Skip to main content Accessibility help
×
Home

Using granite to image the thermal state of the source terrane

  • E-an Zen (a1)

Abstract

It should be possible to infer the thermal state of the source terrane for granitic bodies, provided we have independent means to establish the chemical nature of this terrane. The chemical nature of the granitic rocks, including their degree of hydration, implies the solidus temperature. The concentration of the heat-producing radioactive elements in the granite (K, U, and Th) probably provides an upper estimate of their concentration in the source rock, which is an important thermal parameter. The depth and ambient temperature of the country rock into which the granite magma intruded provide useful boundary conditions for the thermal regime at the crustal level of anatexis. These constraints in turn form the bases for estimating the subcrustal thermal flux as well as the effective thermal interface for enhanced heat flow from below that resulted in anatexis. These inferences, in combination with other field-based parameters such as uplift rates and permissible time lapses for the geological events, permit realistic thermal modelling for the formation of granitic batholiths. The procedure is applied to the Late Cretaceous Pioneer and Boulder batholiths in southwestern Montana, U.S.A. The modelling results suggest that mantle upwelling, not subduction or thrust loading, caused anatexis. The isotopic chemistry of the granitic rocks rules out direct mixing of mantle magma, and field relations rule out crustal thinning as causes for partial melting.

Copyright

References

Hide All
Armstrong, R. L., Taubeneck, W. H. & Hales, P. O. 1977. Rb-Sr and K-Ar geochronometry of Mesozoic granitic rocks and their Sr isotopic composition, Oregon, Washington, and Idaho. GEOL SOC AM BULL 88, 397411.
Arth, J. G.,Zen, , E-an, , Sellers, , George, & Hammarstrom, , Jane, 1986. High initial Sr isotopic ratios and evidence for magma mixing in the Pioneer batholith of southwest Montana: J GEOL 94, 419–30.
Bird, , Peter, 1988. Formation of the Rocky Mountains, western United States: A continuum computer model: SCIENCE 239, 1501–07.
Burnham, C. W., Holloway, J. R. & Davis, N. F. 1969. Thermodynamic properties of water to 1000°C and 10,000 bars. GEOL SOC AM SPEC PAP 132.
Clark, S. P. Jr,Peterman, Z. E. & Heier, K. S. 1966. Abundances of uranium, thorium, and potassium. In Clark, S. P. Jr(ed.) Handbook of physical constants, revised edn, 521–41. GEOL SOC AM MEM 97.
Clemens, J. D. & Vielzeuf, D. 1987. Constraints on melting and magma production in the crust. EARTH PLANET SCI LETT 86, 287306.
DeYoreo, J. J., Lux, D. R. & Guidotti, C. V. 1989. The role of crustal anatexis and magma migration in the thermal evolution of regions of thickened continental crust. In Daly, J. S., Cliff, R. A. & Yardley, B. W. D. (eds) Evolution of metamorphic belts. GEOL SOC LONDON SPEC PUB 43, 187202.
Doe, B. R., Tilling, R. I., Hedge, C. E. & Klepper, M. R. 1968. Lead and strontium isotope studies of the Boulder batholith, southwestern Montana. ECON GEOL 63, 884906.
Doe, B. R., Berger, B. R. & Elliott, J. E. 1986. Lead-isotope evaluation of selected ores and mineral prospects in the Butte and Dillon 1° × 2° quadrangles, Montana. US GEOL SURV OPEN-FILE REP 86–111.
Fleck, R. J. & Criss, R. E. 1985. Strontium and oxygen isotopic variations in Mesozoic and Tertiary plutons of central Idaho. CONTRIB MINERAL PETROL 90, 291308.
Flood, R. H. & Vernon, R. H. 1978. The Cooma granodiorite, Australia: an example of in situ crustal anatexis? GEOLOGY 6, 81–4.
Hanson, R. B. & Barton, M. D. 1989. Thermal development of low-pressure metamorphic belt: results from two-dimensional numerical models. J GEOPHYS RES 94, 10, 363–77.
Haugerud, R. A. 1986. 1DT—an interactive, screen-oriented microcomputer program for simulation of 1-dimensional geothermal histories. US GEOL SURV OPEN-FILE REP 86–511.
Huppert, H. E. & Sparks, R. S. J. 1988. The generation of granitic magmas by intrusion of basalt into continental crust. J PETROL 29, 599624.
James, H. L. & Hedge, C. E. 1980. Age of the basement rocks of southwest Montana. GEOL SOC AM BULL Pt. I, 91, 11–5.
Joplin, G. A. 1942. Petrological studies in the Ordovician of New South Wales I. The Cooma Complex. PROC LINN SOC NSW 67, 156–96.
Joplin, G. A. 1943. Petrological studies in the Ordovician of New South Wales, II. The northern extension of the Cooma Complex. PROC LINN SOC NSW 68, 159–83.
King, P. B. & Beikman, H. M. 1974. Geologic Map of the United States, scale 1:2,500,000: US. Geological Survey.
Lachenbruch, A. H. 1970. Crustal temperature and heat production: implications of the linear heat-flow relations. J GEOPHYS RES 75, 3291–300.
Lachenbruch, A. H. & Sass, J. H. 1977. Heat flow in the United States and the thermal regime of the crust. In Heacock, J. G. (ed.) The earth's crust, its nature and physical properties. AM GEOPHYS UNION, GEOPHYS MONOGR 20, 626–75.
