Granite and Pegmatite Generation Processes
We are investigating granite generation and crystallization processes in the Proterozoic terrane of the Black Hills, South Dakota, and petrogenesis of San Diego pegmatites in the Mesozoic Penninsular Ranges batholith, California. In the Black Hills, students have an opportunity to study processes such as melt generation in the continental crust, the geochemical relationships between protoliths and granites, the generation of rare-mineral and rare-element pegmatites, and the role of fluids in the generation of granites. The work in California focuses on the role of fluxing components in promoting very low temperatures of crystallization of pegmatite melts.
One problem we are interested in are crystallization processes in pegmatites. The picture on the left shows a "line rock", a granite in which tourmaline-rich layers (black) crystallized rhythmically from a granite magma. This outcrop is at Calamity Peak, S.D.. The picture on the right shows the large zoned Tin Mountain pegmatite in the Black Hills. Our work suggests that it crystallized below 400 °C from a silicate melt that contained significant concentrations of fluxing components.
We study the crystallization processes through a combination of mineralogy and fluid inclusion analyses by microthermometry to obtain major gas components and by Inductively-Coupled Plasma Emission and Ion Chromatography techniques to obtain the major and trace element compositions. Picture on the left shows coexisting water-rich and CO2-rich fluid inclusions in quartz from the wall zone of the Tin Mountain pegmatite. Picture on the right shows compositions of fluid inclusions from different zones in the two Black Hills pegmatites. We find that CO2 is a major fluid component in the pegmatites and that Li-carbonate species play a major role in depressing the crystallization temperatures of pegmatite melts.
Papers that came out of our granite research
(some can be downloaded as pdf’s)
Nabelek, P. I., O'Neil, J. R. and Papike, J. J. (1983) Vapor phase exsolution as a controlling factor in hydrogen isotope variation in granitic magmas: The Notch Peak granitic stock, Utah. Earth and Planetary Science Letters, 66, 137-150.
Nabelek, P. I. (1986) Trace element modeling of the petrogenesis of granophyres and aplites in the Notch Peak granitic stock, Utah., American Mineralogist, 71, 460-471.
Nabelek, P. I., Papike, J. J. and Laul, J. C. (1986) The Notch Peak granitic stock, Utah: Origin of reverse zoning and petrogenesis, Journal of Petrology, 27, 1035-1069.
Rockhold, J. R., Nabelek, P. I. and Glascock, M. D. (1987) Origin of rhythmic layering in the Calamity Peak satellite pluton of the Harney Peak Granite, South Dakota: The role of boron. Geochimica et Cosmochimica Acta,, 51, 487-496.
Pallesen, T. J., Nabelek, P. I. and Glascock, M. D. (1988) Compositional and textural zonation in the Silvermine granite, Missouri: The role of liquid fractionation and K metasomatism in the formation of a W-Sn deposit. In: Proc. N. Am. Cont. Tecton. Control Ore Depos., (G. Kisvarsanyi, S. Grant, eds. ), 346-357.
Nabelek, P. I. and Russ-Nabelek, C. (1990) The role of fluorine in the petrogenesis of magmatic segregations in the St. Francois volcano-plutonic terrane, southeastern Missouri. In H. J. Stein and J. L. Hanna, eds., Ore bearing Granite Systems: Petrogenesis and Mineralizing Processes: Geol. Soc. Am. Spec. Pap. 246, 71-87.
Nabelek, P.I., Russ-Nabelek, C. and Denison, J. R. (1992) The generation and crystallization conditions of the Proterozoic Harney Peak leucogranite, Black Hills, South Dakota, USA: Petrologic and Geochemical Constraints. Contributions to Mineralogy and Petrology, 110, 17 3-191.
Nabelek, P.I., Russ-Nabelek, C. and Haeussler, G.T. (1992) Stable isotope evidence for the petrogenesis and fluid evolution in the Proterozoic Harney Peak leucogranite, Black Hills, South Dakota. Geochimica et Cosmochimica Acta, 56, 403-417.
Krogstad, E.J., Walker, R.J., Nabelek, P.I. and Russ-Nabelek, C. (1993) Pb isotopic evidence for mixed sources for Proterozoic granites and pegmatites, Black Hills, South Dakota. Geochimica et Cosmochimica Acta, 57, 4677-4685.
Nabelek, P.I. and Glascock, M.D. (1995) Rare earth element-depleted leucogranites Black Hills, South Dakota: A consequence of disequilibrium melting of monazite-bearing schists. Journal of Petrology, 36, 1055-1071.
Nabelek, P.I. and Ternes, K. (1997) Fluid inclusions in the Harney Peak Granite, Black Hills, South Dakota, USA: Implications for solubility and evolution of magmatic volatiles and crystallization of leucogranite magmas. Geochimica et Cosmochimica Acta, 61, 1447-1465
Nabelek, P.I. (1997) Quartz-sillimanite leucosomes in high-grade schists, Black Hills, South Dakota: A perspective on the mobility of Al in high-grade metamorphic rocks. Geology, 25, 995-998.
Sirbescu, M. and Nabelek, P. I. (1998) Inclusions in the Harney Peak Granite and its associated pegmatites (Black Hills, South Dakota): Implications on geochemical evolution of magmatic fluids in a leucogranite system: PACROFI VII, 64.
Nabelek, P. I. and Bartlett, C. D. (1998) Petrologic and geochemical links between the post-collisional Proterozoic Harney Peak leucogranite, South Dakota, USA, and its source rocks. Lithos, 45, 71-85.
Nabelek, P.I., Bartlett, C., and Glascock, M. (1999) Can trace element distributions in migmatites be used as analogues for granite petrogenesis? Physics and Chemistry of the Earth (A), 24, 295-298.
Nabelek, P.I. (1999)Trace element distribution among rock-forming minerals in Black Hills migmatites, South Dakota: a case for solid-state equilibrium. American Mineralogist, 1256-1269. PDF
Nabelek, P., Sirbescu, M., and Liu, M.(2000) The 1.72 Ga Harney Peak Granite: Culmination of the Trans-Hudson orogeny in the Black Hills, South Dakota. Rocky Mountain Geology, 34, 165-181.
Nabelek, P.I. and Bartlett, C. (2000) Fertility of metapelites and metagraywackes during leucogranite generation: An example from the Black Hills, USA. Transactions of the Royal Society of Edinburgh, 91, 1-14..
Wilke, M., Nabelek, P. I., and Glascock, M. D. (2002) B and Li in metapelites from the Proterozoic Terrane in the Black Hills, South Dakota, USA: Implications for the origin of leucogranitic magmas. American Mineralogist, 87, 491-500. PDF
Sirbescu, M.-L. C. and Nabelek, P.I. (2003) Crystallization conditions and evolution of magmatic fluids in the Harney Peak Granite and associated pegmatites, Black Hills, South Dakota - Evidence from fluid inclusions. Geochimica et Cosmochimica Acta, 67, 2443-2465. PDF
Sirbescu, M.-L. C. and Nabelek, P.I. (2003) Dawsonite: an inclusion mineral in quartz from the Tin Mountain pegmatite, Black Hills, South Dakota. American Mineralogist, 88, 1055-1060. PDF
