Cañadon Asfalto Formation

The Cañadón Asphalt Formation is a lithostratigraphic formation in Argentina. Outcrops can be found along the Río Chubut in the province of Chubut. This sequence of continental sedimentary rocks dated to the Jurassic and is known for its rich fossil fauna, which includes the fossils of dinosaurs with.

Definition and geological framework

The Cañadón Calcáreo lineup counts for Cañadón Asfalto Basin, one to Somuncura Massif belonging sedimentary basins. The range of the formation is controversial, with two competing research opinions exist: After the first opinion of this formation the Las Chacritas member that consists of lacustrine ( deposited in lakes) sediments of the Middle Jurassic is composed of two Subformationen, and the Puesto - Almada member that consists of mainly fluvial ( deposited by rivers ) sediments of the upper Jurassic. The second opinion research classifies the younger Puesto Almada - Members as an independent formation, which is called Cañadón Calcáreo lineup. The following text deals only with the Middle Jurassic section of the formation ( Cañadón Asfalto Formation sensu stricto ), the Upper Jurassic section, see the article Cañadón Calcáreo lineup.

The Cañadón Asfalto Basin has opened up as a result of the early breakup of South America and Africa by extension movements, the structure is called Hemigraben. The Cañadón Asfalto Formation sensu stricto could settle on during the syn- rift stage, ie simultaneously with the tectonic activity of the Hemigrabens. In contrast to lying in the hanging wall Cañadón Calcáreo lineup this formation is verfaltet tectonically.

Below the formation is the Lonco - Trapail Group, which consists of the Cañadón Puelman lineup and the Cerro- Carnerero lineup.

Age

The middle Jurassic Cañadón Asphalt lineup was often dated in the past on the Callovian, based on comparisons of the fossil flora with other formations. More recent studies, based on radiometric dating and pollen analyzes, however, point out that the formation is significantly older and probably came to the deposition between the Board of Toarcian and the lowest of Bathonian.

Lithology

The middle Jurassic Formation consists mainly of lacustrine sediments, especially from thin sheet, marly pelites and limestones, which occasionally basaltic Lavalagen and clastic sediments (conglomerates and breccias ) are interposed.

Fossils

The most famous wide for fossils is located within the village of Cerro Cóndor. For this Fund, the area most dinosaur discoveries of the formation that have been recovered under the direction of paleontologist José Bonaparte in the years 1976-1985 as submitted. Fossils of the formation close invertebrates, plants and vertebrates with a. The most common invertebrates of the formation are mussel Schaler ( Conchostraca ) and mussels ( Bivalvia ). The vertebrate fauna is made up of fish, anurans, turtles, lizards shed, crocodiles, pterosaurs, dinosaurs and mammals. Dinosaurs of the formation include the theropod Piatnitzkysaurus, Condorraptor and Eoabelisaurus, the Heterodontosauriden Manidens and the original sauropods Volkheimeria and Patagosaurus with a.