Bass River Site

Abstract

Background and Operations The Bass River Site was the fourth borehole drilled as part of the New Jersey Coastal Plain Drilling Project, which began with Ocean Drilling Program (ODP) Leg 150X drilling at Island Beach, Atlantic City, and Cape May (Miller et al., 1994a, 1994b, 1996). Bass River was drilled by the New Jersey Geological Survey (NJGS) and Rutgers University and is the first site drilled as part of ODP Leg 174AX, complementing shelf drilling by Leg 174A; future Leg 174AX drilling is planned for 1998 near Corson's Inlet and Ancora, NJ. Funding for Bass River was provided by the NJGS for direct drilling expenses and the National Science Foundation (Earth Sciences Division, Continental Dynamics Program and Ocean Science Division, ODP) for science support. Drilling at Bass River targeted middle Miocene and older sequences, with the primary focus on Upper Cretaceous (Cenomanian-Maastrichtian) to Paleocene strata that previously were poorly sampled. The drilling contractor, Boart Longyear, Inc., continuously cored 1956.5 ft (596.34 m) in October and November 1996 in Bass River State Forest, NJ (39°36′42″N, 74°26′12″W; elevation 28 ft [8.53 m]; New Gretna, NJ, 7.5-min quadrangle); drilling operations were superintended by the Continental Scientific Drilling Office of Texas A&M University. Recovery was excellent (mean recovery = 86.2%; median recovery = 99%), and a gamma log was obtained to total depth (TD). The on-site scientific team provided preliminary descriptions of sedimentary textures, structures, colors, fossil content, identification of lithostratigraphic units, lithologic contacts, and sequences (unconformity-bounded units). Neogene Sequences The Cape May Formation consists of ?Pleistocene-Holocene unconsolidated gravels, gravelly sands, and sandy clays (3−19.7 ft [0.91−6.00 m]). These overlie quartz sands and sandy clays assigned to the ?upper or ?middle Miocene Cohansey Formation (19.7−132.9 ft [6.0−40.5 m]). Three or four sequences were identified in the Cohansey Formation, but their ages are not known because of the absence of calcareous fossils. The lower middle to lower Miocene Kirkwood Formation (132.9−555.3 ft [40.51−169.26 m]) can be divided into four coarsening-upward (shallowing) sequences (Kw2b, Kw2a, Kw1b, Kw1a). These sequences consist of thin to absent basal sands (Transgressive Systems Tracts [TST]) overlain by prodelta clayey silts (lower Highstand Systems Tracts [HST]) that grade upsection to delta front medium-coarse sands (upper HST). Age control on these sequences consist of limited diatom biostratigraphy and Sr-isotopic analyses on the lower sequence (21.4−20.8 Ma).

A biogenic origin for anomalous fine‐grained magnetic material at the Paleocene‐Eocene boundary at Wilson Lake, New Jersey

“…The Wilson Lake core is one of several continental cores drilled into the Paleocene-Eocene neritic inner to middle shelf environment on the North American continental margin [Miller, 1997]. Other proximal cores include the shallow water Clayton core $5 km to the west, as well as the deeper Ancora (45 -70 m depth) and Bass River ($105-140 m depth) cores from Ocean Drilling Program Leg 174AX farther to the east [Miller et al, 1998;Van Sickel et al, 2004]. P-E boundary sediments from Wilson Lake consist of deltaic-neritic inner shelf clays and glauconitic sandstones deposited during a sea level transgression [Gibson et al, 1993].…”

Wilson Lake site

“…A coeval lowermost Eocene kaolinite-rich clay (e.g., Edwards, 1996) was first reported in Virginia and Maryland (Darton, 1948) and defined as the Marlboro Clay by Glaser (1971). It is clear that the coeval kaolinitic clayey silt found in the Wilson Lake corehole is thick (48.2 ft; 14.7 m), lithologically distinct with upper and lower contacts, mappable, and found throughout much of the New Jersey coastal plain (e.g., it is found at Clayton, Medford, Millville, Bass River, Ancora, and Sea Girt sites [Gibson et al, 1993;Sugarman et al, 2010Sugarman et al, , 2005Miller et al, 1998bMiller et al, , 2006) and warrants recognition as a formation in New Jersey. However, the grain size in New Jersey is dominantly clayey silt and following protocols in New Jersey (e.g., Owens et al, 1998), we avoid the use of the term clay and apply the term Marlboro Formation to this unit.…”

“…Bass River, New Jersey (October-November 1996) (Miller et al, 1998b), targeting Upper Cretaceous-Paleocene strata unsampled during Leg 150X. 2.…”

Evidence for reduced export productivity following the Cretaceous/Paleogene mass extinction

“…Here, we present δ 13 C and δ 18 O records from multiple species of planktonic and benthic foraminifera, δ 13 C changes of bulk and organic carbon, and the changes in the mass accumulation rates of total organic carbon (MAR‐C org ) from the New Jersey paleoshelf (Figure ) between ~ 69 and 65 Ma (where the K/Pg boundary is placed at 66.04 Ma) [ Gradstein et al, ]. The Ancora (Hole B) and Bass River coreholes drilled by Ocean Drilling Program Leg 174AX [ Miller et al, , ] provide the most complete K/Pg boundary sections in the New Jersey paleoshelf (Figure ), representing shallower (middle neritic) and deeper shelf environments (middle‐outer neritic), respectively. The updip and downdip comparison of the Ancora and Bass River coreholes allows us to distinguish among the different shelf responses because they recorded: (1) mixed layer to thermocline δ 13 C gradients in planktonic foraminifera, (2) cross‐shelf δ 13 C gradients in benthic foraminifera, and (3) differences in the rate of organic carbon burial across the K/Pg boundary.…”