Synchronous Seafloor Spreading and Subduction at the Paleo‐Convergent Margin of Semail and Arabia

Abstract

The Semail ophiolite is the largest and best‐exposed ophiolite, having preserved intact record of a precollision system related to Neotethyan Ocean closure. Breaking with the alternative models of ophiolite exhumation and emplacement, this paper builds on integrating the joined contribution of tectonic evolution of the continental margin in the premise of the ophiolite obduction. Connecting the along‐strike segmentation of the ophiolite recorded in the lithospheric flow structure, and recent high‐precision dating, results in a 3‐D model of evolution of the ophiolite and its continental margin during Jurassic‐Cretaceous time. Among the relevant characteristics newly accounted, (1) the contamination of the ophiolite by fluids and magmas of continental origin; (2) the discrimination of different types of metamorphics associated to the ophiolite, and conventionally classified metamorphic soles; (3) the instability of the Arabian margin during the Late Jurassic‐Cretaceous times; (4) the new precise ages relating to overlapping of spreading and detachment; and (5) the inferred vergence of Neotethyan closure during late Mesozoic are stressed. The complex stem revealed may relate to processes associated with spreading center subduction at ridge‐trench‐transform (RTT) triple junction, as documented along a convergent margin. The Semail ophiolite emplacement on the Arabia continental margin would result from a temporary Arabian platform‐directed subduction zone that consumed the southern Tethyan plate during Late Jurassic‐Cretaceous time.

Pervasive carbonation of peridotite to listvenite (Semail Ophiolite, Sultanate of Oman): clues from iron partitioning and chemical zoning

“…We present a study of listvenites from the Fanja region in the Semail Ophiolite (Oman), where extensive outcrops are described (Glennie et al, 1974;Stanger, 1985;Wilde et al, 2002;Nasir et al, 2007;Falk and Kelemen, 2015;Boudier and Nicolas, 2018) and where Hole BT1B was drilled during the Oman Drilling Project (OmanDP; Kelemen et al, 2020). We document the relationships between the Fanja listvenites, serpentinized peridotites and adjacent lithologies in the field and downhole, with a focus on rock textures, microstructures and mineral compositions.…”

Geochemical Profiles Across the Listvenite‐Metamorphic Transition in the Basal Megathrust of the Semail Ophiolite: Results From Drilling at OmanDP Hole BT1B

“…(a) Simplified geological map of the Semail ophiolite. Yellow and red stars represent regional occurrences of listvenites and the location of OmanDP Hole BT1B, respectively (after Boudier & Nicolas, 2018); (b) Downhole plots of drilled lithologies, magnetic susceptibility (MS), natural gamma rays (NGR), and mineral proportions (data from Kelemen et al., 2020); mineral proportions are estimated based on thin section observations and X‐ray diffraction analysis.…”

Geochemical Profiles Across the Listvenite-Metamorphic Transition in the Basal Megathrust of the Semail Ophiolite: Results from Drilling at Oman DP Hole BT1B

“…(a) Simplified geological map of the Semail ophiolite. Yellow and red stars represent regional occurrences of listvenites and the location of OmanDP Hole BT1B, respectively (after Boudier and Nicolas [2018]); (b) Downhole plots of drilled lithologies, magnetic susceptibility (MS), natural gamma rays (NGR), and mineral proportions (data from ); mineral proportions are estimated based on thin section observations and X-ray diffraction analysis.…”