【摘要】 采用全取岩心的钻探方法,在1679年三河-平谷8级地震的地震断层两侧各完成了一个深约50m的钻孔。在2个钻孔中分别采集了14C、OSL和TL测年样品,且测定了样品的沉积年代。结合钻孔中揭露出地层的沉积特征,可以把XD1孔中晚更新世地层划分为4段,相应地也可把XD6孔揭露的晚更新世地层划分为4段。2个孔中的地层段可以相互对应,它们的地层沉积时代大致相同。在断层上升盘的XD1孔岩心中,大致按照0.5m的间隔采集样品,在断层下降盘的XD6钻孔岩心中,大致按照1m的间隔采集样品,实验室用高锰酸钾滴定法、邻菲啰啉分光光度法分别测定了每件样品的FeO和Fe2O3含量。分析2个钻孔中同沉积时段地层中FeO、Fe2O3含量,以及Fe2+/Fe3+比值,发现灰黑色沉积物中Fe2+/Fe3+比值大于灰黄色沉积物中Fe2+/Fe3+比值,灰黑色沉积物处于较强的还原环境中。断层上升盘、下降盘同沉积时段地层均为灰黑色时,断层下降盘地层中Fe2+/Fe3+比值大于断层上升盘相应的地层,其沉积的还原环境强于断层上升盘。更多还原

【Abstract】 Using the complete core drilling method,we completed two boreholes on both sides of Xiadian active fault on which an M8.0 earthquake occurred in 1679.From rock cores of the two boreholes,we collected 14C,OSL and TL samples and determined their depositional ages. According to the geochronological data,and in combination with the sedimentary features of the formation in borehole cores,the late Pleistocene strata in XD1 hole can be divided into four stratigraphic sections. And the late Pleistocene revealed by borehole XD6 can also be divided into four stratigraphic sections. Late Pleistocene can be juxtaposed in the two boreholes; the deposition times of corresponding stratigraphic sections are also consistent. We collected some samples from XD1(on the upthrown plate)at a 0.5 meters interval roughly,and from XD6(downthrown plate)at a 1.0 meters interval. In State Key Laboratory of Earthquake Dynamics,we determined the FeO content with potassium permanganate titration method,and the Fe2O3 content using phenanthroline spectrophotometry. Comparing the Fe2+/Fe3+ ratio in same borehole core,we can find that the Fe2+/Fe3+ ratio of gray-black sediment is greater than gray-yellow sediment in the same drilling,and gray-black sediment is in a strongly reducing environment. When the same sedimentary strata are gray-black sediments,Fe2+/Fe3+ ratio in the strata on the fault’s downthrown plate is larger than that on the upthrown plate. The reducing environment for the deposits on the fault’s downthrown plate is stronger than the upthrown plate.更多还原