Isotopic properties of carbonate minerals: searching for hidden environmental changes and their origins

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The goal of my proposed research program is to gain a deeper understanding of the isotopic properties of divalent metal carbonates (1) to provide the scientific community with versatile environmental proxies that allow us to trace current and past environmental changes and (2) to establish reliable biosignature-indicators that can be used to differentiate carbonates of various origins (primary vs. secondary, inorganic vs. biogenic). For several decades, isotopic properties of natural carbonates have been extensively used to reconstruct past climate variations. Nevertheless, most studies focused on the "oxygen" and "carbon" isotope properties of calcium carbonates because of the well-established analytical techniques and the ubiquity of the minerals. The isotopic properties of other elements in calcium carbonates and those of other divalent metal carbonates have attracted far less attention and thus have not been thoroughly investigated. For this reason, I am proposing to investigate the isotopic systematics of non-traditional stable isotopes (e.g., B, Ca, Li, and Fe) as well as clumped isotopes (e.g., Ca13C18O16O2) in a variety of divalent metal carbonate-water systems. The first objective of my research program is to quantify the "equilibrium" isotope fractionations of multiple stable isotopes in the carbonate-water system as a function of temperature and solution chemistry. For example, the Ca-C-O-B-(Li) isotope systematics in the calcite-seawater system will be characterized to develop new multi-element environmental proxies that will allow us to reconstruct paleo-climate, pH, or ocean chemistry. The second objective is to identify biogenic "non-equilibrium" isotope effects of multiple isotopes by disentangling these vital effects from the abiogenic "non-equilibrium" isotope effects on the basis of multi-dimensional stable isotope data arrays collected from a series of laboratory experiments conducted under various experimental conditions. The outcomes of the research program will establish reliable datasets for inorganic systems that will serve to interpret traditional and non-traditional stable isotope compositions of terrestrial and extraterrestrial carbonate specimens.