A geochemical survey on thermal waters discharging in the Beas and Parvati valleys (Kulu District, Himachal Pradesh) and in the Sohna town (Gurgaon District, Haryana) was carried out in March 2002. The Beas and Parvati area is characterized by regional seismogenetic fault segments, thrusts and complex folded structures where deep fluid circulation occurs. Thermal springs have temperatures varying between 35°C and 89°C. The wide range of surface temperatures and water chemistries suggest the mixing, at various degrees, between a deep saline end-member and a shallow freshwater. Based on the high salinity and the enrichment in halogens (Cl, Br), B and Li, the contribution of the deeper end-member seems to be larger for Kulu and Kalath relative to Manikaran and Kasol. Moreover, a large input of crustal volatiles (He, CO₂, H₂) is observed for Kulu and Kalath waters. The high dissolved CO₂ content and its carbon isotopic composition (δ¹³C_TDIC = -2.87 and -7.49‰ vs. PDB for Kulu and Kalath, respectively) point to a deep, prevalent thermo-metamorphic provenance of the carbon dioxide. A general shallow (i.e., organic) origin of carbon dioxide is suggested for Kasol and Manikaran. The estimated deep temperatures based on the quartz geothermometer provide values ranging between 93-114°C for all the thermal waters of the Beas and Parvati valleys. The Sohna thermal spring emerges at 42°C from joints of the seismogenetic Sohna fault. A Na-Cl-HCO₃ composition characterizes this water with very low contents of all the selected minor and trace elements. High dissolved helium content points to a prolonged deep circulation, whereas calculated δ¹³C-CO₂ (-14.23‰ vs. PDB) is indicative of the general shallow origin of carbon dioxide. The estimated deep temperatures are close to the discharge ones, not providing any valuable information about the temperature of the deeper reservoir.

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The Songpan-Ganzi triangular tectonic block is surrounded by the East Kunlun-Qaidam block in the north, the Qiangtang block in the southwest, and the Longmen Shan in the southeast. The Longmen Shan is the eastern margin of the Tibetan Plateau in Central Asia. The tectonic affinity and relationship of these regions with the Yangtze and North China blocks have been rigorously debated. In this paper, we present our recent studies on the geochemistry of the Precambrian to Triassic clastic sedimentary rocks from this area. Detrital zircons were extracted from the sedimentary rocks for U-Pb dating by SHRIMP and LA-ICP-MS. Nd depleted mantle model ages indicate that these provenances have an affinity to the Yangtze craton and Qinling Shan, in contrast to those of the North China craton. All strata, from Cambrian to late Triassic, contain detrital zircon U-Pb ages of 1400 to 600 Ma, with most falling between 900-720 Ma. The Songpan-Ganzi block was the most important part of the Northern Tethys in the Triassic period, in addition to being the largest flysch basin in the world. The Longmen Shan thrust belt comprises both the telescoped, unmetamorphosed, shallow water carbonate-dominated passive margin of the Yangtze craton and its crystalline basement. The western and northern margins of the Yangtze craton, as well as the Qinling Shan, were the sources of sediments in the Songpan-Ganzi block and the Longmen Shan. The oldest dated detrital zircons indicate that the Yangtze craton started forming during the period 2800-2200 Ma. Because the basement of the Yangtze craton experienced multi-episodic intracrustal processes, the oldest basement components account for only a small portion of the provenance components. The detrital zircon ages of 2200-1400 Ma indicate a major contribution of the Qinling Shan and/or the northwestern margin of the Yangtze craton to the clastic sediments in the Songpan-Ganzi block. The presence of detrital zircon of Neoproterozoic to Triassic ages suggests derivation from the Qinling Shan and the western and northern margin of the Yangtze craton. Triassic tectonic movement during this time was at its most intensive and extensive, and led to exhumation of basement in the Yangtze craton and Qinling Shan, along with nascent crustal components and their erosion to the East Tethys.

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At the border between China and Vietnam, a deformed and metamorphosed dome (the Laojunshan-Song Chay Dome) developed at the western prong of the “Caledonian” South China Granitic Fold Belt, north of the Red River fault zone. The main section of the dome, in China, is called the Laojunshan Metamorphic Core Complex. Systematic SHRIMP zircon U-Pb dating has been undertaken on these Caledonian Granites for the first time. The ages of the Nanlao Gneisses (DN4015B), and granites of the Tuantian (LJS-2), Laochengpo (LJS-3) and Nanjiahe (DN4058) Units, are 435.7 ± 6.4, 442.2 ± 8.3, 437.9 ± 9.5 and 418 ± 5.8 Ma respectively. These ages indicate an extended period of igneous activity (ca. 24 million years) that can be divided into two episodes (at ca. 440 and 420 Ma) representing the ages of syn-collisional and post-collisional/late-orogenic granitoid plutons respectively. Inherited zircon with ²⁰⁶Pb/²³⁸U ages of 710 ± 22, 1051 ± 24 and 1657 ± 48 Ma is also present in these samples. The Neoproterozoic zircon might record igneous activity related to the break-up of the Rodinia Supercontinent. Lithogeochemistry results show that most of these rocks are “fractioned” S-type granites related to the Caledonian syn-collisional orogeny. A few of them have affinities to I-type granites produced by partial melting of intermediate-mafic rocks in the upper crust. Based on the geochronology and geochemical data, the inferred provenance and tectonic setting of the granites, and research on geotectonics and regional geology, the granites are interpreted as the products of the Caledonian collision between the Cathaysia and Yangtze blocks, and the fault zones along Shizong-Mile-Luoping-Xingyi-Wangmo-Luodian are proposed to be the southwestern boundary between those two blocks.

