55 Stratigraphy (Posters)

INTEGRATED BIOSTRATIGRAPHIY, PALEOBATHYMETRY, AND SEQUENCE STRATIGRAPHY OF LATE SANTONIAN - EARLY CAMPANIAN SEQUENCES ON NEW JERSEY COASTAL PLAIN: INPLICATION TO GLOBAL SEA-LEVEL

Paper number: 55-18
Program: Technical Sessions
Time: 1:30 PM – 5:30 PM

Authors

Abstract

The New Jersey Coastal Plain (NJCP) provides an excellent location for Cretaceous sea-level studies due to minimal regional tectonic influences (Kominz et al., 1998), and well-developed shallow marine fossiliferous sequences (Miller et al., 1998, 2004). Analysis of the sequences and paleowater depth fluctuations constrains the nature and timing of sea-level changes. Recent studies of the Santonian - Campanian section (Merchantville Formation) in two coreholes (Ancora and Bass River) on NJCP identified existence of concatenated sequences in glauconitic facies (Miller et al., 2004). The lithological expression of unconformities within the Merchantville glauconites is obscure and their resolution requires integrated stratigraphic approach. Here we present detailed litho- and biostratigraphic analyses of the Merchantville Formation sequences in four NJCP coreholes (Sea Girt, Ancora, Millville, and Bass River). Biofacies analysis reveals four benthic foraminiferal assemblages from inner to middle neritic environments. Correlation of the benthic foraminiferal biofacies, the percentage of planktonic foraminifera, and lithologic data suggested water depth estimates from 30 to 75 m. The correlation of the biostratigraphy, benthic foraminiferal biofacies, lithology, and gamma logs delineates unconformities, and identifies three sequences within the Merchantville Formation (Me1, Me2, Me3). The age of these sequences has been constrained by calcareous nannoplankton biostratigraphy (Me1: CC16; Me2: CC17-18; Me3: CC18-19) from 79.1 to 85.0 Ma.

Three Merchantville sequences are evident within all four NJCP coreholes, suggesting that the sequences are regional in extent. Comparison of the New Jersey shallow marine sequences with the deep-sea oxygen isotope record from DSDP Site 511 (Falkland Plateau) revealed two episodes of sea-level decrease synchronous with the oxygen isotope increases. Our data imply that the Merchantville sequence boundaries may be attributed to the global cooling and ice volume increases. Our results support the contention that global sea-level changes during the peak warmth of the Cretaceous were controlled by ice volume variations. We propose future studies on detailed record of oxygen isotope and backstripping analysis of the late Santonian-Campanian interval.