Diagenesis in the Great Bahamas Bank: An Analysis of Mg Isotopes in the Sediment Cores from ODP Site 1003

Abstract

Diagenesis describes the processes which alter the chemical composition and morphology of sediments as they are transformed into lithified rocks. Carbonate diagenesis is important to understand as these minerals are both an important cache of paleoenvironmental information and are susceptible to diagenetic alteration. In this thesis I examine carbonate diagenesis in a sediment core from site 1003 on the slope of the Bahamas platform. The diagenetic processes should leave some pattern in the sediment cores where these processes are occurring. Understanding these patterns and how to determine what diagenetic processes are occurring is crucial to understanding the deposition history and processes that are occurring within a sediment column. By measuring the Mg isotopic ratio of calcium carbonate sediments and associated pore-fluids one can hope to find insight into the patterns that diagenetic processes will leave in the Mg isotopic record. This study focuses on the diagenetic transformation of aragonite to calcite as well as the diagenetic processes that transform calcite into dolomite. Using Mg isotopic ratios of the sediments from Ocean Drilling Platform site 1003 we hope to further the understanding of the diagenetic processes that occur in a carbonate shelf such as the Great Bahamas Bank.