Precise measurements of the calcium (Ca) isotopes have provided constraints on Ca cycling at global and local scales, and quantified rates of carbonate diagenesis in marine sedimentary systems. Key to applying Ca isotopes as a geochemical tracer of Ca cycling, carbonate (bio)mineralization, and diagenesis is an understanding of the impact of multiple factors potentially impacting Ca isotopes in the rock record. These factors include variations in stable isotopic fractionation factors, the influence of local-scale Ca cycling on Ca isotopic gradients in carbonate settings, carbonate dissolution and reprecipitation, and the relationship between the Ca isotopic composition of seawater and mineral phases that record the secular evolution of seawater chemistry.

The applications of calcium-isotope measurements in marine carbonates are explored in several different contexts within this thesis. As a record of global ion fluxes, seawater calcium-isotope ratios can be used as tracers for large weathering imbalances, which develop as a feedback system in response to intervals of climate change. This approach provides valuable constraints on the complex climatic and oceanographic phenomena known as the Oceanic Anoxic Events. Over much longer timescales, the calcium-isotope ratio of seawater is influenced by steady-state processes that reflect the evolution of seawater chemistry. To understand these influences, the modern calcium-isotope budget is assessed quantitatively using a compilation of marine carbonate samples, revealing several distinctive components of the carbonate burial sink that can affect the steady-state balance of the calcium cycle. Changes in the major ion composition of seawater and in the organisms that contribute to sedimentary carbonate burial are shown to contribute significantly to the geological record of seawater calcium-isotope ratios. The importance of skeletal carbonate in the calcium cycle leads to another application of calcium isotopes towards understanding biomineralization. This large and complex topic is approached with calcium-isotope data from two unique growth experiments that constrain some of the mechanisms by which biogenic aragonite acquires its geochemical signatures. This range of topics presents a diverse, but by no means exclusive, sample of the topics that are accessible for investigation through calcium-isotope analysis. The potential of this isotopic tool is demonstrated by the breadth of environments and timescales represented in this work.

Carbon Isotope Stratigraphy, Volume Five in the Advances in Sequence Stratigraphy series, covers research in stratigraphic disciplines, including the most recent developments in the geosciences. This fully commissioned review publication aims to foster and convey progress in stratigraphy with its inclusion of a variety of topics, including Carbon isotope stratigraphy - principles and applications, Interpreting Phanerozoic d13C patterns as periodic glacio-eustatic sequences, Stable carbon isotopes in archaeological plant remains, Review of the Upper Ediacaran-Lower Cambrian Detrital Series in Central and North Iberia: NE Africa as possible Source Area, Calibrating d13C and d18O chemostratigraphic correlations across Cambrian strata of SW, and much more. Contains contributions from leading authorities in the field Informs and updates on all the latest developments in the field Aims to foster and convey progress in stratigraphy, including geochronology, magnetostratigraphy, lithostratigraphy, event-stratigraphy, and more