Lipman, P. W., Prostka, H. J. & Christiansen, R. L. 1972. Cenozoic volcanism and plate-tectonic evolution of the western United States. I. Early and Middle Cenozoic. PHILOS TRANS R SOC LONDON A271, 217–48.
Lowell, W. R. 1965. Geologic map of the Bannack-Grayling area, Beaverhead County, Montana, scale 1:31,680: U.S. Geological Survey, Miscellaneous Geologic Investigations Map 1433.
Lund, , Karen, & Snee, L. W. 1988. Tectonic development of the Salmon River suture zone, western Idaho: Conclusions and questions. GEOL SOC AM ABSTR PROG 20, 429.
Munksgaard, N. C. 1988. Source of the Cooma Granodiorite, New South Wales—a possible role of fluid-rock interactions. AUST J EARTH SCI 35, 363–77.
Patiño-Douce, A. E., Humphreys, E. D. & Johnston, A. D. 1990. Anatexis and metamorphism in tectonically thickened continental crust exemplified by the Sevier hinterland, western North America. EARTH PLANET SCI LETT 97, 290315.
Pearson, R. C. & Zen, , E-an, 1985. Geologic map of the east Pioneer Mountains, Beaverhead County, Montana, scale 1:50,000, with text: U.S. Geological Survey Miscellaneous Field Studies Map MF-1806-A.
Ruppel, E. T., O'Neill, J. M. & Lopez, D. A. 1983. Preliminary geologic map of the Dillon 1° × 2° quadrangle, Montana, scale 1:250,000: US GEOL SURV OPEN-FILE REP 83–168, 2 sheets.
Sahinen, U. M. 1939. Geology and ore deposits of the Rochester and adjacent mining districts, Madison County, Montana. MONTANA BUR MINES GEOL MEM 19.
Sawyer, E. W. 1987. The role of partial melting and fractional crystallization in determining discordant migmatite leucosome compositions: J PETROL 28, 445–73.
Shuster, R. D., Mueller, P. A., D'Arcy, K. & Heatherington, A. 1989. Nd evidence of the age and nature of source regions of the northeastern Idaho batholith and Tobacco Root batholith, Montana. GEOL SOC AM ABSTR PROG 21, 325.
Smedes, H. W., Klepper, M. R. & Tilling, R. I. 1988. Preliminary map of plutonic units of the Boulder batholith, southwestern Montana, scale 1:200,000: US GEOL SURV OPEN-FILE REP 88–238, 1 sheet with text.
Snee, L. W. 1978. Petrography, K/Ar ages, and field relations of the igneous rocks of part of the Pioneer batholith, southwestern Montana (M.A. thesis, Ohio State University, Columbus, Ohio).
Snee, L. W. 1982. Emplacement and cooling of the Pioneer batholith, southwestern Montana (Ph.D. thesis, Ohio State University, Columbus, Ohio).
Streckeisen, A. L. 1973. Plutonic rocks: classification and nomenclature recommended by the IUGS Subcommittee on the systematics of igneous rocks. GEOTIMES 18 (10), 2630.
Stuckless, J. S., Bunker, C. M., Bush, C. A. & VanTrump, , George, Jr 1981. Radioelement concentrations in Archean granites of central Wyoming; US GEOL SURV OPEN-FILE REP 81–948.
Tilling, R. I. 1973. Boulder batholith, Montana—a product of two contemporaneous but chemically distinct magma series. GEOL SOC AM BULL 84, 3879–900.
Tilling, R. I., Klepper, M. R. & Obradovich, J. D. 1968. K-Ar ages and time span of emplacement of the Boulder batholith, Montana. AM J SCI 266, 671–89.
Tilling, R. I. & Gottfried, , David, 1969. Distribution of thorium, uranium, and potassium in igneous rocks of the Boulder batholith region, Montana, and its bearing on radiogenic heat production and heat flow. US GEOL SURV PROF PAP 614–E.
Vielzeuf, D. & Holloway, J. R. 1988. Experimental determination of the fluid-absent melting relations in the pelitic system. CONTRIB MINERAL PETROL 98, 257–76.
Weber, C., Barbey, P., Cuney, M. & Martin, H. 1985. Trace element behaviour during migmatization. Evidence for a complex melt-residuum-fluid interaction in the St. Malo migmatitic dome (France). CONTRIB MINERAL PETROL 90, 5262.
White, A. J. R. & Chappell, B. W. 1977. Ultrametamorphism and granitoid genesis. TECTONOPHYSICS 43, 722.
Wooden, J. L., Mueller, P. A., Mogk, D. A. & Bowes, D. R. 1988. A review of the geochemistry and geochronology of Archean rocks of the Beartooth Mountains, Montana and Wyoming. In Lewis, S. E. & Berg, R. B. (eds) Precambrian and Mesozoic plate margins. MONTANA BUR MINES GEOL SPEC PUBL 96, 2342.
Wyllie, P. J. 1977. Crustal anatexis: an experimental review. TECTONOPHYSICS 43, 4171.
Zen, , E-an, 1988a. Thermal modelling of stepwise anatexis in a thrust-thickened sialic crust. TRANS R SOC EDINBURGH EARTH SCI 79, 223–35.
Zen, , E-an, 1988b. Bedrock geology of the Vipond Park 15-minute, Stine Mountain 7-1/2 minute, and Maurice Mountain 7-1/2 minute quadrangles, Pioneer Mountains, Beaverhead County, Montana. US GEOL SURV BULL 1625.
Zen, , E-an, (in prep.) Generation of magmas of the Pioneer batholith: a geologically constrained thermal model. GEOL SOC AM SPEC PAP.

Keywords

Using granite to image the thermal state of the source terrane

  • E-an Zen (a1)

Metrics

Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed