干旱区生态环境知识资源中心(Arid): Petrology of a Neoproterozoic mantle peridotite-chromitite association from Abu Dahr area, Eastern Desert, Egypt: Infiltration of a boninitic melt in highly depleted harzburgite

Arid

DOI	10.1016/j.jafrearsci.2020.103816
	Petrology of a Neoproterozoic mantle peridotite-chromitite association from Abu Dahr area, Eastern Desert, Egypt: Infiltration of a boninitic melt in highly depleted harzburgite
	Halim, Ali H. Abdel 1; Helmy, Hassan M.1; Elhaddad, Mervet A.2; El-Mahallawi, Mahmoud M.1; Mogessie, Aberra 3
通讯作者	Halim, Ali H. Abdel
来源期刊	JOURNAL OF AFRICAN EARTH SCIENCES
ISSN	1464-343X
EISSN	1879-1956
出版年	2020
卷号	165
英文摘要	Peridotites of Abu Dahr represent the main litho-unit of a Neoproterozoic dismembered ophiolite sequence and are among the best-preserved and well-exposed mantle rocks in South Eastern Desert of Egypt. Here, we present new geochemical and mineral chemical data for peridotites and associated pyroxenites and for chromitites and their platinum-group minerals to constrain their petrogenesis and geotectonic setting. The Abu Dahr ophiolite mantle section consists mainly of harzburgites, cut by pyroxenite dykes and containing dunite-chromitite lenses. The harzburgites are composed of olivine, orthopyroxene, spinel and minor clinopyroxene (<1.0 vol %) and amphibole. Olivine from harzburgites is highly magnesian (Fo 91-93) and Cr-spinel shows a wide-range of Cr2O3 and Al2O3 contents. The enstatite component of orthopyroxene decreases from harzburgite (En = 90-91) to orthopyroxenite (En = 84-87). Amphiboles are represented by magnesiohornblende and tschermakite. The chromitites are massive to disseminated and composed of magnesiochromite with high Cr# (83-93) and Mg# (66-79), and low TiO2 ( < 0.1 wt%) content. Solid inclusions in chromite include olivine, orthopyroxene and hornblende. Laurite (RuS2) is the most common PGM detected in the investigated chromitite samples and forms micrometer-size inclusions in fresh chromite. Various Ni-sulfides are found both in fresh chromite and along serpentine veinlets. Harzburgites have a refractory composition with a very low Al2O3 (0.4-0.8 wt%) and CaO (0.2-1.6 wt%) contents and high bulk-rock Mg# (89-92). Geochemical data suggest that the Abu Dahr peridotites are highly depleted SSZ peridotites formed in a forearc mantle wedge setting by high degrees of hydrous partial melting and emplaced as a result of the collision of the intra-oceanic arc with the Beitan gneisses. The podiform chromitites and orthopyroxenites were formed due to impregnation of mantle wedge harzburgites by boninitic melt. The highly depleted nature of the harzburgite is responsible for the small reserves of chromite ore at Abu Dahr and in the South Eastern Desert in general.
英文关键词	Abu Dahr ophiolite SSZ peridotites Orthopyroxenite Chromitite Forearc mantle wedge Boninitic melt
类型	Article
语种	英语
国家	Egypt ; Austria
收录类别	SCI-E
WOS记录号	WOS:000526109900016
WOS关键词	HIGH-CR CHROMITITES ; SUBDUCTION ZONE ; SUPRA-SUBDUCTION ; TRACE-ELEMENT ; PODIFORM CHROMITITES ; ABYSSAL PERIDOTITES ; CHEMICAL VARIATIONS ; ULTRAMAFIC COMPLEX ; ROCK INTERACTION ; OPHIOLITE
WOS类目	Geosciences, Multidisciplinary
WOS研究方向	Geology
资源类型	期刊论文
条目标识符	http://119.78.100.177/qdio/handle/2XILL650/314848
作者单位	1.Menia Univ, Fac Sci, Dept Geol, Al Minya 61519, Egypt; 2.Assiut Univ, Fac Sci, Dept Geol, Assiut 71515, Egypt; 3.Karl Franzens Univ Graz, Inst Earth Sci, A-8010 Graz, Austria
推荐引用方式 GB/T 7714	Halim, Ali H. Abdel,Helmy, Hassan M.,Elhaddad, Mervet A.,et al. Petrology of a Neoproterozoic mantle peridotite-chromitite association from Abu Dahr area, Eastern Desert, Egypt: Infiltration of a boninitic melt in highly depleted harzburgite[J],2020,165.
APA	Halim, Ali H. Abdel,Helmy, Hassan M.,Elhaddad, Mervet A.,El-Mahallawi, Mahmoud M.,&Mogessie, Aberra.(2020).Petrology of a Neoproterozoic mantle peridotite-chromitite association from Abu Dahr area, Eastern Desert, Egypt: Infiltration of a boninitic melt in highly depleted harzburgite.JOURNAL OF AFRICAN EARTH SCIENCES,165.
MLA	Halim, Ali H. Abdel,et al."Petrology of a Neoproterozoic mantle peridotite-chromitite association from Abu Dahr area, Eastern Desert, Egypt: Infiltration of a boninitic melt in highly depleted harzburgite".JOURNAL OF AFRICAN EARTH SCIENCES 165(2020).