Isotopic Geochemistry Research Papers - Academia.edu (original) (raw)

We tested the potential for sand calcites to serve as a novel paleoclimate archive by investigating their age and formation conditions. Fontainebleau sand calcites are Pleistocene in age (based on 14 C and U-Th dating) and were primarily formed during glacial periods. δ 13 C values increase with the depth at which these sand calcites formed, consistent with open and closed CO 2 systems. Interpretation of the δ 18 O-T relationship in sand calcites points primarily to their formation at a low temperature, around 2°C in shallow ground water and at about 9°C in deeper groundwater settings. Their occurrence, characteristics, and compositions suggest crystallization from paleo-ground waters in permafrost environments. Crystallization of sand calcites was triggered by degassing of cold carbonate-containing surface waters as they infiltrated warmer subsurface groundwater environments. We consider sand calcites to be important indicators of interactions between meteoric water and ground water in Pleistocene periglacial landscapes. Their disposition may point to specific features of periglacial landscapes, and their ages could permit an assessment of landscape incision rates. Large crystals and zoned spheroliths may, in fact, encapsulate continuous high-resolution records of continental glacial and periglacial paleoenvironments.

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- Periglacial Environment, Paris Basin, Isotopic Geochemistry, Regolith Geology
- by Mark Marikos
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- Isotopic Geochemistry

This paper aims to quantitatively assess water losses of Badovc Lake - Kosovo based on both water balance of the lake and water isotopic composition of H-2 and O-18. According to lake water balance, a water loss of 3,738,905 m³ for the hydrologic year 2014, was evaluated. These consistent data favour the opinion that a continuous groundwater outflow from the lake is present and it is conditioned by the intensively
developed fracture system in the lake basement formations. This was also supported by the isotopic analysis (H-2 and O-18) of the sampled waters. Most of water samples taken from hydrologic components of Lake Badovc fall on a linear plot of δH versus δ18O showing an isotopic variation typical for waters evaporated from a lake and fits very well with Global Meteoric Water Line (GMWL), while two rain water samples are isotopically lighter (more negative δ values). Water samples taken from water leakages on the right side of the dam, the piezometer, two wells drilled in the valley downstream of dam, Hajvalia mine gallery and the water flow downstream of the dam, have isotopic composition similar with that of the lake water. Water of Hajvalia mine well shows isotopic composition that falls between that of rain water and lake water.
Considering δ values of rain water (δ2H= -129.6‰, δ18O= -16.56‰) and lake water (δ2H= -67.2‰, δ18O= -9.20‰) and mine water (mixture) (δ2H= -73.3‰, δO= 10.15‰) was found that the fraction of rain water in
mine water ranges from 6% (according H-2) to 10% (according O-18), while the fraction of lake water in mine water varies from 94% (according
H-2) to 90% (according O-18).

- by Arjan Beqiraj
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- Hydrogeology, Hydrochemistry, Stable Isotopes, Isotopic tracers
- by Vincent CHARPENTIER
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- Gulf Studies, South West Asian Studies, The Persian Gulf, Paleoecology

In this work concentrations of minor graphite impurities in virgin graphite of the Ignalina Nuclear Power Plant (Ignalina
NPP) measured by high resolution inductively coupled plasma mass spectrometry (ICP-MS) are presented and applicability of the method for the evaluation of minor graphite impurities is discussed. It is shown that ICP-MS is a promising technique for determination of graphite impurities in 10 ppm – 10 ppt concentration range as a rapid and relatively cheap method. The most important nuclides for evaluation of short- and long-lived activation products in the Ignalina NPP graphite were measured with
the accuracy sufficient for the radioactive waste classification. These results could be used for planning of dismantling and disposal of the Ignalina NPP graphite.

- by Andrius Puzas and +1
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- ICP-MS, X-Ray Fluorescence (XRF) Spectroscopy, Nuclear Wastes Management, Isotopic Analysis

Cam Thuy Permian basalts consisting of thick lava flows and pyroclastic layers appear along both sides of the Song Ma fault zone in Thanh Hoa and in Son La and Ninh Binh provinces, NW Vietnam. The magmatism has been thought to have genetic relationship with Permian volcanism in the Song Da rift zone, which is believed to be part of the Emeishan large igneous province, having been extruded along the Red River shear zone following Paleogene India-Eurasian collision. A set of Cam Thuy volcanic samples including olivine and alkaline basalts was collected in the Lam Son area (Tho Xuan, Thanh Hoa province) to analyze for geochemical major, trace element and Sr-Nd-Pb isotopic composition. The Cam Thuy basalts are high-TiOR 2 R, CaO, FeO*, moderate MgO and SiOR 2 R that plot between the Song Da and Emeishan high-and low-Ti basalt distribution fields and closely overlap that of Song Da's high-Ti field. The primitive mantle and chondrite normalized trace element patterns of Cam Thuy basalts are essentially enriched oceanic island basalt (OIB)-like; this feature, together with crustal contamination-free, chondritic Sr, Nd and Pb initial (255Ma) isotopic composition are certainly of asthenospheric origin. These geochemical and isotopic characteristics are closely analogous to those features observed for the Song Da high-Ti basalts, suggesting similarity in their source of origin. Nevertheless, while the Song Da (and Emeishan) magmatism is signified by the presence of both high-and low-Ti basalts, with the latter being derived from heterogeneous and partially crustal-material contaminated sources in the lithospheric mantle, this low-Ti volcanic rock type has yet to be discovered in the Cam Thuy formation.

