ASSOCIATION BETWEEN WAVE- AND CURRENT-AIDED HYPERPYCNITES AND FLOODING SURFACES IN SHELFAL MUDSTONES: AN INTEGRATED SEDIMENTOLOGIC, SEQUENCE STRATIGRAPHIC, AND GEOCHEMICAL APPROACH

摘要

The Middle to Late Devonian lower Genesee Group of New York has been the focus of sedimentologic, stratigraphic, and paleoecologic studies for over 150 years. Documentation of fluvial discharge events in this succession supports the growing realization that mudstone sedimentation in shelf seas is much more dynamic than commonly appreciated. Although this process has been observed on modern shelves, so far only few examples have been reported from ancient shelf strata. Integrated sedimentologic, sequence stratigraphic, and geochemical data suggest that organic-rich mudstones of the Geneseo Formation were strongly influenced by fluvial-discharge events that carried fine-grained clastics and phytodetritus as turbulent flows from river-mouth regions onto the shelf. These discharge events appear to occur most abundantly during initial flooding at parasequence boundaries, a depositional context that resulted in increased coastal erosion processes and enhanced continental runoff.