earth science

Glen Snyder

Research Scientist

Ph.D (2001) University of Rochester

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Publication list (pdf).

Curriculum vitae (pdf)


Phone: (713)348-4054

Office: Keith Weiss Earth Science 330B

Rice Earth Science
Geothermal and volcanic studies:

Subduction at tectonic margins is responsible for removing oceanic crust and sediments and reintroducing them into the mantle. My Ph.D. research focused on quantifying the degree to which subducted volatile elements are recycled in island arc systems. Crater lakes, fumaroles, and geothermal gases and condensed fluids were sampled in Central America and New Zealand. Analyses were carried out at the University of Rochester Cosmogenic Isotope Laboratory and the Rare Gas Facility. Logistic support was provided by the semi-autonomous insitutions overseeing geothermal production in Costa Rica, Nicaragua, and El Salvador. Further work was carried out in New Zealand's Taupo Volcanic Zone, with the assistance of the Institute of Geological and Nuclear Sciences. Ongoing projects include gas and fluid studies of mud diapirs in New Zealand's forearc region, as well as collaboration with researchers at the USGS in quantifying the flux of halogens from hot springs in the Cascades.

Acidic waters in Poas Crater Lake in Costa Rica are produced by the condensation of magmatic volatiles in the lake water.
Geothermal wells in Central America may be as drilled as deep as 2000 meters. Degassing of CO2 from bicarbonate-rich geothermal reservoirs results in the formation of calcite scale.

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High carbon dioxide gases emitted from Costa Rican geothermal fields (blue squares) are likely due to revolatilization of subducted carbonate. Gases in Nicaragua (red triangles) are more helium rich, and show lower CO2 contents. The geothermal fields in El Salvador (purple triangles) all show extensive helium loss through degassing. Similar degassing is found behind the volcanic front (BVF) in Honduras.
Iodine concentrations in geothermal brines from Costa Rica (Blue squares) and Nicaragua (Red triangles) show mixing of magmatic iodine with geothermally heated groundwater, while fluids from El Salvador (purple diamonds) show iodine enrichment through steam loss. Crater lake water (yellow squares) is a mixture of heated meteoric water and magmatic volatiles. Orange triangles are fumaroles, mudpots, and hotsprings.
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Decay curve for cosmogenic-marine iodine in Central American geothermal fluids. The fluids generally show a mixing between old groundwater (greater than 50 years) and a subducted magmatic source. Several samples show much older iodine ages and may be a result of contamination from organics in the crust beneath the volcanic systems.