Arid
DOI10.1007/s00710-015-0397-z
The Neoproterozoic Abu Dahr ophiolite, South Eastern Desert, Egypt: petrological characteristics and tectonomagmatic evolution
Gahlan, Hisham A.1; Azer, Mokhles K.2; Khalil, Ahmed E. S.2
通讯作者Gahlan, Hisham A.
来源期刊MINERALOGY AND PETROLOGY
ISSN0930-0708
EISSN1438-1168
出版年2015
卷号109期号:5页码:611-630
英文摘要

The Neoproterozoic Abu Dahr ophiolite, South Eastern Desert, Egypt, is one of the best preserved and least dismembered ophiolite successions in the Arabian-Nubian Shield. It contains a Penrose-type ophiolitc sequence from mantle section below mafic crust upward to oceanic sedimentary cover overlying mafic volcanics, although the original magmatic (stratigraphic) contact between the mantle and crustal sections is disrupted by tectonism. The Abu Dahr ophiolite is metamorphosed under grecnschist facies conditions, and low-temperature alteration is widespread. Petrography reveals that: (i) the mantle is homogenous, sernentinized, and dominated by harzburgitc and less abundant dunitc; (ii) the cumulate ultramafics are represented by wehrlite and pyroxenite; and (iii) the crustal section is represented by metagabbros, meta-anorthosites and metabasalts. The Abu Dahr serpentinized peridotites show high Mg# (0.92-0.93), with enrichment of Ni, Cr and Co, and depletion of Al2O3 and CaO, and nearly flat and unfractionated REE chondrite-normalized pattern. Major and trace element characteristics of the Abu Dahr metagabbro and metabasalt (crustal section) indicate a tholeiitic to calc-alkaline affinity. Units of the crustal section have low-Nb and Zr concentrations, low Dy/Yb and relatively elevated La/Yb ratios, high U/Yb and Th/Yb ratios, and LREE enriched chondrite-normalized pattern. All of the Abu Dahr ophiolite units have trace-element signatures characterized by enrichment of LILE over HF SE. Rare and trace element patterns indicate a genetic link between the Abu Dahr mantle, cumulate ultramafics, and crust. Chromian spinel has survived metamorphism and is used as a petrogcnetic indicator in the Abu Dahr serpentinized peridotites. The spine’ is homogeneous with a limited composition, and shows high-Cr# (>0.6) combined with low-TiO2 character (mostly <0.1 wt. %). The Abu Dahr ophiolite is interpreted as a fragment of depleted oceanic lithosphere that experienced high degrees of partial melting (up to 35 %) and originated in a fore-arc setting. Such interpretation contributes to the body of evidence suggesting that tectonomagmatic processes of the Neoprotcrozoic were largely similar to those of the Phanerozoic, implying little, or no significant, change in the geothermal regime of Earth since the Neoproterozoic.


类型Article
语种英语
国家Saudi Arabia ; Egypt
收录类别SCI-E
WOS记录号WOS:000365098100006
WOS关键词HIGHLY DEPLETED PERIDOTITE ; ARABIAN NUBIAN SHIELD ; CHROMIAN SPINEL ; PODIFORM CHROMITITES ; ULTRAMAFIC ROCKS ; SAUDI-ARABIA ; UPPER-MANTLE ; COMPLEXES ; ZONE ; CLASSIFICATION
WOS类目Geochemistry & Geophysics ; Mineralogy
WOS研究方向Geochemistry & Geophysics ; Mineralogy
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/2XILL650/189226
作者单位1.King Saud Univ, Dept Geol & Geophys, Riyadh 11451, Saudi Arabia;
2.Natl Res Ctr, Dept Geol Sci, Cairo 12622, Egypt
推荐引用方式
GB/T 7714
Gahlan, Hisham A.,Azer, Mokhles K.,Khalil, Ahmed E. S.. The Neoproterozoic Abu Dahr ophiolite, South Eastern Desert, Egypt: petrological characteristics and tectonomagmatic evolution[J]. King Saud University,2015,109(5):611-630.
APA Gahlan, Hisham A.,Azer, Mokhles K.,&Khalil, Ahmed E. S..(2015).The Neoproterozoic Abu Dahr ophiolite, South Eastern Desert, Egypt: petrological characteristics and tectonomagmatic evolution.MINERALOGY AND PETROLOGY,109(5),611-630.
MLA Gahlan, Hisham A.,et al."The Neoproterozoic Abu Dahr ophiolite, South Eastern Desert, Egypt: petrological characteristics and tectonomagmatic evolution".MINERALOGY AND PETROLOGY 109.5(2015):611-630.
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