Faulted landforms, slip-rate, and tectonic implications of the eastern Lenglongling fault, northeastern Tibetan Plateau
KAUST DepartmentPhysical Science and Engineering (PSE) Division
KAUST Grant NumberBAS/1/1339-01-01
Embargo End Date2024-01-10
Permanent link to this recordhttp://hdl.handle.net/10754/675037
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AbstractThe Lenglongling fault (LLLF) is an important part of the Qilian-Haiyuan fault (QHF) zone along the NE Tibetan Plateau. The Jinqianghe fault (JQHF) branches off of the LLLF and forms a fault junction that separates middle and eastern LLLF. Currently, it is not well understood how/if strain from the LLLF is transmitted to the JQHF over geologic time scales and how seismically active the eastern section of the LLLF is. Recent studies indicate that the 1927 M8 Gulang earthquake ruptured the middle LLLF and propagated eastward onto the eastern LLLF instead of propagating onto the JQHF. To assess if this concurrent rupture of middle and eastern LLLF is (or might be) a common phenomenon, we measured the Holocene slip-rate at the Huoshaotai site, east of the LLLF – JQHF junction, to compare it with known rates from the middle LLLF. Using displaced geomorphic markers and radiocarbon dating, we determined a Holocene left-lateral slip-rate of 6.0 ± 0.8 mm/a for the eastern LLLF. This rate is only slightly below the consensus slip-rate for the middle LLLF (6.6 ± 0.3 mm/a; 6.4 ± 0.7 mm/a), suggesting a gradual strain transfer and similar seismic activity for both sections. Paleoseismic evidence further suggests that at least three preceding earthquakes may have ruptured both sections simultaneously during the Holocene, indicating that concurrent failure of both sections, as in 1927, may not be uncommon. Concurrent failure of middle LLLF and JQHF is however not reported. Hence, it appears that LLLF and JQHF act as independent seismo-tectonic entities, without substantial strain transfer or concurrent seismic activity. These observations contribute to a better understanding of the QHF zone and the potential for multi-fault rupture along it.
CitationGao, F., Zielke, O., Han, Z., Guo, P., Gai, H., & Dai, C. (2022). Faulted landforms, slip-rate, and tectonic implications of the eastern Lenglongling fault, northeastern Tibetan Plateau. Tectonophysics, 823, 229195. doi:10.1016/j.tecto.2021.229195
SponsorsWe thank Jinrui Liu for sharing the Monte Carlo codes. This work was funded by the National Natural Science Foundation of China (42002231) and the National Nonprofit Fundamental Research Grant of China, Institute of Geology, China Earthquake Administration (IGCEA2022, IGCEA1702) and the Special Project on Earthquake Research, the China Active Fault Survey Project—The South-North Seismic Zone Northern Segment (201408023). Further funding support came from King Abdullah University of Science and Technology (KAUST), Grant BAS/1/1339-01-01. There are no financial conflicts of interests for any author. The topographic data presented are archived in the Mendeley Data repository (Topographic data used in the paper of “Topographic data eastern LLLF”, Mendeley Data, v1, http://dx.doi.org/10.17632/49h6yct4n3.1).