Systematic meteorite collection in the Catalina Dense Collection area (Chile): Description and statistics

Abstract

We present the outcome of search campaigns conducted in the Catalina Dense Collection area (DCA) located in the central depression of the Atacama Desert, Chile. The “Catalina Systematic Collection” (CSC) was assembled through systematic on-foot searches, resulting in a total of 1599 meteorites, before pairing, collected over a surface of 6.80 km². This yielded a recovery density of 235 meteorites per km² (67 meteorites >20 g per km²), making it the densest among hot deserts, even higher than the neighboring El Médano DCA collection. This confirms that the central depression of the Atacama Desert holds the highest meteorite density among hot deserts. We classified 457 meteorites weighing more than 20 g. After correcting for various recovery biases, we estimated a true meteorite density on the ground of 131 meteorites per km² for meteorites >20 g before pairing. Using a probabilistic approach, we calculated an average pairing likelihood, yielding 71 meteorites >20 g per km² after pairing. This high density is likely linked to an old age of the CSC, which would also explain the absence of carbonaceous chondrites, as they are more prone to alteration by abrasion. This long meteorite accumulation period is related to the long-term hyper-aridity and surface stability of the Atacama Desert, which have persisted for several million years. Meteorites from the CSC show less chemical weathering on average than in other hot deserts, despite the long accumulation period. The H/L ratio in the CSC is higher than in meteorites from other hot deserts, Antarctica, and falls, but similar to the El Médano collection, potentially reflecting variations in the composition of the meteorite flux over the past Myr.