Hyolith-dominated Shell Beds from the Lampazar Formation in NW Argentina: Patterns and Processes of Origin in the Late Cambrian (Furongian) Seas of Western Gondwana

摘要: Late Cambrian (Furongian) shell beds in the Salta Province of NW Argentina are unique because presence abundant hyolith skeletal remains within them. Hyolith located mid-upper part Lampazar Formation at Angosto de La Quesera locality, and first recorded accumulations this type lower Palaeozoic South American Andean Basin. The order several mm thick, laterally persistent outcrop scale, with a few metres lateral development. Two types recognised: Type 1 is storm-dominated, event concentration, represented by dispersed to densely packed well preserved gastropod shells (Strepsodiscus austrinus). conchs current oriented long axes parallel unidirectional flow on sandstones surfaces. 2 background, composite concentrations, poorly preserved, comminuted debris associated trilobite sclerites (dominated Parabolina, Beltella Leiostegium). genesis both was controlled primarily physical processes, such as storms and/or wave agitation. thickness, simple internal fabric geometry shown typical Cambrian-style shell-beds.