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Oligocene lamproite containing an Al-poor, Ti-rich biotite, Middle Park, northwest Colorado, USA

  • R. N. Thompson (a1), D. Velde (a2), P. T. Leat (a3), M. A. Morrison (a4), J. G. Mitchell (a5), A. P. Dickin (a6) and S. A. Gibson (a7)...

Abstract

A small 33 ± 0.8 Ma lamproite pluton is exposed in the midst of a 23–26 Ma basalt-rhyolite province in Middle Park, NW Colorado. It contains abundant phlogopite phenocrysts in a fine-grained groundmass of analcime pseudomorphs after leucite, biotite, potassic richterite, apatite, ilmenite and accessory diopside. The phlogopite phenocryst cores contain ∼4 wt.% TiO2, 1% Cr2O3 and 0.2% BaO. The smallest groundmass biotites have normal pleochroism but compositions unlike any previously reported, with ∼2% Al2O3, ∼8% TiO2 and F <1.5%. Apart from those elements affected by leucite alteration, both the elemental and isotopic composition of this lamproite are close to those of the Leucite Hills, Wyoming. Its Nd-isotopic model age (TDM = 1.6 Ga) is outside the Leucite Hills range but within that of other Tertiary strongly potassic magmatism in the region underlain by the Wyoming craton. Evidence from both teleseismic tomography and the mantle xenoliths within other western USA mafic ultrapotassic igneous suites shows that the total lithospheric thickness beneath NW Colorado was probably ∼150–200 km at 33 Ma, when the Middle Park lamproite was emplaced. This is an important constraint on tectonomagmatic models for the Cenozoic evolution of this northernmost part of the Rio Grande rift system.

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Alibert, C., Michard, A. and Albarede. F. (1986) Isotope and trace element geochemistry of the Colorado Plateau volcanics. Geochim. Cosmochim. Acta, 50, 2735-76.
Best, M.G. and Christiansen, E.H. (1991) Limited extension during peak Tertiary volcanism, Great Basin of Nevada and Utah. J. Geophys. Res., 96, 13509-28.
Bol, L.C.G.M., Bos, A., Sauter, P.C.C. and Jansen, J.B.H. (1989) Barium-titanium-rich phlogopites in marbles from Rogaland, southwest Norway. Amer. Mineral., 74, 439-47.
Carlson, R.W. and Irving, A.J. (1994) Depletion and enrichment history of subcontinental lithospheric mantle: an Os, Sr, Nd and Pb isotopic study of ultramafic xenoliths from the northwestern Wyoming Craton. Earth Planet. Sci. Lett., 126, 457-72.
Carlson, R.W., Esperanqa, S. and Svisero, D.P., (1996) Chemical and Os isotopic study of Cretaceous potassic rocks from southern Brazil. Contrib. Mineral. Petrol., submitted.
Carmichael, I.S.E. (1967) The mineralogy and petrology of volcanic rocks from the Leucite Hills, Wyoming. Contrib. Mineral. Petrol., 15, 24-66.
Davis, J.M. and Hawkesworth, CJ. (1995) Geochemical and tectonic transitions in the evolution of the Mogollon-Datil Volcanic Field, New Mexico, U.S.A. Chem. Geol., 119, 31-53.
Davis, P.M., Slack, P., Dalheim, H.A., Green, W.V., Meyer, R.P., Achauer, U., Glahn, A. and Granet, M. (1993) Teleseismic tomography of continental rift zones. In Seismic Tomography: Theory and Practice (Iyer, H.M. and Hirahara, K., eds.), Chapman and Hall, 397439.
Della Ventura, G., Robert, J.L. and Bény, J.M. (1991) Tetrahedrally coordinated Ti4+ in synthetic Ti-rich potassic richterite: evidence from XRD, FTIR and Raman studies. Amer. Mineral, 76, 1134—40.
