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1
Gregorčič, Staša Hamzić, Nives Ogrinc, Russell Frew, Marijan Nečemer, Lidija Strojnik y Tea Zuliani. "The Provenance of Slovenian Milk Using 87Sr/86Sr Isotope Ratios". Foods 10, n.º 8 (27 de julio de 2021): 1729. http://dx.doi.org/10.3390/foods10081729.
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This work presents the first use of Sr isotope ratios for determining the provenance of bovine milk from different regions of Slovenia. The analytical protocol for the determination of 87Sr/86Sr isotope ratio was optimised and applied to authentic milk samples. Considerable variability of 87Sr/86Sr ratios found in Slovenian milk reflects the substantial heterogeneity of the geological background of its origin. The results, although promising, cannot discount possible inter-annual or annual variation of the Sr isotopic composition of milk. The 87Sr/86Sr ratios of groundwater and surface waters are in good correlation with milk, indicating that the Sr isotopic fingerprint in milk is reflective of cow drinking water. The 87Sr/86Sr ratio has the potential to distinguish between different milk production areas as long as these areas are characterised by geo-lithology. Discriminant analysis (DA) incorporating the elemental composition and stable isotopes of light elements showed that 87Sr/86Sr ratio together with δ13Ccas and δ15Ncas values have the main discrimination power to distinguish the Quaternary group (group 6) from the others. Group 1 (Cretaceous: Carbonate Rocks and Flysch) is associated with Br content, 1/Sr and δ18Ow values. The overall prediction ability was found to be 63.5%. Pairwise comparisons using OPLS-DA confirmed that diet and geologic parameters are important for the separation.
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Nguyen Thi Kim, Dung y Thuy Thai Thi Thu. "Study on the removal of interferences for the determination of ⁸⁷Sr/⁸⁶Sr isotopic ratio in petroleum drill-hole water samples using isotope dilution – inductively coupled plasma mass spectrometry (ID – ICP-MS)". Nuclear Science and Technology 8, n.º 4 (1 de septiembre de 2021): 34–43. http://dx.doi.org/10.53747/jnst.v8i4.65.
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87Sr/86Sr isotopic ratio is one of the useful tools that can authenticate the original source of the natural products from the earth-created and/or geological processes. However, the effect of interferences in petroleum drill-holes water sample such as thickness of sample matrix or isotopic signal of 87Rb might cause the low precision of 87Sr/86Sr determination using quadrupole inductively coupled plasma spectrometry (ICP-MS). The elimination of these mentioned effects was thus studied by using the ion - exchange chromatography. Calcium in sample matrix was separated on anionite column (Bio-Rad AG1-X8 resin) in methanol medium with the high efficiency while rubidium wasremoved from strontium on cation exchange resin (Bio-Rad AG50-X8) with strontium recovery over 99%. The isotope dilution technique with 86Sr - enriched isotopic standard solution was used for the control of separation process. The 87Sr/86Sr isotopic ratio was thus determined using ICP-MS with the signal correction by a strontium isotopic ratio standard reference material (NIST SRM 987).
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Wu, W. H., H. B. Zheng y J. D. Yang. "Sr isotopic characteristics in two small watersheds draining typical silicate and carbonate rocks: implication for the studies on seawater Sr isotopic evolution". Hydrology and Earth System Sciences Discussions 10, n.º 6 (21 de junio de 2013): 8031–69. http://dx.doi.org/10.5194/hessd-10-8031-2013.
