Late Ediacaran (605-580 Ma) post-collisional alkaline magmatism in the Arabian-Nubian Shield: A case study of Serbal ring-shaped intrusion, southern Sinai, Egypt

详细信息    查看全文

• 作者：Mokhles K. Azer
• 关键词：Arabian&ndash ; Nubian shield ; Sinai ; Ring-shaped intrusion ; A-type rocks ; Arfvedsonite ; Tetrad REE
• 刊名：Journal of Asian Earth Sciences
• 出版年：2013
• 出版时间：15 November, 2013
• 年：2013
• 卷：77
• 期：Complete
• 页码：203-223
• 全文大小：4067 K

文摘

The Serbal pluton is a late Neoproterozoic (605-580 Ma) post-collisional A-type granites in southern Sinai, Egypt (northernmost Arabian-Nubian Shield, ANS). It is characterized by discontinuous ring-shaped outcrops dislocated by later faulting. The pluton intrudes late Neoproterozoic metamorphic and high-K calc-alkaline rocks. The Serbal pluton mostly comprises an outer zone of alkali feldspar granite surrounding a core of peralkaline granite. Gradational and sharp contacts in the Serbal granites suggest that they were emplaced with a very short time interval, still before complete crystallization of the earlier batch. Serbal granites are highly evolved (75.98-78.52 wt. % SiO₂) and display the typical geochemical characteristics of post-collisional A-type granites, namely high SiO₂, Na₂O + K₂O, FeO^*/MgO, Ga/Al, Zr, Nb, Ga and Y and low CaO, MgO, Ba, and Sr. They are rich in REE and have extreme Eu-negative anomalies (Eu/Eu^* = 0.01-0.23). The chemical characteristics indicate that the peralkaline granite shares many features of granites with the tetrad REE effect. The Serbal pluton evolved through fractional crystallization of a parental magma derived through partial melting of a juvenile crustal protolith that had been extracted from a source having mantle geochemical and isotopic characteristics. The crystallization temperatures using Fe-Ti oxides of the Serbal granites point to their formation at high temperatures, up to 650-850 ¡ãC at a shallow depth of emplacement (<10 km).