川东北石笋记录的38～39 ka B.P.活动事件

通过川东北诺水河溶洞群石笋的年代学分析,发现多支时代跨越35~40kaB.P.的石笋记录了发生时间在38~39 kaB.P.的事件:有的石笋发育中断,有的石笋生长轴心发生了变化,有的石笋则刚刚开始发育。初步的证据显示该事件不是气候成因所为,也不像由于洞穴局部塌陷引起。考虑到秦岭山地是新构造活动十分发育的地区,为此我们推测该事件很可能与某一次构造活动有关,也可能是由一次大规模重力地貌过程(如滑坡)造成。因此,洞穴沉积物(包括石笋、石钟乳和流石等)可望为川东北地区的新构造活动尤其是地震事件研究提供一种新的依据。

THE 38～39 kaB.P. EVENT RECORDED BY MULTI-STALAGMITES FROM NORTHEAST SICHUAN PROVINCE,CHINA

TIMS dating were conducted on more than ten stalagmites which were collected in 2004 from northeast Sichuan,Central China.It was found that four stalagmites covering the period 35~40 ka B.P.recorded the event starting from 38~39 kaB.P..This event was recorded or reflected differently in these stalagmites. One stalagmite(SJ1) was interrupted,one began to grow,and the other two changed their growth centers and axises.This event seems not to be climatically related,nor caused by subsidence of the floor where these stalagmites grew.Considering that the study site,northeast Sichuan lies in Qinling Mountain where neotectonic movement is intensive,we suggest that the event in 38~39 kaB.P.documented by multi-stalagmite recorded a mass movement probably corresponding to a neotectonic event(such as an earthquake),or a massive landslide.Sediments in karst caves here,such as stalagmite,stalactite and flowstone,could provide some new evidences for investigation of the neotectonic movement,especially earthquake in this area.