Tectonic evolution of the crustal section of the Neoproterozoic Jabal Ess ophiolite-arc complex, Midyan terrane, NW Arabian Shield

The Jabal Ess ophiolite arc complex (JEOA) comprises basalt and basaltic andesite lavas and dykes and rare gabbros that range from MORB- and Izu Bonin Marianas forearc basalt (IBM FAB)-like to volcanic arc basalt-like but also comprise high-Mg andesite (HMA) and low-Si boninite (LSB); post-ophiolite formation granitoids intrude the ophiolite complex. Though the mafic rocks have major oxide compositional characteristics similar to MORB and IBM FAB, these mafic rocks exhibit prominent primitive mantle normalized negative Nb/Nb* anomalies and HFSE concentrations that range to much lower than MORB. We posit that the Jabal Ess ophiolite formed in adherence to the subduction initiation rule (i.e., MORB-like lavas followed by HMA and LSB) which is at least partially verified by the fact that LSB diabase are intrusive into lowermost peridotite. U-Pb SHRIMP ages of a lone rhyolite and two granites that intrude ophiolite mafic rocks are 687.6 ± 6.5 Ma and 699.0 ± 6.3 to 702.9 ± 6.2 Ma, respectively, and represent post-collisional granitoids that formed during collision of the Hijaz and Midyan terranes which aided in stitching of the 701–695 Ma Yanbu suture zone.