Helium Isotopes

Helium Isotopes

Helium gas is a trace constituent of groundwater and thermal fluids, and the ratio of 3He to 4He can be measured with a high-precision mass spectrometer to determine whether it is derived from air, from the radioactive decay of uranium and thorium in the crust, or from the mantle. The latter is a characteristic feature of volcanic and geothermal gases.

Geothermal Glossary

Word of the Week – Proppant

Word of the Week – Proppant

Proppant Sand-sized solid grains that are injected in a fluid suspension and used to hold open stimulated fractures in a geothermal reservoir.

Word of the Week – Propylitic Alteration

Word of the Week – Propylitic Alteration

Propylitic Alteration A term borrowed from studies of hydrothermal ore deposits that refers to an assemblage of secondary hydrothermal minerals which forms in igneous rocks. This assemblage is made up of chlorite, illite, feldspar (both Na and K-rich varieties),...

Word of the Week – Rhyolite

Word of the Week – Rhyolite

Rhyolite Light colored fined grained volcanic rock composed of glass, quartz, K-feldspar and plagioclase, with relatively high silica (69-77 wt %). The composition reflects partial melting of continental crust. Rhyolitic volcanism is a feature of both Yellowstone...

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