Arid
DOI10.1007/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
ISSN1437-3254
EISSN1437-3262
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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