Taphonomy and Artificial Time-Averaging of Marsh Foraminiferal Assemblages (Bombay Hook National Wildlife Refuge, Smyrna, Delaware, U.S.A.): Implications for Rates and Magnitudes of Late Holocene Sea-Level Change
Ronald E. Martin, Scott P. Hippensteel, Daria Nikitina, James E. Pizzuto, 2003. "Taphonomy and Artificial Time-Averaging of Marsh Foraminiferal Assemblages (Bombay Hook National Wildlife Refuge, Smyrna, Delaware, U.S.A.): Implications for Rates and Magnitudes of Late Holocene Sea-Level Change", Micropaleontologic Proxies for Sea-Level Change and Stratigraphic Discontinuities, Hilary Clement Olson, R. Mark Leckie
Download citation file:
Foraminiferal assemblages of Bombay Hook National Wildlife Refuge (Smyrna, Delaware, U.S.A.) exhibit substantial variation in spatio-temporal test inputs to marsh sediment and are strongly overprinted by seasonal changes in porewater chemistry. Seasonal surface and near-surface samples are typically not representative of foraminiferal inputs at depth (60 cm). Long-term ecological signals are detected using artificially time-averaged (ATA) assemblages, in which dead and live counts of foraminifera are summed separately for an entire two-year sampling period. Unlike seasonal assemblages, cluster analysis of ATA assemblages reveals a distinct change in assemblages at ∼ 20 cm depth. Differential preservation of foraminifera in the upper 60 cm—and especially the upper 20 cm—of sediment mimics a sharp paleoenvironmental change that could potentially be interpreted as a rapid fall in sea level during a time of documented transgression over the last ∼ 100–200 years.
Figures & Tables
Micropaleontology and biostratigraphy play vital roles for deciphering the stratigraphic record produced by changes in relative sea level, interpreting the history of global sea-level change, and testing models for the causes of sea-level fluctuations due to the variable influences of tectonics, glacio-eustasy, and climate. The stratigraphic architecture developed in response to changing eustasy, accommodation space, and sediment supply along continental margins, in epicontinental seas, and on carbonate platforms can be interpreted using the tools of marine micropaleontology. Microfossils provide chronostratigraphic control and a wealth of paleoenvironmental information about depositional environments as well as post-depositional changes to those environments. This volume demonstrates clearly that micropaleontologic proxies of environmental change provide a powerful dimension to the interpretive potential of stratigraphic sequences produced by changes in relative sea level and eustasy. Studies in the volume range from paralic to bathyal environments, span Pennsylvanian through Holocene stratigraphy, encompass a variety of microfossil groups and include a wide spectrum of techniques and paleoenvironmental proxies. The volume has been designed for graduate students and professionals interested in a wide range of subjects.