Chemical studies of H chondrites. II: Weathering effects in the Victoria Land,Antarctic population and comparison of two Antarctic populations with non-Antarctic falls

We report RNAA data for 14 siderophile, lithophile and chalcophile volatile/mobile trace elements (Ag, Au, Bi, Cd, Co, Cs, Ga, In, Sb, Se, Te, Tl, U, Zn) in interior portions of 45 different H4–6 chondrites (49 samples) from Victoria Land, Antarctica and 5 H5 chondrites from the Yamato Mts., Antarctica.Relative to H5 chondrites of weathering types A and B, all elements are depleted (10 at statistically significant levels) in extensively weathered (types B/C and C) samples, probably by leaching on the ice sheet surface. Contents of 8 elements in extensively weathered samples may provide a qualitative ranking for terrestrial surface residence. Chondrites of weathering types A and B seem compositionally uncompromised and as useful as contemporary falls for trace-element studies. When data distributions for these 14 trace elements in non-Antarctic H chondrite falls and unpaired samples from Victoria Land and from the Yamato Mts. (Queen Maud Land) are compared statistically, numerous significant differences are apparent. Concentrations of 8 elements differ significantly in the Victoria Land and non-Antarctic H5 chondrite populations. Essentially the same compositional differences and ⁵³Mn content and shock history differences appear when H4–6 populations are compared. Contents of 8 elements differ when Queen Maud Land and Victoria Land populations are compared and 5 for the Queen Maud Land/non-Antarctic comparison.These and other differences give ample cause to doubt that the various sample populations derive from the same parent population. The observed differences do not reflect weathering, chance or other trivial causes: a preterrestrial source must be responsible. The least unlikely of these involves a temporal variation in the source regions from which meteoroids derive.