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Strontium (Sr) and neodymium (Nd) isotopic compositions enable identification of dust sources and reconstruction of atmospheric dispersal pathways. The Sr and Nd isotopic compositions in eolian dust change systematically with grain size in ways not yet fully understood. This study demonstrates the grain size effect on the Sr and Nd isotopic compositions in loess and 2006 dust fall, based on analyses of seven separated grain size fractions. The analytical results indicate that Sr isotopic ratios strongly depend on the grain size fractions in samples from all types of eolian dust. In contrast, the Nd isotopic ratios exhibit little variation in loess, although they vary significantly with grain size in samples from a 2006 dust fall. Furthermore, Nd model ages tend to increase with increasing grain size in samples from all types of eolian dust. Comparatively, Sr isotopic compositions exhibit high sensitively to wind sorting, while Nd isotopic compositions show greater sensitively to dust origin. The principal cause for the different patterns of Sr and Nd isotopic composition variability with grain size appears related to the different geochemical behaviors between rubidium (Rb) and Sr, and the similar geochemical behaviors between samarium (Sm) and Nd. The Nd isotope data indicate that the various grain size fractions in loess have similar origins for each sample. In contrast, various provenance components may separate into different grain size fractions for the studied 2006 dust fall. The Sr and Nd isotope compositions further confirm that the 2006 dust fall and Pleistocene loess in Beijing have different sources. The loess deposits found in Beijing and those found on the Chinese Loess Plateau also derive from different sources. Variations between Sr and Nd isotopic compositions and Nd model ages with grain size need to be considered when directly comparing analyses of eolian dust of different grain size.

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An analytical technique for determining boron, zirconium, niobium, hafnium and tantalum contents in rock samples by inductively coupled plasma mass spectrometry (ICP-MS) is described. The rock samples (<30 mg) were decomposed with mannitol-added HF, and dissolved in a 0.015 M HF/0.12 M HNO₃ acid mixture for ICP-MS analysis. Boron, zirconium, niobium, hafnium and tantalum concentrations were measured by the internal calibration curve method using three internal standard elements, beryllium for boron, indium for zirconium and niobium, and rhenium for hafnium and tantalum. Seventeen rock reference samples from the Geological Survey of Japan and the U.S. Geological Survey were analyzed, and the determined concentrations showed good agreement with the reported values obtained by isotope dilution method, as well as with the recommended values. This technique is a simple method for the precise determination of boron, zirconium, niobium, hafnium and tantalum concentrations, and it has wide potential for geochemical application, particularly for the determination of boron.

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Search for a biogeochemical archive of past sulfur pollution is motivated by the need to predict ecosystem health. Sofar, no indicator of local-scale S pollution has existed, while long-range transport of S can already be studied using polar ice records. One archive of S pollution in temperate climate zones could be annual growth rings of trees. However, S concentration patterns in tree rings of most species have been unknown because of negligible S accumulation in wood. We modified a wet chemistry procedure to increase the recovery of S from tree rings, and report time series of S concentrations in six trees from an acidified, spruce die-back affected area of Central Europe. Beech tree rings, despite 4 times lower atmospheric S inputs, exhibited twice higher S concentration in wood than spruce. The period of peak industrial S pollution of the 1980s did not result in enhanced S accumulation in tree rings of either species. Physiological processes rather than S abundance in the ecosystem regulate S storage in tree rings.

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Several processes may contribute to systematic downcore trends in δ¹³C of bulk Sphagnum peat. Whereas changes in water availability during C assimilation may change δ¹³C values in both a negative and positive direction, other processes would always cause a uni-directional shift in δ¹³C. Selective preservation of isotopically light lignin C may lead to more negative δ¹³C values with an increasing depth and age of peat. Anthropogenic change toward lower δ¹³C of atmospheric CO₂ due to massive coal burning since the beginning of the Industrial Revolution would result in lower δ¹³C of the youngest peat layers, and in higher δ¹³C of older peat layers. Emissions of low-δ¹³C methane from wetlands should result in a progressive enrichment of the residual peat substrate in the heavier isotope ¹³C. Consequently, deeper peat would have higher δ¹³C. In a specific peat profile, the downcore trend in δ¹³C will be the result of an interplay between all these isotope-sensitive processes. Most Central European wetlands studied previously show a ¹³C enrichment (i.e., higher δ¹³C values) with an increasing depth and age. Here we focus on sites which showed lower δ¹³C with an increasing depth and age when a single peat core was taken. Replication did not confirm this negative downcore δ¹³C shift. A positive downcore δ¹³C shift is more widespread than previously believed. We suggest that decreasing δ¹³C of atmospheric CO₂ and emissions of low-δ¹³C methane belong to the main controls of the downcore δ¹³C trends in young peat substrate.

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