Abstract
The early Tertiary alkali granite in the Mt. Namsan near Kyongju city is well known as A-type granite. Whole-rock chemistry and Sr and Nd isotopic compositions were investigated in order to constrain the origin of the alkali granite. According to the degree of alumina saturation and the CIPW norm, the alkali granite is peralkaline and the assotiated Bulguksa granite is peraluminous to metaluminous. The element ratios of the alkali granite mostly belong to the A2 group of A-type granite, suggesting that the alkali granite may have emplaced in a post-orogenic environment. The Rb-Sr age of the alkali granite and the assotiated Bulguksa granite is 49.7 ±0.1 Ma. Both granites were derived from a common source of mantle-like, young lower crust, and their parental magma had little or no interaction with the sialic continental crust. According to rare earth element (REE) and other trace element data, the alkali-granite magma was produced by fractionational crystallization of feldspar from Bulguksa-granite magma. The alkali-granite magma contains high F and flourine played a major role in determining the geochemical characteristics of the alkali granite. In conclusion, the A-type nature of the Namsan alkali granite was developed mainly by differentiation of Bulguksa granite and by high F content.
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Choo, S.H., Jin, M.S., Yoon, H.S. and Kim, D.H., 1982, Rb/Sr Age Determinations on Granite Gneiss and Granite in Seosan, Ongeongri Granite, and Mesozoic Granite along the East Coast, Korean Peninsula. Report on Geoscience and Mineral Resources 13, Korea Institute of Energy and Resources, Taejon, p. 193–208.
Clemens, J.D., Holloway, J.R. and White, A.J.R., 1986, Origin of an A-type granite: experimental constraints. Americal Mineralogist, 71, 317–324.
Collins, E.J., Beams, S.D., White, A.J.R. and Chappell, B.W., 1982, Nature and origin of A-type granites with particular reference to southeastern Austrailia. Contributions to Mineralogy and Petrology, 80, 189–200.
Creaser, R.A., Price, R.C. and Wormald, R.J., 1991, A-type granite revisited: assessment of a residual-source model. Geology, 19, 163–166.
Crock, J.G., Lichte, F.E. and Wildeman, T.R., 1984, The group separation of the rare-earth elements and yttrium from geologic materials by cation-exchange chromatography. Chemical Geology, 45, 149–163.
DePaolo, D.J., 1981, A neodymium and strontium isotopic study of the Mesozoic calc-alkaline granitic batholiths of the Sierra Nevada and Peninsular Ranges, California. Journal of Geophysical Research, 86, 10470–10488.
Eby, G.N., 1990, The A-type granitoids: a review of their occurrence and chemical characteristics and speculations on their petrogenesis. Lithos, 26, 115–134.
Eby, G.N., 1992, Chemical subdivision of the A-type granitoids: petrogenetic and tectonic implications. Geology, 20, 641–644.
Faure, G., 1986, Principles of Isotope Geology (2nd edn.). Wiley, New York, 589 p.
Geyh, M.A. and Schleicher, H., 1990, Absolute Age Determination: Physical and Chemical Dating Methods and Their Application. Springer-Verlag, Heidelberg, 83 p.
Harris, N.B.W., Marzouki, F.M.H. and Ali, S., 1986, The Jabel Sayid Complex, Arabian Shield: geochemical constraints on the origin of peralkaline and related granites. Jounal of the Geological Society (London), 143, 287–295.
Harris, N.B.W. and Marriner, G.F., 1990, Geochemistry and petrogenesis of a peralkaline granite complex from the Median Mountains, Saudi Arabia. Lithos, 13, 325–337.
Hess, P.C., 1989, Origins of Igneous Rocks. Harvard University Press, Cambridge, 336 p.
Hildreth, W., 1981, Gradients in silicic magma chambers: implications for lithospheric magmatism. Journal of Geophysical Research, 86, 10153–10192.
