Content area
Abstract
Minor element ratios of marine carbonates are a great repository of paleoceanographic data, both as equilibrium records of changes in minor element ratios of the ocean and as proxies for other environmental and ocean chemistry parameters which may be recorded in carbonate microfossils as a result of kinetic and/or vital effects. The objective of this dissertation is to investigate the cycle of Sr in the ocean and its paleoceanographic utility on a variety of timescales. Chapter 2 explores the use of Sr as an indicator of rapid sea level changes, applied to verify controversial rapid sea level changes in the Early Cretaceous seismic-stratigraphic sea level record. The sensitivity of Sr/Ca ratios to sea level changes over shorter timescales is investigated in Chapter 3, where coupled numerical models of the seawater Sr and Ca budgets are used to simulate the effects of Quaternary sea level changes on the Sr budget of the ocean. Predicted Sr/Ca variations on the order of 1–3% imply the need for corrections to paleotemperatures calculated from the Sr/Ca ratios of scleractinian corals. Foraminiferal Sr/Ca records from several ocean basins for the last 150,000 years, presented in Chapter 4, reveal reproducible Sr/Ca variations of up to 5% which may confirm variation in seawater Sr/Ca ratios. A highly dynamic carbonate budget is needed to simulate such large amplitudes in our model. Cretaceous sea level change and climate are again addressed in Chapters 5 and 6. In Chapter 5, high resolution stable isotopic records are presented from Upper Cretaceous land sections in Italy and Spain. The strong correspondence between positive δ18O excursions and sea level regressions identified by sequence stratigraphy suggests that polar glaciation persisted as the dominant control over rapid eustatic sea level changes through the climatic maximum of the early Upper Cretaceous. In Chapter 6, Maastrichtian Sr/Ca data from three southern ocean DSDP sites and Upper Cretaceous Sr/Ca data from Italy and Spain are presented and briefly discussed.
