EARLY CARBONATE DIAGENESIS IN SLOPE SEQUENCES AND AT THEIR BOUNDARIES, CENOZOIC, OFFSHORE NEW-JERSEY (ODP LEG-150)

This paper reports the genetic links among the depth distribution, min eralogy, and stable isotopic composition of diagenetic carbonates with sedimentation rates and types and preservation of organic matter in t he terrigenous and biogenic sediments of Oligocene and Miocene age on the New Jersey slope. Calcites formed close to the sediment surface at sequence boundaries and maximum flooding surfaces, when the profile o f early-diagenetic reactions was stabilized in the sediment column for extended periods. Dolomites precipitated in the sulfate reduction zon e when diagenetic profiles stabilized during truncation, sequence boun dary formation, and the deposition of lowstand sediments that overlie the sequence boundaries. Most dolomites occur in distal slope sediment s that were deposited before the shelf had prograded into the study ar ea. Siderites formed during a later stage of burial in the methanogeni c zone; they are not directly genetically related to the sequence stra tigraphy of the New Jersey slope. The diagenetic dolomites and siderit es occur in widely separated depth intervals below the present sea flo or. The distribution of the diagenetic carbonates and their preferenti al occurrence in separated depth intervals resulted from different com binations of sedimentation rates and organic matter types and preserva tion.