http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Lee, Mi Jung,Lee, Jong Ik,Choe, Won Hie,Park, Chung-Hwa Geochemical Society of Japan] 2008 Geochemical journal Vol.42 No.2
We present Sr-Nd-Pb isotope data from the Paleocene-Eocene volcanic rocks in King George Island, South Shetland Islands, West Antarctica. The initial isotopic ratios of the analyzed samples display limited variations: <SUP>143</SUP>Nd/<SUP>144</SUP>Nd, 0.512790 to 0.512905 ( εNd, +4.2 to +6.5); <SUP>87</SUP>Sr/<SUP>86</SUP>Sr, 0.703342 to 0.703877 (εSr, -15.6 to -8.0); <SUP>204</SUP>Pb/<SUP>206</SUP>Pb, 18.48 to 18.64; <SUP>207</SUP>Pb/<SUP>204</SUP>Pb, 15.50 to 15.64; <SUP>208</SUP>Pb/<SUP>204</SUP>Pb, 37.99 to 38.41. We interpret these data in combination with previously published trace and isotope data for Meso-Cenozoic volcanic rocks in the South Shetland Islands to gain a better understanding of the geochemical evolution of the mantle source region. The studied rocks are from four volcanic islands and range in age from 143 to 44 Ma. They have high abundances of large ion lithophile elements and light rare earth elements relative to high field strength elements, consistent with products of subduction related magmatism. The systematic inter-island variations are recognized from a comprehensive examination of the trace elements and isotopic compositions. The degree of enrichment of Sr-Nd-Pb isotopic compositions decreases towards younger samples, while the ratios of fluid-mobile elements/ HFSE (Sr/Yb, Pb/Yb and U/Yb) gradually increase. The previous studies on these volcanic rocks concluded that the compositional variations of the South Shetland Islands volcanic suites were mainly controlled by two component mixing between altered MORB and Pacific sediments. However, we here propose that the compositional trends observed in the volcanic rocks of the South Shetland Islands can be created from the addition of a relatively constant subduction component to temporally varying heterogeneous mantle sources. The higher radiogenic Pb and Sr isotopes and lower <SUP>143</SUP>Nd/ <SUP>144</SUP>Nd ratios of the older volcanic rocks from Greenwich and Livingston islands compared to younger rocks can be explained by the significant influence of enriched previously metasomatized mantle material rather than fluids or sediment melts from the subducting slab. In contrast, the geochemical nature of the youngest King George Island volcanic rocks suggests a relatively large contribution of a slab-derived fluid component to the magma generation, but a minor role of the enriched component.
Lee, Seung-Gu,Kim, Tong-Kwon,Lee, Jin-Soo,Lee, Tae Jong,Cho, Byong Wook,Koh, Hee Jae Geochemical Society of Japan] 2008 Geochemical journal Vol.42 No.5
The Dongrae thermal water area located at the southeast margin of the Korean Peninsula is one of the oldest hot springs in Korea and has been used in spas since the 9th Century. In this paper, a geochemical significance of <SUP>87</SUP>Sr/<SUP>86</SUP>Sr ratios from deep thermal water, groundwater, surface water and rainwater in the Dongrae area is discussed. The bedrock of this thermal water-bearing aquifer is composed of Mesozoic granitoids. For temperatures up to 71°C, the thermal water is Na-Cl type, whereas shallow cold groundwater is Ca(-Na)-HCO<SUB>3</SUB> type. <SUP>87</SUP>Sr/<SUP>86</SUP>Sr ratios of the thermal water are in the 0.705651 ± 11-0.705696 ± 12 range and have remained nearly unchanged over the past 4 years (2004-2007). <SUP>87</SUP>Sr/<SUP>86</SUP>Sr ratios of the shallow cold groundwater, surface water and rainwater range from 0.705781 ± 26 to 0.705789 ± 12, 0.706700 ± 14 and 0.707375 ± 11 respectively. <SUP>87</SUP>Sr/<SUP>86</SUP>Sr ratios of the thermal water in the Dongrae area are lower than those of groundwater, surface water, rain water as well as aquifer bearing granite. These Sr isotopic signatures indicate that the circulation rate between thermal water and current meteoric water, including groundwater, surface water and rain water in the Dongrae area should be very slow. Therefore, the thermal water might be derived from a high temperature paleogroundwater reservoir rather than from circulation of young meteoric water heated by current heat sources. Our data show that <SUP>87</SUP>Sr/<SUP>86</SUP>Sr ratios may become an important time lag indicator for the groundwater cycle between deep and shallow groundwater in a fractured granite aquifer system.