- by Vietnam Journal of Earth Sciences and +1
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- Geochemistry, Isotopic Geochemistry
- by Azucena Dótor and +2
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- Environmental Geochemistry (Environmental Studies), Isotopic Geochemistry
- by Vincent CHARPENTIER
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- Gulf Studies, Middle Eastern History, Middle Eastern Studies, Arabian Gulf

The South Nepisiguit River Plutonic Suite consists of various phases of felsic to mafic plutonic rocks of early Devonian age in northern New Brunswick. The felsic portion of this intrusive suite includes a large pluton of homogeneous, peraluminous biotite granite (the Mount Elizabeth Granite), which is flanked on its western side by the alkaline Mount LaTour Granite. New in situ and mineral separate U-Pb Laser Ablation-Inductively Coupled Plasma Mass Spectrometry analyses of monazite and zircon grains from both sides of the suite define a crystallization age of 417.3 ± 0.96 Ma for the Mount Elizabeth Granite and 417.7 ± 4.4 Ma for the Mount LaTour Granite. The new data confirm previous geochronological work and indicate a close temporal relationship between these felsic phases of this plutonic suite.

After travelling in Earth’s interior for up to billions of years, recycled material once injected at subduction zones can reach a subridge melting region as pyroxenite dispersed in the host peridotitic mantle. Here we study genetically related crustal basalts and mantle peridotites sampled along an uplifted lithospheric section created at a segment of the Mid-Atlantic Ridge through a time interval of 26 million years. The arrival of low-solidus material into the melting region forces the elemental and isotopic imprint of the residual peridotites and of the basalts to diverge with time. We show that a pyroxenite-bearing source entering the subridge melting region induces undercooling of the host peridotitic mantle, due to subtraction of latent heat by melting of the low-T-solidus pyroxenite. Mantle undercooling, in turn, lowers the thermal boundary layer, leading to a deeper cessation of melting. A consequence is to decrease the total amount of extracted melt, and hence the magmatic crustal thickness. The degree of melting undergone by a homogeneous peridotitic mantle is higher than the degree of melting of the same peridotite but veined by pyroxenites. This effect, thermodynamically predicted for a marble-cake-type peridotite–pyroxenite mixed source, implies incomplete homogenization of recycled material in the convective mantle.

- by Daniele BRUNELLI
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- Mantle Petrology, Crustal Thickness Study, Rare Earth Elements, Peridotite

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- by Masoud Rostami
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- Environmental Science, Geology, Physics, Stable Isotope Analysis

- by anna cipriani
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- Earth Sciences, Geology, Radiogenic Isotope Geochemistry, Mantle Petrology

RIecent research provides new perspectives on large-scale Early Holocene human interaction within Eurasia, based on ancient DNA or lithic technology. But the extent of regional human mobility is not well known. In this study, we combined two different approaches to investigate regional mobility and social networks in southern Scandinavia. We analyzed strontium isotopes in human teeth and regional lithic raw material use and technology from a Mesolithic site, Norje Sunnansund in southern Sweden (7000 BCE). The lithic raw material composition at the site, and previous archaeological studies, indicated that the inhabitants mainly had utilized an area stretching 30 km southward. The isotopic analysis indicated that at least half of the analyzed individuals had a non-local origin, based on the local isotope signature, but that possibly only a few individuals originated outside the area defined by lithic acquisition. Those few isotopic values and the presence of lithic material as non-local flint and East Swedish microblade-cores in quartz, suggested that people also traveled far, but probably more sporadically. The combined analyzes revealed the complexity of late Boreal hunter-gatherers in South Scandinavia – although some groups appear to have had a limited geographical mobility, contact networks seem to have stretched over long distances.

- by Mathilda Kjällquist and +1
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- Mesolithic Archaeology, Mesolithic Europe, Isotopic Geochemistry

Given that oceanic basalts form by partial melting of mantle peridotites that rise below mid-ocean ridges, peridotite and basalt should have identical Sr and Nd isotope ratios. We tested this concept on parallel sets of peridotites and basalts sampled from an exposed section of lithosphere representing 20 m.y. of accretion at the Mid-Atlantic Ridge. The 143 Nd/ 144 Nd ratios of the basaltic glasses stay constant, whereas those of the peridotitic clinopyroxenes extend both higher and lower than the basalt ratios, suggesting that the constant isotopic composition of the basalts results from mixing of melts released by pe-ridotites from a broad region of the subridge mantle. The degree of melting undergone by the peridotites correlates inversely with their 143 Nd/ 144 Nd ratios. Small-scale isotopic heterogeneity of the peridotites may result from variable premelting metasomatism in the mantle, mostly during periodic, dynamic, subridge upwelling, possibly superimposed upon time-integrated radioactive decay of ancient heterogeneities.