Luminescence Dating and Bracketing Time of the Youngest Toba Tuff Deposits in the Quaternary Sediments of Purna Alluvial Basin,Central India  

作　　者：Singh Ajab K.Srivastava Ashok Chauhan Naveen 

机构地区：[1]Department of Geology,Faculty of Science,University of Malaya,Kuala Lumpur 50603,Malaysia [2]Department of Geology,SGB Amravati University,Amravati 444602,India [3]Physical Research Laboratory,Ahmedabad 380009,India

出　　处：《Journal of Earth Science》2022年第4期1007-1016,共10页地球科学学刊（英文版）

基　　金：financially supported by Science and Engineering Research Board(SERB),New Delhi,India in the form of major research project(No.SB/S4/ES-692/2013)awarded to AKS。

摘　　要：Light gray to yellowish brown youngest Toba tuff(YTT)ash,preserved in the Quaternary sediments of India,have been used as a tool to know depositional and bracketing time period of the same in the sediments through applications of luminescence dating to interpret age connotation of various geological events.Pre-and post-tephra sediments of YTT ash beds from Hudki and Sukali areas of Purna alluvial basin,Central India have been optically dated to interpret the depositional age and bracketing time of the tephra within sedimentary sequences.These sediments are yellowish brown,thinly bedded,laminated,silty clay and host laterally extend discontinued beds of 0.15–0.20 m thickness.The ash is light gray,fine grained and powdery in nature,massive to structureless and lacks any sign of retransportation and redeposition,hence,considered as primary in nature.Total four sediment samples,one each from pre-and post-tephra lithounits of both the localities have been dated through optically stimulated luminescence technique(OSL)equipped with single aliquot regenerative(SAR)procedure on the feldspar grains.It shows pre-and post-tephra ages of 57±5 and 70±4 ka respectively for Hudki and 66±5 and 67±4 ka for Sukali localities.These depositional ages suggest that the ash was bracketed within sediments thousands years after YTT eruption.It is correlatable with the previously reported depositional and absolute ages for the YTT ash from the localities of Ghoghara and Khuntheli,Son Valley;Tejpur,Madhumati River Basin and Jwalapuram,Jurreru Valley.These ages also provide an idea about the period of existence of biological communities represented by the remains of faunal and vegetational activities before and during settlement of the YTT ash in the basin area.

关 键 词：youngest Toba tuff TEPHRA optically stimulated luminescence QUATERNARY SEDIMENTS depositional age 

分 类 号：P512.2[天文地球—地质学] P534.63