GEOCHRONOLOGY, GEOCHEMISTRY AND TECTONIC OCCURRENCE OF TRAVERTINE DEPOSITS IN NEW MEXICO AND ARIZONA

CO₂ springs and associated travertine deposits offer a unique tool to better understand Cenozoic paleohydrology, paleoclimate, and tectonics. Their geochemistry records paleohydrology and paleoclimate, and hence precise dates on these rocks offer a productive venue for evaluating Cenozoic tectonic and climate histories. This study reports the results of precise U/Th dating and stable isotope analysis of well-preserved, extensive Neogene travertine deposits of west-central New Mexico and eastern Arizona, which extend over more than 20 km² at Mesa del Oro, NM, and over more than 30 km² at Springerville, AZ, with a maximum thickness of more than 60 m and 20 m, respectively. New geochronology from Mesa del Oro, NM, reveals ages for the travertine deposits of 56 ka, 253 ka, 361 ka and more than 500 ka. U/Th dates from Springerville, AZ, show that major travertine accumulations also occurred over several time intervals: 350 - 300 ka, 280 – 200 ka and 100 – 36 ka. Stable isotope analyses from Mesa del Oro and Riley, NM, and Springerville, AZ, overlap substantially. They exhibit high δ¹³C values, +2.0‰ to +8.3‰, and δ¹⁸O values ranging from -13.5‰ to -4‰. Riley and Mesa Aparejo travertines (NM) are similar large magnitude, but less-studied, travertine deposits which are part of the ongoing research. Preliminary conclusions based on U/Th and stable isotope data are that travertine deposition at Mesa del Oro, NM, and Springerville, AZ, occurred contemporaneously and that stable isotope signals of Mesa del Oro, NM, the Riley Travertine, NM, and Springerville, AZ, will provide insights into regional paleohydrology and tectonics.