Los Adobes Formation
Los Adobes Formation is an Early Cretaceous geologic formation in Chubut Province, in the Cañadón Asfalto Basin of central Patagonia, Argentina. The formation belongs to the Chubut Group and represents the Early Cretaceous K1 megasequence in the basin, unconformably overlying the Late Jurassic Cañadón Calcáreo Formation and is overlain by the Albian Cerro Barcino Formation.
Los Adobes Formation was deposited in an alluvial to fluvial environment and the mudstones of the overall sandy and conglomeratic unit have provided fossils of a chelid turtle whose indeterminate remains were described by Sterli et al. in 2020.
Description
Los Adobes Formation, the lower unit in the Chubut Group was first described in 1970 by Tasch and Volkheimer. The formation underlies the Cerro Barcino Formation and unconformably overlies the Late Jurassic Cañadón Calcáreo Formation. The formation crops out in the southern Cañadón Asfalto Basin, south of the North Patagonian Massif until the Meseta de Canquel.In the Sierra de Traquetrén, in the extreme northwest of the Cañadón Asfalto Basin, Los Adobes Formation has been thrusted onto the Maastrichtian Paso del Sapo Formation.
The formation is absent in the Cañadón del Zaino around Cerro Baya and Gastre, where the Early Jurassic Las Leoneras and Lonco Trapial Formations as well as the Middle Jurassic Cañadón Asfalto Formation crop out. The oldest overlying formations in this area are the Neogene La Pava and Cráter Formations.