Helium isotope ratios in Yellowstone and Lassen Park volcanic gases

Abstract

Helium isotope ratios (3He/4He) in Lassen Park and Yellowstone Park volcanic gases show large 3He enrichments relative to atmospheric and crustal helium indicating the presence of a dominant mantle-helium component. The ratios in Lassen helium are 8 times atmospheric in acid hot spring gases, and about 3 times atmospheric in the gas phase in near-neutral high-temperature waters; the acid-spring helium is thus isotopically similar to helium in island-arc and other continental-margin orogenic areas. At Yellowstone, however, •he isotopic ratio in helium from the Mud Volcano area, in the eastern part of Yellowstone caldera, is 15.6 times atmospheric, similar to the ratio in helium from Kilauea and Iceland. These high ratios, 15 times atmospheric or greater, are probably distinctively associated with deep-mantle plumes under hot-spots, while ratios about 10 times atmospheric characterize mantle helium in basalt glasses at the crests of mid-ocean rises. The presence of "Kilauea-type" helium at Yellowstone indicates that at least in certain areas the continental crust is essentially transparent to mantle volatiles.

Helium‐3 in the Guaymas Basin: Evidence for injection of mantle volatiles in the Gulf of California

“…Previous isotopic measurements of mantle derived helium have yielded 3 He/ 4 He values ranging from 9 x w-6 for convergent plate boundaries [Craig eta/., 1978a) up to 2.2 X w-s for hot spots such as Kilauea [Craig and Lupton, 1976), Yellowstone National Park [Craig et a/., 1978b) and Iceland [Polak et a/., 1976). In particular, the 3 He/ 4 He ratio in midocean ridge basalt glasSeS varies from 1.2 X 10-S tO 1.7 X 10-5 , averaging 1.4 X w-5 , or about 10 times the atmospheric ratio [Lupton and Craig, 1975;Craig and Lupton, 1976).…”

“…Craig et at., 1978a), and at several hot spots ! Craig and Lupton, 1976;Craig et at. , 1978b;Polak et at., 1976).…”

Regional crustal-scale structures as conduits for deep geothermal upflow

“…The light isotope, 3 He, is primarily present in the Earth's mantle, originating during planetary accretion. 4 He is present in abundance in the Earth's crust, continually produced through radioactive decay of uranium and thorium (Craig et al, 1978;Kennedy et al, 1997Kennedy et al, , 1985Oxburgh and O'Nions, 1987). The ratio of 3 He to 4 He in geothermal fluids is therefore indicative of the relative abundances of mantle and crustal derived volatiles in those fluids.…”

“…Magmatic systems in red are interpreted based on the presence of known local Pleistocene and younger magmatic activity. 3 He/ 4 He data from (Craig et al, 1978;Hunt et al, 2005;van Soest, 2007, 2006; Kennedy et al, 2000;Newell et al, 2005;Tonani et al, 1998;Torgersen and Jenkins, 1982;B.M. Kennedy unpublished data, personnal comm.).…”

“…Kennedy unpublished data, personnal comm.). Background, crustal and mantle 3 He/ 4 He fields from (Craig et al, 1978;Kennedy et al, 1997Kennedy et al, , 1985Kulongoski et al, 2005).…”