Arid
DOI10.1111/j.1440-1738.2009.00689.x
Neoproterozoic podiform chromitites in serpentinites of the Abu Meriewa-Hagar Dungash district, Eastern Desert, Egypt: Geotectonic implications and metamorphism
El Ela, Fawzy F. Abu2; Farahat, Esam S.1
通讯作者Farahat, Esam S.
来源期刊ISLAND ARC
ISSN1038-4871
EISSN1440-1738
出版年2010
卷号19期号:1页码:151-164
英文摘要

Podiform chromitites hosted in serpentinites (after harzburgite and dunite) and talc-carbonate rocks from the Abu Meriewa-Hagar Dungash district (MHD), Eastern Desert of Egypt, together with metagabbros, pillow metavolcanics, and metasediments, form an ophiolitic melange formed during the Neoproterozoic Pan-African Orogeny. The chromitites show massive, disseminated, and nodular textures. Chromite cores in chromitites have high and restricted ranges of Cr# (0.65-0.75) and Mg# (0.64-0.83), implying primary compositions not affected by metamorphism. Therefore, they are used as reliable indicators of parent magma composition and tectonic affinities of these highly metamorphosed rocks. On the contrary, the altered rims are high-Cr, low-Fe3+ spinel (rather than ferritchromit) enriched in Cr, Fe, and Mn, and depleted in Al and Mg (Cr# = 0.75-0.97, Mg# = 0.29-0.79), due to equilibration with interstitial silicates during regional metamorphism up to transitional greenschist-amphibolite facies at about 500-550 degrees C. The primary chromite compositions suggest derivation from a high-Mg tholeiitic, to possibly boninitic, parental magma in a supra-subduction zone (arc-marginal basin) environment, similar to the spatially associated metavolcanic rocks. The MHD chromitites are most probably formed by melt-rock interaction mechanisms. The high Cr# of the investigated chromites suggests high degrees of partial melting of a depleted harzburgite source by interaction with primitive basaltic melt of deeper origin followed by mixing. Such Cr-rich chromites are common in chromitites from the Eastern Desert of Egypt, implying broad thermal anomalies, possibly linked to an important geodynamic feature of the Arabian-Nubian Shield (ANS) evolution. This could revive interest in models that involve asthenospheric uprise, related to plume interaction or most probably due to oblique convergence of arc terranes during early evolution of the ANS.


英文关键词chromitites Egypt Neoproterozoic ophiolites Pan-African serpentinites
类型Article
语种英语
国家Egypt
收录类别SCI-E
WOS记录号WOS:000274907200012
WOS关键词COMPOSITIONAL VARIATION ; PROTEROZOIC-OPHIOLITE ; ULTRAMAFIC COMPLEX ; CRUSTAL EVOLUTION ; CHROMIAN SPINEL ; MANTLE SECTION ; OMAN OPHIOLITE ; CR-SPINEL ; PERIDOTITES ; ORIGIN
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/2XILL650/164744
作者单位1.Menia Univ, Dept Geol, Fac Sci, El Minia 61519, Egypt;
2.Assiut Univ, Fac Sci, Dept Geol, Assiut 71516, Egypt
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GB/T 7714
El Ela, Fawzy F. Abu,Farahat, Esam S.. Neoproterozoic podiform chromitites in serpentinites of the Abu Meriewa-Hagar Dungash district, Eastern Desert, Egypt: Geotectonic implications and metamorphism[J],2010,19(1):151-164.
APA El Ela, Fawzy F. Abu,&Farahat, Esam S..(2010).Neoproterozoic podiform chromitites in serpentinites of the Abu Meriewa-Hagar Dungash district, Eastern Desert, Egypt: Geotectonic implications and metamorphism.ISLAND ARC,19(1),151-164.
MLA El Ela, Fawzy F. Abu,et al."Neoproterozoic podiform chromitites in serpentinites of the Abu Meriewa-Hagar Dungash district, Eastern Desert, Egypt: Geotectonic implications and metamorphism".ISLAND ARC 19.1(2010):151-164.
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