The Hornillos Formation, deposited in the Algarrobal Basin,[2] comprises sandstones, limestones, conglomerates, and caliches, intercalated with lavas and andesiticbreccias and various volcanic rocks. Between these last is a conspicuous layer of rhyo-dactitic lithic tuff, which reaches up to 10 metres (33 ft) in thickness. Bones of indeterminate titanosaurs appear in a marly limestone stratum of 10 metres (33 ft) thick with decimeter-sized calcareous concretions. The smallest pieces were found as rollings, whereas the larger piece was included in the limestone.[3]
The Hornitos Formation formerly was thought to be of Paleocene to Eocene age.[4] The formation may be older and belong to the Early Cretaceous, as a granite intruded the rocks about 105 ± 10 Ma.[5]
G. Chong Diaz. 1985. Hallazgo de restos oseos de dinosaurios en la Formación Hornitos – Tercera Region de Atacama – Chile. IV Congreso Geologico Chileno 152–161
P. Salinas, P. Sepúlveda, and L. G. Marshall. 1991. Hallazgo de restos oseos de dinosaurios (saurópodos) en la Formación Pajonales (Cretácico Superior), Sierra de Almeyda, Región de Antofagasta, Chile: implicancia cronológica [Discovery of skeletal remains of dinosaurs (sauropods) in the Pajonales Formation (Upper Cretaceous), Sierra de Almeyda, Antofagasta Region, Chile: chronological implications]. 6e Congreso Geológico Chileño, Viña del Mar. Resumenes Expandidos. Servicio Nacional de Geología y Mineria, Chile 534-537
Chile
