Hostname: page-component-84b7d79bbc-x5cpj Total loading time: 0 Render date: 2024-07-26T04:16:02.591Z Has data issue: false hasContentIssue false
  • English
  • Français

Rubidium-Strontium Geochronologic Systematics in Igneous Contact Zones: Analog for 90-Sr and 137-Cs Behavior in the Near Field

Published online by Cambridge University Press:  26 February 2011

D. G. Brookins
D. G. Brookins*
Affiliation:
University of New Mexico, Albuquerque, NM 87131
Get access

Abstract

The behavior of 90-Sr and 137-Cs in the near field of a HLW package can be investigated by use of Rb-Sr geochronologic information from igneous contact zones. The chemical behavior of 90-Sr is identical to other Sr isotopes, and Cs behavior is very similar to that of Rb. During igneous intrusion, the effect of heat from the igneous rock, coupled with fluid action, is to perturb Rb-Sr systematics of minerals in the intruded rock. Rb-Sr redistribution diagrams are useful not only for indirectly dating the time of intrusion, but also for determining the extent of closed versus open system conditions in the contact zones. Once open or closed system behavior is determined, the Rb-Sr systematics can be evaluated in terms of diffusion, fluid-induced metasomatism, selective dissolution, other, and coupled processes. All these can be discussed in terms of time-temperaturefluid compositional parameters. Rb migration is controlled predominantly by fluid flow, while diffusion models better explain some Sr isotopic behavior Cs, from geochemical arguments, should be less mobile than Rb. In most cases, even when temperature of the intrusive is 800–1200°C the cooling period on the order of 104 – 105 years, and in a highly convective system, Sr and Rb mobility is on the order of only microns to meters.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 44: Symposium N – Scientific Basis for Nuclear Waste Management VIII , 1984 , 573
Copyright
Copyright © Materials Research Society 1985

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

1. Brookins, D.G., 1984,Geochemical aspects of radioactive waste disposal: Springer-Verlag New York, Inc., New York, NY, 347 p.Google Scholar
2. Brookins, D.G., 1984, Natural analogues for radwaste disposal: elemental migration igneous contact zones: International workshop on natural analogues to the conditions around a final repository for HLW; KBS (Swedish) Tech. Rpt., in press.Google Scholar
3. Hart, S.R., 1964, The petrology and isotopic-mineral age relations of a contact zone in the Front Range, Colorado: J. Geol., v. 72, p. 493–525.Google Scholar
4. Giletti, B.J., 1974, Diffusion related to geochronology: in Geochemical transport and kinetics: Carnegie Instn., Wash. (Hoffman, A.W. et al. , eds.), p. 61–76.Google Scholar
5. Hoffman, A.W., 1973, Strontium diffusion in a basalt melt and implications for Sr isotope geochemistry and geochronology: Carnegie Instn. Yrbk 73, p. 935–941.Google Scholar
6. Hoffman, A.W., and Giletti, B.J., 1970, Diffusion of geochronologically important minerals under hydrothermal conditions: Eclogae Geol. Helv., v. 63, p. 141–150.Google Scholar
7. Foland, K.A., 1974, Alkali diffusion in orthoclase: in Geochemical transport and kinetics: Carnegie Instn. Wash. (Hoffman, A.W. et al. , eds.) p. 77–98.Google Scholar
8. Springer, N. et al. , 1983, One dimensional diffusion of radiogenic 87Sr and fluid transport of volatile elements across the margin of a metamorphosed archaean basic dyke from Saglek, Labrador: Contrib. Mineral Petrol., v. 82, p. 26–33.Google Scholar
9. Brookins, D.G., Abashian, M.S., Cohen, L.H., Wollenberg, H.A., 1981, Radwaste storage in crystalline rocks: a natural analog: Internat. Atomic Energy Sym. 257–44, p. 775–782.Google Scholar
10. Brookins, D.G., Abashian, M.S., Cohen, L.H., and Wollenberg, H.A., 1982, A natural analogue for storage of radwaste in crystalline rocks: 4th Int. Sym. Sci. Nuc. Wste. Mngmt., p. 231–238.Google Scholar
11. Williams, A.E., 1980, Investigation of oxygen-18 depletion in igneous rocks and ancient meteoric-hydrothermal circulation of the Almosa River stock region, Colorado: Unpub. PhD dissertation, Brown Univ.Google Scholar
12. Brookins, D.G., Abashian, M.S., Cohen, L.H., Williams, A.E., Wollenberg, H.A., and Flexser, S., 1983, Natural analogues: Alamosa River Monzonite intrusive into tuffaceous and andesitic rocks: Sci Basis Nuc. Wste. Mngt. VI (Brookins, D.G., Ed.), Elsevier Sci. Pub. Co., NY, p. 299–306.Google Scholar
13. Hanson, G.N., and Gast, P.W., 1967, Kinetic studies in contact metamorphic zones: Geochimica et Cosmochimica Acta, v. 31, p. 1119–1153.Google Scholar
14. Westcott, M.R., 1966, Loss of argon from biotite in a thermal metamorphism: Nature, v. 210, p. 83–84.CrossRefGoogle Scholar
15. Gray, N.H., 1971, Kinetics of contact metamorphic processes: Earth Plan. Sci. Ltters., v. 11, p. 205–210.CrossRefGoogle Scholar
16. Brookins, D.G.,1981, Alkali and alkaline earth element studies at Oklo: Third Intern. Sym. Sci. Basis Nuc. Wste. Mngt. III (Moore, , Ed.), Plenum Press, NY, p. 275–282.Google Scholar
17. Whittaker, E.J.W., and Muntus, R., 1970, Ionic radii for use in geochemistry: Geochim. Cosmochem. Acta, v. 34, p. 945–956.Google Scholar