唐山孙家楼探槽光释光测年及其对古地震事件的指示意义  

OPTICAL DATING OF SUNJIALOU TRENCH IN TANGSHAN AND ITS SIGNIFICANCE FOR PALAEOSEISMIC EVENTS

作　　者：赵俊香[1,2] 江娃利[1] 郭慧[1] 于慎谔[1] 

机构地区：[1]中国地震局地壳应力研究所(地壳动力学重点实验室),北京100085 [2]中国地质大学地球科学与资源学院,北京100089

出　　处：《大地测量与地球动力学》2012年第5期12-16,共5页Journal of Geodesy and Geodynamics

基　　金：中央级公益性科研院所基本科研业务专项(ZDJ2010-24;ZDJ2007-1;ZDJ2007-14)

摘　　要：利用细颗粒(4～11μm)石英简单多片再生法(SMAR)光释光测年技术对横跨1976年唐山地震孙家楼探槽剖面中的样品进行系统测年,研究表明:样品的光释光信号以快组份为主,适合光释光测年。根据年龄数据和深度建立年龄-深度曲线和函数,推算出了剖面的沉积速率。研究结果表明,该地区50～7.16 ka以来,断层两侧沉积速率曲线为两条平行直线。说明该剖面揭示此期间沉积环境稳定,无构造运动,沉积速率很小,为0.03 m/ka,平行线之间0.6 m的距离可能是1976年唐山地震造成。75～50 ka期间,主断层在～50 ka的活动造成地层沉积速率增大,为～0.1 m/ka。同期的次断层活动造成断层西侧沉积速率为东侧的两倍,即～0.2 m/ka。可见,研究区沉积速率发生变化的主要因素是构造运动,非气候成因。We use simplified multiple aliquot regenerative-dose（SMAR） protocol from fine grain quartz（4~11μm） to systematically date samples from Sunjialou trench across Tangshan earthquake zone in 1976.OSL signals of these samples dominated by fast component show that they are suitable for OSL dating.On the basis of the optical ages and the burial depth of samples,the age-depth curve and function of the trench are obtained.Through it we inferred depositional rate.The results suggest that depositional rate curves on both sides of the fault show two parallels between 50 and 7.16 ka,which indicates sedimentary environment are stable and no tectonic movement happened during that time interval.The depositional rate is about 0.03 m/ka and 0.6 meters distance in the range of two parallels is vertical offsets generated by the 1976 Tangshan earthquake.Activity caused by the main fault in about 50 ka leads to depositional rate increase,which is 0.1 m/ka.Coeval activity in the secondary faults causes depositional rate in western segment about twice that of eastern segment,which is 0.2 m/ka.In conclusion,tectonic movement is main factor for depositional rate change in study area but climate change.The depositional rate change may be useful approaches for the palaeoseismic events.

关 键 词：唐山 孙家楼探槽 光释光 沉积速率 构造运动 

分 类 号：P575.6[天文地球—矿物学]