Dymek, R.F. (1983) Titanium, aluminium and interlayer cation substitutions in biotite from high-grade gneisses, West Greenland. Amer. Mineral., 68, 880-99.
Eaton, G.P. (1986) A tectonic redefinition of the Southern Rocky Mountains. Tectonophysics, 132, 163-93.
Eggler, D.H., Meen, J.K., Welt, F., Dudas, F.O., Furlong, K.P., McCallum, M.E. and Carlson, R.W. (1988) Tectonomagmatism of the Wyoming Province. Colo. Sch. Mines Quart., 83, 25-40.
Farmer, G.L. and Boettcher, A.L. (1981) Petrologic and crystal-chemical significance of some deep-seated phlogopites. Amer. Mineral., 66, 1154-63.
Ferriz, F.J., Fernandez Soler, J.M. and Camara, F. (1994) Presencia de afloramientos de lamproitas en las proximidades de Moratalla y Cehegin (Murcia). Bol. Soc. Espan. Mineral. 17, 231-9.
Fitton, J.G., James, D. and Leeman, W.P. (1991) Basic magmatism associated with late Cenozoic extension in the western United States; compositional variations in space and time. J. Geophys. Res., 96, 13693-711.
Foley, S.F. (1992) Vein-plus-wall-rock melting mechanisms in the lithosphere and the origin of potassic alkaline magmas. Lithos, 28, 435—53.
Foley, S.F., Venturelli, G., Green, D.H. and Toscani, L. (1987) The ultrapotassic rocks: characteristics, classification and constraints for petrogenetic models. Earth-Sci. Rev., 24, 81-134.
Frey, F.A. and Green, D.H. (1974) The mineralogy, geochemistry and origin of lherzolite inclusions in Victorian basanites. Geochim. Cosmochim. Acta, 38, 1023-59.
Gans, P.B., Mahood, G.A. and Schermer, E. (1989) Synextensional magmatism in the Basin and Range Province; a case study from the eastern Great Basin. Geol. Soc. Amer. Spec. Paper, 233, 1—53.
Gibson, S.A., Thompson, R.N., Leat, P.T., Dickin, A.P., Morrison, M.A., Hendry, G.L. and Mitchell, J.G. (1992) Asthenosphere-derived magmatism in the Rio Grande rift, western USA: implications for con tinental break-up. In Magmatism and the Causes of Continental Break-up (Storey, B.C., Alabaster, T. and Pankhurst, R.J. eds.), Geol. Soc. London Spec. Publ., 68, 6189.
Gibson, S.A., Thompson, R.N., Leat, P.T., Morrison, M.A., Hendry, G.L., Dickin, A.P. and Mitchell, J.G. (1993) Ultrapotassic magmas along the flanks of the Oligo-Miocene Rio Grande rift, USA: monitors of the zone of lithospheric mantle extension and thinning beneath a continental rift. J. Petrol., 34, 187228.
Gibson, S.A., Thompson, R.N., Leonardos, O.H., Dickin, A.P. and Mitchell, J.G. (1995a) The Late Cretaceous impact of the Trindade mantle plume: evidence from large-volume, mafic, potassic mag-matism in SE Brazil. J. Petrol., 36, 189229.
Gibson, S.A., Thompson, R.N., Dickin, A.P. and Leonardos, O.H. (1995b) High-Ti and low-Ti mafic potassic magmas: key to plume-lithosphere interactions and continental flood-basalt genesis. Earth Planet. Sci. Lett., 136, 149-65.
Harry, D.L. and Leeman, W.P. (1995) Partial melting of melt-metasomatized subcontinental mantle and the magma source potential of the lower lithosphere. J. Geophys. Res., 100, 10255-69.
Hawkesworth, C., Turner, S., Gallagher, K., Hunter, A., Bradshaw, T., and Rogers, N. (1995) Calc-alkaline magmatism, lithospheric thinning and extension in the Basin and Range. J. Geophys. Res., 100, 10271-86.
