干旱区生态环境知识资源中心(Arid): Geochemistry of lamprophyre dykes, Wadi Sikait area, South Eastern Desert, Egypt

Arid

DOI	10.1007/s11631-011-0516-4
	Geochemistry of lamprophyre dykes, Wadi Sikait area, South Eastern Desert, Egypt
	El-Ahmadi, Ibrahim M.; Ahmed, Ragab A.
通讯作者	El-Ahmadi, IM
来源期刊	ACTA GEOCHIMICA
ISSN	2096-0956
EISSN	2365-7499
出版年	2011
卷号	30 期号:3 页码:323-331
英文摘要	The Wadi Sikait area lies at about 95 km southwest of Marsa Alam City along the Red Sea Coast, Eastern Desert, Egypt. It is occupied by Precambrian rocks of ophiolitic melange, metamorphosed sandstones (MSS), gab-bros and monzogranites which were later intruded by lamprophyre dykes and quartz veins. The lamprophyre dykes were extruded in NW-SE and NE-SW trends cutting monzogranites and metamorphosed sandstones. The lamprophyres are porphyritic and composed of clinopyroxene, olivine and amphibole phenocrysts enclosed in a fine-grained groundmass of clinopyroxene, amphibole, opaque and lithium mica. The alteration products are represented by amphibole (tremolite-actinolite and hornblende), carbonate, epidote, chlorite, iddingsite, clay minerals, limonite and serpentine. The Sikait lamprophyre dykes can be classified as alkaline lamprophyres characterized by silica contents ranging from 41.65 wt% to 50.88 wt% and Na2O>K2O. They are enriched in LILE, LREE and HFSE, but strongly depleted in compatible elements such as Cr and Ni relative to the primitive mantle. Sikait lamprophyres have moderate Zr/Hf (35.6-52.8) and Nb/Ta (20.5-22.5) ratios. Most of these features are attributed to the origin of these dykes from the metasomatized mantle affected by subduction-related fluid. These lamprophyres are compositionally similar to Salu lamprophyres in eastern China. The Sikait lamprophyre samples have high LREE (320x10(-6)-419x10(-6)) relative to HREE (20x10(-6)-33x10(-6)) with ratios (LREE/HREE=11.6-18.7) and no negative Eu anomaly (Eu/Eu=0.9-1.04). The relative presence of positive Ce anomaly (Ce/Ce=1.04) in lamprophyre samples suggests the oxidizing condition under which the REEs were precipitated due to the common occurrence of fluorite and apatite.
英文关键词	Sikait lamprophyre metasomatised REEs
类型	Article
语种	英语
收录类别	ESCI
WOS记录号	WOS:000218329800006
WOS类目	Geochemistry & Geophysics
WOS研究方向	Geochemistry & Geophysics
资源类型	期刊论文
条目标识符	http://119.78.100.177/qdio/handle/2XILL650/329741
作者单位	[El-Ahmadi, Ibrahim M.; Ahmed, Ragab A.] Nucl Mat Author, El Maadi POB 530, Cairo, Egypt
推荐引用方式 GB/T 7714	El-Ahmadi, Ibrahim M.,Ahmed, Ragab A.. Geochemistry of lamprophyre dykes, Wadi Sikait area, South Eastern Desert, Egypt[J],2011,30(3):323-331.
APA	El-Ahmadi, Ibrahim M.,&Ahmed, Ragab A..(2011).Geochemistry of lamprophyre dykes, Wadi Sikait area, South Eastern Desert, Egypt.ACTA GEOCHIMICA,30(3),323-331.
MLA	El-Ahmadi, Ibrahim M.,et al."Geochemistry of lamprophyre dykes, Wadi Sikait area, South Eastern Desert, Egypt".ACTA GEOCHIMICA 30.3(2011):323-331.