Along-strike variation in the activation timing of the Cona-Woka rift in Southeastern Tibet linked to complex slab deformation

The geodynamic drivers behind the formation of the north-south trending rifts (NSTRs) in southern Tibet remain critical for understanding the Cenozoic evolution of the Tibetan Plateau. The along-strike spatiotemporal characteristics of individual rift systems is one of the most debated topics. This study investigates the formation and geodynamics of the Cona-Woka rift, the easternmost rift in southern Tibet. To constrain the timing of its initiation, we present new thermochronological data, including apatite and zircon (UTh)/He and biotite ⁴⁰Ar/³⁹Ar ages, from northern and central segments of the rift. Pecube modeling and thermal history analysis indicate that later phases of exhumation on both segments are associated with rift activation, revealing initiation timing of ∼6.68 for the northern segment and ∼7.4–5.0 Ma (most likely ∼5.6–5.0 Ma) for the central. Compiling previous constraints on the southern segment, the results indicate a southward-younging pattern from ∼6.68 to 2.3 Ma along the rift. Compiled constraints on NSTRs activation reveal contrasting initiation trends: near-synchronous initiation in the western rifts, northward younging in the Yadong-Gulu rift, and southward younging in the Cona-Woka rift. These patterns are linked to changes in slab dynamics during eastward detachment. Specifically, the northeastward shift of slab detachment beneath the Yadong-Gulu rift coincides with an observed abrupt slowdown in both rifting development and magmatism, while longitudinal slab tearing beneath the Cona-Woka rift may drive its southward younging trend. This study highlights the complexity of slab deformation, from northeastward to southward tearing beneath two easternmost rifts, in controlling the evolution of NSTRs.