Earth and Planetary Sciences ETDs

Publication Date

7-1-2016

Abstract

Warm and hot springs are present on both sides of the northern Rio Grande rift (RGR). Springs on the western side of the RGR are along faults that extend NE of the Valles Caldera; springs on the east are along faults near Taos, NM. The Valles Caldera is a significant feature near our study site because it had major rhyolite eruptions 1.6 and 1.25 Ma, subsequent rhyolite eruptions lasted until 40-60 ka, and the Caldera now hosts an active magmatically driven geothermal system. The latest volcanism in the Taos Plateau region, near the eastern springs, was older, ~ 2 Ma. We compare spring chemistries using a multi-tracer approach from both spring groups as well as from nearby meteoric springs for comparison. For the western group, we also relate hydrochemistry of western springs to distance from the Valles Caldera. The combined multi-tracer results for Ojo Caliente are interpreted in terms of high CO2 from magmatic sources, high geothermal tracers (Li, B, Na, Cl, Cext, He, Sr), del13C values of -3.5 to -6.8"°, deep circulation through radiogenic basement based on 87Sr/86Sr values of 0.747, and presence of 1.6 to 4.0% mantle derived helium. The eastern springs multi-tracer results show less geothermal input as shown by lower concentrations of CO2 and geothermal tracers, although they have a similar helium isotopic signature of up to ~4% mantle-derived helium. The geothermal tracers at Ojo Caliente hot springs are interpreted to be distal influences of the Valles geothermal system. Volatiles (CO2 and He) as well as small volumes of geothermal water are transported ~60 km along the Embudo accommodation zone and Ojo Caliente fault systems of the Jemez lineament and RGR. These regional basement fault systems provide conduits for vertical and lateral migration of deep gases and solutes to rise and mix with meteoric fluids, verified by mantle helium and endogenic carbon isotopes.

Degree Name

Earth and Planetary Sciences

Level of Degree

Masters

Department Name

Department of Earth and Planetary Sciences

First Committee Member (Chair)

Karlstrom, Karl

Second Committee Member

Fischer, Tobias

Project Sponsors

Experimental Program to Stimulate Competitive Research (EPSCoR) award #IIA-1301346

Language

English

Keywords

Geothermal, Ojo Caliente, Valles Caldera, Hot springs, Helium isotopes, Carbon isotopes

Document Type

Thesis

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