干旱区生态环境知识资源中心(Arid): Mineralogy, M-type tetrad effect and radioactivity of altered granites at the G. Abu Garadi shear zone, central Eastern Desert, Egypt

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DOI	10.1007/s11631-011-0497-3
	Mineralogy, M-type tetrad effect and radioactivity of altered granites at the G. Abu Garadi shear zone, central Eastern Desert, Egypt
	El Nahas, H. A.; El Feky, M. G.; Mira, H.
通讯作者	El Nahas, HA
来源期刊	ACTA GEOCHIMICA
ISSN	2096-0956
EISSN	2365-7499
出版年	2011
卷号	30 期号:2 页码:153-164
英文摘要	The G. Abu Garadi area is covered mainly by metasediments, alkali feldspar granites and stream sediments. The alkali feldspar granite is traversed by a major strike-slip fault trending in an N-S direction as well as two subordinate sets of faults trending NW to WNW for the first one and NE for the second one. These faults represent the shear zones affected by magmatic (syngenetic) as well as hydrothermal (epigenetic) activities causing alteration of the granitic rocks. The most common alteration features are albitization, greisenization and koalinitization. The mass balance calculations of the studied altered samples show enrichments in Zr, Y, Ni, U, Th and Ga and depletions in Zn, Sr, Nb, Ba, Pb, Cu and V. Only the greisenized samples exhibit a significant enrichment in Nb, Sigma REE budget and pronounced lanthanide tetrad effect (M-type), especially TE1,4, while weakly expressed tetrad effects are for the other albitized and koalinitized samples. Mineralogically, the common accessory minerals in the altered samples include samarskite-(Y), betafite, uranothorite, zircon, fluorite and cassiterite. The greisenized granites contain high eU and eTh than the other altered types, where they are characterized by an assemblage of the radioactive minerals; samarskite-(Y), betafite, uranothorite in addition to zircon. The inter-element relationships between U and Th and also their ratios illustrate that the radioelement distribution in these granites is mainly governed by magmatic processes, in addition to post-magmatic ones. The distribution of chemical elements and the fractionation of some isovalents within the shear zone are largely controlled by the newly formed mineral phases. With respect to uranium mobilization, uranium migrated from the host alkali feldspar granites of G. Abu Garadi, while the shear zones acted as traps for the migrated uranium. Moreover, U migrated in the shear zone during greisenization and albitization, and migrated out during koalinitization.
英文关键词	M-type tetrad effect altered granite the G. Abu Garadi shear zone central Eastern Desert Egypt
类型	Article
语种	英语
收录类别	ESCI
WOS记录号	WOS:000218326800002
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/2XILL650/329739
作者单位	[El Nahas, H. A.; El Feky, M. G.; Mira, H.] Nucl Mat Author, POB 530, Cairo, Egypt
推荐引用方式 GB/T 7714	El Nahas, H. A.,El Feky, M. G.,Mira, H.. Mineralogy, M-type tetrad effect and radioactivity of altered granites at the G. Abu Garadi shear zone, central Eastern Desert, Egypt[J],2011,30(2):153-164.
APA	El Nahas, H. A.,El Feky, M. G.,&Mira, H..(2011).Mineralogy, M-type tetrad effect and radioactivity of altered granites at the G. Abu Garadi shear zone, central Eastern Desert, Egypt.ACTA GEOCHIMICA,30(2),153-164.
MLA	El Nahas, H. A.,et al."Mineralogy, M-type tetrad effect and radioactivity of altered granites at the G. Abu Garadi shear zone, central Eastern Desert, Egypt".ACTA GEOCHIMICA 30.2(2011):153-164.