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.

短寿命放射性同位素（Short-lived Radioisotope, SLR）数据针对选定的岩心子样生成：表层单元以2mm的采样间隔取样，至岩心底部则采用5mm的采样分辨率间隔取样。所生成的SLR数据涵盖以下核素的活度（dpm/g）：1）过剩234钍（Excess 234Th）活度，其通过测量总234钍活度并扣除实测或估算的“本底”234钍活度计算得到；2）过剩210铅（Excess 210Pb）活度，其通过测量总210铅活度并扣除实测本底210铅活度（该本底活度以214Pb的295keV、214Pb的351keV以及214Bi的609keV的计数平均值计算得到）；3）137铯（137Cs）活度；以及4）7铍（7Be）活度。在条件适宜时，针对234钍与210铅的活度剖面计算其日历年龄定年结果，并同步计算以cm/yr为单位的线性堆积速率（linear accumulation rates, LAR），以及以g/cm²/yr为单位的质量堆积速率（mass accumulation rates, MAR）。