新疆阜康断裂带中段大黄山探槽晚第四纪沉积物的光释光测年

OPTICALLY STIMULATED LUMINESCENCE DATING OF LATE QUATERNARY SEDIMENTS AT DAHUANGSHAN TRENCH ALONG FUKANG FAULT ZONE,XINJIANG

对新疆阜康断裂带中段大黄山探槽的23个样品进行了细颗粒石英光释光简单多片再生法测年。样品LED12-297等效剂量的预热坪实验结果表明,在220~260℃的预热温度范围内均能获得基本一致的等效剂量值。测年结果显示,样品年龄与地层的时序性一致,表明阜康断裂带为全新世活动断层。根据探槽剖面错断的最新地层及其上覆地层的光释光年龄判断,断层的最新1次古地震事件发生在距今(1.90±0.14)ka^(3.47±0.17)ka。根据地层的垂直位移量与测年结果得到,阜康断层大黄山段的垂直滑动速率为0.17mm/a。

In the study of active faults,obtaining the exact age of the strata is an extremely important step.The optically stimulated luminescence （OSL）dating method,a technique closely related to thermoluminescence（TL）,is developing extensively on dating for Quaternary sediments in recent years.Fukang Faults,located in the eastern Tianshan arc nappe tectonic zone,are typical arc thrusting faults.The dating samples collected from Dahuangshan trench of Fukang Fault zone are used to determine the activity of the fault.23 OSL samples were obtained from the trench.We selected 4～ 1 1μm fine-grained quartz through pre-treatment process and analysed them by using sensitivitycorrected multiple aliquot regenerative-dose （SMAR） protocol.Equivalent dose （De） preheat plateau test is an often used approach to determine the appropriate preheat temperature in OSL dating.The preheat plateau test of sample LED12-297 shows that 220～260℃ are the appropriate preheat plateau temperature regions to get fundamental De.The dating results show that the OSL stratigraphic ages of the samples are consistent with stratigraphic sequence and that Fukang Fault is a Holocene active fault.It is found that the last event of Fukang Fault occurred （1.90±0.14）ka to （3.47±0.17）ka ago.The OSL ages and their related stratigraphic vertical displacement are used to calculate the vertical slip rate of the fault,which is 0.17mm/a.