Suwalong Landslide Cosmogenic Nuclide ¹⁰Be Exposure Dating Study

Due to the human activity,engineering construction,geological structure movement and earthquake,landslide disasters occur frequently,which seriously threat human life and property.Studying the geochronology of ancient landslides will be helpful to deepen the understanding of the formation and development of landslides,which will provide a scientific basis for preventing and controlling landslide disasters.There are a series of large-scale ancient landslides in the upper reaches of Jinsha River,among which,Suwalong landslide located between Batang and Wangdalong village is one of the well preserved large-scale ancient landslides.Studying the landslide geochronology not only helps us to learn the process of landslide occurrence and development,but also provides the basis for the risk assessment of the foundation stability when the traffic and water conservancy projects are constructed in this area.Although there are many experts to study the geochronology of Suwalong landslide,most of them mainly used the indirect dating method to measure the sediment of ancient barrier lake formed by ancient landslides,and the study on direct dating of Suwalong landslide was absence.Cosmogenic nuclide ¹⁰Be exposure dating method can directly reveal the age of landslides.Due to its easy collection and wide range of dating,it has been widely used by geochronologists and geologists.Therefore,in the present study,cosmogenic nuclide ¹⁰Be exposure dating was used to study the geochronology of Suwalong landslide in the upper reaches of Jinsha River.The main research contents and conclusion are as follows:?1?9 kinds of metamorphic rocks were collected from Suwalong landslide,incl-uding 8 kinds of samples from accumulated boulders and 1 from landslide bed.Suwalong landslide,as a bedrock landslide,is mainly composed of metamorphic rocks.The pretreatment experiment of Suwalong landslide samples showed that the composition of metamorphic rocks was complex,and quartz purification was tedious and need longer time.?2?The exposure time data of ¹⁰Be were corrected by shielding factor and erosion rate.Based on the existing relevant data,the occurrence,movement and induced factors of Suwalong landslide were discussed.It was shown that there may be twice sliding in Suwalong landslide,the first sliding was maybe 6289±1502 a,and the second sliding was in 1355 a BP.?3?According to the existing documents of paleoclimate and geological tectonic activities,we found that the first sliding time of Suwalong landslide was consistent with that of paleoearthquake.Thus,it was inferred that the Suwalong landslide may result from the earthquake.The second sliding may be related to the Wangdalong village earthquake.