Alluvial fan and playa sedimentation in an Andean arid closed basin: the Pacencia Group, Antofagasta Province, Chile ( Tertiary).

The mid-Tertiary Pacencia Group comprises over 2km of continental sediments. It was deposited in a half-graben basin thought to have been active since early Tertiary times. Conglomerates along the western basin margin were deposited as longitudinal bars, rare transverse bars and channel fills. To the east, a succession was deposited in playa sub-environments. Lakes existed at various stages and were fed by permanent fluvial systems. The playa sediment were derived from crystalline source areas to the east. Proximal fan facies and sediment sources are now buried under the volcanic Andes.-from Author