کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
6442466 1639841 2016 10 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Research paperInternal U, Th and Rb concentrations of alkali-feldspar grains: Implications for luminescence dating
موضوعات مرتبط
مهندسی و علوم پایه علوم زمین و سیارات ژئوشیمی و پترولوژی
پیش نمایش صفحه اول مقاله
Research paperInternal U, Th and Rb concentrations of alkali-feldspar grains: Implications for luminescence dating
چکیده انگلیسی


- Perthitic and Na-rich grains can contaminate density-separated K-feldspar.
- Identify variability between single grains in U, Th and Rb concentrations.
- Internal beta dose-rates of Rb contribute minimally to total dose-rate.
- Internal alpha dose-rates from U and Th relate to the feldspar composition.
- Selecting the brightest 20% of grains reduces the impact of internal geochemistry.

This study assesses whether internal U, Th and Rb concentrations of single grains of alkali-feldspar can impact upon luminescence dating. Internal alpha dose-rates determined for two sedimentary samples calculated from mean U and Th concentrations accounted for ∼10% of the total dose-rates, while internal beta dose-rates from mean Rb concentrations accounted for ∼2%. Depth profiles of measurements penetrating into each grain show that internal U and Th concentrations varied between grains, where some grains had effective internal alpha dose-rates up to 1.8 Gy/ka (32% of the total dose-rate). K concentrations inferred from Rb (KRb) for individual grains suggest that internal U and Th concentrations are related to the feldspar composition. Grains with KRb > 6% had low U and Th, and grains with KRb < 6% had higher U and Th concentrations. Internal alpha and beta dose-rates of the perthitic and Na-rich grains contaminating the density-separated K-feldspar fractions had a significant impact upon the single-grain De distributions, which was estimated to be equivalent to overdispersion values of ∼10 - 15%. The scatter in the De distributions arising from internal alpha and beta dose-rates for both samples could be reduced by selecting only the brightest 20% of grains for luminescence dating.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Quaternary Geochronology - Volume 35, October 2016, Pages 16-25
نویسندگان
, ,