Because of the significance to the formation and evolution of the Tibetan plateau, the displacement and slip rate of the Altyn Tagh fault have been topics full of disputation. Scientists who hold different opinions on...Because of the significance to the formation and evolution of the Tibetan plateau, the displacement and slip rate of the Altyn Tagh fault have been topics full of disputation. Scientists who hold different opinions on the evolution of Tibet insist on different slip rates and displacements of the fault zone. In the article, study is focused on the late Quaternary slip rate of the Altyn Tagh fault west of the Cherchen River (between 85°E and 85°45’E). On the basis of high resolution SPOT images of the region, three sites, namely Koramlik, Aqqan pasture and Dalakuansay, were chosen for field investigation. To calculate the slip rate of the fault, displacement of terraces was measured on SPOT satellite images or in situ during fieldwork and thermo-luminescence (TL) dating method was used. To get the ages of terraces, samples of sand were collected from the uppermost sand beds that lie just under loess. The method for calculating slip rate of fault is to divide the displacement of terrace risers by the age of its neighboring lower terrace. The displacement of rivers is not considered in this article because of its uncertainties. At Koramlik, the slip rate of the Altyn Tagh fault is 11.6±2.6mm/a since 6.02±0.47ka B.P and 9.6±2.6mm/a since 15.76±1.19ka B.P. At Aqqan pasture, about 30km west of Koramlik, the slip rate is 12.1±1.9mm/a since 2.06±0.16 ka B.P. At Dalakuansayi, the slip rate of the fault is 12.2±3.0mm/a since 4.91±0.39ka B.P. Hence, we get the average slip rate of 11.4±2.5mm/a for the western part of the Altyn Tagh Fault since Holocene. This result is close to the latest results from GPS research.展开更多
By analyzing high-resolution SPOT images and in combination with fieldwork and chronometry, three typical fault-offset sites on the south-middle Altyn Tagh strike-slip fault were studied to obtain the sinistral horizo...By analyzing high-resolution SPOT images and in combination with fieldwork and chronometry, three typical fault-offset sites on the south-middle Altyn Tagh strike-slip fault were studied to obtain the sinistral horizontal slip rate of the fault. At Annanba, the left-lateral strike-slip rate on a branch of the south Altyn Tagh fault is 7.5±1.7 mm/a since 9.36±0.73ka BP. At Seven Spring, the fault has four branches and the left-lateral strike-slip rate on one of them is 2.3±0.5mm/a since 13.86±1.07ka BP, and it is deduced that the total slip-rate of all the four branches is 6.9±1.5～ 9.2±2.0 mm/a since Holocene. At Yuemakeqi, the left-lateral strike-slip rate of the fault is 10.6±3.0mm/a since 4.73±0.38 ka BP. A slip-rate of 7～11mm/a on the middle segment of the Altyn Tagh fault (between 88°30’E and 93°05’E) since Holocene can be deduced from the three sites mentioned above and the result is similar to the latest GPS observation.展开更多
文摘Because of the significance to the formation and evolution of the Tibetan plateau, the displacement and slip rate of the Altyn Tagh fault have been topics full of disputation. Scientists who hold different opinions on the evolution of Tibet insist on different slip rates and displacements of the fault zone. In the article, study is focused on the late Quaternary slip rate of the Altyn Tagh fault west of the Cherchen River (between 85°E and 85°45’E). On the basis of high resolution SPOT images of the region, three sites, namely Koramlik, Aqqan pasture and Dalakuansay, were chosen for field investigation. To calculate the slip rate of the fault, displacement of terraces was measured on SPOT satellite images or in situ during fieldwork and thermo-luminescence (TL) dating method was used. To get the ages of terraces, samples of sand were collected from the uppermost sand beds that lie just under loess. The method for calculating slip rate of fault is to divide the displacement of terrace risers by the age of its neighboring lower terrace. The displacement of rivers is not considered in this article because of its uncertainties. At Koramlik, the slip rate of the Altyn Tagh fault is 11.6±2.6mm/a since 6.02±0.47ka B.P and 9.6±2.6mm/a since 15.76±1.19ka B.P. At Aqqan pasture, about 30km west of Koramlik, the slip rate is 12.1±1.9mm/a since 2.06±0.16 ka B.P. At Dalakuansayi, the slip rate of the fault is 12.2±3.0mm/a since 4.91±0.39ka B.P. Hence, we get the average slip rate of 11.4±2.5mm/a for the western part of the Altyn Tagh Fault since Holocene. This result is close to the latest results from GPS research.
文摘By analyzing high-resolution SPOT images and in combination with fieldwork and chronometry, three typical fault-offset sites on the south-middle Altyn Tagh strike-slip fault were studied to obtain the sinistral horizontal slip rate of the fault. At Annanba, the left-lateral strike-slip rate on a branch of the south Altyn Tagh fault is 7.5±1.7 mm/a since 9.36±0.73ka BP. At Seven Spring, the fault has four branches and the left-lateral strike-slip rate on one of them is 2.3±0.5mm/a since 13.86±1.07ka BP, and it is deduced that the total slip-rate of all the four branches is 6.9±1.5～ 9.2±2.0 mm/a since Holocene. At Yuemakeqi, the left-lateral strike-slip rate of the fault is 10.6±3.0mm/a since 4.73±0.38 ka BP. A slip-rate of 7～11mm/a on the middle segment of the Altyn Tagh fault (between 88°30’E and 93°05’E) since Holocene can be deduced from the three sites mentioned above and the result is similar to the latest GPS observation.
