Comment on ‘‘Impact structures in Africa: A review’’

ACEVEDO, ROGELIO; RABASSA, JORGE; CORBELLA, HUGO; MARÍA JULIA ORGEIRA; PREZZI, CLAUDIA BEATRIZ; PONCE, FEDERICO; MARTÍNEZ, OSCAR; GONZÁLEZ, MAURICIO; ROCCA, MAXIMILIANO; SUBÍAS, IGNACIO

JOURNAL OF AFRICAN EARTH SCIENCES - (Print)

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 2014 vol. 100 p. 755 - 756

1464-343X

We are very thankful for the references in Reimold and Koeberl (2014) Impact structures in Africa: A review regarding our paper on the Bajada del Diablo astrobleme‐strewn field, central Patagonia, Argentina (Acevedo et al. 2009). All suggestions to improve or change our proposed genetic model are certainly welcome, and we are grateful to the cited authors for their interest and inquisitiveness. However, our only disagreement with those remarks is based on their assumption that our paper reports an entire impact crater strewn field in the volcanic Bajada del Diablo area of Argentina. Definitely, this is not at all true, and there is no worse lie than half of the truth. The cited authors have omitted in those paragraphs that refer to our work (pages 67 and 87) our main geologic argument: the impact cratering reached two different but contiguous lithostratigraphic units (Fig. 1), thus overlooking (i) the irrefutable evidence of craters, very close to each other, which have been the result of impacts upon two different geologic environments, since only the ancient volcanic environment has been mentioned, excluding the much modern sedimentary deposits which were also affected, and (ii) the proven fact that volcanic activity in the area ended several million years before the main impact took place. Moreover, the lack (so far) of findings of meteorite fragments or shock metamorphism in the Bajada del Diablo area does not necessarily mean that these craters are not impact craters. As one of the mentioned authors stated just a few years ago: ?At present, however, meteorite components have been identified for less than one‐quarter of the impact structures identified on Earth? (C. Koeberl in Sites of impact, S. Gaz, 2009, p.15). Once more, the absence of evidence is not evidence of absence, but they may be suggesting instead that the impacting object could have been a blasting ice comet or its expansive waves. We would sincerely like to invite our critics to return to box 1, and visit with us this isolated and remote area of Argentine Patagonia, so as to have an in‐situ appreciation of the integrity of our description and interpretation of these craters which we believe have been unjustly questioned. Furthermore, geophysical research about the Bajada del Diablo astrobleme‐strewn field have been recently presented in Acevedo et al. (2012) and Prezzi et al (2012) where magnetic and Bouguer anomalies in the crater G (on basalt) of BdD (Fig. 1) are characteristic of impact structures.