Terrestrial and Marine Palynomorphs as Sea-Level Proxies: An Example from Quaternary Sediments on the New Jersey Margin, U.S.A.
Published:January 01, 2003
Francine M.G. McCarthy, Kevin E. Gostlin, Peta J. Mudie, Jennifer A. Hopkins, 2003. "Terrestrial and Marine Palynomorphs as Sea-Level Proxies: An Example from Quaternary Sediments on the New Jersey Margin, U.S.A.", Micropaleontologic Proxies for Sea-Level Change and Stratigraphic Discontinuities, Hilary Clement Olson, R. Mark Leckie
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Palynomorphs are acid-resistant organic particles which behave aerodynamically and hydrodynamically like silt, and which resist degradation except in oxidizing or highly alkaline conditions. They are present in virtually all marine sediments, from the tropics to the poles and from estuarine to abyssal environments. Reconstructions of Quaternary sea level in cores from the New Jersey shelf (ODP Hole 1072A) and slope (ODP Hole 1073A) based on the modern distribution of palynomorphs across the New Jersey margin as well as the taphonomic alteration of palynological samples agree fairly well with data from other available proxies (e.g., oxygen isotopes). The palynological signatures of sediments on continental margins also provide information about the generation of sequences and sequence boundaries. The palynological character of surfaces identified as sequence boundaries from seismic reflection profiles records the generation of erosional unconformities during extreme lowstand events that altered the geometry of the margin. Very low palynomorph concentrations and presumably oxidized palynological assemblages (containing few protoperidinioid dinocysts or thin-walled pollen grains) characterize erosional unconformities. The strong seismic reflection associated with sequence boundaries results from physical contrast between the transgressive/highstand sediments (with very high palynomorph concentrations, P:D values declining rapidly upcore, and Pinus-dominated pollen assemblages) and underlying the lowstand sediments (with low palynomorph concentrations, high P:D values, taphonomically altered and ecologically mixed palynological assemblages). The palynological content of Quaternary sediments at ODP Sites 1072 and 1073 thus supports the role of eustasy as an important factor in shaping the New Jersey margin.
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Micropaleontologic Proxies for Sea-Level Change and Stratigraphic Discontinuities
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.