ARAGUAINHA IMPACT CRATER, BRAZIL .1. THE INTERIOR PART OF THE UPLIFT

Abstract

Abstract— The central uplift of the 40‐km wide Araguainha impact structure, Brazil, consists of a ring, about 8 km in diameter, of up to 150‐m high blocks of Devonian Furnas sandstone, which surround a central depression of elliptical shape (4.5 × 3.0 km). The depression is occupied by a pre‐Devonian alkali‐feldspar granite, shocked by pressures of 20–25 GPa and permeated by cataclastic shear zones and dikes of shocked granitic material. The granite is flanked and partly covered by several impact breccias: (1) Impact breccia with melt matrix overlies the granite in places and forms hills, bordering the granitic center in the S and SW. It is chemically identical with the granite and consists ..