摘要
在青藏高原东北缘海原断裂带刺儿沟古地震剖面上不仅保存了地震活动的崩积楔遗迹,还发现多层炭屑以及与人类活动有关的铁渣、陶片等遗物,文中运用14C测年法和经红外释光照射后的绿光释光测年法(Post-IR OSL)分别对剖面上的炭屑、烘烤黏土、沉积物等样品进行年龄测定和比对,获得了各炭屑层和人类活动遗迹的年代。测定的人类活动遗迹年代与海原周缘历史记载的强震发生时间序列比对结果表明,刺儿沟人类活动遗迹的形成可能与历史地震无关,过去以炭屑年代作为地层年代来限定古地震发生的时代,建立的古地震事件时序的结果可能不正确,上述工作为进一步研究海原断裂带的强震复发规律和海原地区考古提供了重要的基础资料。
A trench across the Haiyuan active fault zone reveals many layers of charcoal with human bone, scruff, ceramic pieces or hearth ruin as well as three colluvial wedges in Ciergou paleoearhquake profile which is located on the northern margin of Tibet Plateau. It is important to distinguish these historical remnants as whether or not they are the product of earthquake. 12 radiocarbon dates and 6 post-IR OSL dates were determined from charcoal samples corresponding to human activity and sediments or burned clay samples around charcoal samples respectively. The ages of charcoal which mainly range from 1000 to 2400a BP were sharply younger than the age of strata. The age of living site inferred from charcoal with scruff, ceramic pieces, does not agree with timetable of the historical strong earthquake record. This evidence could indicate that the living site ruins is not the product of historical earthquake. The penultimate paleoearthquake prior to 1920 AD earthquake occurred in 21.8 14.5ka which was constrained by post-IR OSL dates. These dates would help to better understand the strong earthquake recurrence interval of the Haiyuan active fault zone.
出处
《地震地质》
EI
CSCD
北大核心
2005年第4期578-585,共8页
Seismology and Geology
基金
国家自然科学基金(40202015)
地震科学联合基金重点课题(201018)共同资助。
