Naturally accumulated doses after pottery manufacture were compared between optically stimulated luminescence (OSL) from quartz grains and infrared-stimulated luminescence (IRSL) from feldspar grains, together with a red-thermoluminescence (RTL) result from quartz grains. Quartz and feldspar extracts from nine Jomon pottery pieces, which were manufactured and used 3,500-6,000 years ago, were subjected to three kinds of luminescence measurements using a new automated luminescence measuring system. Since this system included a small X-ray irradiator, a single-aliquot regenerative-dose (SAR) protocol was applicable to each luminescence dosimetry. Naturally accumulated doses from RTL were higher than OSL- and IRSL-dose results. This is probably due to relatively easy-bleaching effects or unstable luminescence properties related to the OSL in quartz grains and well-known anomalous fading effects of feldspar grains. On the basis of these results, the RTL-luminescence ages, estimated using the accumulated doses and annual doses, are closer to the predicted archaeological ages. In conclusion, it was also confirmed here that the RTL-dating is most suitable dating-method when quartz extracts from burnt archaeological materials are available.

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A geochemical study was carried out on Eocene-Lower Oligocene sedimentary rocks (the Mirador Formation) from the southern Lake Maracaibo Basin, western Venezuela. The goal of this work was the identification of source rock composition and tectonic settings of source areas, and their temporal changes. The geochemistry was also used to investigate attributes of the paleoenvironment. Eighty-nine rock samples were collected and the bulk inorganic geochemistry (Al₂O₃, SiO₂, TiO₂, Fe₂O₃, MnO, CaO, MgO, K₂O, Li, B, Sc, V, Cr, Ni, Zn, Rb, Y, Mo, La, Ce and Th) was determined by ICP-AES; total sulfur was determined in a LECO SC-432 analyzer. Multivariate statistical tools were employed to evaluate the correlation between the different variables. Through cluster-constrained analysis, four subdivisions, or main chemofacies, were defined and correlated with the significant lithologic units. The tectonic setting for the source rock could be a passive margin, and a mixed source was inferred, consisting of recycled sedimentary rocks and igneous and/or meta-igneous rocks of predominantly felsic composition. The most marine-influenced lithological units occur at the bottom of the section.

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The Mugeuk mine was historically the largest gold-silver producer in South Korea, and yielded more than ten metric tons of gold from ores with an average grade of about 8 g/ton Au and Au/Ag ratios near 1:5. Ore deposits consist of >10 subparallel quartz-calcite veins (typically 0.6 to 1.0 m wide) that fill faults and fractures in Jurassic granodiorite and Cretaceous quartz porphyry. Veins formed during six successive hydrothermal events of Late Cretaceous age. Ore mineralogy of the veins is complex, consisting mainly of pyrite and base-metal sulfides with electrum (23-51 atom. % Au), native silver, argentite and silver sulfosalts (polybasite, pyrargyrite). Stage I veins contain no gold and silver (e.g., barren). During stages II to V, economic quantities of gold and silver were precipitated. Stages III and IV represent the culmination of gold precipitation in distinct sulfide bands, whereas stage V represents a shift to dominantly silver deposition. Stage VI veins are barren post-ore quartz-calcite-fluorite. A variety of types of geochemical data indicate that deposition of gold and silver resulted mainly from cooling of ore fluids, accompanying successive incursions of meteoric water into the hydrothermal system. Fluid inclusion data show general decreases of temperature and salinity within each stage. Ore mineral assemblages indicate decreases in the fugacity of sulfur with decreasing temperatures during the deposition of gold and silver. Measured and calculated δ¹⁸O values of hydrothermal fluids decrease generally from +3.0 to -7.4‰ from stages II through VI, and δD values range from -66 to -84‰. The Au-Ag deposits at Mugeuk, in particular their mineralogy, Au/Ag ratios and fluid geochemistry, are the result of episodic meteoric water events within the granite-hosted hydrothermal system. Early stages of the hydrothermal history involved successive introduction of new pulses of meteoric ore fluids, each of which equilibrated with the host granitic rocks at successively higher water-to-rock ratios and lower temperatures during deposition of gold-silver mineralization. Later stages were the result of inundation of the hydrothermal system by isotopically unevolved meteoric waters, resulting in a silver-rich overprint on the earlier gold-silver system.

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The volcanic history of the Shimabara Peninsula, Kyushu, Japan, is divided into two stages; Pre-Unzen volcano stage (4 Ma-500 ka) and Unzen volcano stage (500 ka-present). Pre-Unzen volcanic rocks comprise olivine basalt and two-pyroxene andesite lava flows and pyroclastics. The similarity of trace elements chemistry indicates that Pre-Unzen basalts evolved from different primary magmas originated in the same mantle source. They were differentiated by olivine-dominant fractional crystallization and crustal assimilation. This process produced parental magmas for Pre-Unzen andesite. The evolution of Pre-Unzen andesites can be explained by the combination of plagioclase + pyroxenes + magnetite fractional crystallization and crustal assimilation. Unzen volcanic rocks are composed of hornblende andesite to dacite lava domes, lava flows and pyroclastics. They have petrographical and geochemical features indicating that they were produced by magma mixing. Mafic inclusions are commonly included in Unzen volcanic rocks and show evidence of hybridization between aphyric basalt and phenocryst-rich dacite magma in various ratios. The existence of mafic inclusions with positive Nb anomalies in spidergram indicates an injection of ocean-island type basaltic magmas. The estimated mafic endmember for the dacite magma is an evolved basalt with MgO = 5.5 wt.%. This corresponds to the most evolved composition of the Pre-Unzen basalt and suggests continuous basaltic magma plumbing system throughout the eruptive history of the Shimabara peninsula.

