<abstract xml:lang="en" xmlns="http://www.w3.org/1999/xhtml"><p>This study investigates lacustrine and fluvial sediments on the Sala Us River in the Mu Us Desert in central north China. Significant changes in environmental dose rate in part of the section could be shown to have occurred from measurements of the present day radioactivity and by the age reversal for some samples that had been dated by optically stimulated luminescence (OSL) measurements on quartz. These changes in dose rate can be attributed to recent uptake of radioactive elements found in the sediments; this resulted in significant underestimation of the OSL ages. In this study, the new isochron method using K-feldspar grains has been applied to overcome the effects of changes in dose rate. Calculations are used to show that changes in the environmental dose rate factors, i.e. K, U, Th, water content and cosmic ray flux, and disequilibrium in the U and Th decay chains, e.g. radon escape, have a negligible effect on the isochron age. After applying the new isochron method, the effects of changes in dose rate caused by recent uptake of radioactive elements and changes in past water content were effectively overcome and true ages are obtained; this was verified by repeating the luminescence isochron measurements on samples of overlying and underlying sediments.</p></abstract>

This study investigates lacustrine and fluvial sediments on the Sala Us River in the Mu Us Desert in central north China. Significant changes in environmental dose rate in part of the section could be shown to have occurred from measurements of the present day radioactivity and by the age reversal for some samples that had been dated by optically stimulated luminescence (OSL) measurements on quartz. These changes in dose rate can be attributed to recent uptake of radioactive elements found in the sediments; this resulted in significant underestimation of the OSL ages. In this study, the new isochron method using K-feldspar grains has been applied to overcome the effects of changes in dose rate. Calculations are used to show that changes in the environmental dose rate factors, i.e. K, U, Th, water content and cosmic ray flux, and disequilibrium in the U and Th decay chains, e.g. radon escape, have a negligible effect on the isochron age. After applying the new isochron method, the effects of changes in dose rate caused by recent uptake of radioactive elements and changes in past water content were effectively overcome and true ages are obtained; this was verified by repeating the luminescence isochron measurements on samples of overlying and underlying sediments.

Overcoming Environmental Dose Rate Changes in Luminescence Dating of Waterlain Deposits

Department of Earth Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong, China

Institute of Geography and Earth Sciences, University of Wales, Aberystwyth SY23 3DB, United Kingdom

Geochronometria

This study investigates lacustrine and fluvial sediments on the Sala Us River in the Mu Us Desert in central north China. Significant changes in environmental...

Overcoming Environmental Dose Rate Changes in Luminescence Dating of Waterlain Deposits

Pubblicato online: 28 mar 2008

Pagine: 33 - 40

DOI: https://doi.org/10.2478/v10003-008-0003-z

Parole chiave
optical dating, isochron dating, dose rate, uptake of radioisotopes, K-feldspar

This content is open access.

Overcoming Environmental Dose Rate Changes in Luminescence Dating of Waterlain Deposits

Pubblicato online: 28 mar 2008

Pagine: 33 - 40

DOI: https://doi.org/10.2478/v10003-008-0003-z

Parole chiaveoptical dating, isochron dating, dose rate, uptake of radioisotopes, K-feldspar

This content is open access.

Parole chiave
optical dating, isochron dating, dose rate, uptake of radioisotopes, K-feldspar