Summary: Proc. Natl. Acad. Sci. USA
Vol. 95, pp. 4822­4827, April 1998
Geophysics
The helium paradoxes
DON L. ANDERSON*
Seismological Laboratory 252­21, California Institute of Technology, Pasadena, CA 91125
Contributed by Don L. Anderson, March 4, 1998
ABSTRACT The ratio 3
He 4
He (R) plays a central role in
models of mantle evolution that propose an undegassed lower
mantle, rich in the primordial isotope 3
He. A large primordial
volatile-rich reservoir, a feature of recent models, is incon-
sistent with high-temperature accretion and with estimates of
crustal and bulk Earth chemistry. High R can alternatively
reflect high integrated 3
He (U Th) ratios or low 4
He abun-
dances, as expected in refractory portions of the upper mantle.

Source: Anderson, Don L. - Division of Geological and Planetary Sciences, California Institute of Technology

Collections: Geosciences