Paleomagnetism and anisotropy of magnetic susceptibility of the Tertiary Janggalsay section (southeast Tarim basin): Implications for Miocene tectonic evolution of the Altyn Tagh Range

- The measured Janggalsay section spans a time interval of ~ 22-11 Ma.
- A significant transition of rotation sense occurred around 17-15 Ma.
- The increased uplift of the Altyn Tagh Range was initiated since 16 Ma.

Despite receiving considerable attention, the nature and timing of Cenozoic tectonic evolution of the Altyn Tagh Fault (AFT) remain highly debated. Here we conducted detailed magnetostratigraphy and anisotropy of magnetic susceptibility (AMS) studies on the Cenozoic Janggalsay section, southeast Tarim basin. Magnetostratigraphy indicates that the measured Janggalsay section spans a time interval of ~ 22-11 Ma. The magnetic declination data suggest that the Janggalsay site has rotated significantly counterclockwise (17.2° ± 8.5°) from ~ 22 to 17-15 Ma, while the rotation has terminated from 17-15 to 11 Ma. The results are consistent with a two-stage tectonic model for the ATF, with a phase of large magnitude strike-slip motion along the ATF from the Oligocene to Middle Miocene and a second phase of lower amounts of strike-slip motion and more widespread contraction since the Middle Miocene. The AMS fabric data and sedimentology of the Janggalsay section likely indicate the rapid rock uplift of the Altyn Tagh Range since 16 Ma.