On the viability of detrital Rb-Sr geochronology

Re-examination of sediment samples collected from the Bay of Bengal via laser-ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) Rb-Sr geochronology demonstrates the viability of the Rb-Sr system for use as a detrital chronometer. The age population defined by the Rb-Sr dates essentially reproduces that previously published for detrital 40Ar/39Ar dates. The assumed initial 87Sr/86Sr on the calculated population has some influence on the age of the final population, but that influence can be ameliorated by filtering for higher 87Rb/86Sr ratios. The 87Rb/86Sr ratio cut-off used for such filters to minimize the effect of initial 87Sr/86Sr on the final population is strongly dependant on the age of the material being analysed (i.e. ~> 87Rb/86Sr = 500 @ 250 Ma and ~>87Rb/86Sr = 50 @ 2500 Ma). Finally, Ti-in-biotite temperatures calculated based on data collected during LA-ICP-MS overlap with those calculated for the same material based on electron probe microanalyzer data demonstrating the potential for petrochronolgy based on the Rb-Sr system.