Marine isotope stratigraphy

Abstract

Marine isotope stratigraphy is a widely applied tool in correlating and dating marine strata. It complements many other dating techniques, such as direct radiometric dating, biostratigraphy, and magnetostratigraphy. A large number of stable and radiogenic isotope systems are used in marine isotope stratigraphy, including both a core suite of well-established systems (C, O, and Sr) and a growing list of nontraditional isotope systems. Each isotope system has specific benefits and drawbacks, and no single system is universally applicable across sediment types and ages. Indeed, in many studies, multiple isotope proxies, along with other chemical stratigraphic tools, are applied, with each providing distinct constraints on the timing and origin of geological events. Important considerations in the application of isotope systems are the residence time and behavior of the chemical species of the element in seawater, the types of sediments in which the element is preferentially removed, and the potential of the isotope ratios to be preserved against diagenetic and metamorphic disturbances. Seawater isotope reference curves for the Cenozoic, and in some cases for the entire Phanerozoic, have been produced for many isotope systems, and these provide an excellent framework for indirect dating sediments and sedimentary rocks whose precise ages are not known.