Abstract
The rhyodactic O’Leary Porphyry which forms the Pleistocene (0.233±0.37 m.y.) volcanic domes of O’Leary Peak and Darton Dome in the San Francisco Volcanic Field (northern Arizona, U.S.A.) contains sanidine phenocrysts with oligoclase mantles (rapakivi texture). Rapakivi texture occurs worldwide in silicic rocks of many ages and has been attributed to various igneous and metamorphic processes.
The O’Leary Porphyry contains both mantled and unmantled sanidine (both are Or63–69 Ab30–36An1), oligoclase and quartz phenocrysts, labradorite (An53Ab45Or2) and kaersutite xenocrysts and andesite xenoliths. The compositional range of oligoclase is the same (An11–26Ab70–80Orr–10) for the rapakivi mantles, the oligoclase phenocrysts, and the oligoclase crystals poikilitic within sanidines. Most mantles are discontinuous. The sanidine appears to have been resorbed prior to mantling.
Experimental melting studies on the O’Leary Prophyry show that, for a 15 wgt.% water system, plagioclase crystallized prior to sanidine and quartz crystallized last. The O’Leary Porphyry, although inhomogeneous, plots on a Q-Or-Ab-An diagram well within the plagioclase stability field. Poikilitic plagioclases within sanidines further support crystallization of plagioclase prior to sanidine in the O’Leary Porphyry.
Exsolution of a ternary feldspar to form a plagioclase mantle is the most commonly accepted igneous theory of rapakivi texture formation but has been eliminated as the origin of the O’Leary Porphyry rapakivi. Petrologic models by Tuttle and Bowen and by Stewart are rejected for the O’Leary rapakivi because of inconsistencies with the O’Leary occurrences.
Two theories are viable for the O’Leary rapakivi texture. First, is a decrease in water vapor pressure which would enlarge the plagioclase stability field possibility causing mantling of metastable sanidines. The second and preferred theory is that of an addition of sodium and calcium by basification (chemical assimilation without melting) of the xenoliths within the O’Leary Porphyry. This would move the bulk composition of the melt into the plagioclase field possibly resulting in crystallization of plagioclase on sanidine crystals. Diffusion of sodium and calcium from the xenoliths to sanidine would result in mantling only those crystals near to the xenoliths. Later, convection would result in distribution throughout the melt of rapakivi, unmantled sanidines, and xenolithic kaersutite as is seen in the porphyry. Basic xenoliths are extremely common in rapakivi-bearing rocks. Those within the O’Leary Porphyry are andesitic and show resorption, and in some areas of O’Leary Peak itself, have been drawn out into schlieren.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Backlund, H.G., 1938,The Problems of Rapakivi Granites. Jour. Geology,46, pp. 339–96.
Barth, T.F.W., 1969,Feldspars. Wiley-Interscience, New York, 261 pp.
Bladh, K.L., 1972,Petrology of O’Leary Peak Volcanics, Coconino County, Arizona, Unpubl. M. S. Thesis, The University of Arizona.
-----, 1976,Rapakivi Formation of O’Leary Peak Porphyry. Unpubl. Ph. D. Dissertation, The University of Arizona.
Bryner, L., 1959,Geology of the South Comobabi Mountains and Ko Vaya Hills, Pima County, Arizona. Unpubl. Ph. D. Dissertation, The University of Arizona.
Dawes, P.R., 1966,Genesis of Rapakivi. Nature,209, pp. 569–71.
De Fino, M., La Volpe, L., andLirer, L., 1973,Volcanology and Petrology of the Assab Range (Ethiopia). Bull. Volcanol.,37 pp. 95–110.
Ehrreich, A.L., andWinchell, R. E., 1969,Rapakivi Texture in Rhyolite. Nature,224, pp. 905–6.
Eichelberger, J. C., 1976, personal communication.
Elders, W.A., 1968,Mantled Feldspar from the Granites of Wisconsin. Jour. Geol.,76, pp. 37–49.
Erickson, R.C., 1969,Petrology and Geochemistry of the Dos Cabezas Mountains, Cochise County, Arizona. Unpubl. Ph. D. Dissertation, The University of Arizona.
Foland, K.A., 1974,Alkali Diffusion in Orthoclase. In Hofmann, A.W.et al., (eds.),Geochemical Transport and Kinetics. Carnegie Inst. Washington Publ. 634, pp. 77–98.
Goodspeed, G.E., 1969,Rapakivi Granite from the Salmon River Mountains, Idaho. Geol. Soc. America, Cord. Mtg., pp. 19–20.
Hutchinson, R.M., 1956,Structure and Petrology of Enchanted Rock Batholith, Llano and Gillespie Counties, Texas. Geol. Soc. Am. Bull.,67 pp. 763–806.
