New Mexico Geological Society Annual Spring Meeting — Abstracts

CO₂ springs and associated travertine deposits offer a unique tool to better understand Cenozoic paleohydrology, paleoclimate, and tectonics. Travertine accumulations represent places of persistent and significant mantle CO₂ degassing linked to their tectonic environment. Their geochemistry records paleohydrology and paleoclimate, and hence precise dates on these rocks offer a productive venue for evaluating Cenozoic tectonic and climate histories. Recent U/Th dates from Springerville, Arizona, show that: 1) travertine deposition began before 350 ka, with major accumulations occurring in cycles of approximately 70 ka; 2) the CO₂ of modern travertine-depositing springs is partly derived from the mantle based on ³He/⁴He and CO₂/³He ratios; and 3) incision rates of the Little Colorado River increased markedly in the last 100 ka. On-going work at Mesa Aparejo and Mesa del Oro, New Mexico, reveals similar large magnitude, but less-studied, travertine deposits. Proposed research methods involve radiogenic isotope geochemistry for U-series dating of the travertine, stable isotope geochemistry to evaluate biogenic influences and paleoclimate/paleohydrology fluctuations, geochemical analysis with XRF and electron microprobe, a detailed petrographic study, mapping, and GIS analysis. The data of the three locations will be compared, systematically analyzed, and put into context with the paleohydrology, paleoclimatology and neotectonic processes of the Rio Grande rift - Colorado Plateau region.