Rate of Slip From Multiple Quaternary Dating Methods and Paleoseismic Investigations Along the Talas‐Fergana Fault: Tectonic Implications for the Tien Shan Range

The ~400‐km‐long Talas‐Fergana Fault 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...

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Bibliographic Details
Published in:Tectonics (Washington, D.C.) D.C.), 2019-07, Vol.38 (7), p.2477-2505
Main Authors: Rizza, M., Abdrakhmatov, K., Walker, R., Braucher, R., Guillou, V., Carr, A. S., Campbell, G., McKenzie, D., Jackson, J., Aumaître, G., Bourlès, D. L., Keddadouche, K.
Format: Article
Language:English
Subjects:
active faults
Alluvial fans
Beryllium 10
Continental interfaces, environment
cosmogenic dating
Deformation
Earth Sciences
Earthquakes
Environmental Sciences
Fault lines
Geodetic measurements
Geomorphology
Global Changes
Holocene
Identification
Imagery
Kinematics
luminescence dating
Methods
paleoseismology
Quaternary
Radiocarbon dating
Satellite imagery
Sciences of the Universe
Seismic activity
Spaceborne remote sensing
tectonic geomorphology
Tectonics
Tien Shan
Trenching
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Summary:The ~400‐km‐long Talas‐Fergana Fault 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 Talas‐Fergana Fault. 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/year. This rate is higher than the geodetic measurements, but the discrepancy can be partly explained if the Talas‐Fergana Fault accommodates shortening by counterclockwise rotation around a vertical axis. Paleoearthquakes identified by trenching indicate that at least two primary surface ruptures (and possibly a third) occurred in the past 3,800 years, and that no large earthquake has ruptured the Kyldau segment since at least 420 years B.P. (possibly within the last 2,700 years), making this fault segment a potential candidate to generate an earthquake with M > 7 in the near future. Key Points The 400‐km‐long Talas‐Fergana Fault (TFF) can be subdivided into nine geometric segments A first geological slip rate of 2.2–6.3 mm/year is constrained by geochronological dating of an alluvial fan The TFF may be associated with counterclockwise rotations around a vertical axis. This model reconciles geodetic and geologic slip rates
ISSN:0278-7407
1944-9194
DOI:10.1029/2018TC005188