ARGANATY IMPACT CRATER AND ASSOCIATED RING STRUCTURES, SOUTHERN KAZAKHSTAN

Abstract

The meteorite crater is isometric, with some angularity. The highest evaluation of its rim is 755 m in the south and 712 m in the north. The maximum evaluation of the rim above the crater floor is 305 m. The width of the rim ranges from 7.5 to 11.5 km. On rocky slopes of a gorge cutting the northern part of the rim, there is strong evidence of its overthrust, imbricate structure. The thrust sheets are displaced northward. Ore occurrences, quartz veins, dikes and other small intrusions are confined to points where the crater rim is cut by sublatitudinal, northwestern and, less commonly, meridional faults. An important feature of the Arganaty crater and the associated ring structure is that unconsolidated sandy deposits in its central part are underlain by a leucocratic granite body, which is marked by the magnetic high mentioned above. There is no evidence of shock metamorphism in this granite. Based on experimental data the authors conclude that the crater most probably originated at the Permian-Triassic boundary. The ring structure whose center lies farther west is older. It evidently originated in Permian time.