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DOI | 10.1016/j.jafrearsci.2018.11.007 |
Petrogenesis of Zeiatit gabbroic rocks in the Southern Eastern Desert of Egypt: Discrimination of arc-related Neoproterozoic gabbros | |
Mogahed, Moustafa M. | |
通讯作者 | Mogahed, Moustafa M. |
来源期刊 | JOURNAL OF AFRICAN EARTH SCIENCES
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ISSN | 1464-343X |
EISSN | 1879-1956 |
出版年 | 2019 |
卷号 | 150页码:239-263 |
英文摘要 | The area of Gabal Zeiatit, South Eastern Desert, Egypt represents one of a series of ophiolitic-island arc complexes found within the Arabian-Nubian Shield (ANS). The present study introduces new major, trace, and rare earth element analyses and mineral composition data of gabbroic rocks encountered in this area with the goal of constraining their geotectonic setting. The investigated area consists of two types of gabbroic rocks. The Zeiatit ophiolitic metagabbros (ZMG) are always associated with serpentinites of ophiolitic affinity and were subjected to metamorphism of greenschist to lower amphibolite fades and exhibit tholeiitic affinity and MORB-like characters. Serpentinites and metagabbros are tectonically thrusted over a thick pile of metavolcanic rocks. The Zeiatit intrusive gabbros (ZIG) are related to Egyptian Alaskan-type mafic-ultramafic complexes and intrude the studied ophiolitic rocks and island arc rocks. Geochemical data reveal that both studied gabbroic types originated in sub-arc setting. Mineral chemistry data for the two types of the studied gabbroic rocks indicate that they possess different characteristics. The NiO (< 0.15 wt%) and Fo (< 83 mol.%) contents of olivine from the investigated ZIG are lower than those of the Egyptian ophiolites. The clinopyroxene composition of the ZIG show arc related cumulate. Geochemically, the ZMG exhibit MORB-like and arc-like signatures as they display Ti/V ratios ranging from 14.52 to 21.09. Such phenomenon of hybrid mixture between island arc tholeiite (IAT) and MORB is generally acknowledged being unique to forearc tectonic regime. Moreover, depleted LREE and HFSE and relatively high CaO in the studied ZMG suggest derivation from Cpx-rich mantle at forearc tectonic setting. The ZIG have Nb/Yb (0.28-1.04) and Th/Yb (0.1-0.42) which are typical for oceanic island arcs. The ZIG are highly depleted in Nb, Ta, and Zr, but enriched in Ba, Pb, Sr, U and Th suggest their derivation from a meta-somatized lithospheric mantle source that modified by hydrous fluids derived from the subducting slab in a subduction zone. ZIG have Th/Ta (0.69-2.05) and Ta/Hf (0.16-0.28) indicating that they were mainly derived from partial melting of a depleted mantle source, being mixed with crustal material. The present geochemical and mineralogical studies revealed that, the investigated ZMG are fragment of oceanic lithosphere probably developed in a supra-subduction zone environment and originated by 10-30% partial melting of a spinel lherzolite mantle in a sub-arc (forearc) setting at shallow depth which consistent with the most recent conclusions of the Egyptian ophiolitic metagabbros. However, the investigated ZIG are akin to the Alaskan-type rocks. |
英文关键词 | Egypt Eastern desert Gabal Zeiatit area Ophiolitic metagabbros Alaskan rocks Forearc tectonic regime Volcanic-arc setting |
类型 | Article |
语种 | 英语 |
国家 | Egypt |
收录类别 | SCI-E |
WOS记录号 | WOS:000460195100018 |
WOS关键词 | ALASKAN-TYPE COMPLEX ; MAFIC-ULTRAMAFIC COMPLEX ; ARABIAN-NUBIAN SHIELD ; TRACE-ELEMENT ; SM-ND ; GEOCHEMICAL DISCRIMINATION ; TECTONOMAGMATIC EVOLUTION ; CLINOPYROXENE COMPOSITION ; QUANTITATIVE-ANALYSIS ; SUPERIOR PROVINCE |
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/2XILL650/216601 |
作者单位 | Benha Univ Egypt, Geol Dept, POB 13518, Banha, Egypt |
推荐引用方式 GB/T 7714 | Mogahed, Moustafa M.. Petrogenesis of Zeiatit gabbroic rocks in the Southern Eastern Desert of Egypt: Discrimination of arc-related Neoproterozoic gabbros[J],2019,150:239-263. |
APA | Mogahed, Moustafa M..(2019).Petrogenesis of Zeiatit gabbroic rocks in the Southern Eastern Desert of Egypt: Discrimination of arc-related Neoproterozoic gabbros.JOURNAL OF AFRICAN EARTH SCIENCES,150,239-263. |
MLA | Mogahed, Moustafa M.."Petrogenesis of Zeiatit gabbroic rocks in the Southern Eastern Desert of Egypt: Discrimination of arc-related Neoproterozoic gabbros".JOURNAL OF AFRICAN EARTH SCIENCES 150(2019):239-263. |
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