NOBLE-GASES AND NITROGEN IN MUONG-NONG TEKTITES

Three samples of Muong Nong tektites have been studied for N and noble gases. The isotopic composition of noble gases is airlike. The noble gas amounts are much higher in Muong Nong tektites than in splash-form tektites. As compared to air, He and Ne have been enriched, most like ly due to inward diffuion from ambient air, subsequent to glass format ion. Nitrogen contents range from 0.3 to 1.34 ppm, with a non-atmosphe ric delta(15)N ranging from 8 to 17 parts per thousand. The release pa ttern of delta(15)N clearly shows the presence of two N components. Hi gher N/Ar-36 values than those of air, together with positive delta(15 )N show that a major portion of N in Muong Nong tektites is a remnant from the sedimentary source material.