Rizza et al_2019_correctedMS_submitted.pdf (3.23 MB)
Rate of slip from multiple Quaternary dating methods and paleoseismic investigations along the Talas-Fergana Fault: tectonic implications for the Tien-Shan Range
journal contributionposted on 2019-07-03, 11:37 authored by M Rizza, K Abdrakhmatov, RT Walker, R Braucher, V Guillou, A Carr, G Campbell, D McKenzie, J Jackson, G Aumaitre, DL Bourles, K Keddadouche
The ~400 km-long Talas-Fergana fault (TFF) is one of a series of major right-lateral strike-slip faults that cross the Tien Shan Range. This fault has been recognized as active in the late-Holocene and accommodates part of the deformation induced by the ongoing Indo-Asian collision. The kinematics and the role of this strike-slip fault are poorly understood with no large earthquakes reported in the instrumental or historical catalogs, and no well-constrained geological slip-rate estimates. Here we used high-resolution satellite imagery to present a first detailed analysis of the fault segmentation. We identified nine geometric segments based on strike variations for the TFF. Along the Kyldau segment, through morphological analyses of an offset alluvial fan and the application of multiple dating methods (10Be, 26Al, 36Cl, luminescence and radiocarbon), we calculated a late Quaternary slip rate ranging from 2.2 to 6.3 mm/yr. This rate is higher than the geodetic measurements, but the discrepancy can be partly explained if the TFF accommodates shortening by counterclockwise rotation around a vertical axis. Paleo-earthquakes identified by trenching indicate that at least two primary surface ruptures (and possibly a third) occurred in the past 3800 years, and that no large earthquake has ruptured the Kyldau segment since at least 420 years BP (possibly within the last 2700 years), making this fault segment a potential candidate to generate an earthquake with M>7 in the near future.
This research was partly run under the Earthquakes without Frontiers project, funded by NERC and ESRC (grant code: EwF_NE/J02001X/1_1). This work was supported by the NERC Radiocarbon Facility NRCF010001 (allocation number 1763.1013). We are grateful to the expertise of Dr Xiaomei Xu at the Keck C cycle AMS Lab, University of California, Irvine for radiocarbon analyses of TAL-13 TR2. This work was supported by public funds received in the framework of GEOSUD, a project (ANR-10-EQPX-20) of the program “Investissements d’Avenir” managed by the French National Research Agency (ANR). Pléiades images provided by the French Space Agency CNES in the framework of ISIS Programme. We are grateful to Jules Fleury who has taken the aerial pictures of the Talas991 Fergana Fault using a drone in summer 2017. The cosmogenic nuclides dating was supported by the National Program TelluS-ALEAS (SHEAR project) of CNRS/INSU. The cosmogenic measurements were performed at the ASTER AMS National Facility (CEREGE, Aix-en994 Provence), which is supported by the INSU/CNRS, the ANR through the "Projets thématiques d’excellence" program for the "Equipements d’excellence" ASTER-CEREGE action and IRD. We would like to thank I. Schimmelpfennig and L. Benedetti for fruitful discussions in the use and calculation of 36 997 Cl. We thank all those involved in the 2013 and 2017 field998 seasons, in particular Anaigul for her efficient camp management, our drivers Mokhtar, Sogon and Ivan and Azat Moldobayev, Sultan Baikulov and Erkin Rahimdinov for their field assistance. K. Blisniuk, J.A. Thompson Jobe, Taylor Schildgen and J. Bruce H. Shyu provided constructive reviews and comments that helped improve the original manuscript.
Author affiliation/Organisation/COLLEGE OF SCIENCE AND ENGINEERING/School of Geography, Geology and the Environment/Physical Geography
- AM (Accepted Manuscript)