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Abstract. We systematically investigated Sr isotopic characteristics of small silicate watershed – the tributary Xishui River of the Yangtze River, and small carbonate watershed – the tributary Guijiang River of the Pearl River. The results show that the Xishui River has relatively high Sr concentrations (0.468–1.70 μmol L−1 in summer and 1.30–3.17 μmol L−1 in winter, respectively) and low 87Sr/86Sr ratios (0.708686–0.709148 in summer and 0.708515–0.709305 in winter), which is similar to the characteristics of carbonate weathering. The Guijiang River has low Sr concentrations (0.124–1.098 μmol L−1) and high 87Sr/86Sr ratios (0.710558–0.724605), being characterized by silicate weathering. In the Xishui River catchment, chemical weathering rates in summer are far higher than those in winter, indicating significant influence of climate regime. However, slight differences of 87Sr/86Sr ratios between summer and winter show that influence of climate on Sr isotope is uncertainty owing to very similar Sr isotope values in silicate and carbonate bedrocks. As 87Sr/86Sr ratios in the Xishui River are lower than those in seawater, they will decrease 87Sr/86Sr ratio of seawater after transported into oceans. Previous studies also showed that some basaltic watersheds with extremely high chemical weathering rates reduced the seawater Sr isotope ratios. In other words, river catchments with high silicate weathering rates do not certainly transport highly radiogenic Sr into oceans. Therefore, it may be questionable that using the variations of seawater 87Sr/86Sr ratio to indicate the continental silicate weathering intensity. In the Guijiang River catchment, 87Sr/86Sr ratios of carbonate rocks and other sources (rainwater, domestic and industrial waste water, and agricultural fertilizer) are lower than 0.71. In comparison, some non-carbonate components, such as, sand rocks, mud rocks, shales, have relatively high Sr isotopic compositions. Moreover, granites accounted for only 5% of the drainage area have extremely high 87Sr/86Sr ratios with an average of over 0.8. Therefore, a few silicate components contained in carbonate rocks obviously increases the Sr isotopic compositions of the river water, and results in a positive effect on the rise of 87Sr/86Sr ratio of seawater. Therefore, the relation between Sr isotope evolution of seawater and continental weathering rate is complex, 87Sr/86Sr ratios of underlying bedrock in catchment could be an important controlling factors.
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Rossi, Mattia, Paola Iacumin y Gianpiero Venturelli. "87Sr/86Sr Isotope Ratio as a Tool in Archaeological Investigation: Limits and Risks". Quaternary 7, n.º 1 (11 de enero de 2024): 6. http://dx.doi.org/10.3390/quat7010006.
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During the last forty years, the use of strontium isotopes in archaeology and biogeochemical research has spread widely. These isotopes, alone or in combination with others, can contribute to trace past and present environmental conditions. However, the interpretation of the isotopic values of strontium is not always simple and requires good knowledge of geochemistry and geology. This short paper on the use of strontium isotopes is aimed at those who use this tool (archaeologists, but not only) but who do not have a thorough knowledge of mineralogy, geology, and geochemistry necessary for a good understanding of natural processes involving these isotopes. We report basic knowledge and suggestions for the correct use of these isotopes. The isotopic characteristics of bio-assimilable strontium depend not so much on the isotopic characteristics of the bulk rock as, rather, on those of its more soluble minerals. Before studying human, animal and plant remains, the state of conservation and any conditions of isotopic pollution should be carefully checked. Samples should be collected according to random sampling rules. The data should be treated by a statistical approach. To make comparisons between different areas, it should be borne in mind that the study of current soils can be misleading since the mineralogical modification of soil over time can be very rapid.
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Alekseeva, L. P. y S. V. Alekseev. "Strontium and 87Sr/86Sr isotopic ratio of ground brines in the northeastern Angara-Lena artesian basin". Earth sciences and subsoil use 44, n.º 2 (17 de junio de 2021): 98–105. http://dx.doi.org/10.21285/2686-9993-2021-44-2-98-105.
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The purpose of this study is to identify the major formation processes of the ionic and isotopic composition of chloride brines in the sedimentary basins of the Siberian platform. The object and subject of research are deep-seated strong, very strong and extremely saturated brines as well as their strontium content and the ratio of Sr stable isotopes. The groundwater ionic-salt composition was determined by traditional methods (titrimetric, gravimetric, flame photometry), the 87Sr/86Sr isotopic ratio was measured using mass-spectrometers (Irkutsk, Russia and Canada). The brines lying at the depth of 1500–3000 m were tapped and classified into saline and subsalt hydrogeological formations. Their feature is high salinity (385–530 g/L) and high content of strontium (2.3–7 g/L). The 87Sr/86Sr isotopic ratio ranges from 0.708 to 0.713062. By isotopic composition most of the brine samples are close to the waters of the Vendian-Cambrian paleoocean. However, some brine samples from the subsalt part of the sedimentary section of the basin are significantly enriched in the isotope 87Sr compared to the paleoocean waters and other samples. It could be due to the substantial input of 87Sr into the brines during the long-term interaction of groundwater with the host Lower Cambrian sandstones.