James, R.S., andHamilton, D.L., 1969,Phase Relations in the System NaAlSi3O8-KAlSi3O8-CaAl2Si2O8at 1 Kilobar Water Vapor Pressure. Contr. Miner. Petrol.,21, pp. 111–41.
Karner, F.R., 1968,Compositional Variation of the Tunk Lake Granite Pluton, Southeastern Maine. Geol. Soc. Am. Bull.,79, pp. 193–222.
Larrabee, D.M., Spencer, C.W., andSwift, D.J.P., 1965,Bedrock Geology of the Grand Lake Area Aroostook, Hancock, Penobscot, and Wash Cos., Maine. U.S. Geol. Survey Bull., 1201-E.
Lofgren, G., 1974,An Experimental Study of Plagioclase Crystal Morphology: Isothermal Crystallization, Am. Jour. Sci.,274, pp. 243–73.
Lowell, G.R., andSides, J.R., 1973The Occurrence and Origin of Rapakivi Granite in the St. Francois Mountains Batholith of Southeastern Missouri (abs.) Geol. Soc. America, North-Central Sec. Mtg., pp. 332–33.
Marmo, V., 1971,Granite Petrology, and the Granite Problem. Elsevier, Amsterdam, 244 pp.
Medford, G.A., 1973,Calcium Diffusion in a Mugearite Melt. Can. Jour. Earth Sci.,10, pp. 394–402.
Moore, R.B., Wolfe, E.W., andUlrich, G. E., 1974,Geology of the Eastern and Northern Parts of the San Francisco Volcanic Field, Arizona, In Karlstrom, T.N.V., Swann, G.A., and Eastwood, R.L. (eds.),Geology of Northern Arizona Pt. II. Area studies and field guides.
Orville, P.M., 1972,Plagioclase Cation Exchange Equilibria with Aqueous chloride Solution: Results at 700°C. and 2000 Bars in the Presence of Quartz. Am. Jour. Sci.,272, pp. 234–72.
Phillips, E.R., 1972,The Rapakivi Texture in an Adamellite from the New England Batholith, New South Wales. Proc. R. Soc. Qd.,83, pp. 89–98.
Prucha, J.J., 1946,The Ravakivi Granite of Waupaca, Wisconsin. Unpubl. Ph. D. Thesis, University of Wisconsin.
Richter, W., 1966,Die Feldspate des Granites von Eisenkappel (Karnten) und seines Randporphyres. Min. Pet. Mitt., Tschermacks,11, pp. 439–58.
Riederer, J., 1966,Rapakivifeldspate in moldanubischen Graniten. Min. Pet. Mitt., Tschermacks,11, pp. 29–40.
Rucklidge, J.C., andGasparrini, E.L., 1969,EMPADAR VII, a Computer Program for Processing Electron Microprobe Analytical Data. Dept. of Geology, Univ. of Toronto, Toronto, Canada.
Sahama, T.G., 1945.On the Chemistry of the East Fennoscandian Rapakivi Granites. Bull. Comm. Geol. Finlande,136, pp. 15–67.
Savolahti, A., 1956,The Akvenisto Massif in Finland, Bull. Comm. Geol. Finlande, 174 pp.
Sederholm, J.J., 1967,Selected Works-Granites and Migmatites, 608 pp.
Simonen, A., andVorna, A., 1969,Amphibole and Biotite from Rapakivi. Bull. Comm. Geol. Finlande, 238 pp.
Stewart, D.B., 1959,Rapakivi Granite from Eastern Penobscot Bay, Maine, Congreso Geologicor Internacional XX Sesion-Cuidad de Mexico 1956 Seccion XI-A Petrologia y Mineralogia, pp. 293–320.
Terzaghi, R. D., 1940,Rapakivi of Head Harbor Island, Maine. Am. Mineral.,25, 111–22.
Tuttle, O.F., andBowen, N. L., 1958,Origin of Granite in the Light of Experimental Studies in the System NaAlSi3O8KalSi2O8-SiO2-H2O. Geol. Soc. Am. Mem. 74.
Volborth, A., 1962,Rapakivi-type Granites in the Pre-Cambrian Complex of Gold Buttle, Clark County, Nevada. Geol. Soc. Am. Bull.73, pp. 813–32.
Vorma, A., 1971,Alkali Feldspars of the Wiborg Rapakivi Massif in Southeastern Finland. Bull. Comm. Geol. Finlande, 246 pp.
Winkler, H.G.F., 1967,Petrogenesis of Metamorphic Rocks. Springer-Verlag, New York, 237 pp.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Bladh, K.L. Rapakivi texture from the O’Leary Porphyry, Arizona (U.S.A.). Bull Volcanol 43, 155–171 (1980). https://doi.org/10.1007/BF02597618
Received:
Revised:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF02597618