Publication Date:
2017-04-04
Description:
The chemistry of Yellowstone fumarole gases shows the existence of two component waters, type MC, influenced by the
addition of deep mantle fluid, and type CC, influenced by crustal interactions (CC). MC is high in 3He/4He (22 Ra) and low in
4He/40Ar ( 1), reflecting input of deep mantle components. The other water is characterized by 4He concentrations 3–4 orders
of magnitude higher than air-saturated meteoric water (ASW). These high He concentrations originate through circulation in
Pleistocene volcanic rocks, as well as outgassing of Tertiary and older (including Archean) basement, some of which could be
particularly rich in uranium, a major 4He source. Consideration of CO2–CH4–CO–H2O–H2 gas equilibrium reactions indicates
equilibration temperatures from 170 C to 310 C. The estimated temperatures highly correlate with noble-gas variations,
suggesting that the two waters differ in temperature. Type CC is 170 C whereas the MC is hotter, at 340 C. This
result is similar to models proposed by previous studies of thermal water chemistry. However, instead of mixing the deep
hot component simply with cold, meteoric waters we argue that addition of a 4He-rich component, equilibrated at temperatures
around 170 C, is necessary to explain the range in fumarole gas chemistry.
Description:
Published
Description:
265–278
Description:
2.4. TTC - Laboratori di geochimica dei fluidi
Description:
4.5. Studi sul degassamento naturale e sui gas petroliferi
Description:
JCR Journal
Description:
restricted
Keywords:
hydrothermal fluids
;
Yellowstone Plateau
;
04. Solid Earth::04.03. Geodesy::04.03.06. Measurements and monitoring
;
04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry
;
04. Solid Earth::04.08. Volcanology::04.08.01. Gases
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
