Dorotea Formation
The Dorotea Formation is a geological formation in the Río de Las Chinas Valley of the Magallanes Basin in Patagonian Chile whose strata date back to the Campanian to Maastrichtian of the Late Cretaceous.
Description
The Dorotea Formation was first described by Katz in 1963. The formation comprises sandstones with frequent conglomerate lenses, concretionary levels and claystones. The Dorotea Formation includes calcareous sandstones with abundant marine invertebrate and fragmentary vertebrate fossils. Hervé et al. obtained a maximum radiometric age of 67.4 ± 1.5 Ma from detrital zircons contained in sandstones of the Dorotea Formation. Near the top of the formation is an iridium anomaly, correlated with the Cretaceous–Paleogene boundary; this is the southernmost K–Pg boundary site known from South America.The mudstones and sandstones of the formation were deposited in a fluvial environment. The formation conformably overlies the Tres Pasos Formation and is unconformably overlain by the Lutetian to Bartonian Man Aike Formation. The thickness of the formation ranges from in the Sierra Baguales in the north to in the eponymous Sierra Dorotea in the south.