Research on the stalagmites sedimentary chronology - A case study on no. 1 stalagmite of Shuinan cave in Guilin, China

The stalagmite P1,P2 of Panlong cave and stalagmite X1 of Xiangshui cave in Guilin(which their ages are 30 ka BP,over 350 ka BP and 56ka BP,respectively),the stalagmite D3,D4 of Dongge cave and stalagmite Y1 of Yaman cave in Libo(which their ages are from 64 ka BP to 19ka BP,over 155 ka BP and from 53ka BP from 7.3 ka BP,respectively),the stalagmite Q14,Q16 of Qixing cave in Duyun(which their ages are from 64 ka BP to 19ka BP,over 155 ka BP and from 53ka BP from 7.3 ka BP, respectively),Guizhou,and the stalagmiteLL1,LL5 of Linhua cave in longshan(which their ages are from 60 ka BP to 21a BP,and from 80ka BP from 6 ka BP,respectively),Hunan,have been studied and integrated for many years.The characteristics of depositional cycles,micro-lamina and bedding plane structure in large stalagmites with height from 150cm to 400cm have obviously typicalness and representativeness.The dating precision low of the present Quaternary chronological scale will progressively be replaced on the basis of macroscopic and microscopic deposit characteristics and systematic dating ages from stalagmites in caves.Author has established the chronological scale from 150ka to 250ka BP in Guilin areas on the basis of 11 depositional cycles from N0.1 stalagmite of Shuinan cave and relative deposit characteristics and using of high precisional TIMS-U series dating.We suggest that the division boundary of chronology between the late Pleistocene and the middle Pleistocene is ca.200ka BP as the bottom boundary of Quaternary chronology is over 2500 ka.The boundary of chronology locates at third depositional hiatuse from N0.1 stalagmite of Shuinan cave,which formed 3mm weathering crust and has a markedness difference at the upper and lower material texture and structure.The carbon and oxygen isotope from the cold deposit stalagmites in 11 depositional cycles are a heavy or positive trend and the maximum value point is an abrupt point of transferring cold or depositional hiatus surface.The duration of 11 depositional hiatuses has obvious difference,in which the duration of third and ninth depositional hiatuses is 20ka,2ka,respectively.The information of the synthetically geology and climate is a good correlation and possible evident of reconstructing paleoclimate and environment.