干旱区生态环境知识资源中心(Arid): Multiple Stages of Carbonation and Element Redistribution during Formation of Ultramafic-Hosted Magnesite in Neoproterozoic Ophiolites of the Arabian-Nubian Shield, Egypt

Arid

DOI	10.1086/700652
	Multiple Stages of Carbonation and Element Redistribution during Formation of Ultramafic-Hosted Magnesite in Neoproterozoic Ophiolites of the Arabian-Nubian Shield, Egypt
	Azer, Mokhles K.1; Gahlan, Hisham A.2,3; Asimow, Paul D.4; Mubarak, Heba S.1; Al-Kahtany, Khaled M.2
通讯作者	Azer, Mokhles K.
来源期刊	JOURNAL OF GEOLOGY
ISSN	0022-1376
EISSN	1537-5269
出版年	2019
卷号	127 期号:1 页码:81-107
英文摘要	We present a study of the serpentinized peridotites of the Ghadir-Mohagar-Ambaut area, Egypt. They represent the mantle section of a dismembered ophiolite, tectonically emplaced over a volcanosedimentary succession of island arc assemblages. The serpentinites are variably metamorphosed from greenschist to lower-amphibolite facies, metasomatized, and altered, including development of talc-carbonate and quartz-carbonate rocks, especially along shear zones and fault planes. Nevertheless, some samples contain relics of primary chromian spinel, olivine, and pyroxenes. Relict textures and whole-rock compositions (Mg#[molar Mg/(Mg+Fe2+)]=0.92-0.93, with low Al2O3 and CaO contents) both suggest harzburgite protoliths. The high Mg# and Ni contents of relict olivine and the high Cr# (molar Cr/(Cr+Al)) of fresh chromian spinel cores indicate that the protoliths experienced high degrees of partial melt extraction (similar to 34%-39%), well beyond the limit for exhaustion of clinopyroxene from the residue and consistent with formation in a forearc suprasubduction zone environment. The serpentinized ultramafic rocks in the study area are divided into massive serpentinite, serpentinite-hosted magnesite masses, and magnesite-filled veins. The carbonation and formation of magnesite ores took place through two metasomatic stages; the first is represented by the magnesite masses and associated with deep-seated metasomatism and alteration during serpentinization, whereas the second, vein-forming stage postdates serpentinization and occurred during obduction of the ophiolite. The differences in chemical composition between massive serpentinite and serpentinite-hosted magnesite masses suggest leaching of some elements and enrichment of others during carbonation; MgO, Cr, and Ni are depleted, whereas Fe2O3, CaO, MnO, Nb, Ba, Cu, Pb, Sr, and Zn are enriched in the serpentinite-hosted magnesite masses, relative to the host massive serpentinite.
类型	Article
语种	英语
国家	Egypt ; Saudi Arabia ; USA
开放获取类型	Green Accepted
收录类别	SCI-E
WOS记录号	WOS:000454585300005
WOS关键词	CENTRAL EASTERN DESERT ; MARIANA FORE-ARC ; PODIFORM CHROMITITES ; CHROMIAN SPINEL ; CR-SPINEL ; PETROLOGICAL CHARACTERISTICS ; TECTONOMAGMATIC EVOLUTION ; CHEMICAL CHARACTERISTICS ; PERIDOTITE XENOLITHS ; CRUSTAL EVOLUTION
WOS类目	Geology
WOS研究方向	Geology
来源机构	King Saud University
资源类型	期刊论文
条目标识符	http://119.78.100.177/qdio/handle/2XILL650/217054
作者单位	1.Natl Res Ctr, Dept Geol Sci, Cairo, Egypt; 2.King Saud Univ, Dept Geol & Geophys, Riyadh 11451, Saudi Arabia; 3.Assiut Univ, Dept Geol, Assiut 71516, Egypt; 4.CALTECH, Div Geol & Planetary Sci, Pasadena, CA 91125 USA
推荐引用方式 GB/T 7714	Azer, Mokhles K.,Gahlan, Hisham A.,Asimow, Paul D.,et al. Multiple Stages of Carbonation and Element Redistribution during Formation of Ultramafic-Hosted Magnesite in Neoproterozoic Ophiolites of the Arabian-Nubian Shield, Egypt[J]. King Saud University,2019,127(1):81-107.
APA	Azer, Mokhles K.,Gahlan, Hisham A.,Asimow, Paul D.,Mubarak, Heba S.,&Al-Kahtany, Khaled M..(2019).Multiple Stages of Carbonation and Element Redistribution during Formation of Ultramafic-Hosted Magnesite in Neoproterozoic Ophiolites of the Arabian-Nubian Shield, Egypt.JOURNAL OF GEOLOGY,127(1),81-107.
MLA	Azer, Mokhles K.,et al."Multiple Stages of Carbonation and Element Redistribution during Formation of Ultramafic-Hosted Magnesite in Neoproterozoic Ophiolites of the Arabian-Nubian Shield, Egypt".JOURNAL OF GEOLOGY 127.1(2019):81-107.