The Omani basement is a critical window into the Neoproterozoic tectonic geography of the Mozambique Ocean and the amalgamation of Gondwana. It is located east of the juvenile arc terranes of the Arabian–Nubian Shield, yet the relationship between the two is not well understood. Magmatic and detrital zircon samples were analysed from four main basement terranes: Mirbat, the Huqf, Jebel Ja'alan and Al Jobah. The U–Pb (zircon) ages from igneous samples give ages between 838 and 765 Ma. The Lu–Hf and oxygen isotopes show that the zircons are juvenile (ɛ _Hf ( t ) values 10.5–8.7), with low δ ¹⁸ O values ( c. 2–6‰). Detritus from sediments in Mirbat, the southernmost basement outcrop, preserves a main age peak at c. 786 Ma, with Lu–Hf between +6.05 and +12.64. Lu–Hf isotopic data for Proterozoic detrital zircons from Jebel Ja'alan suggest that this region was depositionally connected to a source yielding both evolved Tonian and Neoarchean to Paleoproterozoic detritus. These sources could correlate to the terranes in India and South China, which record similarly low δ ¹⁸ O values. These data support a model in which Oman formed in its own tectonic domain, accreting onto the Neoproterozoic active margin of a continent. Supplementary material : All U–Pb, hafnium and oxygen data, and figures including all weighted average plots and initial ¹⁷⁶ Hf/ ¹⁷⁷ Hf v. ²⁰⁶ Pb/ ²³⁸ U age to aid in identifying Pb-loss in the data are available at https://doi.org/10.6084/m9.figshare.c.4682363

Low‐grade Ni‐laterite deposits are irregularly developed overlying mafic/ultramafic protoliths in the northern Oman Mountains. Concentrations, distribution patterns, and mobility of platinum‐group elements (PGEs) are investigated in some Ni‐laterite profiles from the Oman ophiolite as potential unconventional PGE resource. The ultramafic protoliths display the lowest PGE contents (average total = 35 ppb) that are similar to the PGE contents in the overlying saprolite zones. The PGE content increased upward in the laterite profile, where the highest total PGE contents (∼253 ppb) are recorded in the oxide and ferricrete/clay‐rich zones. The highest PGE content corresponds to Pt > Ru > Pd, while the lowest PGE content mostly corresponds to Os < Rh < Ir. The general positive correlation between PGE contents and both Cr₂O₃ and Fe₂O₃ contents and the positive trend of the chondrite‐normalized PGE patterns in the Ni‐laterite profiles reflect the formation of PGE‐Fe nanoparticle alloys that are hosted by Fe‐rich oxyhydroxides or due to the residual accumulation of chromite in the oxide/clay‐rich zone during the lateritization process. The PGE distribution patterns and positive correlation of total PGE content with the ultramafic index of alteration indicate that PGE can be mobilized in different proportions in the surficial environment upon progressive lateritization processes. The high content of total PGE in the Oman Ni‐laterite is in good agreement with PGE‐rich laterite deposits worldwide. Consequently, the Oman deposits can be considered as an unconventional PGE resource if adequate extraction and refining processes are applied for their recovery from the possible upcoming Ni production.

The Amlah terrane, NW Yemen, comprises a suite of calc-alkaline tonalitic to granodioritic gneisses bounded by mafic volcanic and probable ophiolites. Occupying a key location between the largely juvenile arc terranes of the Saudi Arabian Shield and their correlatives in NW Yemen to the west and continentally influenced terranes of central Yemen to the east, it allows evaluation of models for the final assembly of the Arabian Shield. A field, geochemical, isotopic and geochronological study was undertaken in order to constrain the evolution of the Amlah terrane and its tectonic setting. Calc-alkaline gneisses dated between c. 760 and 670 Ma have Nd- and Pb-isotopic signatures indicative of minor involvement of older continental crust in their petrogenesis. Syn- and post-tectonic intrusions dated between c. 635 and 605 Ma show that suturing of the Amlah terrane was complete by around 640 Ma. These data are used to infer that the Amlah terrane developed as an Andean-style marginal arc on an extended western margin of the Paleoproterozoic continental Abas terrane. The western margin of the Amlah terrane is interpreted as the continuation into Yemen of the Nabitah suture Zone, which separates eastern (oceanic) and western (continent-influenced) arc terranes in Saudi Arabia.