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Crustal versus mantle sources of granitic magmas: a two-parameter model based on Nd isotopic studies

Published online by Cambridge University Press:  03 November 2011

Donald J. DePaolo ,
Frank V. Perry  and
W. Scott Baldridge
Donald J. DePaolo
Affiliation:
Donald J. DePaolo, Center for Isotope Geochemistry, Department of Geology and Geophysics ,University of California, Berkeley, California 94720,U.S.A.; Earth Sciences Division, Lawrence Berkeley Laboratory, Berkeley, California 94720, U.S.A
Frank V. Perry
Affiliation:
Frank V. Perry, Department of Geology, University of New Mexico, Albuquerque, NM 87131, U.S.A.
W. Scott Baldridge
Affiliation:
W. Scott Baldridge, Earth and Environmental Sciences Division, Los Alamos National Laboratory, Los Alamos, NM 87545, U.S.A.
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Abstract

Temporal and spatial variations in the Nd isotopic compositions of Tertiary caldera-forming rhyolite tuffs, and Cretaceous and Tertiary granites of the western U.S.A. are used as a basis for a model that accounts for the observed proportions of crustal versus mantle contributions to silicic magmas in terms of two parameters: the ambient crustal temperature and the rate of supply of basaltic magma from the mantle. The crustal contribution to silicic igneous rocks is measured in terms of the Neodymium Crustal Index (NCI). The relationships between crustal temperature, basalt supply and NCI are quantified using a model of a magma chamber undergoing continuous recharge, wall-rock assimilation and fractional crystallisation. From the model, a critical value of the ratio of basalt recharge-to-assimilation, (r/a)c, is deduced, which increases with decreasing crustal temperature. The r/a value must exceed (r/a)c to allow the volume of differentiated magma to increase, a prerequisite for developing large volumes of silicic magma. Strongly peraluminous (or S-type) magmas (NCI = 0·8–1), form under conditions of high crustal temperature and low basalt supply. Metaluminous or I-type granites form over a wide range of conditions (NCI = 0·1–1), generally where basalt supply is substantial. In individual long-lived volcanic centres, the large-volume high-silica ignimbrites are associated with the highest r/a and lowest NCI values, indicating that these magmas are typically differentiates of mantle-derived basaltic parents.

Keywords

Assimilationfractional crystallisationignimbritemagma chamberrhyolite
Type
Research Article
Information
Earth and Environmental Science Transactions of The Royal Society of Edinburgh , Volume 83 , Issue 1-2: Second Hutton Symposium: The Origin of Granites and Related Rocks , 1992 , pp. 439 - 446
Copyright
Copyright © Royal Society of Edinburgh 1992

