Noble gas studies on the host phase of high 3He/4He ratios in deep-sea sediments

Elemental abundances and isotopic compositions of noble gases were determined for a magnetic separate and chemically leached samples from deep-sea sediments (14029.61'S, 158052.98'W). High 3He/4He ratios suggesting the presence of cosmic material were observed in all samples, and especially enriched in magnetic fractions. Ne isotopes and light noble gas abundances suggested that the high 3He/4He ratio was of solar wind origin and not due to cosmic ray spallation. However, heavy noble gases (Kr and Xe) were of atmospheric origin. Altogether the noble gases were well explained by a mixture of solar wind implanted on interplanetary dust particles (IDPs) and terrestrial noble gas fractionated from the atmosphere. The degree of contamination of IDPs in the magnetic fractions was estimated to be about 100 ppm. (author)