Piston core ELT49-53 sediments show no correlation between ³He and ⁶⁰Fe, and sedimentary ³He appears to be dominated by the presence of interplanetary dust particles (IDPs). Because ³He is not supplied in significant amounts by SN ejecta, the absence of a ³He-⁶⁰Fe correlation provides additional, although circumstantial evidence for the supernova hypothesis. Large uncertainties in the relatively small number of sediment ⁶⁰Fe measurements currently limit a firmer conclusion.

The extraterrestrial ³He accumulation rate in ELT49-53 from 3.2 to 1.7 Ma was 0.88±0.26×10^-12 cm³ STP/g/kyr, similar to IDP ³He flux estimates from previous sedimentary and ice core records that span both shorter and longer time scales. ⁴He and ⁶⁰Fe accumulation rates during this time interval were 0.11±0.04×10^-6 cm³STP/cm²/kyr and 1.9±0.5×10⁴ atoms/cm²/kyr. Bulk sediment [⁴He] is strongly anti-correlated with sediment CaCO₃ content, evidence for modulation of the terrigenous and cosmic sedimentary fractions primarily by changes in biogenic carbonate deposition. Although the dominant terrigenous source has not been uniquely identified at the Indian Ocean deposition site, it resembles eolian material from the continental interior of Australia, and shows a narrow range of ³He/⁴He (from 2-4×10^-8, 0.015-0.030 R_A) over the last ∼3 Myrs.