According to a new investigation in the northern Hexi corridor,the remains of two surface rupture zones were discovered on the southern margin fault of the Helishan. One rupture has a length of approximately 7km and t...According to a new investigation in the northern Hexi corridor,the remains of two surface rupture zones were discovered on the southern margin fault of the Helishan. One rupture has a length of approximately 7km and the other 10km. The two surface rupture zones might have been produced by the latest earthquake event. On the surface rupture is continuous scarp and free face caused by the rupture. The scarp is about 1 ～ 1. 5m high and on some sites,nearly up to 2m. According to the OSL results,the latest T1 terrace and higher flood plain forming in 3000a B. P. are dislocated by the fault. The above reveals the rupture age to be later than the T1 terrace. However,in the historical data and earthquake catalogue,we didn't find related information about the fault and surface rupture in this area. The 180 A. D. Biaoshi M8. 0 earthquake and the 756 A. D. Zhangye-Jiuquan M7. 0 earthquake are documented in historical data. It is inferred by textual research that the two earthquakes are related to the northern marginal fault of Yumushan in the south of the basin. Due to a lack of reliable evidence,there are still many arguments on this inferred conclusion. Thus we hold that the two surface rupture zones were produced by one of the two large earthquakes or other unrecorded historical event. The research on the activity and surface rupture of this fault can offer valuable information for the tectonic study and strong earthquake risk estimates of this region in the future.展开更多
地表侵蚀速率是衡量地貌演化的一个重要因子。本研究利用原地宇宙成因核素^(10)Be和26Al对合黎山西南部地表岩石侵蚀速率进行了首次测定。结果显示:约30 ka以来,合黎山西南部的地表岩石侵蚀速率约为24 mm?ka^(-1)。这一结果与已见报道...地表侵蚀速率是衡量地貌演化的一个重要因子。本研究利用原地宇宙成因核素^(10)Be和26Al对合黎山西南部地表岩石侵蚀速率进行了首次测定。结果显示:约30 ka以来,合黎山西南部的地表岩石侵蚀速率约为24 mm?ka^(-1)。这一结果与已见报道的其他基岩侵蚀速率值一致。这一结果与Small et al获得的非干旱地区的基岩侵蚀速率也基本一致,但是显著高于干旱的南极地区和半干旱的澳大利亚。^(10)Be和26Al获得的侵蚀速率的良好一致性表明本研究中所用侵蚀模式的有效性。所得的侵蚀速率小于Palumbo et al测定的合黎山平均流域侵蚀速率(99 mm?ka-1),原因解释尚待更多地点和样品的研究。展开更多
基金supported by the Joint Earthquake Science Foundation (B07007)the Foundation of Base Science of Institute of Geology,CEA (DFIGCEA0607122)the Foundation of State Key Laboratory of Earthquake Dynamics (LED0607)
文摘According to a new investigation in the northern Hexi corridor,the remains of two surface rupture zones were discovered on the southern margin fault of the Helishan. One rupture has a length of approximately 7km and the other 10km. The two surface rupture zones might have been produced by the latest earthquake event. On the surface rupture is continuous scarp and free face caused by the rupture. The scarp is about 1 ～ 1. 5m high and on some sites,nearly up to 2m. According to the OSL results,the latest T1 terrace and higher flood plain forming in 3000a B. P. are dislocated by the fault. The above reveals the rupture age to be later than the T1 terrace. However,in the historical data and earthquake catalogue,we didn't find related information about the fault and surface rupture in this area. The 180 A. D. Biaoshi M8. 0 earthquake and the 756 A. D. Zhangye-Jiuquan M7. 0 earthquake are documented in historical data. It is inferred by textual research that the two earthquakes are related to the northern marginal fault of Yumushan in the south of the basin. Due to a lack of reliable evidence,there are still many arguments on this inferred conclusion. Thus we hold that the two surface rupture zones were produced by one of the two large earthquakes or other unrecorded historical event. The research on the activity and surface rupture of this fault can offer valuable information for the tectonic study and strong earthquake risk estimates of this region in the future.
文摘地表侵蚀速率是衡量地貌演化的一个重要因子。本研究利用原地宇宙成因核素^(10)Be和26Al对合黎山西南部地表岩石侵蚀速率进行了首次测定。结果显示:约30 ka以来,合黎山西南部的地表岩石侵蚀速率约为24 mm?ka^(-1)。这一结果与已见报道的其他基岩侵蚀速率值一致。这一结果与Small et al获得的非干旱地区的基岩侵蚀速率也基本一致,但是显著高于干旱的南极地区和半干旱的澳大利亚。^(10)Be和26Al获得的侵蚀速率的良好一致性表明本研究中所用侵蚀模式的有效性。所得的侵蚀速率小于Palumbo et al测定的合黎山平均流域侵蚀速率(99 mm?ka-1),原因解释尚待更多地点和样品的研究。
