高精度热电离质谱(TIMS)铀系法洞穴沉积物(石笋)年龄的研究

Timing on Cave Deposit (Stalagmites) by High Precision Thermal Ionization Mass Spectrometry (TIMS)

用高精度热电离质谱技术测定石笋的年龄 ,初步建立了热电离质谱铀系年龄的方法。 4个样品的测定结果复现性较好 ,铀含量、同位素比值及年龄值与标准值吻合 ,数据的精度大大提高 ,显示了质谱铀系年龄方法具有样品量少、时间短。

Cave calcium has turned out to be a very important data bank of paleoclimatic evolution.Stalagmite,flow stone and calcite veins in caves,like tree rings,ice cores,loess and lacustrine deposits,contain precise records of past environmental variation.Deciphering of these 'codes' would contribute significantly to a better understanding of environmental changes on a global scale and would thereby enable us to make a better prediction of the future trend of climatic and environmental evolution. Highly precise dating is one of the problems in global change study and is recently considered as a hot point in the Quaternary geology.With high sensitive and high precision U Th disequilibrium method,Quaternary geology age by thermal ionization mass spectrolmetry (TIMS) has been determined.This has obtained significant achievements in palaeoclimate,palaeoenvironment,palaeo ocean,archaeology and modern volcanism magmatism studies.In this paper,we have determined Chinese standard sample stalagmite (GBW4412,GBW4413) and international standare sample Cpra;s(RKM 4) By MAT 262 mass spectrometer.The measured U content,isotopic ration and age value comply with that of the standard sample very well,indicating that an ideal tool for precise timing,which is the TIMS method is analysis also of advantages such as rapid,high precision and low sample comsuption.