Matrix effect primarily impacts the accuracy and precision of zircon LA-ICP-MS U-Pb data.This paper describes three types of matrix effect in zircon LA-ICPMS U-Pb dating,i.e.,the element matrix effect,high Ddpa or ura...Matrix effect primarily impacts the accuracy and precision of zircon LA-ICP-MS U-Pb data.This paper describes three types of matrix effect in zircon LA-ICPMS U-Pb dating,i.e.,the element matrix effect,high Ddpa or uranium matrix effect and alpha dose matrix effect,and illustrates the correction of these three effects.In addition,we point out the limitation and possible problems of the existing correction methods.展开更多
Garnet occurs in a wide range of rock types,from mantle peridotites to granites,from eclogites to skarns.In recent years,garnet LA-ICP-MS(Laser Ablation Inductively Coupled Plasma Mass Spectrometry)U-Pb dating has pro...Garnet occurs in a wide range of rock types,from mantle peridotites to granites,from eclogites to skarns.In recent years,garnet LA-ICP-MS(Laser Ablation Inductively Coupled Plasma Mass Spectrometry)U-Pb dating has provided a powerful solution for retrieving the ages of rock formations,but successful dating is often prohibited by the low concentration of U.However,the concentration of U,a trace element of garnet,is unknown prior to the LA-ICP-MS analysis.In this study,we propose that the U concentration in garnet can be predicted by the contents of major and minor elements,which can be quantitatively obtained by EPMA(electron probe microanalysis).Using a supervised machine learning method(neural network),a model is trained to discriminate U-rich(>2 ppm)and U-poor(<2 ppm)garnets,based on EPMA results.Results of cross validation shows that the model has an average accuracy of~92%and is a powerful tool in detecting datable U-rich garnet.To facilitate the use of the discriminator,it is programmed as a stand-alone Microsoft Excel spreadsheet(HighUGarnet)and users directly paste the molar proportions of garnet end members into it and obtain the discrimination result.展开更多
文摘Matrix effect primarily impacts the accuracy and precision of zircon LA-ICP-MS U-Pb data.This paper describes three types of matrix effect in zircon LA-ICPMS U-Pb dating,i.e.,the element matrix effect,high Ddpa or uranium matrix effect and alpha dose matrix effect,and illustrates the correction of these three effects.In addition,we point out the limitation and possible problems of the existing correction methods.
基金financially supported by the National Natural Science Foundation of China(Nos.41872078 and 41502069)the Young Elite Scientists Sponsorship Program by CAST(No.YESS20180143)+1 种基金Fundamental Research Funds for the Central Universities(No.FRF-TP-18-017A3)the 111 Project of the Ministry of Science and Technology,China(No.BPO719021).
文摘Garnet occurs in a wide range of rock types,from mantle peridotites to granites,from eclogites to skarns.In recent years,garnet LA-ICP-MS(Laser Ablation Inductively Coupled Plasma Mass Spectrometry)U-Pb dating has provided a powerful solution for retrieving the ages of rock formations,but successful dating is often prohibited by the low concentration of U.However,the concentration of U,a trace element of garnet,is unknown prior to the LA-ICP-MS analysis.In this study,we propose that the U concentration in garnet can be predicted by the contents of major and minor elements,which can be quantitatively obtained by EPMA(electron probe microanalysis).Using a supervised machine learning method(neural network),a model is trained to discriminate U-rich(>2 ppm)and U-poor(<2 ppm)garnets,based on EPMA results.Results of cross validation shows that the model has an average accuracy of~92%and is a powerful tool in detecting datable U-rich garnet.To facilitate the use of the discriminator,it is programmed as a stand-alone Microsoft Excel spreadsheet(HighUGarnet)and users directly paste the molar proportions of garnet end members into it and obtain the discrimination result.
