Stable Rate of Slip Along the Karakax Section of the Altyn Tagh Fault from Observation of Interglacial and Postglacial Offset Morphology and Surface Dating

Digital elevation maps obtained using TanDEM‐X and Pleiades data combined with newly obtained surface age estimates using cosmogenic radionuclide (CRN) and optically simulated luminescence (OSL) methods are used to quantify the slip rate along the western section of the Altyn Tagh Fault in southern...

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Bibliographic Details
Published in:Journal of geophysical research. Solid earth 2020-05, Vol.125 (5), p.n/a
Main Authors: Peltzer, Gilles, Brown, Nathan D., Mériaux, Anne‐Sophie, van der Woerd, Jerome, Rhodes, Edward J., Finkel, Robert C., Ryerson, Frederick J., Hollingsworth, James
Format: Article
Language:English
Subjects:
Age
alluvial fan
Alluvial fans
Altyn Tagh Fault
Canyons
Clustering
cosmogenic radionuclide
Dating
Degradation
Diffusion
Diffusion rate
Digital mapping
Earth Sciences
Escarpments
Fault scarps
Geological time
geomorphology
Geophysics
GEOSCIENCES
Holocene
Interglacial periods
Morphology
Mountains
Offsets
optically simulated luminescence
Radioisotopes
Sciences of the Universe
Slip
Tectonics
Terraces
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Summary:Digital elevation maps obtained using TanDEM‐X and Pleiades data combined with newly obtained surface age estimates using cosmogenic radionuclide (CRN) and optically simulated luminescence (OSL) methods are used to quantify the slip rate along the western section of the Altyn Tagh Fault in southern Xinjiang. The reconstruction of the conical shape of massive alluvial fans inferred to be from the Eemian (115±7 ka) from CRN dating shows consistent left‐lateral offsets of 300±20 m, yielding a slip rate of 2.6±0.3 mm/year. Successive episodes of incision have left cut terraces inset in wide canyons, 10–25 m below the fans' surface. The incision was followed by the deposition of a broad terrace of early Holocene age, which is reincised by modern stream channels. Near the village of Shanxili, a 200 m wide valley is partially dammed by a shutter ridge displaced by the fault. A fill terrace deposited upstream from the ridge has an OSL age of 8.8±0.6 ka. The 23±2 m offset of the riser incising the terrace indicates a minimum postdepositional movement on the fault, yielding a Holocene rate of 2.6±0.5 mm/year, consistent with the 115‐ka average slip rate. Scarp degradation analysis using mass diffusion reveals a nonlinear relationship between fault displacement and degradation coefficient along the progressively exposed fault scarp, a pattern suggesting either seismic clustering or variable diffusion rate since the Eemian. Together with the Gozha Co‐Longmu Co fault to the south, the Karakax section of the Altyn Tagh Fault contributes to the eastward movement of the western corner of Tibet. Key Points Offset alluvial fans in Karakax Valley record sinistral displacement history along Altyn Tagh Fault Terrace ages determined by OSL and CRN dating methods yield fault stable slip rate of 2.6 mm/a over 115 ka Seismic clustering or variable erosion rate linked to climate may explain observed fault scarp degradation variations
ISSN:2169-9313
2169-9356
DOI:10.1029/2019JB018893