Elemental abundances and isotopic compositions of He and Ne were determined by stepwise heating for a magnetic separate of deep-sea sediments and its 3 M HCl resistant fractions. High 3He/4He ratios (2-3¿10-4) and solar 20Ne/22Ne ratios (12--14) were observed in all temperature fractions for these samples. The major release temperatures of 4He were at 1000 ¿C, whereas 20Ne at 1200 ¿. These results suggest that solar He and Ne re tightly trapped inside the grains with nearly uniform isotopic ratios. The magnetic separate lost about 75% of its 3He against 37% weight loss during the 3 M HCl treatment indicating that solar He and Ne are relatively enriched in the fine fraction and/or on the surface of magnetite grains. It is likely that the solar wind with its high energy tail is responsible for the extratrrestrial noble gasses in deep-sea sediments. Alternatively, solar wind He and Ne were redistributed ni the magnetite during atmospheric entry and tightly trapped inside the grains. ¿ American Geophysical Union 1990