EGU2020-10132
https://doi.org/10.5194/egusphere-egu2020-10132
EGU General Assembly 2020
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

Investigating lateral variations in the kinematics of active deformation along the Western Kunlun mountain front (Xinjiang, China): structural and morphological analysis of the Hotan anticline

Christelle Guilbaud1, Martine Simoes1, Laurie Barrier1, Jérôme Van der Woerd2, Guillaume Baby1, Haibing Li3, Jiawei Pan3, Paul Tapponnier4, and Déborah Harlet1,5
Christelle Guilbaud et al.
  • 1Université de Paris, Institut de physique du globe de Paris, CNRS, F-75005 Paris, France
  • 2Université de Strasbourg, CNRS, Institut de Physique du Globe de Strasbourg UMR 7516, F-67000, Strasbourg, France
  • 3Institute of Geology, Chinese Academy of Geological Science, Beijing, China
  • 4now at Institute of Crustal Dynamics, China Earthquake Administration, Beijing, China
  • 5Université de Grenoble

The Western Kunlun Range is a mountain range located at the northwestern boundary of the Tibetan Plateau, facing the Tarim Basin. Our previous combined structural and morphological investigations of the mountain front, nearby the city of Pishan where a Mw 6.4 earthquake occurred in 2015, revealed the existence of a duplex uplifting Cenozoic strata, in which only the most frontal blind ramp is presently active and slips at a probable rate of 2 to 2.5 mm/yr. Located ~100 km further east along the mountain front, the Hotan anticline seems to present a different structure from surface geology, as older strata from Mesozoic and Paleozoic outcrop. Additionally, some authors proposed that the deformation would be here accommodated by a large blind basement thrust sheet, in clear contrast with the duplexes documented further west.

To further document potential lateral variations in the structural style and how they may affect the kinematics of active deformation along the mountain front of the Western Kunlun, we carry out a structural and morphological analysis of the Hotan anticline. We build structural cross-sections based on seismic reflection profiles, and calculate the incremental uplift recorded by dated fluvial terraces to quantify shortening rates over the last ~300 kyr. Our analysis reveals that a duplex structure, located below the basement thrust sheet, presently accommodates active deformation at a rate of 0.5 to 2.5 mm/yr, with a preferred rate of ~1.6 to 2.3 mm/yr. In more detail, uplifted terraces reveal that all ramps of the duplex are active in the case of the Hotan anticline, while only the most frontal ramp is documented as active in the case of the Pishan anticline further west. These results indicate that the style and rate of active shortening are rather homogeneous all along the mountain front, in contrast with the first impression provided by surface geology. Moreover, the discrepancy between surface geology and active morphology reveals progressive structural changes over geological times, from a blind basement ramp to duplexes. However, in the details, active deformation still remains segmented as its partitioning on the various ramps of the duplexes is variable along strike.

How to cite: Guilbaud, C., Simoes, M., Barrier, L., Van der Woerd, J., Baby, G., Li, H., Pan, J., Tapponnier, P., and Harlet, D.: Investigating lateral variations in the kinematics of active deformation along the Western Kunlun mountain front (Xinjiang, China): structural and morphological analysis of the Hotan anticline, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10132, https://doi.org/10.5194/egusphere-egu2020-10132, 2020.