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References

Bennett, V. C. & DePaolo, D. J. 1988. Proterozoic crustal history of the western United States as determined by Neodymium isotopic mapping. GEOL SOC AM BULL 99, 674–85.2.0.CO;2>CrossRefGoogle Scholar
DePaolo, D. J. 1985. Isotopic studies of processes in mafic magma chambers. J PETROL 26, 925–51.CrossRefGoogle Scholar
DePaolo, D. J. 1988. Neodymium isotope geochemistry. Heidelberg: Springer.CrossRefGoogle Scholar
DePaolo, D. J., Linn, A. M. & Schubert, G. 1990. The continental crustal age distribution: Methods of determining mantle separation ages from Sm-Nd isotopic data and application to the western United States. J GEOPHYS RES 96, 2, 071–88.Google Scholar
DePaolo, D. J., Perry, F. V. & Baldridge, W. S. 1991. Neodymium isotopic monitor of basalt influx rates and eruption potential in continental magmatic systems. GEOL SOC AM ABSTR 23, A396.Google Scholar
Farmer, G. L. & DePaolo, D. J. 1983. Origin of Mesozoic and Tertiary granite in the western U.S. and implications for pre-Mesozoic crustal structure. I. Nd and Sr isotopic studies in the geocline of the northern Great Basin. J GEOPHYS RES 88, 3, 379–401.Google Scholar
Farmer, G. L. & DePaolo, D. J. 1984. Origin of Mesozoic and Tertiary granite in the western U.S. and implications for pre-Mesozoic crustal structure. II. Nd and Sr isotopic studies of Cu- and Mo-mineralized granite in the Precambrian craton. J GEOPHYS RES 89, 10, 141–60.Google Scholar
Farmer, G. L., Perry, F. V., Semken, S., Crowe, B., Curtis, D. B. & DePaolo, D. J. 1989. Isotopic evidence on the structure and origin of subcontinental lithospheric mantle in southern Nevada. J GEOPHYS RES 94, 7, 885–98.Google Scholar
Farmer, G. L., Broxton, D. E., Warren, R. G. & Pickthorn, W. 1991. Nd, Sr, and O isotopic variations in metaluminous ash-flow tuffs and related volcanic rocks at the Timber Mountain/Oasis Valley caldera complex, SW Nevada: Implications for the origin and evolution of large volume silicic magma bodies. CONTRIB MINERAL PETROL 109, 53–68.CrossRefGoogle Scholar
Gardner, J. N. & Goff, F. 1984. Potassium-Argon dates from the Jemez volcanic field: Implications for volcanic activity in the north-central Rio Grande Rift. In Baldridge, W. S., Dickerson, P. W., Riecker, R. E. & Zidek, J. (eds) RioGrande Rift: Northern New Mexico, New Mexico Geological Society, Socorro, 35th Annual Field Conference, Oct. 11–13, 1984, Socorro: New Mexico Geological Society.Google Scholar
Hildreth, W., Halliday, A. N. & Christiansen, R. L. 1991. Isotopic and chemical evidence concerning the genesis and contamination of basaltic and rhyolitic magma beneath the Yellowstone Plateau volcanic field. J PETROL 32, 63–138.CrossRefGoogle Scholar
Halliday, A. N., Mahood, G. A., Holden, P., Metz, J. M., Dempster, T. J. & Davidson, J. P. 1989. Evidence for long residence times of rhyolitic magma in the Long Valley magmatic system: the isotopic record in precaldera lavas of Glass Mountain EARTH PLANET SCI LETT 94, 274–90.CrossRefGoogle Scholar
Huppert, H. E. & Sparks, R. S. J. 1988. The generation of granitic magmas by intrusion of basalt into continental crust. J PETROL 29, 599–624.CrossRefGoogle Scholar
Johnson, C. M. 1991. Large-scale crust formation and lithosphere modification beneath Middle to Late Cenozoic calderas and volcanic fields, western North America. J GEOPHYS RES 96, 13, 485–507.Google Scholar
Kushiro, I. 1982. Density of tholeiite and alkali basalt magmas at high pressures. YEARB CARNEGIE INST WASHINGTON 81, 305–9.Google Scholar
Marshall, B. D. & DePaolo, D. J. 1989. Calcium isotopes in igneous rocks and the origin of granite. GEOCHIM COSMOCHIM ACTA 53, 917–22.CrossRefGoogle Scholar
McKenzie, D. 1985. The extraction of magma from the crust and mantle. EARTH PLANET SCI LETT 74, 81–91.CrossRefGoogle Scholar
Musselwhite, D. S., DePaolo, D. J. & McCurry, M. 1989. The evolution of a silicic magma system: Isotopic and chemical evidence from the Woods Mountains volcanic center, eastern California. CONTRIB MINERAL PETROL 101, 19–29.CrossRefGoogle Scholar
Perry, F. V., Baldridge, W. S. & DePaolo, D. J. 1987. Role of asthenosphere and lithosphere in the generation of late Cenozoic basaltic rocks from the Rio Grande rift and adjacent regions of the southwestern United States. J GEOPHYS RES 92, 9, 193–213.Google Scholar
Perry, F. V., Baldridge, W. S., DePaolo, D. J. & Shafiqullah, M. 1990. Evolution of a magmatic system during continental extension: The Mount Taylor volcanic field, New Mexico. J GEOPHYS RES 95, 19, 327–48.Google Scholar
Perry, F. V., DePaolo, D. J. & Baldridge, W. S. 1991. Isotopic evidence for a decline in crustal contributions to caldera-forming rhyolites of the western United States during the middle to late Cenozoic. GEOL SOC AM ABSTR 23, A441.Google Scholar
Perry, F. V., DePaolo, D. J. & Baldridge, W. S. 1992. Isotopic evidence for a decline in crustal contributions to caldera-forming rhyolites of the western United States during the middle to late Cenozoic. GEOL SOC AM BULL (submitted).Google Scholar
Rudnick, R. L. 1990. Nd and Sr isotopic compositions of lower-crustal xenoliths from North Queensland, Australia: Implications for Nd model ages and crustal growth processes. CHEM GEOL 83, 195–208.CrossRefGoogle Scholar
Stewart, B. W. & DePaolo, D. J. 1990. Isotopic studies of processes in mafic magma chambers: II. The Skaergard intrusion, East Greenland. CONTRIB MINERAL PETROL 104, 125–41.CrossRefGoogle Scholar
Stewart, B. W. &. DePaolo, D J. 1992. Diffusive isotopic contamination of mafic magma by coexisting silicic liquid in the Muskox intrusion. SCIENCE 255, 708–11.CrossRefGoogle ScholarPubMed
Wendlandt, E. & DePaolo, D. J. 1992. Nd and Sr isotope chronostratigraphy of Colorado Plateau lithosphere: Implications for magmatic and tectonic underplating of the continental crust. EARTH PLANET SCI LETT (submitted).CrossRefGoogle Scholar