Study of melt produced bodies observed at Henbury crater region

Abstract

During the impact of the Henbury meteorite with ground rock a shower of molten droplets were produced which quickly solidified in oxide phases of meteorite and rock components. A study of these has provided information on relative volatilities of various oxides during the impact process. Spherical and non spherical bodies derived from target rock and meteorite components were found in samples of soil in the Henbury crater region. From a study of the composition of these bodies, the compositions of the meteorite and the target rock, it has been possible to separate the bodies into three separate groups. A major finding was the depletion of SiO 2 in the production of both Group 1 and Group 3 bodies. Group 3 bodies are not fractionated to the same extent as Group 1. Comparing the compositions with the composition of the target rock, the general order of fractionation of the Group 3 melt is SiO 2 > Na 2O > K 2O and MgO > Al 2O 3 and TiO 2 and for Group 1 Na 2O > SiO 2 > MgO and K 2O > Al 2O 3 and TiO 2. Comparing the compositions of Group 1 and Group 3 bodies with no reference to the target rock we get the general order of volatility to be Na 2O > MgO > K 2O > TiO 2, SiO 2 and Al 2O 3, the significant change being the place of SiO 2. Group 2 bodies, in general, showed similar degrees of fractionation to Group 1.