Journal of Geophysical Research: Solid Earth

Magnetostratigraphy of Cenozoic sediments from the Xining Basin: Tectonic implications for the northeastern Tibetan Plateau

Authors

  • Shuang Dai,

    1. Key Laboratory of Western China's Environmental Systems, Ministry of Education of China and College of Resources and Environment, Lanzhou University, Gansu, China
    2. Institute of Tibetan Plateau Research, Chinese Academy of Science, Beijing, China
    Search for more papers by this author
  • Xiaomin Fang,

    1. Key Laboratory of Western China's Environmental Systems, Ministry of Education of China and College of Resources and Environment, Lanzhou University, Gansu, China
    2. Institute of Tibetan Plateau Research, Chinese Academy of Science, Beijing, China
    Search for more papers by this author
  • Guillaume Dupont-Nivet,

    1. Paleomagnetic Laboratory, Faculty of Science, Utrecht University, Utrecht, Netherlands
    Search for more papers by this author
  • Chunhui Song,

    1. Key Laboratory of Western China's Environmental Systems, Ministry of Education of China and College of Resources and Environment, Lanzhou University, Gansu, China
    Search for more papers by this author
  • Junping Gao,

    1. Key Laboratory of Western China's Environmental Systems, Ministry of Education of China and College of Resources and Environment, Lanzhou University, Gansu, China
    Search for more papers by this author
  • Wout Krijgsman,

    1. Paleomagnetic Laboratory, Faculty of Science, Utrecht University, Utrecht, Netherlands
    Search for more papers by this author
  • Cor Langereis,

    1. Paleomagnetic Laboratory, Faculty of Science, Utrecht University, Utrecht, Netherlands
    Search for more papers by this author
  • Weilin Zhang

    1. Key Laboratory of Western China's Environmental Systems, Ministry of Education of China and College of Resources and Environment, Lanzhou University, Gansu, China
    Search for more papers by this author

Abstract

[1] The Xining subbasin of the Longzhong basin holds the longest continuous Cenozoic stratigraphic record at the margin of the northeastern Tibetan Plateau. Despite a rich biostratigraphic content (including the Xiejia mammal fauna), the tectonic evolution of the basin is largely unconstrained. In this study we present stratigraphic, biostratigraphic, and magnetostratigraphic results that provide a basis for reconstructing the Cenozoic tectonic evolution of the Xining basin with respect to adjacent regions of the northeastern Tibetan Plateau. Magnetostratigraphic analysis from three red bed sections in the Xining basin indicates continuous deposition at low and nearly constant accumulation rates (average 2.2 cm/kyr) from 52.0 to 17.0 Ma. We interpret this result to indicate that no major regional tectonic event implying large sediment accumulation variations has affected the Xining basin deposition during this considerable time window. In detail, accumulation rate variations outline a three-stage evolution with 1.8 cm/kyr from 52.0 Ma to 34.5 Ma, 4.1 cm/kyr from 34.5 to 31.0 Ma, and 2.3 cm/kyr from 31.0 to 17.0 Ma. The second-order increase between 34.5 and 31.0 Ma can be interpreted to result from either a distal tectonic event or to be of climatic origin. Although the region was tectonically quiescent for much of the Cenozoic, tectonic activity occurred during basin initiation (or reactivation) at circa 55.0–52.5 Ma and during intense basin deformation after 17.0 Ma.

Ancillary