Sedimentary basin evolution and its implications for outward expansion of the northeastern Tibetan Plateau: Insights from the Tongxin Basin, China
Abstract The basin history of the northeastern Tibetan Plateau provides an ideal record for understanding the tectonic evolution of the plateau. We present high-resolution magnetostratigraphy and cosmogenic 10Be/26Al burial chronology from the Tongxin Basin in the Arcuate Ranges area in the northeastern Tibetan Plateau and reconstruct a long depositional history ranging from >21.7 to 4.6 Ma. Our new chronologic data suggest that a broad N-S-trending elongated basin existed during the Late Oligocene-Early Miocene (>21.7–16.5 Ma). WNW-trending faulting initiated at ca. 16.5 Ma and resulted in the formation of some fault-bounded basins outward from the western margin of the broad basin, but did not strongly affect the deposition within the basin region. Subsequently, intense northeastward compression elevated both WNW- and NWN-trending mountain ranges at ca. 7.6 Ma. Thrust-induced surface uplift elevated basin sediments and formed piggy-back basins in the hanging-wall blocks, reflecting the northeastward expansion of the northeastern Tibetan Plateau.