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Dynamics and optical nature of fluorescent dissolved organic matter (FDOM) were investigated in two rivers (Kurose and Ohta) in Hiroshima prefecture, Japan during 2002-2003, by measuring dissolved organic carbon (DOC) and three-dimensional excitation emission matrix fluorescence (3-D EEM). In monthly collected samples, DOC varied from 43 to 146 μM C at upstream sites in both rivers, and from 130 to 349 μM C and from 45 to 164 μM C in Kurose and Ohta downstream, respectively. The 3-D EEM of FDOM in the river waters identified three characteristic peaks, indicating the occurrence of fulvic acids (peak F), fluorescent whitening agents (peak W), and protein-like substances (peak T). The upstream FDOM in the both river waters and the downstream FDOM in the Ohta river contained the peaks F and T, identified by comparing with that of the Suwannee River Fulvic Acid (SRFA) and tryptophan and their photo-irradiated standards. The 3-D EEM of FDOM in Kurose downstream waters, however, contained the peaks W and T. The ratio of fluorescence intensity for peak F or W to DOC (FI/DOC-index) was estimated to be high (2.00 ± 0.51 to 2.09 ± 0.38 QSU (quinine sulphate unit)/μM C) at Kurose downstream compared to Ohta rivers (0.73 ± 0.35 to 0.74 ± 0.38 QSU/μM C) and to the Kurose River upstream (0.55 ± 0.22 to 0.65 ± 0.21 QSU/μM C), and the absolute FI values were several times higher in Kurose downstream waters than Kurose upstream and Ohta river waters. Moreover, the studies on the photo irradiation experiments of the standard FDOMs indicated that the peak W is easily photo-decomposed while the peak F appears to be photo-resistant. These results indicate that the chemical properties of FDOM in the Kurose downstream waters are different from those in the Kurose upstream and Ohta river waters.

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The water chemistry data obtained from a sandy aquifer in the Trout Lake basin of northern Wisconsin, USA were reinvestigated in order to explain the chemical behavior of sodium concentration in groundwater. Monovalent cations such as sodium and potassium dissolved in groundwater generally remain within narrow concentration ranges. In contrast, calcium and magnesium concentrations show continuously increasing trends due to continuous weathering of aquifer materials, of which reactive minerals are dominated by sodic plagioclase. The similar trend observed in groundwaters contaminated with NaCl-deicer suggests that this unusual chemical behavior of monovalent cation is caused by cation exchange reactions. In other words, when Na ions are introduced into the groundwater system, only a minor fraction of the Na ion (~5%) partitions into the aqueous phase, whereas the majority replaces divalent cations adsorbed on the exchangeable sites of the sediments. However, the cation exchange capacity (CEC) measured for the sandy sediment (~4 meq/kg) is insufficient to cause the observed consistent Na concentration under a batch condition (stagnant groundwater with no molecular diffusion) of cation exchange. Results of transportive exchange calculations suggest that Na concentration can be effectively "buffered" as the NaCl-contaminated groundwater flows even when the CEC was very low (1 meq/kg) because flowing groundwater can interact with more cation exchange sites than that under stagnant conditions. It is also suggested that the buffering of Na concentration due to cation exchange can partly explain the "Ca-excess problem" that has been noted previously in the study area.

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Some practical aspects of a closed n-pentane trap used for separation of SO₂ from CO₂ and vice versa for precise δ¹⁸O and δ³⁴S measurements are described. It is a cold finger sealed inside a large-diameter glass tube that is filled with n-pentane. This trap has several advantages (1) complete separation of the two gases within a few of minutes, (2) no fire risk because the inflammable pentane is present in a closed system, (3) low cost because the pentane in the trap will never evaporate, and (4) ease of use.

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In order to obtain precise rare earth element (REE) compositions of sedimentary reference rocks issued by the Geological Survey of Japan (JSd-1, -2, JSl-1, -2, JLk-1), we analyzed their REEs by inductively-coupled plasma mass spectrometry (ICP-MS) using methods employing both acid digestion (HF-HClO₄) and carbonate fusion (Na₂CO₃-H₃BO₃). Analytical precision of these methods was estimated by analyzing JB-1a and BCR-1 with the same procedure. Analyses of these two reference rocks show good reproducibility and close agreement with compilation values, except for Ho in JB-1a and Tm in BCR-1. CI-normalized REE patterns of JB-1a and BCR-1 compilation values show deviations for Ho and Tm, respectively, from the smooth patterns. Therefore, the compilation values of those elements may be somewhat in error. After acid digestion of JSd-1, -2, JSl-1, -2 and JLk-1, 2-40% of total REEs were remained in the residues, i.e., secondary fluorides and/or undigested minerals. However, subsequent carbonate fusion effectively recovered the remained REEs. Analytical results by this study show relatively good agreement with compilation values, except for Pr, Ho, Er and Tm, and smooth REE patterns normalized to CI-chondrite. The REE patterns of compilation values show anomalous deviations of Pr, Ho Er, and Tm, suggesting that compilation values of these elements may be in errorneous. This study emphasizes that combined method of acid digestion and alkali fusion is an effective method for recovering REEs in sedimentary rocks for bulk REE determination.

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Wrong:See PDF attached
Right:See PDF attached

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