Detachment Fault‐Hosted Subduction Re‐Initiation of the (Ultra)Slow‐Spreading Western Neo‐Tethys in the Jurassic

Abstract

Subduction initiation in oceans is key to understanding regional and global plate tectonics and ocean basin dynamics; however, its genetic mechanism is still enigmatic. The most famous model that predicts intraoceanic subduction initiation along transform faults or fracture zones (i.e., the Subduction Initiation Rule) has been widely used to explain arc‐like geochemical signatures within the Neo‐Tethyan ophiolites, but fails to account for the speculation and/or calculation of a sub‐parallel relationship between the Jurassic subduction zones and paleo ridges of the western Neo‐Tethys. Here, we propose a ridge‐parallel detachment fault‐hosted subduction re‐initiation model for the Jurassic western Neo‐Tethys. Based on field geological and geochemical evidence, we show that the Refahiye ophiolite in the İzmir–Ankara–Erzincan suture of northern Turkey has diagnostic characteristics indicative of (ultra)slow seafloor spreading. An (ultra)slow‐spreading nature also characterizes many Neo‐Tethyan ophiolites from the Alps to Southeast Asia, either at mid‐ocean ridges or in suprasubduction zones. Due to its extremely weak nature, detachment faults were probably a key candidate for the Jurassic intraoceanic subduction re‐initiation of the western Neo‐Tethys in response to far‐field compression after its long‐lived northward subduction. This model is applicable to both the Jurassic and Early Cretaceous ophiolites, but is questionable for the Late Cretaceous ophiolites. Its utility deponds on the kinematics of ancient plate boundaries and compositions of ophiolites. The detachment fault‐hosted subduction re‐initiation model can explain the arc‐like geochemical features of the Jurassic western Neo‐Tethyan ophiolites, but its effect on the structure and component of ophiolites is diverse.