Crustal Imaging and Characterization Team

USGS Luminescence Dating Laboratory

Luminescence Age Equation, Equivalent Dose, and Dose Rate

• Controlling Assumptions - TL Method
• Luminescence Age Equation
• Determination of Equivalent Dose (DE)
• Determination of Dose Rate (DR)

Controlling Assumptions - TL and OSL Method

• Complete Zeroing - Exposure to sunlight or intense heat (>150°C) for an extended period of time
• Stable Luminescence Present - Plateau Test (TL only)
• Accurate Determination of the Dose Rate (DE) and Past Moisture Content

The Luminescence Age Equation

Age = DE / DR

DE is measured in grays (absorbed dose) and commonly known as the Equivalent Dose or paleodose

DR is measured in gray/Ka and commonly known as the Comprised of K , U, Th, Rb, and cosmic ray components

Determination of Equivalent Dose (DE)

• Additive Dose - usually multiple aliquots
• Partial Bleach - assumes a mix of grains with varying partial bleaches
• Total Bleach - assumes complete zero
• Regeneration - usually single aliquot or more rarely single grain

Determination of Dose Rate (DR)

• Neutron Activitation - U, Th, K , Rb
• γ Spectrometry - U, Th, K (Lab & Field)
• Atomic Absorption - K , Rb
• Alpha Counting - ZnS scintillation user for α
• Inductively Coupled Plasma - Mass Spectrometry (ICP-MS)
• Flame Photometry - K

Next: Contributions to Sediments

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