The Heterogeneous Mantle Transition Zone Beneath the Tarim Craton and Adjacent Region: Insight Into the Thermal Processes by the Cenozoic Reactivation

Abstract The Tarim craton of central Asia, a stable continental block sandwiched between the Tianshan orogen and the Tibetan Plateau, has experienced significant tectonic reactivation due to the Cenozoic India‐Eurasia collision. Previous tomographic studies have identified lithospheric subduction along the Tibet‐Tarim and Tianshan‐Tarim boundaries. However, it is unclear what the fate of the subducted lithosphere is, and how much of it is subducted or detached into the mantle transition zone (MTZ). To investigate these issues, we use the recently deployed portable seismic array inside the Tarim Basin, along with stations in the surrounding regions, to estimate the structure of MTZ with receiver function analysis. Our key findings include: (a) An anomalously thickened MTZ beneath eastern Tarim, confirmed through systematic sedimentary and crustal correction tests to represent a detached cold lithospheric slab rather than near‐surface artifacts; (b) A locally thinned MTZ (∼6 km thinner than the global average) beneath central Tarim, possibly due to hot mantle upwelling potentially triggered by peripheral slab subduction; (c) Along the Tianshan orogen, MTZ thickness variations (thin in western vs. thick in central sections) resemble previous observations, while contrasting MTZ characteristics between Pamir (relatively thin) and Hindu Kush (thickened) regions suggest different slab penetration depths beneath these two regions.