A comparison of hydrocarbon gases from natural sources in the northwestern United States
- Geological Survey, Menlo Park, CA (United States)
The northwestern United States hosts a remarkable quantity and variety of thermal springs, seeps, and other natural-gas sources. Although many studies have dealt with the liquids and nonhydrocarbon gases emanating from these sources, few have focused on hydrocarbon gases. Of these gases, methane in particular is now recognized as an important reactive trace gas in the Earth's atmosphere that plays a significant role in global warming because of its greenhouse properties. To understand better the magnitude and occurrence of emissions of hydrocarbons from natural sources to the atmosphere, we have begun a survey of these gases throughout the northwestern United States. This area encompasses a number of different tectonic provinces: The Yellowstone hot spot, the northern Basin and Range Province, the Cascade volcanic arc, and the Cascadia subduction complex. Each province hosts springs and seeps with some unique compositions owing to the geological processes operating there. Methane is present in each area at concentration levels ranging from about 2 parts per million by volume (ppm-v) to 95.6 percent (by volume). Hydrothermal activity in the Yellowstone area produces spring gases containing less than 4 percent methane, with carbon dioxide as the balance gas. The Grand Teton National Park area, immediately to the south, has a wide variety of gas compositions with either methane, carbon dioxide, or nitrogen as the primary gas component. Where methane is abundant, higher molecular weight hydrocarbon gases (ethane, ethene, propane, propene, isobutane, and n-butane) are also found in ppm-v concentrations. In the northern Great Basin, thermal springs and seeps typically occur along fault zones at the base of mountain ranges. Methane concentrations range from 0.2 to 47 percent, with higher molecular weight hydrocarbon concentrations from 0 to 3,100 ppm-v. 47 refs., 8 figs., 4 tabs.
- OSTI ID:
- 6877380
- Journal Information:
- United States Geological Survey, Professional Paper; (United States), Vol. 1570
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
EARTH CRUST
RESOURCE POTENTIAL
METHANE
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CALIFORNIA
CARBON DIOXIDE
COLUMBIA RIVER
MONTANA
NEVADA
OREGON
SAMPLING
SUBDUCTION ZONES
WYOMING
YELLOWSTONE NATIONAL PARK
ALKANES
CARBON COMPOUNDS
CARBON OXIDES
CHALCOGENIDES
DEVELOPED COUNTRIES
HYDROCARBONS
NORTH AMERICA
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PUBLIC LANDS
RESOURCES
RIVERS
STREAMS
SURFACE WATERS
USA
030200* - Natural Gas- Reserves
Geology
& Exploration