Chae, Gi-Tak,Yun, Seong-Taek,Kwon, Man-Jae,Kim, Yi-Seop,Mayer, Bernhard Geochemical Society of Japan] 2006 Geochemical journal Vol.40 No.1
<P>We performed batch dissolution experiments on different sized granite and biotite in pure water, in order to better understand the source and geochemical behavior of fluoride in groundwater. Very high concentrations of fluoride (up to 6-10 mg/l) were observed from granite leaching. Correlations between leached ions suggest that fluoride possibly origi-nates from dissolution of biotite. After ~500 hrs, fluoride concentration gradually decreased because of the supersatura-tion with respect to fluorite as a result of the build-up of sufficient Ca ions by dissolution of Ca-bearing plagioclase. Biotite dissolution experiments also showed that the fluoride concentrations are controlled by the attainment of fluorite saturation, which depends on the removal of Ca ion by adsorption and/or cation exchange on the surface of clay minerals. In summary, this study indicates that occurrence and behavior of fluorine in groundwater are mainly controlled by fluorite precipitation as a function of Ca concentration which depends on several geochemical processes such as dissolution of Ca-bearing minerals, calcite precipitation, and adsorption and/or cation exchange.</P>
Jung Lee, Mi,Ik Lee, Jong,Garcia, Daniel,Moutte, Jaques,Terry Williams, C.,Wall, Frances,Kim, Yeadong Geochemical Society of Japan] 2006 Geochemical journal Vol.40 No.1
<P>The phoscorite-carbonatite complex in the Sokli alkaline-carbonatite massif, northern Finland, comprises five stages of intrusions of phoscorites and carbonatites (P1-C1, P2-C2 and P3-C3 for phoscorites and calcite carbonatites;D4 and D5 for dolomite carbonatites). The phoscorites and calcite carbonatites at Sokli usually occur as pairs with the same mineral assemblages. Pyrochlore is found in the majority of rock types in the Sokli phoscorite-carbonatite complex, shows wide compositional variation and seems to preserve evolution trends of host rocks. Crystallization of pyrochlore begins from the P2-C2 phoscorite and calcite carbonatite and continues up to the latest D5 dolomite carbonatite. Pyrochlore in the early stage P2-C2 rocks has high U and Ta contents. These elements suddenly decrease from the P3-C3 rocks, on the other hand, Th and Ce contents increase. The compositions of the late generations from the D4 and D5 rocks are close to that of an ideal end-member pyrochlore with formula <TEX>$(Ca,Na)_2Nb_2O_6$</TEX> F. The Nb/Ta ratio and F content of pyrochlore increase from P2-C2 to the latest D5 dolomite carbonatite. The composition and evolutionary history of pyrochlore from the phoscorites are distinguished from those of the associated calcite carbonatites. Pyrochlore from the calcite carbonatites shows larger A-cation deficiencies compared to those from the paired phoscorites. Ta and Zr contents are slightly higher in pyrochlore from the calcite carbonatites, whereas Ti is generally higher in pyrochlore from the associated phoscorites. Moreover, pyrochlore from the phoscorites always shows a longer and more complex crystallization history compared to that of the same stage carbonatites. This indicates that the chemical condition was clearly different in the two systems during the crystallization of pyrochlore. Based on these results, together with the previous mineralogical and geochemical studies on the Sokli phoscorite-carbonatite complex, we propose a liquid immiscibility process as the most possible seg-regation mechanism of the two associated rocks. The composition of pyrochlore in the late dolomite carbonatites is dis-tinct and always lies on the evolutional trend of the earlier varieties. This implies that the dolomite carbonatites are the final magmatic products of the Sokli phoscorite-carbonatite system.</P>