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

Abstract

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Petrogenesis of gold-bearing listvenites from the carbonatized mantle section of the Neoproterozoic Ess ophiolite, Western Arabian Shield, Saudi Arabia

“…The chemical composition of the Jabal Ess serpentinite is quite typical among ophiolitic serpentinites in the Arabian Shield (e.g. Gahlan et al, 2020b, Abuamarah et al, 2020. The concentrations of TiO 2 (<0.1 wt.%), Al 2 O 3 (<0.8 wt.%), CaO (0.3-1.2 wt.%), K 2 O (<0.01 wt.%) and Na 2 O (<0.02 wt.%) are all quite low, the analyses are dominated by SiO 2 (36.84-39.04 wt.%), MgO (36.8-41.7 wt.%), Fe 2 O 3 (7.6-8.5 wt.%), and LOI (12.75-15.45 wt>%).…”

“…In this regard, the Ess ophiolite share a common tectonic setting with most Arabian Shield ophiolites, fragments of oceanic lithosphere emplaced J o u r n a l P r e -p r o o f Journal Pre-proof above a subduction zone in a forearc setting (e.g. Gahlan et al, 2020 a, b;Abuamarah et al, 2020).…”

“…The ophiolitic rocks of the Arabian Shield are fragments of upper mantle and oceanic crust that were obducted, tectonically emplaced over continental crust, and preserved above sea level. Most Arabian Shield ophiolites have been dismembered through multiple phases of alteration, deformation and metamorphism (e.g., Stern et al, 2004;Johnson et al, 2004;Gahlan et al, 2020 a, b;Abuamarah et al, 2020). Their ultramafic mantle sections have been conspicuously altered by circulation and infiltration of various hydrothermal fluids at various temperatures, leading to assemblages including serpentinite, listvenite and talc-carbonate rocks.…”

Direct dating rodingitization in the northern North China Craton using garnet U–Pb geochronometry

“…There is no diagnostic feature for zircon that crystallized during rodingitization. In contrast, garnets produced during rodingitization are characterized by hydrous grossular and andradite (Abuamarah et al., 2023; Rossman & Aines, 1991), These garnets are distinctly different from those crystallized in basaltic to andesitic liquids or formed during regional metamorphism, which mostly have a pyralspite composition (Alonso‐Perez et al., 2009; Müntener et al., 2001). The garnets in samples 14JH52 and 14JH53 show high andradite plus grossular contents of 83.5–89.9 mol.% (Figure 3a).…”

Origin and evolution of Neoproterozoic metaophiolitic mantle rocks from the eastern Desert of Egypt: Implications for tectonic and metamorphic events in the Arabian-Nubian Shield

“…Olivine relicts show a compositional range (Fo 91-94 ; Table III) like that of primary olivine of mantle rocks in the Egyptian Eastern Desert ophiolites (Fo 89-96 ) (Abdel-Karim et al, 2018;Khalil and Azer, 2007;Khedr and Arai, 2013;Moussa et al, 2021Moussa et al, , 2022Obeid et al, 2016). The high Fo contents are akin to those in the ANS ophiolitic ultramafic rocks and fore-arc peridotites (Abuamarah et al, 2020;Stern et al, 2004) but are clearly distinct from those in olivine from the non-ophiolitic mafic-ultramafic intrusions in the ANS (Fo= 77.5-86.5: Abd El-Rahman et al, 2012;Azer and El-Gharbawy, 2011;Azer et al, 2016Azer et al, , 2017Farahat and Helmy, 2006;Gahlan et al, 2023;Ghoneim, 1989;Helmy and El Mahallawi, 2003). Their Fo and NiO contents fall within the range of the SSZ ophiolitic serpentinites of the EDE and overlap those of the olivine mantle array (Fig.…”