Arid
DOI10.1007/s001260050287
Petrological characteristics of podiform chromitites and associated peridotites of the Pan African Proterozoic ophiolite complexes of Egypt
Ahmed, AH; Arai, S; Attia, AK
通讯作者Ahmed, AH
来源期刊MINERALIUM DEPOSITA
ISSN0026-4598
EISSN1432-1866
出版年2001
卷号36期号:1页码:72-84
英文摘要

Mafic-ultramafic fragments of a dismembered ophiolite complex are abundant in the late Precambrian Pan African belt of the Eastern Desert of Egypt and north-east Sudan. The ultramafic bodies in the Eastern Desert of Egypt are mostly characterised by the harzburgite-dunite-chromitite association. Because of their severe metamorphism, almost all primary silicates were converted to secondary minerals and we use the chrome spinel as a reliable petrogenetic indicator. The podiform chromitite deposits are common as small and irregularly shaped masses in the central and southern parts of the Eastern Desert. They strongly vary in texture, degree of alteration and chemical composition of chrome spinel. The podiform chromitites exhibit a wide range of composition from high Cr to high Al varieties. The Cr of chrome spinel ranges from 0.65 to 0.85 in dunite, quite similar in the high-Cr chromitite, whereas it is around 0.5 in harzburgite. Primary hydrous mineral inclusions, amphibole and phlogopite, in chrome spinel are reported for the first time from the Pan African Proterozoic podiform chromitites. The petrological characteristics of Pan African podiform chromitites and associated peridotites of Egypt are similar to those of Phanerozoic ophiolites. The Proterozoic podiform chromitites may have formed in the same way as the Phanerozoic ones, namely by melt-harzburgite reaction and subsequent melt mixing. The similarity of the mantle section of the late Proterozoic and the Phanerozoic ophiolites suggests that the thermal conditions controlling genesis of the crust-mantle system basically have not changed since the late Proterozoic era. The Pan African harzburgite is very similar to abyssal peridotite at fast-spreading ridges, and the high-Cr, low-Ti character of spinel in chromitite and dunite indicates a genetic link with a supra-subduction zone setting. The late Proterozoic ophiolites of Egypt are possibly a fragment of oceanic lithosphere modified by are-related magmatic rocks, or a fragment of back-arc basin lithosphere.


类型Article
语种英语
国家Japan ; Egypt
收录类别SCI-E
WOS记录号WOS:000166222000006
WOS关键词COMPOSITIONAL VARIATION ; SPINEL PERIDOTITES ; CHROMIAN SPINEL ; OMAN OPHIOLITE ; FLUID PHASE ; DEPOSITS ; OLIVINE ; RICH ; DISSOLUTION ; INCLUSIONS
WOS类目Geochemistry & Geophysics ; Mineralogy
WOS研究方向Geochemistry & Geophysics ; Mineralogy
资源类型期刊论文
条目标识符http://119.78.100.177/qdio/handle/2XILL650/141479
作者单位(1)Kanazawa Univ, Fac Sci, Dept Earth Sci, Kanazawa, Ishikawa 9201192, Japan;(2)CMRDI, Cairo, Egypt
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GB/T 7714
Ahmed, AH,Arai, S,Attia, AK. Petrological characteristics of podiform chromitites and associated peridotites of the Pan African Proterozoic ophiolite complexes of Egypt[J],2001,36(1):72-84.
APA Ahmed, AH,Arai, S,&Attia, AK.(2001).Petrological characteristics of podiform chromitites and associated peridotites of the Pan African Proterozoic ophiolite complexes of Egypt.MINERALIUM DEPOSITA,36(1),72-84.
MLA Ahmed, AH,et al."Petrological characteristics of podiform chromitites and associated peridotites of the Pan African Proterozoic ophiolite complexes of Egypt".MINERALIUM DEPOSITA 36.1(2001):72-84.
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