Arcabuco Formation

The Arcabuco Formation (Formación Arcabuco, Jar, JKa) is a geological formation of the Altiplano Cundiboyacense, Eastern Ranges of the Colombian Andes. The formation consists of thick beds of light-coloured quartzitic sandstones and conglomerates with occasional shales and dates to the Late Jurassic and Early Cretaceous periods; Tithonian to Berriasian epochs. Dinosaur footprints have been found in the Arcabuco Formation near the Iguaque anticlinal outside Chíquiza, Boyacá.

Etymology
The formation was first defined by Scheibe in 1938 and named after Arcabuco, Boyacá. The type section of the Arcabuco Formation was redefined in 1985 by Galvis and Rubiano around Villa de Leyva.

Lithologies
The Arcabuco Formation is characterised by a sequence of light- to pink-coloured fine quartzitic sandstones and conglomerates with red shales up to 50 m in thickness intercalated. In the Arcabuco Formation, in the Iguaque Anticlinal, dinosaur tracks have been found. The overhanging rock shelter of Sáchica in Sáchica, Boyacá, consists of the sandstones of the Arcabuco Formation.

Stratigraphy and depositional environment
The 500 to 800 m thick Arcabuco Formation unconformably overlies the Girón Formation and is overlain by the Rosablanca and Cumbre Formations. The age has been estimated to be Late Jurassic to Early Cretaceous. Stratigraphically, the formation is time equivalent with the Guavio and La Naveta Formations of the eastern and southern Altiplano respectively. The Arcabuco Formation has been deposited in a rift basin setting.

Outcrops
The Arcabuco Formation is found apart from its original type locality near Arcabuco, in the anticlinal of Lake Iguaque between Villa de Leyva, Sáchica and Chíquiza, where the formation has been redefined in the Arcabuco Anticlinal.