Carbonate Geochronology and CO2 Fluxes

The solid earth plays a major role in the long-term geologic carbon cycle. Atmospheric, oceanic, and mantle derived CO2 or CO2-rich fluids reacts with silicate minerals and/or dissolved cations in the lithosphere to form secondary carbonate minerals in a variety of geological environments (regional metamorphism, contact metamorphism, subduction zone metamorphism, hydrothermal and ore-forming systems in the continental and oceanic crust, sedimentary basins, and weathering). In order to interrogate and quantify matters of rate, timing, and flux of CO2 (and hydrothermal fluid flow in general) within the lithosphere over geologic (i.e. >1 Myrs) timescales, we seek to develop an accurate and precise carbonate geochronometer.

Carbonate geochronology has proven to be a significant challenge due to natural complexities and analytical limitations. Our developmental emphasis will be on the less-frequently tested Sm/Nd system for carbonates, and on the subsequent integration and cross-checking of Sm/Nd and U/Pb data. Preliminary data show that carbonate minerals datable by Sm/Nd do exist, though the context and identity of the datable mineral’s occurrence is not clear.

Relevant Grant Support

NSF Grant EAR-1019845 “Collaborative Research: Geochronology of Carbonate Mineralization in the Lithosphere”, 9/1/10, PI: Baxter; Co-PI: Maher

Selected Papers

Henjes-Kunst, F., Prochaska,W., Niedermayr, A., Sullivan, N., Baxter, E. 2014. Sm-Nd dating of hydrothermal carbonate formation: the case of the Breitenau magnesite deposit (Styria, Austria). Chemical Geology, 387, p. 184-201 (PDF)