Mineralogy, geochemistry, and geotectonic significance of the Neoproterozoic ophiolite of Wadi Arais area, south Eastern Desert, Egypt

Alteration of primary Cr-spinel mineral composition from the Suru Valley ophiolitic peridotites, Ladakh Himalaya: Their low-temperature metamorphic implications

“…In the studied peridotites, the relic olivine grains range in composition from Fo 90 -Fo 92 and are similar to the primary olivine relics of ophiolitic peridotites (meta-ultramafics) from the south Eastern Desert (SED), Egypt (Fo 89-96 after Khudeir 1995; Khalil and Azer 2007;Khedr and Arai 2013;Obeid et al 2016), Fawakhir area of Central Eastern Desert (CED), Egypt (Fo 89-92 after Abdel-Karim et al 2018) and Spongtang ophiolite peridotites (Fo 87-92 after Jonnalagadda et al 2019). This olivine chemistry corresponds to chrysotile and/or forsterite composition (Dick and Bullen 1984).…”

“…The Cr-spinel in the studied peridotites has higher Cr 3+ # ([40) akin to that of ophiolitic peridotites of Bela, Muslimbagh-Zhob and Waziristan from Pakistan (Arif and Jan 2006), SED and CED from Egypt (Farahat et al 2011;Ahmed et al 2012;Abdel-Karim et al 2016;Obeid et al 2016) and Spongtang ophiolite from Ladakh Himalaya (Jonnalagadda et al 2019). However, the Cr-spinel has lower Cr 3+ than Tidding Suture Zone serpentinites from eastern Himalaya (Singh and Singh 2011) and higher than Manipur ophiolitic peridotites from Indo-Myanmar orogenic belt (Singh 2009), Shergol ophiolitic peridotites from western Ladakh (Bhat et al 2017b) and Kamyaran ophiolitic peridotites from Iran (Veisinia et al 2018).…”

Genesis and Tectonic Implications of the Kabr El‐Bonaya Ultramafic Rocks, Sinai Peninsula, Egypt: Constraints from Mineralogical and Geochemical Characteristics

“…Mineralogically, the NiO (<0.24 wt%) and Fo (> 81.41) contents of olivines of the studied ultramafic rocks (Table S1) are lower than those of the Egyptian ophiolites (Fo = 92-96, e.g. Abd El-Rahman et al, 2009;Ahmed, 2013;Khedr and Arai, 2013;Khalil et al, 2014;Gahlan et al, 2015;Obeid et al, 2016), but are generally similar to those of the Egyptian Alaskan-type ultramafic rocks (Fig. 5a) (Helmy and El Mahallawi, 2003;Farahat and Helmy, 2006;Abd El-Rahman et al, 2012;Khedr and Arai, 2016).…”

“…Data sources: The Alaskan-type complexes of Quetico and Samuel Lake (Pettigrew and Hattori, 2006); Union Bay (Polaris) and Duke Island (Irvine, 1967;Irvine, 1974); Blashke Island (Himmelberg et al, 1986); Motaghairat (Halim et al, 2016); Abu Hamamid (Farahat and Helmy, 2006;Helmy et al, 2014); Genina Gharbia (Helmy et al, 2014); Gabbro Akarem (Helmy and El Mahallawi, 2003), Dahanib (Khedr and Arai, 2016); Alaskan Complexes (Irvine, 1974) and Arabian Shield (Habtoor et al, 2016); (b) olivine Fo versus NiO diagram for the studied ultramafic rocks. Alaskan global trend (Krause et al, 2007), the field of the Egyptian ophiolite based on the published data (El-Bahariya, 2003;Ali et al, 2010;Ahmed, 2013;Khedr and Arai, 2013;Gahlan et al, 2015;Obeid et al, 2016;Mogahed, 2019) and Alaskan mafic-ultramafic intrusions drawn based on the published data (Helmy and El Mahallawi, 2003;Farahat and Helmy, 2006;Abd El-Rahman et al, 2012;Habtoor et al, 2016); (c) variation of olivine Fo versus olivine MnO (wt%), showing a reverse correlation for the studied peridotites. Fields of Genina Gharbia and Dahnib Alaskan-type complex are drawn based on the data of Helmy et al, (2014) and Khedr and Arai (2016); (d) Mg # versus Cr # variation diagram for the studied chromian spinel.…”

Suprasubduction-zone origin of the podiform chromitites of the Bir Tuluhah ophiolite, Saudi Arabia, during Neoproterozoic assembly of the Arabian Shield

“…In general, boninite is characteristic of intra-oceanic fore-arcs (e.g., Beccaluva et al, 2004;Dilek et al, 2008), supporting a fore-arc setting for the ultramafic rocks of Bir Umq. All the analyzed fresh Cr-spinel cores have low or negligible Fe 3+ # = Fe 3+ /(Fe 3+ +Cr+Al) < 0.03, which is characteristic of primary mantle-derived spinels (Hattori and Guillot, 2007;Gahlan et al, 2015;Obeid et al, 2016;Bernstein et al, 2013;Azer, 2014).…”