Early to Middle Miocene Glacioeustasy Derived from Backstripped New Jersey Shelf and Deep-Sea Oxygen Isotopic and Mg/Ca Records

We provide Myr-scale eustatic estimates for the early to middle Miocene using two approaches, 1-dimensional backstripping of 3 coreholes from the NJ shelf and scaling deep-sea δ18O records. We dated lower to middle Miocene sequences changes at three sites (Integrated Ocean Drilling Program Expedition 313 Sites M27, M28, and M29) on the inner-middle continental shelf offshore New Jersey. Despite challenges posed by shallow-water sediments, age resolution is typically ×0.5 Myr and in many sequences is as good as ×0.25 Myr. Our chronology provides a baseline for regional and interregional correlations and sea-level reconstructions; the timing of sequence boundaries matches the deep sea oxygen isotopic record implicating glacioeustasy as a major driver for forming sequence boundaries. We reconstructed paleowater depths on the transect (which provides a more complete stratigraphic record than onshore, albeit still punctuated by hiatuses) and conducted 1-dimensional backstripping, accounting for the effects of compaction, loading, and thermal subsidence. We compiled a high-resolution (kyr-scale) composite deep sea benthic foraminiferal δ18O record, including new data from Sites 747 and 751. We scale this to sea level by removing long-term (>Myr scale) temperature changes using Mg/Ca records (Cramer et al., 2009) and bracketing the ice-volume versus temperature contribution on the Myr scale as 50-50 and 80-20%. Backstripping shows that Myr sea-level changes are typically 25 m, with the largest ~50 m. Our scaled-eustatic estimate similarly shows 20-50 m changes in the early to middle Miocene, consistent with the growth and decay of the east Antarctic ice sheet.