ATMOSPHERIC XENON IN THE COSMIC OBJECTS - GEOCHEMICAL AND COSMOCHEMICAL CONSEQUENCE

Experimental data analysis shows the different cosmic objects (the Moo n, chondrites, achondrites) often have xenon with isotope composition close or even the same as that in the Earth's atmosphere. The presence of such xenon and estimation of the primary (solar) xenon isotope com position that differs from the generally accepted leads to the followi ng cosmochemical and geochemical conclusions: the Earth's xenon (witho ut spallation component) as well as xenon of some other cosmic objects has the same composition as the solar one so-we can omit the primary xenon fractionation in this model. Xenon of the carbonaceous and norma l chondrites is a mixture of the solar xenon and xenon enriched in bot h light and heavy components. Agreement between isotope compositions i ncluding spallation component, atmospheric xenon, xenon of achondrites (especially of the SNC group) as well as that of some lunar samples p oints to the identical Xe/Pu ratio in the protomatter of these objects . The most probable analogue of the Protoearth matter is SNC-chondrite s or precursors but not the carbonaceous and/or normal chondrites.