Short-lived radioisotope geochronology

Short-lived Radioisotope (SLR) data are generated for selected core sub-samples at 2mm sampling intervals for “surficial unit” and 5mm sampling resolution intervals to base of cores. SLR data generated include sample activity (dpm/g) of: 1) Excess 234Th activity, which is calculated by measuring the total 234Th activity and the subtraction of the measured or estimated “background” 234Th activity, 2) Excess 210Pb activity, which is calculated by measuring the total 210Pb activity and subtraction of the measured background 210Pb activity (average of 214Pb; 295keV, 214Pb: 351keV, and 214Bi; 609keV), 3) 137Cs activity, and 4) 7Be activity. Where appropriate, age dating is calculated in calendar years for 234Th and 210Pb activity profiles, as well as linear accumulation rates (LAR) expressed as cm/yr, and mass accumulation rates (MAR) expressed as g/cm2/yr.