Hearn, B.C., Jr., (1989) Alkaline ultramafic magmas in north-central Montana, USA: genetic connections of alnOite, kimberlite and carbonatite. In Kimberlites and Related Rocks, 1 (Jaques, A.L., Ferguson, J. and Green, D.H., eds.), Geol. Soc. Austr. Spec. Publ., 14, 109-19.
Houston, R.S., Duebendorfer, E.M., Karlstrom, K.E. and Premo, W.R. (1989) A review of the geology and structure of the Cheyenne belt and Proterozoic rocks of southern Wyoming. Geol. Soc. Amer. Spec. Pap., 235, 1-12.
Humphreys, E.D. and Dueker, K.G. (1994) Western U.S. upper mantle structure. J. Geophys. Res., 99, 9615-34.
Izett, G.A. (1974) Geologic map of the Trail Mountain quadrangle, Grand County, Colorado. U. S. Geol. Surv. Map, GQ-1156.
Izett, G.A. (1975) Late Cenozoic sedimentation and deformation in northern Colorado and adjoining areas. Mem. Geol. Soc. Amer., 144, 179–209.
Izett, G.A. and Barclay, C.S.V. (1973) Geologic map of the Kremmling quadrangle, Grand County, Colorado. U. S. Geol. Surv. Map, GQ-1115.
Kuehner, S.M., Edgar, A.D. and Arima, M. (1981) Petrogenesis of the ultrapotassic rocks from the Leucite Hills, Wyoming. Amer. Mineral., 66, 663-77.
Leat, P.T., Thompson, R.N., Morrison, M.A., Hendry, G.L. and Dickin, A.P. (1988) Silicic magmas derived by fractional crystallization from Miocene minette, Elkhead Mountains, Colorado. Mineral. Mag. 52, 577-85.
Leat, P.T., Thompson, R.N., Morrison, M.A., Hendry, G.L. and Dickin, A.P. (1990) Geochemistry of mafic lavas in the early Rio Grande rift, Yarmony Mountain, Colorado, U.S.A. Chem. Geol., 81, 23-43.
Leat, P.T., Thompson, R.N., Morrison, M.A., Hendry, G.L. and Dickin, A.P. (1991) Alkaline hybrid mafic magmas of the Yampa area, NW Colorado, and their relationship to the Yellowstone mantle plume and lithospheric mantle domains. Contrib. Mineral. Petrol., 107, 310-27.
Lipman, P.W. (1980) Cenozoic volcanism in the western United States: implications for continental tectonics. In Continental Tectonics, U.S. Nat. Acad. Sci., 161-74.
Luhr, J.F. and Kyser, T.K. (1989) Primary igneous analcime: the Colima minettes. Amer. Mineral., 74, 216-223.
McKenzie, D.P. (1989) Some remarks on the movement of small melt fractions in the mantle. Earth Planet. Sci. Lett., 95, 53–72.
Mitchell, R.H. and Bergman, S.C. (1991) Petrology of Lamproites. Plenum Press, 1—447.
Mitchell, R.H., Platt, R.G. and Downey, M. (1987) Petrology of lamproites from Smoky Butte, Montana. J. Petrol., 28, 645-77.
Mokhtari, A, Wagner, C. and Velde, D (1985) Presence of late crystallizing ferriannite-rich annite in basic eruptive rocks from Morocco. Neues Jahrb. Mineral. Mh., 513-20.
Pearson, D.G., Rogers, N.W., Irving, A.J., Smith, C.B. and Hawkesworth, C.J. (1995) Source regions of kimberlites and lamproites: constraints from Re-Os isotopes. Sixth Kimb. Conf., Novosibirsk, Russia, extended abs., 430—2.
Sahama, T.G. (1974) Potassium-rich alkaline rocks. In The Alkaline Rocks (Sorensen, H., ed.), John Wiley, 96109.
