Abstract
An extensive study of helium isotopes in fluids collected from surface springs, fumaroles and wells across the northern Basin and Range Province reveals a systematic trend of decreasing 3He/4He ratios from west to east. The western margin of the Basin and Range is characterized by mantle-like ratios (6-8 Ra) associated with active or recently active crustal magma systems (e.g. Coso, Long Valley, Steamboat, and the Cascade volcanic complex). Moving towards the east, the ratios decline systematically to a background value of ∼0.1 Ra. The regional trend is consistent with extensive mantle melting concentrated along the western margin and is coincident with an east-to-west increase in the magnitude of northwest strain. The increase in shear strain enhances crustal permeability resulting in high vertical fluid flow rates that preserve the high helium isotope ratios at the surface. Superimposed on the regional trend are "helium spikes", local anomalies in the helium isotope composition. These "spikes" reflect either local zones of mantle melting or locally enhanced crustal permeability. In the case of the Dixie Valley hydrothermal system, it appears to be a combination of both.
| Original language | English (US) |
|---|---|
| Title of host publication | Geothermal Resources Council Transactions - GRC 2006 Annual Meeting |
| Subtitle of host publication | Geothermal Resources-Securing Our Energy Future |
| Pages | 429-433 |
| Number of pages | 5 |
| Volume | 30 I |
| State | Published - Dec 1 2006 |
| Externally published | Yes |
| Event | GRC 2006 Annual Meeting: Geothermal Resources-Securing Our Energy Future - San Diego, CA, United States Duration: Sep 10 2006 → Sep 13 2006 |
Other
| Other | GRC 2006 Annual Meeting: Geothermal Resources-Securing Our Energy Future |
|---|---|
| Country | United States |
| City | San Diego, CA |
| Period | 9/10/06 → 9/13/06 |
Fingerprint
Keywords
- Basin and Range
- Dixie Valley
- Exploration
- Fault hosted permeability
- Helium isotopes
ASJC Scopus subject areas
- Geology
- Energy Engineering and Power Technology
- Electrical and Electronic Engineering
Cite this
A systematic regional trend in helium isotopes across the Northern Basin and Range Province, Western North America. / Kennedy, B. Mack; Van Soest, Matthijs.
Geothermal Resources Council Transactions - GRC 2006 Annual Meeting: Geothermal Resources-Securing Our Energy Future. Vol. 30 I 2006. p. 429-433.Research output: Chapter in Book/Report/Conference proceeding › Conference contribution
}
TY - GEN
T1 - A systematic regional trend in helium isotopes across the Northern Basin and Range Province, Western North America
AU - Kennedy, B. Mack
AU - Van Soest, Matthijs
PY - 2006/12/1
Y1 - 2006/12/1
N2 - An extensive study of helium isotopes in fluids collected from surface springs, fumaroles and wells across the northern Basin and Range Province reveals a systematic trend of decreasing 3He/4He ratios from west to east. The western margin of the Basin and Range is characterized by mantle-like ratios (6-8 Ra) associated with active or recently active crustal magma systems (e.g. Coso, Long Valley, Steamboat, and the Cascade volcanic complex). Moving towards the east, the ratios decline systematically to a background value of ∼0.1 Ra. The regional trend is consistent with extensive mantle melting concentrated along the western margin and is coincident with an east-to-west increase in the magnitude of northwest strain. The increase in shear strain enhances crustal permeability resulting in high vertical fluid flow rates that preserve the high helium isotope ratios at the surface. Superimposed on the regional trend are "helium spikes", local anomalies in the helium isotope composition. These "spikes" reflect either local zones of mantle melting or locally enhanced crustal permeability. In the case of the Dixie Valley hydrothermal system, it appears to be a combination of both.
AB - An extensive study of helium isotopes in fluids collected from surface springs, fumaroles and wells across the northern Basin and Range Province reveals a systematic trend of decreasing 3He/4He ratios from west to east. The western margin of the Basin and Range is characterized by mantle-like ratios (6-8 Ra) associated with active or recently active crustal magma systems (e.g. Coso, Long Valley, Steamboat, and the Cascade volcanic complex). Moving towards the east, the ratios decline systematically to a background value of ∼0.1 Ra. The regional trend is consistent with extensive mantle melting concentrated along the western margin and is coincident with an east-to-west increase in the magnitude of northwest strain. The increase in shear strain enhances crustal permeability resulting in high vertical fluid flow rates that preserve the high helium isotope ratios at the surface. Superimposed on the regional trend are "helium spikes", local anomalies in the helium isotope composition. These "spikes" reflect either local zones of mantle melting or locally enhanced crustal permeability. In the case of the Dixie Valley hydrothermal system, it appears to be a combination of both.
KW - Basin and Range
KW - Dixie Valley
KW - Exploration
KW - Fault hosted permeability
KW - Helium isotopes
UR - http://www.scopus.com/inward/record.url?scp=34548169302&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=34548169302&partnerID=8YFLogxK
M3 - Conference contribution
SN - 1604230010
SN - 9781604230017
VL - 30 I
SP - 429
EP - 433
BT - Geothermal Resources Council Transactions - GRC 2006 Annual Meeting
ER -