Aorounga Central

Aorounga Crater

Aorounga Crater is an impact structure located in northern Chad, recognized for its distinct multi-ring morphology. The exposed remnant of the crater measures approximately 12.6 kilometers in diameter, with its age estimated to be less than 345 million years, placing it within the Carboniferous period or younger. The crater's geological features include outer and inner rings that rise about 100 meters above the surrounding plain, separated by a relatively flat depression. A possible central uplift structure, about 1.5 kilometers in diameter, is also noted within the depression.

Geological Significance

The impact origin of Aorounga is supported by the observation of shock deformation and shock metamorphic effects in quartz grains from the surrounding sandstones. Photogeological investigations initially suggested either a granite diapir or an impact crater, but later research, including sample collection and analysis, confirmed the impact hypothesis. The structure is composed of fine-grained, well-sorted, slightly carbonate-bearing sandstone, possibly of Upper Devonian age. The crater is recognized as a multi-ring structure, with a central complex, a strong elevation ring, a flat annulus, and an outer ring.

Location and Associated Features

Aorounga Crater is situated in northern Chad, approximately 110 kilometers southeast of the Emi Koussi volcano in the Tibesti Massif. The crater is accompanied by two nearby circular features revealed by Space Shuttle SIR-C radar, which may be related impact craters, suggesting Aorounga might be part of a crater chain. If this hypothesis holds true, the exposed Aorounga crater is sometimes referred to as Aorounga South. The landscape around the crater is characterized by linear rock ridges called yardangs, formed by wind erosion, and actively migrating sand dunes.