High-density bioturbated sandstones in the Mississippian Mauch Chunk Formation, eastern Pennsylvania, USA: Implications for continental ecospace exploitation

Continental communities represented by complex, rapidly evolving invertebrate ecosystems first appeared during the Early Palaeozoic Era and are recorded in surface and subsurface bioturbation. The Mississippian-age Mauch Chunk Formation contains several high-density bioturbated, fine-grained sandstones that are preserved as erosively based fluvial channel fills. Several of these channel sandstone bodies are almost completely homogenized by subsequent bioturbation throughout their entire thickness, up to a maximum depth of 1.6m. The Mauch Chunk ichnofossil record demonstrates that high-density bioturbation occurred at least 30my prior to the Permian and well before its widespread distribution in the Triassic. Hence, the Late Mississippian high-density bioturbated sandstones demonstrate a much earlier high-density exploitation of the continental subsurface ecospace than previously known. ► We have discovered intensely bioturbated channel deposits in Mississippian deposits. ► Intense bioturbation has homogenized these channel deposits. ► These deposits push back the onset of intense ecospace utilization by 30myr.