Gas Flux Sampling

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Exploration Technique: Gas Flux Sampling

Exploration Technique Information
Exploration Group: Field Techniques
Exploration Sub Group: Field Sampling
Parent Exploration Technique: Gas Sampling
Information Provided by Technique
Lithology:
Stratigraphic/Structural: High flux can be indicative of conduits for fluid flow.
Hydrological:
Thermal: Anomalous flux is associated with active hydrothermal activity.
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Gas Flux Sampling:
Gas flux sampling measures the flow of volatile gas emissions from a specific location and compares it to average background emissions. Anomalously high gas flux can be an indication of hydrothermal activity.
Other definitions:Wikipedia Reegle


 
Introduction
Gas flux sampling is an exploration technique that measures volatile gases emanating from a hydrothermal system. Typical geothermal resources expel anomalously high concentrations of volatile gases (CO2, CH4, N2O, He, etc.) indicating the presence of permeable and potentially high temperature resources.

U.S. Geological Survey scientists measuring the CO2 flux at Kilauea, Hawaii. Photo from the USGS Volcanic Hazards Program website.[1]

 
Use in Geothermal Exploration
Gas flux sampling is considered to be an effective exploration technique for “hidden” geothermal resources that lack obvious surface manifestations, such as fumaroles, geysers, hot springs, etc.[2][3] Hydrothermal activity brings volatile gases and liquids into the near-surface environment that have different compositions, both chemically and isotopically, than typical meteoric fluids. This process causes a relatively high flux of certain gases compared to what is typical of average background gas concentrations, which is indicative of hydrothermal activity and permeable conduits for fluid flow at depth.[4][5][2][3]

 
Field Procedures
There are several factors that can help indicate where to conduct gas flux sampling in the field; near a known geothermal resource, in geologically or structurally similar settings as a known geothermal resource, or where there has been vegetation kill associated with high CO2 soil concentrations.[6][3] Prior to sampling it is necessary to understand what the background emissions are by studying the geology, climate, vegetation, and wildlife of the particular environment. Arnorsson, et al., (2006) briefly discuss methods and techniques of sampling fluids from a geothermal system.[7]



 
Data Access and Acquisition
There are many ways to measure gas flux as discussed by Lewicki and Oldenburg (2004),[3] most of which utilize some type of accumulation or flux chamber and a field analyzer to determine the flux of hydrothermal gases at each sample point. For example, Bergfeld, et al., (2001) discuss a case study in which the CO2 flux was measured using an infrared gas analyzer and accumulation chamber.[6]

A gas accumulation chamber used for CO2 flux measurement in volcanic hazard monitoring. Photo from the USGS Volcanic Hazards Program website.[1]

 
Best Practices
The limitations of different accumulation chambers for measuring the flux of various types of gases should be considered when selecting equipment for use in the field. The distribution and placement of accumulation chambers across the area under study must also be dense enough to achieve adequate resolution when flux measurements are plotted as gas concentration maps during data visualization.
 
Potential Pitfalls
When interpreting gas flux data, analysts should be aware of the different inputs and processes that can influence the flux of hydrothermal gases in the near-surface environment. For example, data from Roosevelt Hot Springs, UT suggests that interaction with gases from microbiological processes and other sources can complicate the interpretation of gas flux and soil-gas measurements over geothermal systems.[2] It should also be noted that the limitations of different gas accumulation chambers are unique, and may cause varying degrees of interference with the natural gas flux through an area. Interference in measuring the true flux of hydrothermal gases may affect the results of geochemical modeling of gas dispersion in the near-surface environment.[3]










Page Area Activity Start Date Activity End Date Reference Material
Gas Flux Sampling (Evans, Et Al., 2001) Unspecified


Gas Flux Sampling (Klein, 2007) Unspecified


Gas Flux Sampling (Laney, 2005) Unspecified


Gas Flux Sampling (Lewicki & Oldenburg) Unspecified


Gas Flux Sampling (Lewicki & Oldenburg, 2004) Unspecified


Gas Flux Sampling (Lewicki & Oldenburg, 2005) Unspecified


Gas Flux Sampling At Akutan Fumaroles Area (Kolker, Et Al., 2010) Akutan Fumaroles Area


Gas Flux Sampling At Black Warrior Area (DOE GTP) Black Warrior Area


Gas Flux Sampling At Brady Hot Springs Area (Lechler And Coolbaugh, 2007) Brady Hot Springs Area


Gas Flux Sampling At Desert Peak Area (Lechler And Coolbaugh, 2007) Desert Peak Area


Gas Flux Sampling At Dixie Valley Geothermal Area (Iovenitti, Et Al., 2013) Dixie Valley Geothermal Area 2012 2013


Gas Flux Sampling At Haleakala Volcano Area (Thomas, 1986) Haleakala Volcano Area


Gas Flux Sampling At Hualalai Northwest Rift Area (Thomas, 1986) Hualalai Northwest Rift Area


Gas Flux Sampling At Kawaihae Area (Thomas, 1986) Kawaihae Area


Gas Flux Sampling At Kilauea East Rift Geothermal Area (Thomas, 1986) Kilauea East Rift Geothermal Area 1978 1986


Gas Flux Sampling At Lahaina-Kaanapali Area (Thomas, 1986) Lahaina-Kaanapali Area


Gas Flux Sampling At Lightning Dock Area (Cunniff & Bowers, 2005) Lightning Dock Area


Gas Flux Sampling At Long Valley Caldera Geothermal Area (Bergfeld, Et Al., 2006) Long Valley Caldera Geothermal Area 2006


Gas Flux Sampling At Long Valley Caldera Geothermal Area (Lewicki, Et Al., 2008) Long Valley Caldera Geothermal Area 2008


Gas Flux Sampling At Lualualei Valley Area (Thomas, 1986) Lualualei Valley Area


Gas Flux Sampling At Maui Area (DOE GTP) Maui Area


Gas Flux Sampling At Mauna Loa Northeast Rift Area (Thomas, 1986) Mauna Loa Northeast Rift Area


Gas Flux Sampling At Mccoy Geothermal Area (DOE GTP) Mccoy Geothermal Area


Gas Flux Sampling At Mokapu Penninsula Area (Thomas, 1986) Mokapu Penninsula Area


Gas Flux Sampling At Olowalu-Ukumehame Canyon Area (Thomas, 1986) Olowalu-Ukumehame Canyon Area


Gas Flux Sampling At Socorro Mountain Area (Owens, Et Al., 2005) Socorro Mountain Area


Gas Flux Sampling At Steamboat Springs Area (Lechler And Coolbaugh, 2007) Steamboat Springs Area



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