A rapid and precise routine Pb isotope analytical technique for rock samples was developed using multiple collector inductively coupled plasma mass spectrometry (MC-ICP-MS). The mass discrimination of the Pb isotope ratios was corrected with the ²⁰⁵Tl/²⁰³Tl ratio of a Tl isotope reference material (NIST SRM 997) added to samples. The optimization of the analytical parameters and the minimization of the memory and matrix effects enabled to acquire the Pb isotope data rapidly (three samples per hour) with a reproducibility of 0.01% by consumption of 150 ng Pb per analysis. Repeated analyses of a Pb isotope reference material, NIST SRM 981, gave the average values of ²⁰⁶Pb/²⁰⁴Pb = 16.9308 ± 0.0010, ²⁰⁷Pb/²⁰⁴Pb = 15.4839 ± 0.0011, and ²⁰⁸Pb/²⁰⁴b = 36.6743 ± 0.0030 (2σ).
Pb isotope ratios of eleven Geological Survey of Japan rock reference samples were determined using this technique. In anion-exchange chemical separation, complete removal of Hg and Tl from the Pb fraction was confirmed. It was revealed that the Tl-normalization minimized the matrix effects caused by remaining impurities and medium, and the reproducibility of seven independent analyses of JB-2 was comparable to that of NIST SRM 981. Pb isotope ratios obtained for the rock reference samples showed a good agreement with those given previously.

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The isotopic compositions of Os, Nd, and Sr, as well as major elements of dunites, spinel lherzolites, websterite, and serpentinite from the Nikubuchi ultramafic cumulous complex in the Sambagawa metamorphic belt (SMB) were investigated. The Nikubuchi ultramafic complex is a layered cumulate and is surrounded by a metagabbro massif in the SMB. We obtained a Sm-Nd whole-rock isochron of the Nikubuchi complex with an age of 138 ± 18 (2σ) Ma and an initial ¹⁴³Nd/¹⁴⁴Nd ratio of 0.51270 ± 3. The Nikubuchi complex contains well preserved protogranular textures and cumulous layering structures, and has good correlation coefficients among the major element abundances, which indicate an event before the Sambagawa metamorphism. The ε_Nd values of 138 Ma (+3.5 to +5.3) correspond to the isotope signatures of ocean island basalt (OIB) or island arc basalt (IAB), and not mid-ocean ridge basalt (MORB). Taking the results of previous studies into consideration, the most likely origin of the Nikubuchi complex is that of a fragmented block of residual cumulate formed by the OIB magma chamber. The Rb-Sr isotope system has been disturbed by hydration and/or metamorphism after 138 Ma, and the Re-Os isotope system also has no valid isochron. One of the possible causes is that rhenium addition by hydration has occurred subsequent to 60 Ma. The results of the isotope systems show that hydration can cause disturbance in Re-Os systems but not in Sm-Nd systems. This probably reflects differences between these systems in resistance of the host phase.

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Mesozoic volcanic rocks exposed in the Songliao basin form a major part of the basin fill and are the important petroleum reservoir rocks. Petrogenesis of these volcanic rocks and their tectonic setting, however, are poorly understood due to lack of sufficient chemical and isotopic data. These volcanic rocks cover a wide compositional spectrum ranging from basaltic trachyandesite to high-silica rhyolite. They can be divided into two formations, the upper Jurassic Huoshiling formation (157-146 Ma) with dominant dark gray andesite and the lower Cretaceous Yingcheng formation (136-113 Ma) with dominant yellowish rhyolite. Compositionally, these rocks are peraluminous to metaluminous, high-K to medium-K, calc-alkaline. They are enriched in large-ion lithophile and light rare earth elements, depleted in high field strength and heavy rare earth elements, and commonly display negative anomalies of Nb, Ti and P. Initial ⁸⁷Sr/⁸⁶Sr ratios and initial ε_Nd-values of these volcanic rocks range from 0.7034 to 0.7106 and from -3.4 to 5.3, respectively, and their δ¹⁸O values vary from 3.2‰ to 14.8‰. Initial ²⁰⁶Pb/²⁰⁴Pb and ²⁰⁷Pb/²⁰⁴Pb ratios have ranges of 17.65 to 18.22 and 15.52 to 15.57, respectively. The characteristic in Nd and Sr isotopic composition probably indicates a mixing of enriched MORB-like material and crustal component. Primary magmas for both the Jurassic and Cretaceous volcanic rocks could be derived from metasomatized enriched MORB-like sources, but the Cretaceous rhyolites commonly show crustal assimilation indicated by high initial ⁸⁷Sr/⁸⁶Sr ratios and low initial ε_Nd values. Whether the volcanic rocks in the Songliao basin formed related either to the post-collisional setting of the Mongolia-Okhotsk suture or the subduction of the western Pacific plate remains to be discussed.

