In the Lahaul-Spiti region of Himachal Pradesh two meta-granite bodies (Jispa granite and Ratilaman granite) emplaced in the low grade Haimanta Formation which is tectonically overlying the Central Crystallines. Field, petrographical and geochemical features of these meta-granites are compared with the orthogneisses of the Central Crystallines. Geochemical signatures of these meta-granites and orthogneisses suggest that they are products of peraluminous melt generated by partial melting of older crustal rock, with high A/CNK values and higher normative corundum. Decrease in Fe₂O₃, MgO, CaO, TiO₂, Sr and Zr and enhancement in K₂O, SiO₂ and Rb as well as Rb/Sr ratios from melanocratic (margin) to leucocratic (core) portion of these bodies indicate that they are consistent with fractional crystallization processes. Decrease of total REE, moderate LREE/HREE ratios and more pronounced negative Eu anomalies are also in accord with fractional crystallization. The heat source for these lower Paleozoic granite magmas may be due to the lithospheric extension which resulted in mantle melting beneath the crust which led to anomalous heat flow, and triggered crustal melting. Felsic magmas thus produced have intruded into shallow crustal levels.

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The source characteristics and magmatic evolution history of granitic rocks in the central Ogcheon Belt, Korea, were investigated based upon Sr-Nd-Pb isotope systematics. The granitic rocks are divided into three types; the Permian to Triassic granites distributed near the Boeun area (PTG), the Daebo granitic batholith (DBG), and Cretaceous Sogrisan Granite (SOGR). Well fitted Rb-Sr whole rock isochrons of the PTG yield geologically significant ages (256 Ma for the Baegrock Granodiorite (BRGD), 230 Ma for the Boeun Granite (BOGR), and 216 Ma for the Chungsan Granite (CHGR)). Rb-Sr isotope data of the DBG do not form isochrons of geologically reasonable ages, suggesting that the batholith was formed by discrete magmatic events. Variation of initial Sr and Nd isotope ratios in the PTG can be explained by a simultaneous assimilation and fractional crystallization (AFC) model. The BRGD has the most primitive Sr-Nd-Pb isotopic signature among the PTG. Based on mass balance calculation, the relatively high but strongly negative ε_Nd(t) of the BRGD is difficult to explain by an interaction of mantle-derived melt with crustal materials. Field observation and low initial ⁸⁷Sr/⁸⁶Sr ratios of the BRGD contradict the possibility of its derivation exclusively from the upper crustal source region. The isotopic signature of the BRGD is taken to be largely inherited from the continental lower crust. Primitive BRGD samples have relatively higher ε_Nd(t) values than the other granites, indicating that the crustal formation age of the lower crust is younger than that of the upper crust. Less radiogenic Sr and Pb isotope ratios of the BRGD indicate that Rb, U, and Th (and other large ion lithophile elements ?) depletion has been maintained in the lower crust for a geologically long time. ε_Nd(t) values of the DBG are strongly related to their locality, indicating local heterogeneity in the source region. Inconsistent variation of the DBG in ε_Nd(t) vs. ε_Sr(t) plot precludes a mixing model between primitive melt and upper crustal materials. Relatively constant ε_Nd(t) and variable ε_sr(t) of the SOGR reflects the effect of simultaneous assimilation and fractional crystallization of feldspars. Ranges of initial Sr, Nd and Pb isotopic compositions of the SOGR are quite similar to those of the other, older granites, which implies a similarity of source materials between them.

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Analcime is common in magmatic rocks of the alkaline basalt-phonotephrite-phonolite suite of the Mecsek Mts., Hungary. Besides the occurrence of xenomorphic groundmass analcime, wedge-shaped crystals between feldspars, and products of feldspar and nepheline alteration, analcime also occurs in calcite ocelli formed in basaltic dikes. Microscopic textures of these ocelli are characteristic of rapidly crystallized carbonate melt, suggesting that the ocelli are droplets of carbonate-rich melt separated from the silicate magma by liquid immiscibility. This carbonate would have crystallized below magmatic temperatures, and above hydrothermal ones. Thus, the analcime might be regarded as transitional between primary magmatic (P type) and hydrothermal (H type) analcimes. SEM studies reveal that the analcimes of the ocelli form euhedral crystals whose surfaces are smooth without signs of the porous texture characteristic for products of leucite alteration. Chemical compositions determined by electron microprobe are close to the theoretical NaAlSi₂O₆·H₂O formula, with minor Ca substitution. X_Si values (0.642 to 0.686) fall between the ranges of analcimes considered to be of primary magmatic and hydrothermal origins, whereas the low Fe contents indicate relationships with H type ones. Oxygen isotope compositions of silicate minerals in lavas and dikes and calcite ocelli in dikes have been determined in order to investigate the preservation of magmatic compositions, and the effect of low-temperature isotope exchange. The most positive δ¹⁸O values among the studied mineral separates were found in the analcimes (17.5 to 19.0‰). Based on comparisons with oxygen isotope compositions of calcites of the ocelli (13.0 to 13.3‰) and amphiboles (7.4‰) of their host rock, this ¹⁸O-enrichment could be a result of retrograde oxygen isotope exchange with magmatic fluids at decreasing temperatures. Effects of low-temperature isotope exchange appear also in the amphiboles, biotites and feldspars of the Mecsek series, resulting in increasingly more positive δ¹⁸O ranges (5.1 to 7.4‰, 7.2 to 7.4‰, and 7.6 to 15.0‰, respectively) as a function of sensitivity to retrograde isotope exchange. Primary magmatic compositions have been preserved in pyroxenes (6.0 to 6.5‰), indicating generation of basaltic melt by low degree partial melting of mantle peridotite.

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Radon concentrations measured from July 1990 to January 1993 at Gyokusen-do limestone cave on Okinawa vary from 10 to 3000 Bq/m³ and show significant and consistent seasonal variations, higher in summer and lower in winter. Concentration variations are controlled mainly by the exchange of air between external and internal cave air. During winter inblowing external cold air with a large density exchanges with cave air and dilutes the radon. In the summer, when the external air is relatively warmer than the cave air, the cold cave air stagnates and radon accumulates.

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Water solubilities in albite (Ab)-orthoclase (Or) join and JR-1 rhyolite melts at 1000°C and up to 2000 bars were determined by the “excess of water” method using an internally heated pressure vessel (IHPV) with rapid quenching and a secondary ion microprobe mass spectrometer (SIMS). We have found that secondary hydration of run product glass with coexisting aqueous fluid occurs during quenching. The hydration is significant in sodium-rich glass. The bulk analysis of such secondary hydrated run-products will cause overestimation of the water solubility, while the true water solubility can be obtained by micro-analysis on non-attacked portion of the glass. The apparent compositional dependence in the published water solubility data could be due to the secondary hydration of run product glass. Newly determined water solubility for the Ab-Or join and rhyolite melts is expressed as H₂O (mol%) = 0.19 √P_H2O (bar), at 1000°C.

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