Metamorphic Sole Chronicles Protracted Subduction Initiation of the Neo-Tethys
Jie Shen;Jingen Dai;Kai Yang
metamorphic solesubduction initiationgeochronology
Subduction, a fundamental force in plate tectonics, remains obscure due to the scarcity of evidence regarding its initiation. Metamorphic soles (MSs), formed by high-temperature metamorphism of the subducted plate during subduction initiation (SI), offer invaluable insights into this enigmatic stage. Here we re-evaluate the timing of MS formation in the central Yarlung Zangbo Ophiolite (YZO) by combining zircon, apatite, and titanite U-Pb ages with their REE patterns. Our results indicate that the earliest and latest recorded ages of the MSs being 146 Ma and 115 Ma, while their protolith formed no later than 159 Ma . The notably older protolith, compared to both the MS and the prevailing YZO (130-120 Ma), implies that Neo-Tethys SI in the YZO likely transpired along a transform fault or fracture zone between oceanic lithospheres of differing ages. The broad age ranges for MS underscore a protracted SI spanning nearly 25 Ma, delineated into two stages: (1) the stagnant stage (~146 Ma-130 Ma) marked by a slow rate and a dry mantle and (2) the unlocking stage (~130-120 Ma) was characterized by an accelerated rate and rapid upper plate extension, resulting in the formation of the YZO. We also report late-stage of MS younger than the YZO. This study provides critical constraints on the timing and duration of the Neo-Tethys SI, highlighting the extended and intricate interplay between subduction and exhumation processes.
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Jie Shen;Jingen Dai;Kai Yang.Metamorphic Sole Chronicles Protracted Subduction Initiation of the Neo-Tethys.DDE Repository.2024-01-01.doi:10.12297/dpr.dde.202401.1