Textural responses to evolving mass-flows: an example from the Devonian Asen Formation, central Norway

Abstract

AbstractThe Asenvågoya Conglomerate is a thin (c. 6 m) conglomeratic body composed of mass-flow deposits and enveloped by braided-stream sandstones and conglomerates. The section studied represents the proximal part of a small-radius alluvial fan built out from the basin margin towards a flood basin. The fan was possibly generated by escarpment creation, or rejuvenation, in response to syndepositional faulting along the basin margin, and comprises sand-matrix-supported and clast-supported, sheet-like conglomerates. There is an upward change through the sequence from stream flow and surging mass-flow, through fully turbulent mass-flow and sheet flow to cohesive mass-flow deposits and then a return of braided-stream alluvium at the top of the sequence. The fan wedge demonstrates the wide range of textures possible within a ‘mass-flow” system.