Campanian conifer woods from Estancia La Aurora, Cañadón Asfalto Basin, Patagonia Argentina

Abstract

Conifer fossil woods from the Campanian Puntudo Chico Formation were studied. The specimens were collected at the Estancia La Aurora, Cañadón Asfalto Basin, Chubut Province, Patagonia, Argentina. The parautochthonous petrified woods, which have well-preserved anatomy, were transported a short distance from their original habit and deposited within fluvial channels. The use of transmitted light and scanning electron microscopes allowed to identify the diagnostic characters. This paper corroborates the presence of Brachyoxylon currumillii and the first mention of Cupressinoxylon sp. cf. C. artabeae in the Puntudo Chico Formation. The new specimens of Podocarpoxylon mazzonii confirm that this taxon is a common and abundant element in the Cretaceous to Eocene floristic assemblages. Based on 51 growth-rings, the mean ring width, and Mean Sensitivity (MS) were 1.68 mm (0.62–2.92 mm) and 0.33 (0.27–0.40) respectively. These fossil trees indicate that they developed under temperate and humid conditions, with slightly sensitive from year to year with a terminal event representing a cessation or retardation of cambial activity. Other paleoclimatic proxies including geological and fossil data indicate that the Puntudo Chico Formation was deposited under temperate-warm and humid conditions, with some semi-arid events.