Fig.. Simplified distribution map of the pre-aso volcanic rocks adapted from Geological Survey of Japan Map Series 1: 50,000, Ono and Watan

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1 Jour. Geol. Soc. Japan, Vol. 115, No. 12, p , December 2009 Petrography and whole-rock geochemistry of pre-aso lavas from the caldera wall of Aso volcano, central Kyushu Masaya Miyoshi, Kuniyuki Furukawa, Taro Shinmura, Madoka Shimono and Toshiaki Hasenaka Graduate school of Science and Technology, Kumamoto University, Kurokami , Kumamoto , Japan ; Present address; Beppu Geothermal Research Laboratory, Institute for Geothermal Sciences, Kyoto University, Noguchibaru, Beppu, Oita , Japan Faculty of Economics, Aichi University, Kurozasa 370, Miyoshi-cho, Nishikamo-gun, Aichi , Japan Faculty of Economics, Kumamoto Gakuen University, Oe 2-5-1, Kumamoto , Japan Abstract Pre-caldera volcanism in the Aso area.. Ma, central Kyushu, is characterized by effusive eruptions of multiple lava flows. To clarify the chemical evolution of the magma chamber beneath the Aso area, we investigated the petrological characteristics of these lavas where exposed in the caldera wall. The pre-caldera lavas are divided into eight types with distinct petrographic and compositional characteristics: A. cpx-ol basalt, B. ol- px andesite, C. ol-hb- px andesite, D. px andesite, E. hb- px andesite, F. hb andesite, G. px-hb dacite, and H. bt-hb rhyolite. Incompatible trace element modeling demonstrated that these eight types did not originate via simple fractional crystallization. The phase assemblages and abundances of phenocrysts of the precaldera andesite-rhyolite differ from those of the caldera-forming and post-caldera andesite rhyolite. In addition, the pre-caldera andesiterhyolite contain relatively low concentrations of incompatible trace elements compared to the caldera-forming and post-caldera andesiterhyolite. These observations may indicate that the physical conditions and/or chemical compositions of the source materials that gave rise to the andesite-rhyolite magmas differed between the pre-caldera and caldera-forming stages. Keywords: Aso, pre-caldera volcanism, petrography, bulk-rock geochemistry Corresponding author; M. Miyoshi, miyoshi@bep.vgs.kyoto-u.ac.jp Hunter ka;, 2001;, 1991 Aso-1 Aso ka ;,, ka, 1985, CThe Geological Society of Japan

2 Fig.. Simplified distribution map of the pre-aso volcanic rocks adapted from Geological Survey of Japan Map Series 1: 50,000, Ono and Watanabe, The pre-aso volcanic rocks are divided into five types by Ono and Watanabe 1985 : biotite rhyolite; hornblende dacite; hornblende andesite; pyroxene andesite; basalt. Data sources of K Ar ages: Kaneoka and Kojima 1970 ; Ono et al ; Kamata 1985 ; Watanabe et al ; Matsumoto et al SiO km 18 km

3 Fig.. Sample locality map of pre-aso volcanic rocks. Shaded texts show geographic names.

4 , 1985, 1965, 1985 Fig. 1;, Fig. 1 5 K Ar : 2 Ma, Ma NEDO, 1991 : 0.8 Ma, Ma, Ma, Ma NEDO, 1991 : Ma, Ma NEDO, 1991: 0.6 Ma NEDO, 1991 : 0.4 Ma, 1970, NEDO, Ma Ma ka Ma, ka Fig. 1 Fig X Philips PANalytical MagiX PRO Fig.. Reported eruption ages of pre-aso volcanic rocks: A ol cpx basalt; B ol 2px andesite; C ol hb 2px andesite; D 2px andesite; E hb 2px andesite; F hb andesite; G 2px hb dacite; H hb bt rhyolites. Data sources of K Ar ages: Kaneoka and Kojima 1970 ; Ono et al ; Kamata 1985 ; Watanabe et al ; NEDO 1990 ; Matsumoto et al Mori and Mashima 2005 Table 1 2 SiO2 A H Table 3 A : TMPA49, TMPA49B, PAS-BA04, PAS-BA Ma: NEDO, 1991 : PAS- BA07, PAS-BA07B 2 Ma:, 1982; 0.6 Ma: NEDO, 1991 B : TTPA45, TTPA46 : PRAS Ma;, 1989 B C : BCPA40, BCPA41, BCPA43 : PRAS11 D : Daikanbo 0.8 Ma:, Ma: NEDO, 1991 : PRAS15 : TTPA44U, TTPA47, TTPA48 : HYPA35, HYPA Ma: NEDO, 1991 : PRAS18, PRAS22, PRAS Ma:, Ma:, 1989 D E : PRAS25 :