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Wu, W. H., H. B. Zheng, J. H. Cao y J. D. Yang. "Sr isotopic characteristics in two small watersheds draining silicate and carbonate rocks: implication for studies on seawater Sr isotopic evolution". Hydrology and Earth System Sciences 18, n.º 2 (13 de febrero de 2014): 559–73. http://dx.doi.org/10.5194/hess-18-559-2014.
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Abstract. We systematically investigated the Sr isotopic characteristics of a small silicate watershed, the Xishui River a tributary of the Yangtze River, and a small carbonate watershed, the Guijiang River a tributary of the Pearl River. The results show that the two rivers have uncommon Sr isotopic characteristics compared with most small watersheds. Specifically, the silicate watershed (Xishui River) has relatively high Sr concentrations (0.468 to 1.70 μmol L−1 in summer and 1.30 to 3.17 μmol L−1 in winter, respectively) and low 87Sr/86Sr ratios (0.708686 to 0.709148 in summer and 0.708515 to 0.709305 in winter). The carbonate watershed (Guijiang River) has low Sr concentrations (0.124 to 1.098 μmol L−1) and high 87Sr/86Sr ratios (0.710558 to 0.724605). As the 87Sr/86Sr ratios in the Xishui River are lower than those in seawater, the 87Sr/86Sr ratio of seawater will decrease after the river water is transported to the oceans. Previous studies have also shown that some basaltic watersheds with extremely high chemical weathering rates reduced the seawater Sr isotope ratios. In other words, river catchments with high silicate weathering rates do not certainly transport highly radiogenic Sr into oceans. Therefore, the use of the variations in the seawater 87Sr/86Sr ratio to indicate the continental silicate weathering intensity may be questionable. In the Guijiang River catchment, the 87Sr/86Sr ratios of carbonate rocks and other sources (rainwater, domestic and industrial waste water, and agricultural fertilizer) are lower than 0.71. In comparison, some non-carbonate components, such as sand rocks, mud rocks, and shales, have relatively high Sr isotopic compositions. Moreover, granites accounted for only 5% of the drainage area have extremely high 87Sr/86Sr ratios with an average of greater than 0.8. Therefore, a few silicate components in carbonate rocks obviously increase the Sr isotopic compositions of the river water.
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Cellier, Robin, Sylvain Bérail, Julien Barre, Ekaterina Epova, Anne-Laure Ronzani, Cornelis Van Leeuwen, Stanislas Milcent, Patrick Ors y Olivier F. X. F. X. Donard. "Specificity and Origin of the Stability of the Sr Isotopic Ratio in Champagne Wines". Molecules 26, n.º 16 (23 de agosto de 2021): 5104. http://dx.doi.org/10.3390/molecules26165104.
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The 87Sr/86Sr ratio of 39 Champagnes from six different brands, originating from the whole “Appellation d’Origine Contrôlée” (AOC) Champagne was analyzed to establish a possible relation with the geographical origin. Musts (i.e., grape juice) and base wines were also analyzed to study the evolution of the Sr isotopic ratio during the elaboration process of sparkling wine. The results demonstrate that there is a very homogeneous Sr isotopic ratio (87Sr/86Sr = 0.70812, n = 37) and a narrow span of variability (2σ = 0.00007, n = 37). Moreover, the Sr concentrations in Champagnes have also low variability, which can be in part explained by the homogeneity of the bedrock in the AOC Champagne. Measurements of the 87Sr/86Sr ratio from musts and base wines show that blending during Champagne production plays a major role in the limited variability observed. Further, the 87Sr/86Sr of the musts were closely linked to the 87Sr/86Sr ratio of the vineyard soil. It appears that the 87Sr/86Sr of the product does not change during the elaboration process, but its variability decreases throughout the process due to blending. Both the homogeneity of the soil composition in the Champagne AOC and the blending process during the wine making process with several blending steps at different stages account for the unique and stable Sr isotopic signature of the Champagne wines.
