干旱区生态环境知识资源中心(Arid): Gold-sulfide mineralization in the Sir Bakis mine area, Central Eastern Desert, Egypt

Arid

DOI	10.1007/s00531-021-02154-1
	Gold-sulfide mineralization in the Sir Bakis mine area, Central Eastern Desert, Egypt
	Abdelkareem, M.; El-Shazly, A. K.
通讯作者	Abdelkareem, M (corresponding author)，South Valley Univ, Geol Dept, Qena 83523, Egypt. ; Abdelkareem, M (corresponding author)，South Valley Univ, Remote Sensing Lab, Qena 83523, Egypt.
来源期刊	INTERNATIONAL JOURNAL OF EARTH SCIENCES
ISSN	1437-3254
EISSN	1437-3262
出版年	2022-01
英文摘要	The Sir Bakis area in the central Eastern Desert of Egypt hosts orogenic type gold deposits in shear-related, structurally controlled, quartz veins. These NNW-SSE-trending veins cross-cut Precambrian metavolcanics and granitoids of the Arabian Nubian shield that formed during the Pan-African Orogeny (780-610 Ma). The primary ore mineral assemblage consists of pyrite (As <3.6%), chalcopyrite (Zn <1.5%), galena (Zn <0.2%, Te < 0.48%), sphalerite (7.9-8.9% Fe), magnetite (Ti, Cr, and Mn below detection), and gold (9-20% Ag). Gold also occurs as a texturally late mineral along with hessite (<7% Au), silver, electrum (Au0.63Ag0.32), and covellite (Zn <2.4%; Ag < 2.2%) that develop along rims and fractures of primary minerals. Three different types of fluid inclusions in vein quartz were observed: Type A are 3-phase (2 liquids + gas) solitary inclusions; Type B are 2-phase (liquid + gas) inclusions in clusters or isolated, and Type C are 2-phase (liquid + gas) inclusions in healed fractures mostly crossing grain boundaries. Microthermometric measurements show that eutectic melting points (Tm e ) for type A inclusions fall between - 63 and - 51 degrees C (most similar to - 56 degrees C), whereas type B inclusions have four distinct modes at - 66 degrees, - 55 degrees, - 35 degrees, and - 22 degrees C. Type A inclusions record average clathrate melting temperatures of similar to 9.3 degrees C. All inclusions homogenize consistently through the disappearance of the vapor, with final homogenization temperatures (T-h) for type B and C inclusions recorded at 263 and 240 degrees C, respectively. Analysis of microthermometric measurements on early type A and B fluid inclusions suggests that low salinity, CH4-bearing, aqueous-carbonic fluids (XH2O =0.38-0.61; XCO2 = 0.26-0.53; XCH4 = 0.05-0.1; XNa+ =0.005-0.013) were among the earliest trapped (in type A), followed by mostly aqueous, either CO2-bearing or CO2-free fluids (in type B inclusions; XH2O =0.61-0.99; XCO2 < 0.04; XNa+ = 0.0006-0.025; XMg2+ = 0.01-0.13, XCa2+ < 0.0014, XCl- < 0.26). Ore-bearing fluids were likely CH4-bearing, aqueous-carbonic fluids similar to those trapped in type A inclusions. These fluids were likely metamorphic in origin, and leached Au from ultramafic and mafic ophiolitic rocks, carrying it in the form of bisulfide complexes. Ore minerals were precipitated upon oxidation as the fluids migrated to shallower crustal levels through the deep seated shear zones. Sphalerite thermobarometry and microthermometric analysis of early inclusions suggest that the primary ore mineral assemblage formed at T 280-300 degrees C, P >4 kbar. Textural analysis of vein minerals and microthermometric measurements suggest that pyrite and galena likely recrystallized with quartz during late-stage deformation, leading to the reprecipitation of Au and Ag at T = 220-150 degrees C, P < 1 kbar. The two-stage evolution of Sir Bakis ore is consistent with genetic models proposed for many orogenic Au deposits that invoke subduction/collision followed by extension, and with the tectonic history of the central Eastern Desert which records regional metamorphism and intrusion of syncollisional magmas, followed by crustal extension, shearing, and postorogenic magmatism.
英文关键词	Orogenic gold Sir Bakis Eastern Desert of Egypt Fluid inclusions Secondary ore minerals
类型	Article ; Early Access
语种	英语
收录类别	SCI-E
WOS记录号	WOS:000746778600001
WOS关键词	TRACE-ELEMENT GEOCHEMISTRY ; METAMORPHIC CORE COMPLEX ; BANDED IRON FORMATIONS ; FLUID INCLUSIONS ; OROGENIC-GOLD ; PHASE-RELATIONS ; SPHALERITE GEOBAROMETER ; COMPUTER-PROGRAMS ; OXYGEN FUGACITY ; DEPOSITS
WOS类目	Geosciences, Multidisciplinary
WOS研究方向	Geology
资源类型	期刊论文
条目标识符	http://119.78.100.177/qdio/handle/2XILL650/377082
作者单位	[Abdelkareem, M.] South Valley Univ, Geol Dept, Qena 83523, Egypt; [Abdelkareem, M.] South Valley Univ, Remote Sensing Lab, Qena 83523, Egypt; [El-Shazly, A. K.] Marshall Univ, Dept Geol, Huntington, WV 25755 USA
推荐引用方式 GB/T 7714	Abdelkareem, M.,El-Shazly, A. K.. Gold-sulfide mineralization in the Sir Bakis mine area, Central Eastern Desert, Egypt[J],2022.
APA	Abdelkareem, M.,&El-Shazly, A. K..(2022).Gold-sulfide mineralization in the Sir Bakis mine area, Central Eastern Desert, Egypt.INTERNATIONAL JOURNAL OF EARTH SCIENCES.
MLA	Abdelkareem, M.,et al."Gold-sulfide mineralization in the Sir Bakis mine area, Central Eastern Desert, Egypt".INTERNATIONAL JOURNAL OF EARTH SCIENCES (2022).