THE STRUCTURE AT SIERRA AMBATO, CATAMARCA, ARGENTINA: A NEW METEORITE IMPACT SITE?

ACEVEDO, R.D.; ROCCA, M.; ALONSO, R.; RABASSA, J.; PONCE, J.F.

Cairns

Encuentro; 75th Annual Meteoritical Society Meeting (2012), Carnis, Australia; 2012

A new possible impact crater was discovered during routine flights by Mr. Jorge A. Viaña in Catamarca Province: the structure at Sierra Ambato (28º 03’ 23.22” S, 66º 03’ 11.06” W), located at Sierras Pampeanas (3,500m.a.s.l). It has 1.0 km in diameter. The crater feature is a clear ring with a raised rim and a central depression on the eastern slope at the top of the chain. The area all around the crater is full of radial and concentric fractures and faults. The structure has been a bit flattened by the erosion. The local geology is in no conflict with an origin by a meteorite impact. The district is composed of an upper Precambric-lower Cambric metamorphic basement intruded by Ordovician-Carboniferous granitic rocks. Gondwanic paleosurfaces of upper Jurassic-Cretaceous age appear to cut the structure. Sierra de Ambato’s crater cannot be a volcanic neck or caldera. Its morphology is quite different, e.g. has a raised rim and there are no visible lava floods coming from the crater itself. No volcanic features have been so far reported for this site. Fracturing structures are typical of simple type-impact craters. This crater is probably a quite eroded simple-type meteorite impact crater. Its age is estimated as post-Paleozoic (probably Cenozoic, pre Jurassic). Further investigation of this interesting crater is in progress.