Ichnofabric of Sandstones Deposited in High-Energy Nearshore Environments: Measurement and Utilization

Phanerozoic high-energy nearshore terrigenous clastic deposits characteristically contain trace fossil assemblages dominated by Skolithos or Ophiomorpha. The different geometries of these burrows result in the production of different types of ichnofabrics. In order to document extent of bioturbation aseries of ichnofabric indices designed for strata deposited in this environment can be used. Data collected with this method reveal that ichnofabric index 1 (no bioturbation) constitutes nearly 50% of all but one of the six Phanerozoic stratigraphic sections that were studied. Nearly complete to complete reworking of original physical sedimentary structures is unusual in the studied post-Paleozoic sections, which are dominated by Ophiomorpha. In contrast, studied lower Paleozoic sections contain Skolithos piperock, reflecting complete disruption of original physical structures, which commonly alternates with non-bioturbated strata, resulting in a type of biostratification.