SOME PETROLOGICAL, GEOCHEMICAL AND GENETI C PECULIARITIES OF HYPABYSSAL ALKALINE ULTRABASIC ROCKS BY AN EXAMPLE OF POLZENITIC-ALKALINE PICRITIC COMPLEX OF JETTY OASIS (EASTERN ANTARCTIC, PRINCE-CHARLES MOUNTAINS)

Short geological, petrographical and geochemical description of alkali ne ultrabasic hypabissal rocks of Jetty oasis in Eastern Antarctic is presented. These rocks comprise a series of small stocks, sills and dy kes amd form three successively formed groups: 1) rushaitic tuffisite breccia; 2) polzenites; 3) alkaline picrites and olivine melanephelini tes with nodules of abyssal peridotites of spinel and pyrop facies. So me of reported rocks are characterised by the secondary enrichment in potassium up to the predominantly potassium alkalinity as a result of subsolidus autometasomatic phlogopitisation. The similar process is co nsidered also as a factor of potassium enrichment of kimberlites. The absence of connection of lamprophyric, kimberlitic and lamproitic diat remes (explosive pipes) with the surface volcanism is argued.