Biostratigraphy and Depositional Environments of Late Jurassic and Early Cretaceous Carbonate Sediments in Baltimore Canyon Basin

E. R. Ringer, H. L. Patten

Shell Offshore and partners recently drilled three deep-water tests offshore New Jersey. These wells provide additional information concerning the biostratigraphy and depositional environments of Late Jurassic through Early Cretaceous strata of the Baltimore Canyon basin. Dinoflagellates, foraminifera, and calpionellids provide the biostratigraphic framework. Information from these wells, coupled with prior well data and seismic geometries, document: (1) an Oxfordian through early Kimmeridgian, progradational, shallow marine shelf sequence containing the microfossils, Alveosepta jaccardi, Ctenidodinium chondrum, and Geiselodinium paeminosum; (2) a late Kimmeridgian through early Berriasian, aggradational, shallow marine shelf sequence with microfossils including Everticyc ammina virguliana, Trocholina elongata, Ambonoshaera jurassica, Dingodinium jurassicum, and Gochteodinia mutabilis. Analyses of cores from shelf margin sediments demonstrate reef-flat bioclastic grainstones and reef-front hydrozoan boundstones which contain Calpionella alpina and Tubiphytes sp. in micritic intervals; (3) Berriasian to intra-Valanginian (Calpionella alpina/Tintinnopsella carpathica large variety zone to T. carpathica large variety zone) deep marine, lime wackestones -packstones (probably allodapic in part) rich in planktonic microfossils. Numerous dictyonine-grade hexactinellid sponge fragments and Tubiphytes sp. are also present. This interval is probably equivalent to the Artimon Member of the Abenaki Formation described from the Nova Scotian subsurface; (4) Valanginian deposits are succeeded by a basinward-thinning wedge of Hauterivian through mid-Albian siliciclastics and carbonates including Aptian (pre-Globigerinelloides algerianus zone) progradational, shelf-margin, carbonate shoals. The close of the Early Cretaceous is recorded by late Albian transgressive deposits (Globigerinelloides" breggiensis and Planomalina buxtorfi zones).

AAPG Search and Discovery Article #91043©1986 AAPG Annual Convention, Atlanta, Georgia, June 15-18, 1986.