The Greywacke problem

Publisher Website
Google Scholar
Abstract
Greywacke is a kind of sandstone in which the sand grains are set in a fine “muddy” matrix. The fine grained matrix is at once the essential characteristic of greywacke and the essence of the greywacke problem. The mode and environment of deposition of greywackes can be inferred from their sedimentary structures and from their lithological and palaeontological associations. Many greywackes are recognised as deep water marine turbidites; others are shallow water marine sediments; and yet others are fluviatile. Modern sediments of comparable origin, whether found in nature or produced experimentally, are not greywackes. Thus, if the principle of uniformitarianism is applied, the peculiar texture of greywackes cannot be an original detrital feature, but must be the result of post‐depositional alteration of “normal sand”. Several independent lines of evidence support the post‐depositional alteration hypothesis for the origin of greywacke.