ADVANCES IN DISENTANGLING TEMPERATURE, TECTONICS AND HYDROCLIMATE SIGNALS FROM STABLE ISOTOPE VALUES OF TERRESTRIAL CARBONATES (Invited Presentation)

Terrestrial sedimentary basins evolve in response to tectonic and climatic changes, and stable isotope records from sedimentary archives are used to infer these paleoclimatic and topographic changes. However, these stable isotope datasets are integrated records of climatic and tectonic change. Studies must therefore be carefully designed in order to successfully determine either the local climatic response of a basin to global climate change, or the signal of elevation change that helps determine the role of tectonics in environmental change and basin evolution. Carbonate clumped isotope thermometry has reinvigorated terrestrial paleoclimatology and paleoaltimetry, because it provides more constrained estimates of the oxygen isotope values of water from which the carbonate formed in addition to paleotemperature. Thus, it has the potential to yield significantly more information about past temperatures, tectonics and hydroclimate change than from oxygen isotope values of carbonates alone. However, through application of this technique to numerous terrestrial sedimentary basins, the community has determined other factors that are important to constrain to extract as much information as possible out of clumped isotope-based studies. For both paleoaltimetry and paleoclimate studies, the importance of large datasets is clear, both to accurately determine magnitudes of temperature change as well as to produce climate averages that are needed to estimate ancient elevation. Careful carbonate facies determination is also critical, both to evaluate the effects of diagenesis, but also to separate temperature and water oxygen isotope changes that may be due to differences in carbonate formation between environments rather than from true climatic changes. Carbonates likely do not often form uniformly throughout the year, which underscores the need to understand how different seasons will respond to climatic and tectonic changes. Finally, much less has been done to understand how similar issues may affect the estimates of oxygen isotope values of the formation water. We will present examples of these challenges, as well as studies in progress that will help us better understand how best to use clumped isotope data to understand the records of climatic and tectonic change that are preserved in sedimentary basins.