Global implications of lower to middle Eocene sequence boundaries on the New Jersey coastal plain: The icehouse cometh

We document nine lower-middle Eocene sequences on the New Jersey coastal plain and compare them with global dO and Haq et al. records. Early Eocene hiatuses do not match dO changes, and it is unlikely that they are the result of glacioeustasy, consistent with an ice-free early Eocene. Early-middle Eocene (49–43 Ma) evidence for a link between sequences and dO is equivocal, and the presence of large ice sheets is uncertain. Beginning in the late-middle Eocene (43–42 Ma), concomitant increases in planktonic and benthic dO records coincide with the timing of hiatuses on the New Jersey coastal plain and a change from carbonate-dominated to siliciclastic-dominated sedimentation. These represent the development of the Antarctic ice cap and the beginning of the “icehouse” world. Of the 14 sequences predicted by Haq et al. for this interval, 9 are resolvable on the New Jersey margin, and the other 5 appear to be combined with others. We conclude that although ice-volume changes controlled sequences since at least 42 Ma, mechanisms for sea-level change prior to then are still not fully understood.