Pozant1-Karsant1ophiolite in Turkey,which include(1)anhydrous silicate type such as olivine and clinopyroxene, (2)hydrous silicate type such as amphibole and phlogopite,(3)composite type such as the association of serpentine,wollas-tonite and clinopyroxene,(4)and uncommon mineral type such as apatite and platinum group element sulfide.The occurrence of hydrous mineral and the high Mg# of some minerals(e.g.,olivine Mg#= 95.4—97.1,clinopyroxene Mg#= 92.0—99.0, amphibole Mg#= 88.9—99.8)suggest that parental magmas of the chromite are rich in Mg and water contents.Besides the in-clusions of apatite and uvarovite,it is reported,for the first time,that calcite and wollastonite inclusions in chromite,which, together with high-CaO features in silicate minerals,indicate Ca-enrichment.The elevated Ca contents in melts are favorable in stabilizing Cr3+in silicate melt,while crystallization of Ca-bearing minerals could result in Cr enrichment in the melts.The Ca-rich component was probably derived from Ca-enriched rocks in subducting slab.
Keywords：ophiolitechromiteinclusionparental magmamineralogypetrology
Publication Date：2018-01-01
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：13( 1038-1050 )