The South Eastern Desert (SED) of Egypt is one of the most promising areas in Egypt; it is widely explored for exploring the rare earth elements (REEs) and uranium-bearing ores. It is a main part of the Arabian-Nubian Shield (ANS). Therefore, the present study concerns with Sikait-Nugrus area as one of the most prolific sites in this region. The study provides a detailed geological, structural, and mineralogical investigation of the monzogranites to describe and characterize the various alteration types and sequence. For this purpose, remote sensing, geochemical and petrographical techniques were applied. The remote sensing technique helped in constructing a detailed geologic map of the study area to follow up strictly the alteration zone of the Sikait-Nugrus area. Petrographically, the granites predominates in the study area, they are described as slightly and highly altered monzogranites. The slightly altered one is composed mainly of quartz (~ 20–35%), alkali feldspar (~ 25–30%), plagioclase (~ 25–30%), and mica (~ 5–15%), while accessory minerals are represented by zircon and monazite. On the other hand, the portion of this granite close to the shearing zone is intensively altered and characterized by sericitization as the main alteration processes. This sheared portion is characterized by accessory minerals as, uranothorite, allanite, fluorite and Nb-minerals (ishikawaite). Minerlogically, the altered monzogranites are predominated by the following mineral groups: (1) radioactive minerals as uranyl silicates (soddyite, uranophane and kasolite), and thorium minerals (thorite and uranothorite), (2) Nb–Ta minerals (betafite, plumbobetafite, columbite, fergusonite, and aeschynite), (3) REE minerals (monazite, cheralite and xenotime), and (4) zircon and fluorite as accessory minerals. Geochemically, the recorded pattern of the REEs tetrad effect (M-type) for the highly altered samples indicate that these granites are highly evolved and affected by late stage of hydrothermal alteration and the effective water-rich alteration processes that connected to intensive physico-chemical changes. The total REE concentrations equal 241.8 and 249.75 ppm for the highly and slightly altered samples. A significant mass change (MC) was analyzed by the isocon technique (22.95 & 11.11) and volume change (VC) (1.8 &-7.99) for the highly and slightly altered samples, respectively. The mass balance calculations and the isocon diagrams revealed that some major oxides were removed from the slightly altered monzogranites and transformed later into highly altered monzogranites with increasing the alteration intensity due to the impacts of hydrothermal alteration processes. The studied area is virgin, where no detailed studies have been applied to this region. It is extendable to other parts of the Arabian-Nubian Shield in around the Red Sea in Egypt, Sudan, Saudi Arabia and Yemen. The applied technical workflow is also extendible to other surface analogues everywhere.

中文翻译：

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二长花岗岩的热液蚀变过程：埃及东部沙漠的案例研究：遥感、地球化学和矿物学的影响


埃及东南沙漠（SED）是埃及最有前途的地区之一；它被广泛用于勘探稀土元素（REE）和含铀矿石。它是阿拉伯-努比亚地盾（ANS）的主要部分。因此，本研究将 Sikait-Nugrus 地区视为该地区最多产的地点之一。该研究对二长花岗岩进行了详细的地质、结构和矿物学调查，以描述和表征各种蚀变类型和序列。为此，应用了遥感、地球化学和岩石学技术。遥感技术帮助绘制了研究区详细的地质图，严格跟踪Sikait-Nugrus地区的蚀变带。从岩相学来看，研究区域以花岗岩为主，它们被描述为轻微且高度蚀变的二长花岗岩。轻微蚀变的主要成分为石英（约 20–35%）、碱长石（约 25–30%）、斜长石（约 25–30%）和云母（约 5–15%），副矿物为以锆石和独居石为代表。另一方面，该花岗岩靠近剪切带的部分蚀变强烈，以绢云母化为主要蚀变过程。该剪切部分的特征是副矿物，如铀铅矿、钠长石、萤石和铌矿物（石川石）。 从矿物学角度来看，蚀变二花岗岩主要由以下矿物组组成：（1）放射性矿物，如铀酰硅酸盐（钠铁矿、铀辉石和高钾长石）和钍矿物（钍铁矿和铀钍矿），（2）铌-钽矿物（β铁矿、铅β铁矿、 (3)稀土矿物（独居石、白铍石、磷钇矿），(4)副矿物锆石、萤石。从地球化学角度来看，高度蚀变样品的稀土元素四分体效应（M型）记录模式表明，这些花岗岩是高度演化的，并受到热液蚀变晚期和与强烈的物理化学作用相关的有效富水蚀变过程的影响。变化。对于高度和轻微改变的样品，稀土元素总浓度分别为 241.8 和 249.75 ppm。通过等值线技术（22.95 和 11.11）和体积变化（VC）（1.8 和-7.99）分别对高度和轻微改变的样品分析了显着的质量变化（MC）。质量平衡计算和等值线图表明，一些主要氧化物从轻微蚀变的二长花岗岩中去除，随后转变为高度蚀变的二花岗岩，并且由于热液蚀变过程的影响，蚀变强度增加。研究区域是处女地，尚未对该区域进行详细研究。它可以延伸到埃及、苏丹、沙特阿拉伯和也门红海周围阿拉伯-努比亚地盾的其他地区。所应用的技术工作流程还可以扩展到世界各地的其他表面类似物。