Oligocene/Early Miocene E/W‐Shortening in the Oman Mountains Related to Oblique Arabia‐India Convergence

Abstract

Field survey, literature review, geological map interpretation, GPlates reconstruction and LA‐ICP‐MS U‐Pb dating of synkinematic calcite demonstrate that ∼E/W‐shortening in eastern Oman was significant and related to oblique convergence of Arabia and India from 32.5 to 20 Ma. Approximately N/S‐striking contractional structures, WNW to NNW‐striking sinistral faults and ∼E/W‐striking normal faults characterize a ∼250 km × ∼50 km wrench corridor in the eastern Oman Mountains (Hajar Wrench Corridor, HWC). Numerous faults/folds indicate that deformation of the HWC is widely distributed but concentrated along WNW to NNW‐striking major faults at the SW margin of the Saih Hatat Dome, forming the Hajar Shear Zone, which reactivated basement faults. GPlates reconstructions reveal that N‐drifting India rotated 8° counter‐clockwise with respect to fixed Arabia from 32.5 to 20 Ma, leading to a minimum of 100 km E/W convergence between both plates. This convergence created the sinistral HWC with a displacement of a few to several tens of kilometers. Independently from the GPlates time constraints, two U‐Pb ages of synkinematic calcites, crystallized along faults during HWC movement, yield compatible ages of 30.08 ± 0.47 and 22.31 ± 2.15 Ma (2 standard error). E/W‐shortening also affected the northern Oman Mountains, creating the ∼N/S‐striking Hagab Thrust in the Musandam Peninsula and the Jabal Hafit Anticline.

Uplift Dynamics of the Obducted Northeastern Continental Margin of the Arabian Peninsula, Sultanate of Oman

“…Late Cretaceous to early Eocene uplift of the southern Segments 2–3 (Quriyat Corridor and Salma Plateau) was lower compared to that of the Saih Hatat Dome. However, pronounced uplift occurred during Oligocene‐Miocene tectonic events (e.g., Corradetti et al., 2020; Fournier et al., 2006; Jacobs et al., 2015; Scharf et al., 2022).…”

“…The presence of shallow‐marine middle‐late Miocene formations in the Quriyat Corridor and Sur Corridor suggests that the corridors were the last to be exhumed (Wyns et al., 1992a, 1992b), which corroborates the idea of block‐like uplift in northeastern Oman. Eastern Arabia was affected by deformation during the late Eocene to Miocene by two tectonic events (Corradetti et al., 2020; Fournier et al., 2006; Hansman et al., 2017; Scharf et al., 2019, 2022). Deformation triggered the reactivation of parts of the basement faults, which resulted in block‐like uplift of parts/segments of the Arabian crust, that is, the Salma Plateau (Figure 10e).…”

“…The Qalhat Fault is a similarly oriented major fault in the eastern part of the study area (Figures 1 and 2; Wyns et al., 1992a). Other faults, striking NW/SE are the Ja'alan Fault, Issmaiya Fault Zone and Wadi Mansah Fault Zone (WMFZ; Callegari et al., 2022; Moraetis et al., 2018; Scharf et al., 2019, 2022; Figure 2). These faults probably originated during the late Paleozoic breakup of Pangea (Blendinger et al., 1990; Chauvet et al., 2009; Moraetis et al., 2018; Scharf et al., 2019) and were eventually reactivated during the Cenozoic (Mattern, Bolhar, et al., 2021).…”

“…Uplift of >2,000 m at the Salma Plateau (Figure 1) started after the mid‐Eocene and is still active (e.g., Hoffmann et al., 2013, 2020; Moraetis et al., 2018; Searle, 2007; Wyns et al., 1992b). Reasons for the ongoing uplift are debated and are (a) possibly linked to bending/forebulge formation of the Arabian lithosphere related to the ongoing Arabia‐Eurasia convergence (e.g., Kusky et al., 2005; Rodgers & Gunatilaka, 2002; Yuan et al., 2016), and/or (b) convergence between the Arabian and Indian plates since the Oligocene/Miocene (e.g., Corradetti et al., 2020; Fournier et al., 2006; Scharf et al., 2022), and/or (c) some uplift of marine terraces reflecting serpentinization and associated volume increase of ultramafic rocks (Ermertz et al., 2019; Hoffmann et al., 2020). In addition, the published chronologies pertaining to the uplifted terraces show incongruities and possible dating limitations for this particular geographical area which are yet to be constrained.…”

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After the emplacement of the ophiolite at ∼75 Ma (Searle, 2007), Oman's margin was exposed to NNE/SSW-directed shortening, which formed the Makran subduction zone where the oceanic lithosphere in the Sea of Oman is being subducted below Eurasia/India (Scharf et al, 2022). Plate convergence around the previous circum-Tethys continents have created tectonic markers through the imprint of eustatic sea level (ESL) fluctuations and vertical plate movements (Pedoja et al, 2011(Pedoja et al, , 2014.

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