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A new experimental method (evaporation method) for calcium carbonate precipitation in aqueous solution was attempted in order to develop a convenient and controllable experimental technique for obtaining precise trace element partition coefficients. Calcite crystals were formed by evaporation of H₂O from the aqueous mother solution using a dehumidifier, and the consumed Ca ions were supplied from a refill solution to maintain supersaturation. This method has been tested for Sr and Ba partition coefficients using NaCl (3.5%) solution under room temperature and pressure. The results of two runs give Sr partition coefficients of 0.0585 and 0.0546, and Ba partition coefficients of 0.0302 and 0.0275 for growth rates of 152 and 499 μmol · m^-2 · hr^-1, respectively. It was found that this method has several merits for partitioning experiments: (1) pH of the solution is close to the natural ones, for example, pH of 8.08 in the present case is close to that of seawater; (2) chemical composition of the mother solution can be chosen to imitate natural composition; (3) the crystal growth rate is controllable in a relatively small range and is measurable; and (4) temperature and P_CO2 pressure can be controlled. The relative errors of the partition coefficients in the present study were estimated to be about 5%. The results seem to be promising, and suggest that more precise determination of partition coefficients could be possible via more careful experimental handling and improving the apparatus.

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Ion microprobe U-Pb dating of apatite is applied to a fossil tooth of a Allosaurid derived from the Hasandong Formation in the Gyeongsang basin, southeastern Korea. Twelve spots on a single fragment of the fossil dentine yield a Tera-Wasserburg concordia intercept age of 115 ± 10 Ma (2σ; MSWD = 0.59) on a ²³⁸U/²⁰⁶Pb-²⁰⁷Pb/²⁰⁶Pb-²⁰⁴Pb/²⁰⁶Pb diagram. The age provides a constraint on the depositional age of the fossil in its host Hasandong Formation as Early Aptian. The success of the ion microprobe dating depends on the heterogeneities of diagenetically incorporated U and Pb at the few hundred μm scale, the consequent variations in Pb isotopic compositions due to radioactive decay and the closed-system behavior of U and Pb. There are at least three end-members to explain the variations of minor chemical components such as FeO, SiO₂ and Al₂O₃, and trace elements such as Th, U and rare earth elements (REE) in the sample by a simple mixing model. They are (1) very low minor and REE, very high common Pb with variable U abundances, (2) low common Pb, high minor, REE, and U abundances, and (3) low minor, common Pb, and U with intermediate REE abundances, even though groups (2) and (3) may consist of a larger group. Various contributions of the three (and/or two) end-members during diagenetic prosesses may cause the elemental fractionation of U and Pb in a fossil tooth.

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Mesozoic mafic dikes are widely distributed in Luxi (Mengyin and Zichuan) and Jiaodong regions of the Shandong Peninsula, China, providing an opportunity of investigating the nature of the lost lithospheric mantle beneath the North China Craton (NCC). The mafic dikes are characterized by strong depletion in high field strength elements (HFSE), enrichment in light rare earth elements (LREE), highly variable Th/U ratios, high initial (⁸⁷Sr/⁸⁶Sr)_i (0.7050-0.7099) and negative ε_Nd(T) (-6.0 to -17.6). They were derived from melting of metasomatized portions of the subcontinental lithospheric mantle, followed by fractionation of clinopyroxenes. The similarity in Nd isotopic compositions between the Mengyin gabbro dikes and the Paleozoic peridotite xenoliths suggests that ancient lithospheric mantle was still retained at 120 Ma below Mengyin, although the ancient lithospheric mantle in many other places beneath NCC had been severely modified. There might be multiple enrichment events in the lithospheric mantle. An early-stage (before or during Paleozoic) rutile-rich metasomatism affected the lithospheric mantle below Mengyin, Jiaodong and Zichuan. Since then, the lithospheric mantle beneath Mengyin was isolated. A late-stage metasomatism by silicate melts modified the lithospheric mantle beneath Jiaodong and Zichuan but not Mengyin. The removal of the enriched lithospheric mantle and the generation of the mafic dikes may be mainly related to the convective overturn accompanying Jurassic-Cretaceous subduction of the paleo-Pacific plate.