5 Table. Modal analysis of representative rock samples from each type of pre-aso volcanic rocks. : Sample localities are shown in Fig. 2. Abbreviations: ol=olivine; opx=orthopyroxene; cpx=clinopyroxene; hb=hornblende; bt=biotite; gm=groundmass; ph=phenocryst. BCPA Ma: NEDO, 1991 : KDPA38, BCPA Ma: NEDO, 1991 : PRAS12, PRAS13 : HYPA29 HYPA Ma:, 1989 : HB-AN F : PRAS24, PRAS Ma F G : PRAS30, PRAS30B H : BT-RH: PRAS16, PRAS Ma:, 1970, NEDO, , B C D E B C, D, E

6 Table. Major and trace element data for samples of pre-aso volcanic rocks. : Sample localities are shown in Fig. 2. Fig. 3 C G A Ma Fig. 3 TTPA33 TTPA33B Fig. 2 2 K2O Table 2 K2O TTPA33 TTPA33B , mm A; Fig..A 2.5 mm, vol. 1.6 mm, 3 14 vol. 0.8 mm, 5 vol. 0.5 mm, 1 vol.

7 Table. continued B; Fig..B 4 mm, vol. 1.5 mm, 1 4 vol. 2 mm, 5 8 vol. 2 mm, 1 3 vol. 0.5 mm, 1 vol.

8 Table. continued Table. Criteria for classifying the pre-aso volcanic rocks into eight types. K Ar age data source: a: NEDO 1991 ; b: Ono et al ; c: Watanabe et al ; d: Kamata 1985 ; e: Kaneoka and Kojima Abbreviations are the same as Table 1. C; Fig..C 4 mm, vol. 1.5 mm, 1 vol.4 mm, 5 7 vol. 2 mm, 1 3 vol. 3 mm, 1 vol. 0.5 mm, 1 2 vol.

9 Fig.. Microscopic photographs of the pre-aso volcanic rocks: A ol cpx basalt; B ol 2px andesite; C ol hb 2px andesite; D 2px andesite; E hb 2px andesite; F hb andesite; G 2px hb dacite; H hb bt rhyolites. Abbreviations: ol = olivine; cpx = clinopyroxene; opx = orthopyroxenea; hb = hornblende; bt = biotite; pl = plagioclase

10 Fig.. Major elements TiO2, Al2O3, Fe2O3, MgO, CaO, Na2O, K2O and P2O5 vs. SiO2 for the pre-aso volcanic rocks. D; Fig..D 4 mm, vol. 2 mm, 2 11 vol. 2 mm, 6 vol. 0.5 mm, 1 2 vol. E; Fig..E 2 mm, vol. 2 mm, 2 5 vol. 2 mm, 2 vol. 3 mm, 3 vol. 0.5 mm, 2 vol.

11 Fig.. Trace elements Ba, Rb, Sr, Ni, V, Zr, Nb, Y, Cr vs. SiO2 for the pre-aso volcanic rocks. F; Fig..F 2 mm, vol. 2 mm, 1 vol. 0.5 mm, 2 vol. G; Fig..G 2 mm, vol. 1 mm, 1 vol.1 mm, 1 vol. 1 mm, 7 11 vol. 0.5 mm, 2 3 vol.

12 Fig.. Rb Nb, Rb Zr and Rb Sr diagrams for the eight types from pre-aso volcanic rocks. Shaded areas and thick dotted lines show the compositional ranges formed by simple fractional crystallization. Symbols are the same as Figs. 5 and 6. H; Fig..H 2 mm, 5 vol. 2 mm, 1 vol. 1 mm, 1 vol. 0.4 mm, 1 vol.

13 Fig.. Incompatible trace elements vs. SiO2 for the pre-aso volcanic rocks, caldera forming stage pyroclastic flow deposits Aso-1 to Aso-4 and post-caldera volcanic products. Data sources: Hunter 1998 ; Miyoshi et al Thick lines indicate Low K, Medium K, High K and Shoshonite rock series boundary LeMaitre et al., 1989; Rickwood, Symbols are the same as Figs. 5 and 6. SiO2 Fig. 5 6 TiO2 Al2O3 Na2O MnO P2O5 Sr Ni Nb Y Cr SiO wt. B C D E F A SiO2 53 wt. G SiO wt. G H SiO wt. H SiO2 Rb Nb Rb Zr Rb Sr Fig. 7 A G, Green, 1994; Rollinson, 1993 A: TMPA49, B: PRAS28, C: BCPA40, D: PRAS15, E: HB-AN, F: PRAS27, G: PRAS30Table 1 Rb Nb Zr Sr D A B C D E F Rb Nb Zr D 0.1 Sr D G Rb Nb Zr Sr D D Fig. 7.a-7.j Rb Zr Rb Sr A A, B H A Fig. 7.d 7.e 7.f B E C G H E F B Rb B