Hwang, B.H., 1995, A Petrological Study on the Granitic rocks of the Kyeongju Area. M.S. thesis, Pusan National University, Pusan, 70 p.
Jacobsen, S.B., 1988, Isotopic constraints on crustal growth and recycling. Earth and Planetary Science Letters, 90, 315–329.
Kerr, A. and Fryer, B.J., 1993, Nd isotopic evidence for crustmantle interaction in the generation of A-type granitoid suites in Labrador, Canada. Chemical Geology, 104, 39–60.
Kwon, S.-T., 1991, Sm-Nd isotopic study of the Phanerozoic granitoids of Korea: implication for the origin of crust and tectonics. 46th Conference of the Geological Society of Korea (Abstract), Seoul, Nov. 8–9, p. 528–529.
Lee, M.J., 1995, Mineralogy and Geochemistry of the Granitic Rocks Distributed in the Kyeongju Area. M.S. thesis, Seoul National University, Seoul, 96 p.
Lee, M.J., Lee, J.I. and Lee, M.S., 1995, Mineralogy and major element geochemistry of A-type alkali granite in the Kyeongju area, Korea. Journal of the Geological Society of Korea, 31, 583–607.
Na, C.K., 1994, Genesis of Granitoid Batholiths of Okchon Zone, Korea and Its Implications for Crustal Evolution. Ph. D. thesis, University of Tsukuba, Tsukuba, 154 p.
Na, C.K., Nakano, T., Ito, T., Sakagawa, M. and Kajiwara, Y., 1992, Analysis of the rare-earth elements in rocks using cation-exchange chromatography and inductively coupled plasma atomic emission spectrometry. Annual Report 18, Institute of Geoscience, Tsukuba, 94–97.
Norrish, K. and Hutton, J.T., 1969, An accurate X-ray spectrographic method for the analysis of a wide range of geological samples. Geochimica Cosmochimica Acta, 33, 431–453.
Pearce, J.A., Harris, N.B.W. and Tindle, A.G., 1984, Trace element discrimination diagrams for the tectonic interpretation of granitic rocks. Journal of Petrology, 25, 956–983.
Taylor, R.P., 1984, Role of fluorine in melt depolymerization, lanthanide fractionation, and the genesis of granophile deposits, 37th Confernce of Geological Association of Canada (Abstract), Ottawa, May 19–21, p. 110.
Turner, S.P., Foden, J.D. and Morrison, R.S., 1992, Derivation of A-type magmas by fractionation of basaltic magma: an example from the Pathway Ridge, South Austrilia. Lithos, 28, 151–179.
Whalen, J.B., Currie, K.L. and Chappell, B.W., 1987, A-type granites: geochemical characteristics, discrimination and petrogenesis. Contributions to Mineralogy and Petrology, 95, 407–419.
Whalen, J.B., Jenner, G.A., Currie, K.L., Barr, S.M., Longstaffe, F.J. and Hegner, E., 1994, Geochemical and isotopic characteristics of granitoids of the Avalon Zone, southern New Brunswick: possible evidence for repeated delamination events. Journal of Geology, 102, 269–282.
Wilson, M., 1989, Igneous Petrogenesis. Unwin Hyman, London, 466 p.
Yun, S.H. and Hwang, I.H., 1990, Petrology and geochemical characteristics of the granitic rocks in Namsan area, Kyeongju. Journal of the Korean Earth Science Society, 11, 51–66.
Yun, S.H., Lee, S.W. and Ko, J.S., 1994, Petrogenesis and geochemical characteristics of A-type granite with particular references to the Namsan Granite, Kyeongju. 3rd Conference of Petrological Society of Korea (Abstract), Seoul, September, 9, p. 178–179.
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Kim, CS., Kim, GS. Petrogenesis of the early Tertiary A-type Namsan alkali granite in the Kyongsang Basin, Korea. Geosci J 1, 99–107 (1997). https://doi.org/10.1007/BF02910481
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DOI: https://doi.org/10.1007/BF02910481