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The Triassic to Lowermost Jurassic mudrocks from continental redbeds of the Longi-Taormina Unit (Calabria-Peloritani Arc; southern Italy) have been mineralogically, chemically and petrographically analyzed, in order to reveal their complex history, which record an important phase of the geological evolution of the Mediterranean area.
The Late Triassic corresponds with a low first-order sea level stand and a time of high continental emergence whereas the Early Jurassic was the time of the initiation of the first-order sea level rise in the mid-Mesozoic, generally marked by a transgressive trend.
The mineralogical assemblage, dominated by the occurrence of illite and illite/smectite mixed layers, coupled to the CIA index and to the A-CN-K plot, indicates post-depositional K-enrichments.
Palaeoweathering indices (CIW and PIA ratios) suggest that the source experienced intense weathering and that they likely record a recycling effect from their metasedimentary basement rocks. A recycling effect is also suggested by the distribution of Al₂O₃, TiO₂, and Zr. In the Zr/Sc vs. the Th/Sc plot the redbeds are not clustered along the primary compositional trend but fall along a trend involving zircon addition and thus sediment recycling. Recycling could significantly affect the weathering indices which likely monitor a cumulative effect including a first cycle of weathering at the source rocks. Weathering occurred under hot, episodically humid climate with a prolonged dry season. Wet-humid conditions favored the formation of stream channels that eroded the soil profiles, whereas the dry season promoted the sedimentation. The climate alternation in the Early Jurassic favored recycling.
An additional provenance terrane occurring in the basement, including metavolcanic rocks having mafic composition cannot be excluded, since the Eu anomaly is slightly higher than the PAAS value. Although the effects of recycling on REE distribution are uncertain, the Eu/Eu^* should increase, as more feldspar is destroyed during weathering and diagenesis. This involves that the Eu/Eu^* ratio could monitor a supply of low Eu/Eu^* mafic detritus which compensate for the recycling effect by reducing Eu/Eu^*. Eu released during the dissolution of feldspar could be retained by clay minerals contributing to minimize the recycling induced increase of the Eu-anomaly. This may involve that the recycling effect on the Eu-anomaly was minor and that the low Eu/Eu^* mafic detritus supply was also minor. The subordinate importance of a mafic supply is confirmed also by other provenance proxies including the La-Th-Sc plot and the Cr/V and Y/Ni ratios.
The proportions of illitic layers in I/S mixed layers coupled with the illite crystallinity values, expressed as Kübler Index (KI), suggesting an estimated temperature experienced by the Longi Units in the range of 100-150°C. Starting from this range the diagenetic/tectonic evolution should correspond to a lithostatic/tectonic loading of about 4-5 km.

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The Qinghai-Tibet Plateau has developed immature soils since the late Pliocene period when it was uplifted. The objectives of this paper were (i) to investigate native major and trace elements of the immature soils in the Kekexili region in the Plateau; (ii) to evaluate the bioavailability of selected trace elements in the soils; (iii) to better understand the factors affecting accumulation and depletion of the elements and their bioavailability over a long history of alto-cryic pedogenesis. Cambosols and Aridosols are dominant soil types in this region while Gleyosols and Primosols are minor types. These coarse-textured soils have high soil pH and free carbonate content. The soil profile often developed a mattic or humic epipedon with high organic matter content in the topsoil. The contents of Ca, Mg, Na, and Sr in the Kekexili soils were significantly higher than the average values of Chinese soils, and also the world average, while the contents of Fe, Al, Ti, Mn, P, Co, Cr, and Ba in the former soils lower than those in the latter soils. The accumulation or depletion of elements was mainly dependent on soil carbonate content. The bioavailability of Fe, Zn, and Mn was positively related to the levels of organic matter in the surface soil. Results indicate that though these soils had a long history of pedogenesis, they were still relatively immature due to weak geochemical cycles but the bioavailability of nutrients in topsoil was high.

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