摘要
为了研究断层崩积楔各部位沉积物光释光信号晒退情况及崩积楔形成年龄,利用中颗粒石英（63~90μm）单片再生法（SAR）对山西忻定盆地西田探槽断层崩积楔3个部位的4个样品进行光释光（OSL）定年。选择一代表性样品（08-OSL-22）进行等效剂量（DE）、LN/TN、循环比率、回授率与预热温度的关系分析,结果表明预热温度260℃、预热时间10 s为样品最佳预热条件。4个样品的测片循环比率基本在0.9~1.1之间,回授率均小于5%,表明所采用的中颗粒SAR法流程可以很好地校正测量过程中产生的释光感量变化,其等效剂量可信。利用等效剂量分布直方图和累积频率图,发现古地形面和坡积物的样品晒退均匀,崩积层样品则较差。对于晒退较差的样品利用累积频率法得到其等效剂量,从而得到崩积楔的近似年龄。最后获得该期崩积楔的形成年龄为（27.09±0.71）ka。
In order to detect the degree of optically stimulated luminescence（OSL） signal bleaching of sediments in each sites of the fault collapse wedge and its formation age,a method of middle grain single aliquot regenerative dose（SAR） procedure was used to implement OSL dating for the four samples from three sites of the fault collapse wedge in Xitian trench of Xinding basin,Shanxi.A representative sample was chosen to analyze the relationship among equivalent dose（DE）,LN/TN,recycling ratio,recuperation and preheat temperature.The results reveal that the aliquots need go through preheating at 260 ℃ for 10 s.For the four samples,the recycling ratio values of aliquots are almost between 0.9 and 1.1 and the recuperation values are below 5%,which indicates that the procedure of SAR method can successfully correct the OSL sensitivity change during measurement and the equivalent dose is creditable.The equivalent dose distribution and cumulation frequency of samples are analyzed;it can be found that the samples from palaeotopography surface and deluvium are bleaching equally and those from colluvium are worse.The approximate equivalent dose of the colluvium samples can be derived with cumulation frequency and at last,the formation age of this fault collapse wedge is measured as 27.09±0.71 ka.
出处
《现代地质》
CAS
CSCD
北大核心
2011年第2期356-362,共7页
Geoscience
基金
中国地震局地壳应力研究所基本科研业务专项(ZDJ2010-24
ZDJ2007-14
ZDJ2010-4)
地震行业科研专项(200908001
200708028)
关键词
断层崩积楔
光释光
单片再生法
等效剂量
忻定盆地西田探槽
fault collapse wedge
optically stimulated luminescence（OSL）
single-aliquot regenerative-dose（SAR） method
equivalent dose
Xitian trench of Xinding basin
