CHEMICAL RELATIONSHIPS AMONG IRGHIZITES, ZHAMANSHINITES, AUSTRALASIAN TEKTITES AND HENBURY IMPACT GLASSES

Analytical data for 40 elements are presented for three irghizites (tektite-like forms) and two zhamanshinites (impact glasses) from the Zhamanshin impact structure (Lat. 49°N, Long. 61°E), 200 km north of the Aral Sea, Kazakstahn SSR, USSR. Comparative data for 10 Australasian tektites (3 javanites, 5 australites, an indochinite and a philippinite), Henbury impact glass and parental Henbury subgreywacke sedimentary rocks are also presented. There is close similarity in composition between the three silica-rich samples from Zhamanshin (two irghizites and one zhamanshinite) and the high Mg-Cr tektites from Java, except that the irghizites contain high Ni and Co contamination from the impacting body. The silica-rich zhamanshinite is nearly identical in composition to Henbury impact glass. The refractory trace elements and REE show close similarities among all 17 silica-rich samples, although the tektites show a smaller spread in composition compared with the samples from Zhamanshin. All the silica-rich samples have REE patterns consistent with derivation from terrestrial sedimentary rocks of post-Archean age. All are thoroughly terrestrial. The silica-poor zhamanshinite and irghizite have Al, Na, K, Ni, Cr, Th, U and REE abundances consistent with derivation from a basaltic andesite parent material. The close similarity in chemistry and age between the silica-rich samples from Zhamanshin and Javan tektites from the Australasian strewnfleld warrants a close examination of the Zhamanshin impact structure as a possible source region for the Australasian tektites. © 1979.