Benha University

عمرو عبدالناصر علي خليل

أستاذ مساعد

كلية العلوم جيولوجيا

Petrological and geochemical characterization of Abu Murrat syn-orogenic I-type and post-orogenic A-type neoproterozoic granitoids, North Eastern Desert, Egypt

Scientific Reports • 2026
العودة
معلومات البحث
المؤلفون Amr El-Awady; Doaa A Abdelnaiem; Sherif Kharbish; Beril Tanç Kaya; Amr Abdelnasser
الكلمات المفتاحية Not Available
المجلة العلمية Scientific Reports
الناشر NATURE PORTFOLIO
المجلد 16
العدد Not Available
الصفحات 22249
publication.type International
رابط البحث Open Link
المواد المرفقة Not Available
الملخص
The Abu Murrat area, Northern Eastern Desert (NED) of Egypt, exposes two Neoproterozoic granitoid suites recording successive Pan-African evolution. The older syn-orogenic suite comprises quartz diorite, tonalite, and granodiorite, whereas the younger post-orogenic suite consists mainly of monzogranite with minor syenogranite. The syn-orogenic rocks have a moderate SiO2 (59.7‒69.3 wt%), high CaO (4.0‒7.3 wt%), Na2O (4.7‒5.7 wt%), and MgO (0.6‒2.2 wt%), and weak Eu anomalies (Eu/Eu*= ~0.8‒1). Field relations, modal QAP classification, and R1–R2, normative Ab–An–Or, A/NK–A/CNK, Ga/Al, and Nb–Y–Rb diagrams indicate calc-alkaline, magnesian, dominantly metaluminous volcanic-arc/I-type affinities. Their evolution involved assimilation and fractional crystallization (AFC), shown by decreasing MgO, Fe2O3T, TiO2, CaO, P2O5, and Sr with increasing SiO2, variable K/Rb and Ba/Nb, declining CaO/Na2O, and feldspar-controlled depletion of Eu, Sr, and Ba. The post-orogenic granites are richer in SiO2 (70.2‒75.8 wt%), K2O (5.1‒8.0 wt%), Rb (78‒178 ppm), Ga/Al, and HFSE, but poorer in CaO (0.6‒1.5 wt%) and MgO (0.04‒0.62 wt%). They also exhibit strong Eu anomalies (Eu/Eu*= ~0.05‒0.39), consistent with a within-plate A-type affinity. Zircon saturation temperatures are higher in the post-orogenic suite (~ 794–835 °C) than in the syn-orogenic granitoids (~ 635–731 °C), and monazite saturation estimates show a comparable tendency. The post-orogenic melts are interpreted as products of tonalitic lower-crustal melting during post-collisional extension, probably promoted by slab break-off and lithospheric delamination. Abu Murrat thus records the transition from subduction-related I-type arc magmatism to post-collisional A-type magmatism during Pan-African orogen collapse.
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