Long-Term Sea-Level Fluctuations Driven by Ocean Basin Dynamics

Abstract

Earth's long-term sea-level history is characterized by widespread continental flooding in the Cretaceous period (approximately 145 to 65 million years ago), followed by gradual regression of inland seas. However, published estimates of the Late Cretaceous sea-level high differ by half an order of magnitude, from approximately 40 to approximately 250 meters above the present level. The low estimate is based on the stratigraphy of the New Jersey margin. By assimilating marine geophysical data into reconstructions of ancient ocean basins, we model a Late Cretaceous sea level that is 170 (85 to 270) meters higher than it is today. We use a mantle convection model to suggest that New Jersey subsided by 105 to 180 meters in the past 70 million years because of North America's westward passage over the subducted Farallon plate. This mechanism reconciles New Jersey margin-based sea-level estimates with ocean basin reconstructions.

Eustatic variations during the Paleocene‐Eocene greenhouse world

“…Indeed, the unusually low oxygen isotopic ratios of late Paleocene-early Eocene benthic foraminiferal calcite (0 -1%) suggest little ice, even after accounting for warm bottom water temperatures [Miller et al, 1987;Zachos et al, 2001]. With limited continental ice and average deep ocean temperatures of 8 -15°C, early Paleogene sea level should have been 70-80 m higher than present-day, assuming a similar volume for the overall ocean basin, or upward of 120 m higher than present-day, if this volume was significantly smaller [Müller et al, 2008]. However, small ice sheets may have existed on elevated regions of Antarctica throughout the early Paleogene, and these could have contributed to low-amplitude sea level variations [Miller et al, 1998a;Speijer and Wagner, 2002;DeConto and Pollard, 2003;Miller et al, 2005b].…”

“…[6] Although recent sea level curves [Miller et al, 2005a] are closer to general expectations [Müller et al, 2008], some key uncertainties still exist, particularly regarding higher-order cycles. First, peak Cenozoic sea level appears to occur >1 Ma before the EECO and maximum Cenozoic temperatures (Figure 1).…”

“…Temperature scale is based on the assumption that no continental ice prevailed. Sea level curves are from Haq et al [1987], Miller et al [2005a], Kominz et al [2008], and Müller et al [2008]. Müller et al [2008] represents variations in ocean basin volume in meters of sea level assuming no ice sheets and a constant volume of ocean water.…”

Late Pleistocene gray whales (Eschrichtius robustus) offshore Georgia, U.S.A., and the antiquity of gray whale migration in the North Atlantic Ocean

“…The two gray whale specimens reported here, radiometrically aged to 41 ka and 48 ka, provide two separate indications that the general area of JY Reef was submerged at this time. The strong differences in Plio-Pleistocene climatic eustatic sea-level change models (Stocker and Marchal, 2000;Müller et al, 2008;Rohling et al, 2009) show a wide range of possible sea-level ranges during the late Pleistocene. While some models show sea-level at JY Reef to be very similar to that of today (Chabreck, 1988), others show JY Reef to be a dry land (Dodge et al, 1983;Cutler et al, 2003).…”

Reconstructing plate-motion changes in the presence of finite-rotations noise

“…Knowledge of these kinematics is therefore of paramount importance to make geodynamic inferences on sea-level change 1,2 , interactions between mantle plumes and the lithosphere 3 and dynamic topography 1,4-6 among others. Over the last decades great efforts have been made to reconstruct Earth's plate motions at progressively finer temporal resolution from observations of the ocean-floor spreading 7 .…”