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DOI | 10.1007/s00531-014-1103-9 |
Pan-African adakitic rocks of the north Arabian-Nubian Shield: petrological and geochemical constraints on the evolution of the Dokhan volcanics in the north Eastern Desert of Egypt | |
Obeid, Mohamed A.1; Azer, Mokhles K.2 | |
通讯作者 | Obeid, Mohamed A. |
来源期刊 | INTERNATIONAL JOURNAL OF EARTH SCIENCES
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ISSN | 1437-3254 |
EISSN | 1437-3262 |
出版年 | 2015 |
卷号 | 104期号:3页码:541-563 |
英文摘要 | The Precambrian basement of Egypt is part of the Red Sea Mountains and represents the north-western part of the Arabian-Nubian Shield (ANS). Five volcanic sections are exposed in the Egyptian basement complex, namely El Kharaza, Monqul, Abu Had, Mellaha and Abu Marwa. They are located in the north Eastern Desert (ED) of Egypt and were selected for petrological and geochemical studies as they represent the Dokhan volcanics. The volcanics divide into two main pulses, and each pulse was frequently accompanied by deposition of immature molasse type sediments, which represent a thick sequence of the Hammamat group in the north ED. Compositionally, the rocks form a continuum from basaltic andesite, andesite, dacite (lower succession) to rhyodacite and rhyolite (upper succession), with no apparent compositional gaps. These high-K calc-alkaline rocks have strong affinities to subduction-related rocks with enriched LILEs (Rb, Ba, K, Th, Ce) relative to high field strength elements (Nb, Zr, P, Ti) and negative Nb anomalies relative to NMORB. The lower succession displays geochemical characteristics of adakitic rocks with SiO2 > 53 wt%, Al2O3 > 15 wt%, MgO > 2.5 wt%, Mg# > 49, Sr > 650 ppm, Y < 17 ppm, Yb < 2 ppm, Ni > 25 ppm, Cr > 50 ppm and Sr/Y > 42.4. They also have low Nb, Rb and Zr compared to the coexisting calc-alkaline rhyodacites and rhyolites. The highly fractionated rhyolitic rocks have strong negative Eu anomalies and possess the geochemical characteristics of A-type suites. Trace element geochemical signatures indicate a magma source consistent with post-collisional suites that retain destructive plate signatures associated with subduction zones. The adakitic rocks in the northern ANS are generated through partial melting of delaminated mafic lower crust interacting with overlying mantle-derived magma. The Dokhan volcanics were likely generated by a combination of processes, including partial melting, crystal fractionation and assimilation. |
英文关键词 | Neoproterozoic Arabian-Nubian Shield Dokhan volcanics Calc-alkaline Adakite Egypt |
类型 | Article |
语种 | 英语 |
国家 | Egypt |
收录类别 | SCI-E |
WOS记录号 | WOS:000351519400002 |
WOS关键词 | TRONDHJEMITE-GRANODIORITE TTG ; PRECAMBRIAN HAMMAMAT GROUP ; GEBEL-UMM-TAWAT ; K CALC-ALKALINE ; HIGH-MG-NUMBER ; CRUSTAL EVOLUTION ; CONTINENTAL-CRUST ; POSTCOLLISIONAL MAGMATISM ; SEDIMENTARY SUCCESSIONS ; ZIRCON GEOCHRONOLOGY |
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/2XILL650/187977 |
作者单位 | 1.Fayoum Univ, Dept Geol, Fac Sci, Al Fayyum, Egypt; 2.Natl Res Ctr, Dept Geol, Cairo 12662, Egypt |
推荐引用方式 GB/T 7714 | Obeid, Mohamed A.,Azer, Mokhles K.. Pan-African adakitic rocks of the north Arabian-Nubian Shield: petrological and geochemical constraints on the evolution of the Dokhan volcanics in the north Eastern Desert of Egypt[J],2015,104(3):541-563. |
APA | Obeid, Mohamed A.,&Azer, Mokhles K..(2015).Pan-African adakitic rocks of the north Arabian-Nubian Shield: petrological and geochemical constraints on the evolution of the Dokhan volcanics in the north Eastern Desert of Egypt.INTERNATIONAL JOURNAL OF EARTH SCIENCES,104(3),541-563. |
MLA | Obeid, Mohamed A.,et al."Pan-African adakitic rocks of the north Arabian-Nubian Shield: petrological and geochemical constraints on the evolution of the Dokhan volcanics in the north Eastern Desert of Egypt".INTERNATIONAL JOURNAL OF EARTH SCIENCES 104.3(2015):541-563. |
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