The La Madera Travertines, Rio Ojo Caliente, northern New Mexico: Investigating the linked system of CO2-rich springs and travertines as neotectonic and paleoclimate indicators
— Laura Crossey, Karl E. Karlstrom, Dennis L. Newell, Ara Kooser, and April Tafoya
The La Madera travertine and CO2-rich spring system of northern New Mexico provides a linked data set to examine neotectonics and mantle-to-surface fluid interconnections in the area of intersection of the Rio Grande rift and Jemez lineament. Water chemistry modeling shows that most of the CO2 is endogenic (derived from deep geologic sources), with subordinate amounts from dissolution of carbonate and from organic sources. Spring waters are high in arsenic, salts, and metals that mix with and detract from water quality in the regional aquifers, potentially including the Buckman wells near Santa Fe. 3He/4He data from CO2-rich hot and cool springs have values ranging from 6.16 to 0.09 RA (77 to 1% mantle helium), with highest values in the Valles caldera, approaching MORB values (8 RA). Mantle degassing is interpreted as a neotectonic signal of active upwelling of asthenospheric mantle beneath the Jemez low seismic velocity mantle anomaly. These CO2 vents align along the NE- and N-trending, tectonically active, extensional faults and fault jogs that parallel the Jemez lineament. The regional continuity and neotectonic activity along these structures suggest an active Embudo-Jemez transfer zone that extends through the Albuquerque, Española, and San Luis basins. Endogenic fluid flux along this zone takes place in fault systems and is driven by geothermal pressure gradients. Travertines are deposited by CO2-rich waters that ascend along faults and hence they provide a record of past and ongoing mantle 3He and CO2 degassing. U-series dating so far, with ages back to >500 ka, suggests an episodicity in deposition of large volumes of travertine that may reflect regional wet periods with high groundwater head. Abundant deposition in the 200-100 ka range may provide a local record of the transition from the penultimate glaciation (135 ka) to the ensuing interglacial (125 ka) that is documented globally by the transition from marine oxygen isotope stage 6 to oxygen isotope stage 5. U-series dates on travertine-cemented terraces also provide precise river incision rates that vary from 100-300 m/Ma indicating differential landscape evolution across the region influenced by both regional tectonism and climate change.
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- Crossey, Laura; Karlstrom, Karl E.; Newell, Dennis L.; Kooser, Ara; Tafoya, April, 2011, The La Madera Travertines, Rio Ojo Caliente, northern New Mexico: Investigating the linked system of CO2-rich springs and travertines as neotectonic and paleoclimate indicators, in: Geology of the Tusas Mountains and Ojo Caliente Area, Koning, Daniel J.; Karlstrom, Karl E.; Kelley, Shari A.; Lueth, Virgil W.; Aby, Scott B., New Mexico Geological Society, Guidebook, 62nd Field Conference, pp. 301-316.