Glacioeustasy during the middle Eocene? Insights from the stratigraphy of the Hampshire Basin, UK

Sedimentary and fossil evidence supports episodic uplift in the eastern part of the Hampshire Basin during the Bartonian, which at present precludes the calculation of eustatic sea-level. However, the amplitude and frequency of water-depth variations identified in the Barton Clay Formation, and correlations to published sea-level curves, are consistent with a component of these changes being glacioeustatic during the middle Eocene. There is also evidence for a large excursion (δ18O > 1‰) in the mono-specific benthic foraminiferal oxygen-isotope record (Alum Bay) ~ 39.9 Ma, which is correlated to the isotope excursion at the 'middle Eocene climatic optimum' previously reported in the Southern Ocean, and other localities. A contemporaneous water-depth increase of ~ 40 m at Alum Bay may indicate that a component of this 'global' oxygen-isotope excursion results from a reduction in continental ice storage.