Salvioli-Mariani, E. and Venturelli, G. (1996) Temperature of crystallization and evolution of the Jumilla and Cancarix lamproites (SE Spain), as suggested by melt and solid inclusions in minerals. Europ. J. MineraL, 8, 1027-39.
Snyder, G.L. (1980) Geologic map of the northernmost Gore Range and southernmost Northern Park Range, Grand, Jackson and Routt Counties, Colorado. U. S. Geol. Surv. Map, 1-1114.
Steiger, R.H. and Jfiger, E. (1977) Convention on the use of decay constraints in geo- and cosmochronology. Earth Planet. Sci. Lett., 86, 359-62.
Thompson, R.N., Morrison, M.A., Hendry, G.L. and Parry, S.J. (1984). An assessment of the relative roles of crust and mantle in magma genesis: an elemental approach. Phil. Trans. Roy. Soe. Lond., A310, 549-90.
Thompson, R.N., Leat, P.T., Dickin, A.P., Morrison, M.A., Hendry, G.L. and Gibson, S.A. (1989) Strongly potassic mafic magmas from lithospheric mantle sources during continental extension and heating: evidence from Miocene minettes of north-west Colorado, U.S.A. Earth Planet. Sci. Lett., 98, 139-5.
Thompson, R.N., Gibson, S.A., Leat, P.T., Mitchell, J.G., Morrison, M.A., Hendry, G.L. and Dickin, A.P. (1993) Early Miocene continental extension-related basaltic magmatism at Walton Peak, northwest Colorado: further evidence on continental basalt genesis. J. Geol. Soc. Lond., 150, 277-92.
Tweto, O. (1979a) The Rio Grande rift system in Colorado. In Rio Grande Rift: Tectonics and Magmatism (Riecker, R.E., ed.), Amer. Geophys. Union, 33-56.
Tweto, O. (1979b) Geologic map of Colorado. Scale 1:500,000. U. S. Geol. Surv. Map.
Venturelli, G., Capedri, S., Barbieri, M., Toscani, L., Salvioli-Mariani, E. and Zerbi, M. (1991). The Jumilla lamproite revisited: a petrological oddity. Europ. J. Mineral., 3, 123-45.
von Blanckenburg, F. and Davies, J.H. (1995) Slab breakoff: a model for syncollisional magmatism and tectonics in the Alps. Tectonics, 14, 120—31.
Wagner, C. (1987) Contributions a l'étude minéralogi-que et géochimique des roches hyperalcalines potassiques. Lamproites et roches voisines. Unpublished Thèse de Doctorate d'lÉtat, Université P. et M. Curie, 87-23, 273 pp.
Wagner, C. and Velde, D. (1986) The mineralogy of K-richterite-bearing lamproites. Amer. Mineral., 71, 17-37.
Wagner, C. and Velde, D. (1987) Aluminous spinels in lamproites: occurrence and probable significance. Amer. Mineral., 72, 689-9.
Wendlandt, R.F. (1977) Barium-phlogopite from Haystack Butte, Highwood Mountains, Montana. Ann. Rept. Carnegie Inst. Wash. Ybk., 76, 534-9.
Wilkinson, J.F.G. and Hensel, H.D. (1994) Nephelines and analcimes in some alkaline igneous rocks. Contrib. Mineral. Petrol., 118, 79-91.
Wilkinson, P., Mitchell, J.G., Cattermole, P.J. and Downie, C. (1986) Volcanic chronology of the Meru-Kilimanjaro region, northern Tanzania. J. Geol. Soc. Lond., 143, 601-5
Woolley, A.R., Bergman, S.C., Edgar, A.D., Le Bas, M.J., Mitchell, R.H., Rock, N.M.S. and Scott Smith, B.H. (1996) Classification of lamprophyres, lamproites, kimberlites, and the kalsilitic, melilitic and leucitic rocks. Canad. Mineral., 34, 175—86.

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