Mode of Occurrence and Composition of Impact-Generated and Impact-Modified Formations

Abstract

Interior structure of the Puchezh-Katunki astrobleme and composition and distribution of impact-transformed and impact-generated formations are described based on data obtained from extensive drilling and geophysical surveys. Three main morphostructural elements are distinguished: (1) outer ring terrace (outer ring terrace) of 15–30 km wide complicated by narrow and shallow radial trough and overlain by a thin blanket variegated allogenic breccia; (2) annular trough with an outer diameter of 40–42 km and depth ca. 1.9–1.6 km, filled with various allochtonous impact-derived rock units (mainly allogenic breccias after sedimentary rocks) overlain by crater lake deposits and more recent sediments; (3) central uplift of 8–10 km in diameter and up to 2 km high with a central pit up to 0.5 km deep. The latter is composed of blocks of both crystalline basement and sedimentary rocks; it stand out sharply by strong gravity and magnetic highs.