The newly confirmed Luizi impact structure, Democratic Republic of Congo—Insights into central uplift formation and post-impact erosion

Abstract

Rocks exposed within the uplifted central part of meteorite impact structures come from signifi cant stratigraphic depths, in some cases as much as several kilometers. On Earth, cen- tral uplifts are commonly the fi nal and only feature of an impact crater that remains after the rest of the structure is lost to erosion. However, the crater-forming process that results in the formation of intricate features such as central peak and peak rings is poorly understood. Much of our knowledge is based on extraterrestrial observations; as on Earth, there are very few unequivocal examples of impact craters with well-preserved peak and ring morphologies, because of erosion. In this study we describe the ~17-km-diameter Luizi structure (Katanga region, Democratic Republic of Congo), a moderate-sized complex crater, with an intermedi- ate ring (~5.2 km in diameter), and an ~2-km-wide circular central ring around a central depression. For the fi rst time, unique evidence of shock metamorphism, in the form of macro- scopic shatter cones and multiple sets of microscopic planar deformation features in quartz and feldspar grains, is described, confi rming the meteorite impact origin of the structure. Our observations at Luizi provide insights into the formation of mid-sized impact craters on Earth, adding to the evidence that, in the case of sedimentary target lithologies, structural ring struc- tures within the central uplift may form by the collapse of an unstable central peak. Given the preservation state of the Luizi crater, it cannot be excluded that structural rings may be a common feature for mid-size craters developed in layered target rocks.