High-resolution sulfur isotope records of the Paleozoic and a detailed geochemical study of the Late Cambrian SPICE event utilizing sulfur isotope stratigraphy, metal chemistry and numerical modeling

Carbonate-associated sulfate (CAS) is an emerging proxy for the sulfate sulfur isotope composition of seawater. The high-resolution chemostratigraphic records permitted by CAS afford new insight into the sulfur cycle during Earth's history. Chapter 1 investigates the effects of meteoric diagenesis on CAS concentration and sulfur isotope compositions in the Key Largo Limestone. These results imply that CAS sulfur isotopes are resistant to resetting by meteoric diagenetic processes. Next, Chapter 2 explores the high-resolution carbon and sulfur isotope records from several intervals of the Paleozoic and shows that the carbon and sulfur isotope records were progressively decoupled over the Paleozoic due to rising marine sulfate concentrations and increasing terrestrial carbon burial. Chapter 3 is a more detailed investigation of one of the intervals from the second chapter, the Late Cambrian SPICE. In addition to a global investigation of the carbon and sulfur isotope records of the SPICE, numerical geochemical box modeling was undertaken to explore the dynamics of the carbon and sulfur cycles during this interval. Chapter 4 tests, and ultimately verifies, the conclusions drawn in Chapter 3 about the redox conditions of the Middle to Late Cambrian ocean by utilizing the molybdenum isotope chemistry of the Late Cambrian Alum Shale.