Geochemistry, mineralogy, and radioactivity of the Abu Furad Area, Central Eastern Desert, Egypt

• 作者: A. M. El Mezayen E. K. Abu Zeid W. S. Hosny M. G. El-Feky S. M. Omar S. A. Taalab
• 来源期刊: 地球化学学报(英文）
• 关键词: Hydrothermal alterations Major oxide and trace elements Radiometry Mineralogy Geochemistry Altered syenogranites Egypt
• 年，卷（期）: 2019,（2）
• 页码范围: 307-326
• 页数: 19页
• 语种: 英文
• DOI: 10.1007/s11631-018-0302-7

摘要

Abu Furad is in the Central Eastern Desert, Egypt. It comprises metasediments, metavolcanics, metagabbros, syn- to late-orogenic granites, and post-orogenic granites, in addition to numerous dykes and veins of different shapes and composition invading all the older rocks cropping out in the study area. Field, petrographic, mineralogical, and chemical investigations led to the classification of Abu Furad granites as quartz diorite, tonalite, granodiorite, and syenogranites.Major oxide and trace element data revealed that the syn- to late-orogenic granites and post-orogenic granites are peraluminous. Syn- to late- orogenic granites originated from calc-alkaline volcanic arc–related magma; while the post-orogenic granites (syenogranite) are highly fractionated, calc-alkaline granite from a within plate regime. Radiometrically, the studied quartz diorite, tonalite, and granodiorite had lower uranium and thorium contents and higher eU/eTh ratios than the syenogranites. This may indicate that the syn- to late-orogenic rocks originated from sources depleted in these elements. The average eTh/eU ratio of syenogranites was higher than that of average continental crust, suggesting that the syenogranites are relatively depleted in U. The studied altered syenogranites were strongly enriched in U and Th compared to the Earth's crust. On the other hand, the average of eU in pegmatites is lower than the global average for uraniferous pegmatites. The most recorded accessory minerals in the altered syenogranites were thorite, fergusonite, samarskite, columbite, zircon, monazite, xenotime, apatite, fluorite, sphene, atacamite, and malachite, in addition to chromium and nickel inclusions.