Geochemistry of trace elements in the extraterrestrial matter examined by the X-ray fluorescence method with synchrotron radiation

Abstract

X-ray fluorescence analysis with synchrotron radiation (XFA-SR) has been applied for the determination of incompatible trace elements (Rb, Sr, Y, Zr, Nb, Ba, La and Ce) in some extraterrestrial samples. A distribution of these elements in lunar whole rocks and their minerals, in the matrix, chondrules and CaAl-rich inclusions from various chondrites has been investigated. The XFA-SR analytical technique for very small objects ranging from 2 mm to 300 μm has been described. The specific basaltic group of Luna-20, geochemically similar to Luna-24 VLT basalt, has been established. The points of intersection of the HAB-VHA rock trend and the TB rock trend on the bi-element correlation diagrams probably correspond to the concentration levels of these trace elements in the parent magmas. Distribution of trace elements in rock-forming minerals and in their host rocks showed two trends: early and late crystallizations with an inversion of the Y/Zr ratio. The difference in trace element distribution in chondrules, matrix and CaAl-rich inclusions from the chondrites has been shown. This indicates a varied genesis for these objects.