Abstract-More than 140 thermal waters of Japan were studied isotopically and chemi cally. Highly saline brines at Arima and Takarazuka, Hyogo-Ken, and Ishibotoke near Osaka indicate wide ranges of 5180 and 51) values from meteoric values of 5`0 = -8.2 and SD = -50.0 %o SMOW to highly shifted values of +6.5 and -27.8 %o, respectively. The isotopic values of these brines vary proportionally with chloride concentration irrespec tive of temperature, carbonate concentration or locality. These saline waters are iso topically and chemically best explained as the mixtures of local meteoric waters and a saline brine of C 1 = 43,700 ppm, 5180 = +8 %o and 8D = -30 to -25 %o. The latter is most likely the "residual magmatic, metamorphic or geothermal" fluid associated with upper Cretaceous rhyolitic and granitic rocks and Ryoke metamorphic rocks in which these brines are found. Thermal waters at Ikeda and in adjacent areas, Shimane-Ken and at Senami, Niigata-Ken, are similar to the Arima brines in the isotopic and major element chemistry, but are much more diluted by the respective local meteoric waters.Many of the thermal waters along the ocean coasts are isotopically intermediate between oceanic and local meteoric waters and are considered to be mixtures of the two types of water. As a result of hydrothermal mineral-sea water interaction, the coastal thermal waters differ considerably in the chemistry from fresh sea water and are typical of Na-Ca-Cl type. The coastal thermal waters isotopically and chemically may be similar, if not the same, to submarine hydrothermal ore fluids responsible for the Kuroko type mineralization. The isotopic values and their relationship to salinity, however, widely differ from one system to another depending on the hydrogeological conditions of each system. The coastal thermal waters at Ibusuki of Ata Caldera, Kagoshima-Ken, for instance, are significantly affected by the waters from three crater lakes, Lake Ikeda, Unagi-Ike and Kagami-Ike, in which the 5180 and 6D values are meteorologically balanced at such high values as -2.6 and -19.4%o, respectively. Many thermal waters of neutral chloride type in the "green tuff" regions of the inner Honshu also are simple meteoric in origin without showing any significant isotopic shifts, although the waters are relatively high in salinity and SO4/Cl ratios. INTRODUCTIONMost of the thermal spring systems in Japan are closely associated with Tertiary to Recent volcanic and plutonic rocks. Most of the springs are in the "green tuff regions that contain Miocene geosynclinal sediments with abundant submarine pyro clastic rocks and lava flows (Fig. 1). The "green tuffs" also are the host rocks for many "Kuroko" ore deposits . Chemical and geological evidence led many Japanese investigators (e.g. NAKAMURA, 1962; UZUMASA, 1965; YUHARA and SENO, 1969) to believe that the waters and dissolved chemical species of Japanese thermal water systems originate from at least three major sources, that is, volanic, oceanic (present-day), and fossil or connate, the last...

Morimotoite, Ca3TiFe2+Si3012, has been found in contaminated rocks which are considered to be a kind of endoskarn at Fuka, Bitchu-Cho, Okayama Prefecture, Japan. Morimotoite is derived from andradite, Ca3Fe3 § by the substitution Ti + Fe z+ = 2Fe 3 § It is associated with calcite, vesuvianite, grossular, wollastonite, hematite, prehnite, fluorapatite, perovskite, zircon, baddeleyite and calzirtite. It is cubic with space group Ia3d. The unit cell dimension a is 12.162(3) A. Its refractive index n is 1.995(2) and the density 3.75(2) g cm -3 (meas.), 3.80 g cm -3 (calc.). The Mohs' hardness is 7.5. Calculation of the analytical data on the basis of twelve oxygen atoms and eight cations shows that this mineral has a simplified chemical formula Ca3 (Ti,FeZ §247247 where Ti > Fe 2+ > 0.5. Morimotoite was synthesized at low oxygen fugacities, 650 and 700~ and 1 kbar total pressure.

No abstract

Kornerupine, (A, Mg, Fe)(Al, Mg, Fe) 9 (Si, Al, B) 5 O 21 (OH, F), is known from only five mafic or ultramafic settings worldwide (of the .70 localities overall). We report a sixth occurrence from Akarui Point in the Lützow-Holm Complex, East Antarctica, where two ruby corundum (0.22-0.34 wt% Cr 2 O 3 )-plagioclase lenses are found at the same structural level as boudinaged ultrabasic rocks in hornblende gneiss and amphibolite. Ion microprobe analyses of kornerupine give 13-59 ppm Be, 181-302 ppm Li, and 5466-6812 ppm B, corresponding to 0.38-0.47 B per 21.5 O; associated sapphirine also contains B (588-889 ppm). Peak metamorphic conditions are estimated to be 770-790 8C and 7.7-9.8 kbar. Kornerupine encloses tourmaline and plagioclase, which suggests the prograde reaction tourmaline (1) þ plagioclase (.An34) þ sapphirine + spinel ! kornerupine þ corundum (ruby) þ plagioclase (,An82) + (fluid or melt). Alternatively, kornerupine and tourmaline could have formed sequentially under nearly constant P-T conditions during the infiltration of fluid that was originally B-bearing, but then progressively lost Na (or gained Ca) and B through reaction with mafic rocks. Kornerupine later reacted with H 2 O-CO 2 fluid in cracks at P-T conditions in the andalusite stability field: kornerupine þ plagioclase þ (Na, K, + Si in fluid) ! tourmaline þ biotite þ corundum (sapphire) + magnesite + andalusite þ (Ca in fluid). Secondary tourmaline differs from the included tourmaline in containing less Ti and having a higher Na/(Na þ Ca þ K) ratio. There are two possible scenarios for introducing B into the lenses: (1) infiltration of boron-bearing aqueous fluids released by prograde breakdown of muscovite in associated metasedimentary rocks; (2) hydrothermal alteration of mafic and ultramafic rocks by seawater prior to peak metamorphism. The latter scenario is consistent with an earlier suggestion that Akarui Point could be part of an ophiolite complex developed between the Yamato-Belgica and Rayner complexes.

Nifontovite and olshanskyite, two rare hydrous calcium borate minerals, have been found in crystalline limestone near gehlenite-spurrite skarns at Fuka, Okayama Prefecture. Nifontovite occurs as aggregates of tabular crystals up to 5 cm long and 1.5 cm wide, and rarely as enhedral crystals up to 1 mm long. Olshanskyite occurs as anhedral masses, or as micro-twinned platy crystals up to 1 cm long. Wet chemical analyses give the empirical formulae Caa.052Bs.991Ot.03s(OH)Iz'l.96H20 and Ca2.sssB3.997(OH)ls on the basis of O = 20 for nifontovite and OH=18 for olshanskyite, respectively. The formulae are consistent with those from type localities.The X-ray powder data for these minerals were determined with accuracy. The unit cell parameters of nifontovite agree closely with those published previously. X-ray studies show that olshanslodite is triclinic with the possible space group P! or P1 and a = 9.991(5), b = 14.740(11), c = 7.975(3) A, 0c = 94.53(4), [3 = 69.08(3), y = 112.44(5) and Z = 3. The density 2.19 g cm -~ (meas.) obtained for olshanskyite agrees with the estimated ideal value 2.31 gcm -3 (calc.). Nifontovite was formed by hydrothermal alteration of an anhydrous borate, and olshanskyite was formed by hydrothermal alteration of nifontovite and the anhydrous borate.