Lithology and sedimentology of the Lajas Formation (Middle Jurassic) in the southern part of the Neuquén Basin, Argentina

Abstract

Lithology and sedimentology of the Lajas Formation (Middle Jurassic) in the southern part of the Neuquén Basin, Argentina?. The Lajas Formation (Bathonian to Lower Callovian) is the mixed facial, mainly deltaic link between the marine Cura Niyeu Formation (Bajocian) and the (here) continental Lotena Formation (mainly Middle Callovian). In the Lajas Formation marine and lagoonal coastal sediments, frequently with coquinas, appear as well as fluvial to deltaic channel sediments and delta plain sediments. The latter commonly are fining-upwards-sequences. The lithology of the rocks, the types of sequences and the main sedimentary structures are described. The environmental development of the Lajas Formation is shown. The sediments are coming from the west; possibly they are to be derived too from the basement and triassic of the Sierra Chacai Co.