Biofacies and Lithofacies Evidence for Paleoenvironmental Interpretations of Upper Neogene Sequences on the New Jersey Continental Shelf (Odp Leg 174A)
Published:January 01, 2003
Miriam E. Katz, Kenneth G. Miller, Gregory S. Mountain, 2003. "Biofacies and Lithofacies Evidence for Paleoenvironmental Interpretations of Upper Neogene Sequences on the New Jersey Continental Shelf (Odp Leg 174A)", Micropaleontologic Proxies for Sea-Level Change and Stratigraphic Discontinuities, Hilary Clement Olson, R. Mark Leckie
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We evaluate late Miocene–Recent paleoenvironments, paleobathymetry, and depositional facies recovered at two sites drilled by Ocean Drilling Program Leg 174A on the New Jersey continental shelf. Based on seismic stratigraphy, previous studies suggested that the New Jersey margin sequences are primarily either highstand deposits or lowstand systems tracts. However, benthic foraminiferal biofacies and planktonic foraminiferal abundances proved to be key to deciphering systems tract development. By integrating foramin-iferal, lithologic, and downhole logging evidence within a seismically defined sequence stratigraphic framework, we show that Pleistocene sequences cored by Leg 174A are characterized by transgressive and highstand deposits, whereas Miocene sequences consist of lowstand, transgressive, and highstand deposits, with repeated flooding surfaces indicating parasequences. We propose that the erosion responsible for the shelf sequence boundaries can be attributed to mean lowerings of base level in response to changes in the mean states of glaciation that marked: (1) the Miocene increase in ice volume and glacioeustatic lowering; (2) the transition to Northern Hemisphere–dominated glaciation; and (3) the transition to the large eustatic fluctuations of the middle–late Pleistocene.
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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.