North Horn Formation, Utah Paleocene-Eocene Thermal Maximum Clumped Isotopes VanDeVelde, J.H.; Bowen, G.J.; Passey, B.H.; Bowen, B.B. VanDeVelde, J.H. Bowen, G.J. Passey, B.H. Bowen, B.B. thermal maximum earth science/paleoclimate/others (Axhandle Canyon>LATITUDE 39.4109>LONGITUDE -111.6994) The precipitation of primary dolomite in soil is rare and controversial, and its occurrence indicates highly unusual geochemical and climatic conditions. We utilize isotopic and petrographic techniques, including clumped isotope thermometry, to evaluate diagenetic alteration and preservation of primary climatic signal in dolomitic paleosol nodules from a section spanning the Paleocene-Eocene boundary in central Utah. Isotopic measurements differentiate samples into groups that may be interpreted in terms of alteration; however moderate burial depths and extreme warmth during the interval of soil formation make it difficult to reach definitive conclusions from isotope values alone. With the addition of petrographic analysis, including cathodoluminescence and scanning electron microscopy, we are able to identify textural differences between samples suggesting differing amounts of recrystallization. We conclude that while some nodules have experienced significant diagenetic alteration the original nodule mineralogy is dolomite, and the majority of sampled nodules retain a primary paleoclimate signal. Early Paleogene temperatures recorded at this site are considerably warmer than those suggested for the continental interior from alternate proxies, a result that may be partially the result of the clumped isotope temperatures recording warm season soil temperatures, rather than mean annual air temperature. Soil water isotopic composition is suggestive of heightened aridity, particularly through the Paleocene-Eocene Thermal Maximum (PETM). STUDY NOTES: Clumped isotope study of pedogenic carbonates from North Horn Fm. paleosols NCDC-Paleoclimatology https://www.ncdc.noaa.gov/data-access/paleoclimatology-data - Bauer Bruce Investigator : VanDeVelde, J.H. Investigator : Bowen, G.J. Investigator : Passey, B.H. Investigator : Bowen, B.B. 2014-01-21 ONLINE Files online, ASCII https://www.ncdc.noaa.gov/paleo/study/16035 https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/vandevelde2013/axhandle2013.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/vandevelde2013/axhandle2013.txt English https://www.ncdc.noaa.gov/paleo/study/16035 https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/vandevelde2013/axhandle2013.txt Justin H. VanDeVelde, Gabriel J. Bowen, Benjamin H. Passey, Brenda B. Bowen2013Climatic and diagenetic signals in the stable isotope geochemistry of dolomitic paleosols spanning the Paleocene-Eocene boundaryGeochimica et Cosmochimica Acta109254-26710.1016/j.gca.2013.02.005http://www.sciencedirect.com/science/article/pii/S0016703713000823 START YEAR: 57000000 cal yr BP * END YEAR: 55000000 cal yr BP -111.6994 39.4109 -111.6994 39.4109