干旱区生态环境知识资源中心(Arid): Geochemistry and mineralogy of the Jebel Aja Igneous Intrusion and the associated exotic pegmatites, Arabian Shield, Saudi Arabia

Arid

DOI	10.1016/j.lithos.2021.106395
	Geochemistry and mineralogy of the Jebel Aja Igneous Intrusion and the associated exotic pegmatites, Arabian Shield, Saudi Arabia
	Gahlan, Hisham A.; Asimow, Paul D.; Azer, Mokhles K.; Ma, Chi; Al-Kahtany, Khaled M.; Hakeem, Alaa Y.
通讯作者	Gahlan, HA (corresponding author), King Saud Univ, Coll Sci, Dept Geol & Geophys, Riyadh 11451, Saudi Arabia.
来源期刊	LITHOS
ISSN	0024-4937
EISSN	1872-6143
出版年	2021
卷号	400-401
英文摘要	We describe the Jebel Aja igneous intrusion (JAII), which sits at the farthest northeastern edge of the exposed Arabian Shield in Saudi Arabia. The JAII consists of late Neoproterozoic post-collisional A-type granites, and was emplaced during tectonic extension. It is a composite pluton consisting of a granitic core (monzogranite, sye-nogranite and alkali feldspar granite) surrounded by a later phase of alkaline and peralkaline granites. Peg-matites occur as pockets and dykes at the contact between the alkaline/peralkaline granites and syenogranite. The pegmatites have sharp contacts with their host granites and show variable colors (principally pink and white), grain sizes, textures, and mineral compositions. We report here that the white pegmatites host pockets with a unique mineralogy that includes the first observation of pyroxmangite, thortveitite and thale ' nite-(Y) in the whole Arabian Shield as well as a novel (Sc, Y, vacancy)-rich pyroxenoid and a vacancy-rich bustamite with excess octahedral Si. The pyroxmangite-dominated lithology also features accessory quartz, albite, spessartine, pyrochroite, muscovite, and fluorite. The presence of pyroxmangite rather than rhodonite, together with vacancy-rich and Si-excess pyroxenes, suggests an elevated pressure of emplacement. The granites of the JAII are highly evolved and have undergone extreme fractional crystallization of feldspars, leading to increases in the concentration of volatile and incompatible elements in the residual melt, which resulted eventually in injection of coeval pegmatites into the mostly solidified host granite. The syenogranite and alkaline/peralkaline granite of the JAII contain sodic amphibole and have geochemical characteristics common among within-plate rare-metal bearing A-type rocks. They have positive Nb-Ta anomalies that increase from syenogranite to alkaline/per-alkaline granite. The pink pegmatite is highly mineralized and contains high concentrations of Nb (1540-1769 mu g/g), Ta (103-136 mu g/g), Y (1116-1616 mu g/g), Zr (6362-9707 mu g/g), Hf (215-264 mu g/g), Th (278-384 mu g/g), U (110-147 mu g/g), and n-ary sumation REE (2334-3251 mu g/g).
英文关键词	Arabian Shield Aja igneous intrusion Pegmatites Pyroxmangite Thortveitite Thalenite-(Y) Bustamite
类型	Article
语种	英语
开放获取类型	Green Accepted
收录类别	SCI-E
WOS记录号	WOS:000700575600001
WOS关键词	A-TYPE GRANITES ; SOUTH EASTERN DESERT ; PLUTONIC ROCKS ; RING COMPLEX ; DISCRIMINATION ; PYROXMANGITE ; ORIGIN ; REGION ; MINERALIZATION ; NOMENCLATURE
WOS类目	Geochemistry & Geophysics ; Mineralogy
WOS研究方向	Geochemistry & Geophysics ; Mineralogy
来源机构	King Saud University
资源类型	期刊论文
条目标识符	http://119.78.100.177/qdio/handle/2XILL650/368245
作者单位	[Gahlan, Hisham A.; Hakeem, Alaa Y.] King Saud Univ, Coll Sci, Dept Geol & Geophys, Riyadh 11451, Saudi Arabia; [Gahlan, Hisham A.] Assiut Univ, Fac Sci, Dept Geol, Assiut 71516, Egypt; [Asimow, Paul D.; Ma, Chi] CALTECH, Div Geol & Planetary Sci, Pasadena, CA 91125 USA; [Azer, Mokhles K.] Natl Res Ctr, Dept Geol Sci, Cairo 12622, Egypt; [Al-Kahtany, Khaled M.] King Saud Univ, Coll Sci, Seism Studies Ctr, Riyadh 11451, Saudi Arabia
推荐引用方式 GB/T 7714	Gahlan, Hisham A.,Asimow, Paul D.,Azer, Mokhles K.,et al. Geochemistry and mineralogy of the Jebel Aja Igneous Intrusion and the associated exotic pegmatites, Arabian Shield, Saudi Arabia[J]. King Saud University,2021,400-401.
APA	Gahlan, Hisham A.,Asimow, Paul D.,Azer, Mokhles K.,Ma, Chi,Al-Kahtany, Khaled M.,&Hakeem, Alaa Y..(2021).Geochemistry and mineralogy of the Jebel Aja Igneous Intrusion and the associated exotic pegmatites, Arabian Shield, Saudi Arabia.LITHOS,400-401.
MLA	Gahlan, Hisham A.,et al."Geochemistry and mineralogy of the Jebel Aja Igneous Intrusion and the associated exotic pegmatites, Arabian Shield, Saudi Arabia".LITHOS 400-401(2021).