Magnetostratigraphy of Cenozoic deposits in the western Qaidam Basin and its implication for the surface uplift of the northeastern margin of the Tibetan Plateau

- Huatugou section is composed of Shangganchaigou, Xiayoushashan and Shangyoushashan Formations.
- The Xiayoushashan Formation is assigned to early-middle Miocene.
- Accumulation rates in the Qaidam Basin were higher than that in northeastern margin of the Tibetan Plateau since Oligocene.
- Accumulation rate increasing since ∼15 Ma in basin suggest significant deformations around the basin.

Thick Cenozoic deposits in the northwestern Qaidam Basin record erosion of the Altyn Tagh and high terrain west of that basin and presumably the concurrent growth of the northeastern Tibetan Plateau. A detailed magnetostratigraphic study of the Huatugou section, northwestern Qaidam basin, reveals that this section spans the period from ∼30 to ∼11 Ma. Magnetostratigraphic and sedimentological studies indicate that the accumulation rate abruptly increased near ∼15 Ma. The acceleration in sedimentation rate suggests enhanced tectonic deformation in the Qaidam basin since 15 Ma that may have begun simultaneously with accelerated deformation along the Altyn Tagh, Kunlun, and Haiyuan faults, which contributed to the growth history of the Qaidam basin and its surroundings since ∼15 Ma.