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DOI | 10.1007/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
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ISSN | 0930-0708 |
EISSN | 1438-1168 |
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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