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The SE Tibetan Plateau, tectonically situated in the eastern India-Eurasia oblique convergence zone, has experienced multiple stages of deformation since the Cenozoic. Three major tectonic boundaries—the Ailaoshan-Red River, Chongshan-Lincang-Inthanon, and Gaoligong-Mogok shear zones—delineate the first-order tectonic framework in this region. The most striking structural features in the block interiors are a series of NW- and NE-trending fault systems, such as the Dayingjiang, Longlin-Ruili, Nantinghe, Red River, Weixi-Qiaohou, and Lancang-Genma faults, which have conjugate geometric relationships. In this study, we review these structures' geometric and kinematic characteristics and deformation histories. A synthesis of existing geological observations, geomorphological analysis, and chronological data reveal three major Cenozoic tectonothermal events, including crustal shortening, strike-slip shearing, and kinematic reversal. The boundary structures controlled the tectonic extrusion of plateau material during the early Oligocene-early Miocene. In the mid-late Miocene, NW- and NE-trending fault systems mostly experienced diachronous slip-sense inversions. The onset and spatial trend of regional kinematic reversal are constrained by existing chronologic data. Together with geophysical and geodetic observations, the activity and geodynamic drivers of the major fault systems and regional deformation styles are explored, revealing that the SE Tibetan Plateau underwent a transition from discrete (lateral block extrusion) to diffuse deformation in the mid-late Miocene. The intracontinental crustal deformation and its coupling with dynamic processes at depth during the plateau growth are discussed in the context of the India-Eurasia convergence. [ABSTRACT FROM AUTHOR]

The poorly dated Gonjo (or Gongjue) Basin, located on the intensely deformed Qiangtang terrane of Tibet where it curves around the Eastern Himalaya Syntaxis, preserves a >3000 m thick terrestrial sedimentary sequence that formed during regional crustal shortening. Here, we present a high-resolution magnetostratigraphy, revealing a 69-41.5 Ma age range, providing robust timing of Late Cretaceous to Eocene shortening in central Tibet. Paleomagnetic declinations moreover show that the Gonjo Basin experienced ~30° clockwise rotation since 52 Ma, consistent with models predicting bending of the Qiangtang terrane associated with shearing along the stable South China Block during Tibetan shortening. Our new age results reveal that the Gonjo Basin correlate with the Hoh Xil Basin in that it underwent a major increase in sedimentation rate, first at 69 Ma, then at 52 Ma, likely indicating enhanced shortening rates during these times. Interestingly, these time periods coincide with the rapid acceleration and deceleration of India-Asia convergence, respectively. We tentatively ascribe the 69 Ma event to increased friction driven by rapid Indian plate subduction resulting from a push force in the Indian ocean. The increase of sedimentation rate at 52 Ma coincides with the dramatically slowdown of India, suggesting that the deceleration corresponds to enhanced friction at the India-Asia plate contact, causing Tibetan shortening. We will discuss subduction scenarios that may explain the delay between ~52 Ma Tibetan shortening and recent India-Asia collision estimates of ~58 Ma. [ABSTRACT FROM AUTHOR]

• New high-resolution magnetostratigraphic study constrains the Gonjo Basin from 69 to 41.5 Ma. • Rapid SR and rotation periods suggest pulses of Tibetan crustal shortening at 69-67 Ma and 52-48 Ma. • Tibetan crustal shortening pulses correlate with India-Asia convergence rate. Models that aim to explain the causes of the significant Indian plate motion acceleration around 70 Ma, and the subsequent deceleration around 52 Ma predict different scenarios regarding crustal shortening of the Tibetan Plateau, which can be tested by precisely determining the timing of regional shortening events in Tibet. Here we attempt to determine this timing by presenting a high-resolution magnetostratigraphy of a ∼3.5 km thick sedimentary sequence in the syn-contractional Gonjo Basin, east-central Tibet. We successfully isolated the primary remanence as confirmed by positive fold and reversal tests. Correlation to the geomagnetic polarity time scale reveals a 69–41.5 Ma age for the Gonjo Basin sedimentary succession. Average sedimentation rates indicate two episodes of enhanced sediment accumulation rate at 69–64 Ma and 52–48 Ma, which coincide with periods of vertical axis rotation recorded in the basin fill. This coincidence suggests a tectonic cause, which given regional structures we interpret as shortening pulses. Our results are similar to those from basins elsewhere in southern, central and northern Tibet, suggesting plateau-wide, synchronous shortening pulses at ∼69–64 Ma and ∼52–48 Ma. These pulses are synchronous with major acceleration and deceleration of India-Asia convergence rate, suggesting that both the acceleration and deceleration of India-Asia convergence may be associated with enhanced crustal deformation in Tibet, which we use to evaluate previous dynamic models explaining the Indian plate motion changes and India-Asia collision processes. [ABSTRACT FROM AUTHOR]