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 δ¹⁸O and Haq et al. records. Early Eocene hiatuses do not match δ¹⁸O 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 δ¹⁸O 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 δ¹⁸O 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.