14 Fig. 7.g 7.h 7.i C D E C B F G H C B F C Rb C Fig. 7.j 7.k D E Fig. 7.m 7.n 7.o F G H G H B, C, F, G, H A G Fig. 7 B PRAS28 E TTPA44 C BCPA40 D TTPA48 E BCPA54 C G A Ma 40,, SiO2 Figs. 5, 6A H Sr Nd , A 5 40 vol. 5 vol. 10 vol. Aso vol. 1 vol. 1 vol., 1985;, 2005; Kaneko et al., 2007 B, C, D, E, F 5 10 vol. 1 5 vol. B 1 5 vol. C 1 vol. E 3 vol.f 1 vol. D 2 10 vol., 6 vol., vol., 1 2 vol. G 3 mm 5 10 vol. H :, vol. 1 vol. A 1, 2005 A A 10 vol. SiO2 K2O,, 1985; Kamata, 1989;, 2001 K2O P2O5, Ba, Rb, Zr, Nb, Y Fig. 8 A SiO wt. SiO wt. Fig. 8 SiO2 K2O Medium-K Medium-K High-K

15 Medium-K Shoshonite Fig. 8 P2O5 Ba Rb Zr Nb Y K2O Fig. 8 SiO2 2008, SiO2, 2006; Furukawa, A: B: C: D: E: F: G: H: 2 A B C F G H 6 3 SiO2 18 X Furukawa, K., 2006, Geology and Petrology of Silicic Volcanism in Extensional Plate Convergent Zone. PhD Thesis, Kyoto University, Japan, 118p. Furukawa, K., Miyoshi, M., Shinmura, T. and Arakawa, Y., 2008, Jour. Geol. Soc. Japan,, Green, T.H., 1994, Experimental studies of trace-element partitioning applicable to igneous petrogenesis-sedona 16 years later. Chemical Geol.,, Hunter, A.G., 1998, Intracrustal controls on the coexistence of tholeiitic and calc-alkaline magma series at Aso volcano, SW Japan. Jour. Petrol.,, Kamata, H., 1985, Jour. Geol. Soc. Japan,, Kamata, H., 1989, Volcanic and structural history of the Hohi volcanic zone, central Kyushu, Japan. Bull. Volcanol.,, Kaneko, K., Koyaguchi, T. and Furukawa, K., 2006, Chikyu Monthly,, Kaneko, K., Kamata, H., Koyaguchi, T., Yoshikawa, M., Furukawa, K., 2007, Repeated large-scale eruptions from a single compositionally stratified magma chamber: An example from Aso volcano, Southwest Japan. Jour. Volcanol. Geotherm. Res.,, Kaneoka, I. and Kojima, M., 1970, Bull. Volcanol. Soc. Japan,, LeMaitre, R. W., Bateman, P., Dudek, A., Keller, J., LameyreLeBas, M. J., Sabine, P, A., Schmid, R., Sorensen, H., Streckeisen, A., Woolley, A. R. and Zanettin, B., 1989, A Classification of Igneous Rocks and Glossary of Terms. Oxford, Blackwell, 193p. Matsumoto, T., Uto, K., Ono, K. and Watanabe, K., 1991, K-Ar Fall Meet. Volcanol. Soc. Japan, Abst., 73 Miyoshi, M., Hasenaka, T. and Sano, T., 2005, Bull. Volcanol. Soc. Japan,, Mori, Y. and Mashima, H., 2005, X-ray fluorescence analysis of major and trace elements in silicate rocks using 1: 5 dilution glass beads. Bull. Kitakyushu Mus. Nat. Hist. Human Hist. Ser. A Natural Histo-

16 ry, 12p. NEDO, 1991, 2 3. NEDO Press 280p Ono, K., 1965, Jour. Geol. Soc. Japan,, Ono, K., Shimokawa, K., Soya, T. and Watanabe, K., 1982, 1979 Science and Technology Agency press, Ono, K. and Watanabe, K., 1983, Chikyu Monthly,, Ono, K. and Watanabe, K., 1985, 5 1 Geol. Map Volcano., Aso 4, Geol. Surv. Japan Rickwood, P.C., 1989, Boundary lines within petrologic diagrams which use oxides of major and minor elements. Lithos,, Rollinson, H.R., 1993, Using Geochemical Data; evaluation, presentation, interpretation. Longman Singapore Publ. ltd., 352p. Watanabe, K., 2001, Development of Aso Volcano 7, Ichinomiya, Kumamoto, 241p Watanabe, K., Itaya, T., Ono, K. and Takada, H., 1989, K- Ar Bull. Volcanol. Soc. Japan,, English translation from the original written in Japanese Miyoshi, M., Furukawa, K., Shinmura, T., Shimono, M. and Hasenaka, T., 2009, Petrography and wholerock geochemistry of pre-aso lavas from the caldera wall of Aso volcano, central Kyushu. Jour. Geol. Soc. Japan,, SiO2

N Fig.1 Map showing the location of Komochi volcano (open star). The contours show the depth of upper surface of subducting Pacific plate (grey lines)

N Fig.1 Map showing the location of Komochi volcano (open star). The contours show the depth of upper surface of subducting Pacific plate (grey lines) No.53 2018 pp.77 96 102 Whole-rock Chemistry for Radial Dike Rocks in the Komochi Volcano, Central Japan: Summary of Analytical Data of 102 Dikes Masaki TAKAHASHI, Seiji KUBO, Naoaki TAKASUGI, Tamotsu