Slab tear along a subducting passive margin and related E-MORB/OIB-affinity magmatism in southeastern Tibet

A joint subduction of the oceanic-continental plates exerts primary controls on the tectonomagmatism alongside trench-perpendicular ocean-continental transitional (OCT) belts. Such OCT belts trigger substantial crustal density contrasts since lateral pressure gradients create where a mature oceanic lithosphere terminates against a thicker continental lithosphere. This study investigates the conjunction between the southernmost Yushu–Yidun Arc belt and the Longmen Shan Fault system in northeastern Tibetan Plateau, exploring the interaction of these two large-scale linear structures. Geological evidences compiled reveals that an OCT belt previously defined the Longmen Shan Fault, separating the South China Continent from the Garze–Litang Ocean. This OCT belt lying on the southeastern edge reacted with the subducted Garze–Litang oceanic lithosphere with subsequently tearing of its subduction front causing the upwelling of asthenosphere. This model plausibly interprets the distinctive magmatism in the study region, where the asthenosphere-sourced mafic lavas are tightly intercalated with normal arc-like igneous rocks