UPPERMOST CAMPANIAN MAESTRICHTIAN STRONTIUM ISOTOPIC, BIOSTRATIGRAPHIC, AND SEQUENCE STRATIGRAPHIC FRAMEWORK OF THE NEW-JERSEY COASTAL-PLAIN

Firm stratigraphic correlations are needed to evaluate the global sign ificance of unconformity bounded units (sequences). We correlate the w ell-developed uppermost Campanian and Maestrichtian sequences of the N ew Jersey Coastal Plain to the geomagnetic polarity time scale (GPTS) by integrating Sr-isotopic stratigraphy and biostratigraphy. To do thi s, we developed a Maestrichtian (ca. 73-65 Ma) Sr-isotopic reference s ection at Deep Sea Drilling Project Hole 525A in the southeastern Atla ntic Ocean. Maestrichtian strata can then be dated by measuring their Sr-87/Sr-86 composition, calibrating to the GPTS of S. C. Cande and D. V. Kent (1993, personal commun.), and using the equation Age (Ma) = 3 7 326.894 - 52 639.89 (Sr-87/Sr-86). Sr-stratigraphic resolution for t he Maestrichtian is estimated as +/-1.2 to +/-2 m.y. At least two unco nformity-bounded units comprise the uppermost Campanian to Maestrichti an strata in New Jersey. The lower one, the Marshalltown sequence, is assigned to calcareous nannofossil Zones CC20/21 (approximatelyNC19) a nd CC22b (approximatelyNC20). It ranges in age from approximately74.1 to 69.9 Ma based on Sr-isotope age estimates. The overlying Navesink s equence is assigned to calcareous nannoplankton Zones CC25-26 (approxi mately NC21-23); it ranges in age from 69.3 to 65 Ma based on Sr-isoto pe age estimates. The upper part of this sequence, the Tinton Formatio n, has no calcareous planktonic control; Sr-isotopes provide an age es timate of 66 +/- 1.2 Ma (latest Maestrichtian). Sequence boundaries at the base and the top of the Marshalltown sequence match boundaries el sewhere in the Atlantic Coastal Plain (Owens and Gohn, 1985) and the i nferred global sea-level record of Haq et al. (1987); they support eus tatic changes as the mechanism controlling depositional history of thi s sequence. However, the latest Maestrichtian record in New Jersey doe s not agree with Haq et al. (1987); we attribute this to correlation a nd time-scale differences near the Cretaceous/Paleogene boundary. High sedimentation rates in the latest Maestrichtian of New Jersey (Shrews bury Member of the Red Bank Formation and the Tinton Formation) sugges t tectonic uplift and/or rapid progradation during deposition of the h ighstand systems tract.