Abstract
Gabal (G.) El-Mueilha Granitic rocks are represented by an oval shaped stock that intruding thesurrounding older rock units including ophiolitic melange, metavolcanics, older granitoids and youngergabbros and sending several offshoots into them. The study area is affected by several fault systems inNW-SE, NE-SW and N-S directions. Petrographically, these younger granites are mainly represented bymuscovite granite (syenogranite) that shows different degrees of albitization especially at the peripheralparts of the stock beside the ferrugination and silicification. The main accessory minerals are cassiterite,fluorite, zircon, beryl, monazite, thorite and uranothorite which are responsible for the radioactiveanomalies in G. El-Mueilha syenogranitic mass. The airborne gamma ray spectrometry shows highradioactive anomaly restricted to the younger granitic mass relative to the other surrounding rocks that havelow to moderate radioactivity. The eTh/eU ratio of G. El-Mueilha syenogranite indicates U-enrichmentespecially during albitization processes.
Highlights
The Arabian–Nubian Shield (ANS) is widely exposed tract of juvenile Neoproterozoic continental crust (1000–525 Ma) on Earth (Kröner, 1985; Stern, 1994; Johnson et al, 2011; Robinson et al, 2014) which are mainly formed by accretion of several intra-oceanic arcs along ophiolitic sutures (e.g. Kröner, 1985; Stoeser and Camp, 1985; Vail, 1985; Quick, 1991; Johnson, 1998; Stern and Johnson, 2010; Ali et al 2009, 2010, 2016)
The K contour map (Fig.30) shows the overall spatial distribution of the relative potassium concentrations in the study area. It indicates that serpentinites and related rocks represent the low level; while the intermediate level ranges from 7 to 10 percent, which is associated with the older granitoids and metavolcanics
El-Mueilha syenogranitic mass are ferrugination, silicification and albitization, which are restricted to the fault planes as well as the peripheral parts of the pluton along their contacts with the surrounding metavolcanics
Summary
The Arabian–Nubian Shield (ANS) is widely exposed tract of juvenile Neoproterozoic continental crust (1000–525 Ma) on Earth (Kröner, 1985; Stern, 1994; Johnson et al, 2011; Robinson et al, 2014) which are mainly formed by accretion of several intra-oceanic arcs along ophiolitic sutures (e.g. Kröner, 1985; Stoeser and Camp, 1985; Vail, 1985; Quick, 1991; Johnson, 1998; Stern and Johnson, 2010; Ali et al 2009, 2010, 2016). The classification of granitoid rocks in the ANS include the syn- to late-orogenic granitoid assemblages (880–610 Ma), and post-orogenic to anorogenic granitoid assemblages (600–475 Ma), previously known as older granitoids and younger granites, respectively (Greenberg, 1981; Ries et al, 1983; Bentor, 1985; Stern and Hedge, 1985; Hassan and Hashad, 1990; Abdel-Rahman, 1995; Eliwa et al, 2006; Moussa et al, 2008 and Ali et al, 2012). Gabal El-Mueilha younger granitic mass is considered as a topographic mark in the study area (703 m a.s.l.). It is located in the southern Eastern Desert, between latitudes 24° 51' and 24° 56' N and longitudes 33° 58' 10'' and 34° 03' 50'' E (Fig.).
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