SLIP RATES OF THE RIYUE MT. FAULT AT DEZHOU SEGMENT SINCE LATE PLEISTOCENE |
| |
| Authors: | LI Zhi-min SU Peng HUANG Shuai-tang TIAN Qin-jian YIN Xiang |
| |
| Affiliation: | 1. Qinghai Earthquake Administration, Xining 810001, China;
2. Key Laboratory of Active Tectonics and Volcano, Institute of Geology, China Earthquake Administration, Beijing 100029, China;
3. Earthquake Administration of Xinjiang Uygur Autonomous Region, Urumqi 830011, China;
4. Key Laboratory of Earthquake Prediction, Institute of Earthquake Science, China Earthquake Administration, Beijing 100036, China |
| |
| Abstract: | The Riyue Mt. Fault is a secondary fault controlled by the major regional boundary faults (East Kunlun Fault and Qilian-Haiyuan Fault). It lies in the interior of Qaidam-Qilianshan block and between the major regional boundary faults. The Riyue Mt. fault zone locates in the special tectonic setting which can provide some evidences for recent activity of outward extension of NE Tibetan plateau, so it is of significance to determine the activity of Riyue Mt. Fault since late Pleistocene to Holocene. In this paper, we have obtained some findings along the Dezhou segment of Riyue Mt. Fault by interpreting the piedmont alluvial fans, measuring fault scarps, and excavating trenches across the fault scarp. The findings are as follows:(1) Since the late Pleistocene, there are an alluvial fan fp and three river terraces T1-T3 formed on the Dezhou segment. The abandonment age of fp is approximately (21.2±0.6) ka, and that of the river terrace T2 is (12.4±0.11) ka. (2) Since the late Pleistocene, the dextral strike-slip rate of the Riyue Mt. Fault is (2.41±0.25) mm/a. In the Holocene, the dextral strike-slip rate of the fault is (2.18±0.40) mm/a, and its vertical displacement rate is (0.24±0.16) mm/a. This result indicates that the dextral strike-slip rate of the Riyue Mt. Fault has not changed since the late Pleistocene. It is believed that, as one of the dextral strikeslip faults, sandwiched between the the regional big left-lateral strike-slip faults, the Riyue Mt. Fault didn't cut the boundary zone of the large block. What's more, the dextral strike-slip faults play an important role in the coordination of deformation between the sub-blocks during the long term growth and expansion of the northeast Tibetan plateau. |
| |
| Keywords: | Riyue Mt Fault activity rates Dezhou segment geomorphic markers Late Pleistocene |
|
|