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Bujakaite, M. I., V. Yu Lavrushin y B. G. Pokrovsky. "Strontium isotopic composition in waters of mud volcanoes of Azerbaijan". Литология и полезные ископаемые, n.º 5 (20 de octubre de 2019): 391–403. http://dx.doi.org/10.31857/s0024-497x20195391-403.
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The isotopic composition of strontium was studied in the waters of 22 Azerbaijan mud volcanoes, in which the isotope composition of oxygen and hydrogen, as well as the concentration of macro and micro elements, was previously [Lavrushin et al., 2015] determined. 87Sr/86Sr ratios in the waters of Azerbaijan mud volcanoes are within 0.70670.7083. The minimum ratio was established in Neftechala Yuzhnaya volcano, located in the south of the territory ‒ in the Kura region, which is characterized by the lowest average values of 87Sr/86Sr = 0.70700.0003 and 18O = 2.01.8 compared to volcanoes situated northern ‒ in Shemakha ‒ Gobustan, Absheron and Caspian regions (87Sr/86Sr average = 0.70760.0005, 18O average = 4.82.5). The relation between the strontium isotopic composition and the isotopic composition of oxygen suggests that the formation of the isotopic characteristics of the mud volcanic waters of Azerbaijan involves two main sources, one of which is predominantly associated with sedimentary carbonates of Cretaceous-Paleogene age, and the second, prevailing in the Kura region, has traces of isotopic exchange with volcanic rocks. The role of strontium dissolved in the sea water, as well as strontium, which could be extracted from modern terrigenous sediments of the Caspian Sea and terrigenous clay rocks of the Maikop series in the mud volcanic waters of Azerbaijan is insignificant.
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Sighinolfi, Simona, Caterina Durante, Lancellotti Lisa, Lorenzo Tassi y Andrea Marchetti. "Influence of Chemical and Physical Variables on 87Sr/86Sr Isotope Ratios Determination for Geographical Traceability Studies in the Oenological Food Chain". Beverages 4, n.º 3 (1 de agosto de 2018): 55. http://dx.doi.org/10.3390/beverages4030055.
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This study summarizes the results obtained from a systematic and long-term project aimed at the development of tools to assess the provenance of food in the oenological sector. 87Sr/86Sr isotope ratios were measured on a representative set of soils, branches, and wines sampled from the Chianti Classico wine production area. In particular, owing to the high spatial resolution of the 87Sr/86Sr ratio in the topsoil, the effect of two mill techniques for soil pretreatment was investigated to verify the influence of the particle dimension on the measured isotopic ratios. Samples with particle sizes ranging from 250 to less than 50 µm were investigated, and the extraction was performed by means of the DIN 19730 procedure. For each sample, the Sr isotope ratio was determined as well. The obtained results showed that the 87Sr/86Sr ratio is not influenced by soil particle size and may represent an effective tool as a geographic provenance indicator for the investigated product.
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Baffi, C. y P. R. Trincherini. "Food traceability using the 87Sr/86Sr isotopic ratio mass spectrometry". European Food Research and Technology 242, n.º 9 (31 de mayo de 2016): 1411–39. http://dx.doi.org/10.1007/s00217-016-2712-2.
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Catarino, S., F. P. Castro, J. Brazão, L. Moreira, L. Pereira, J. R. Fernandes, J. E. Eiras-Dias, A. Graça y P. Martins-Lopes. "87Sr/86Sr isotopic ratios in vineyard soils and varietal wines from Douro Valley". BIO Web of Conferences 12 (2019): 02031. http://dx.doi.org/10.1051/bioconf/20191202031.
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The assessment of wine authenticity is of utmost importance in the current context of a growing market globalization. The strontium isotopic ratio 87Sr/86Sr is a well-established tool for dating and tracing the origin of rocks and minerals with special interest for wine traceability. A study was developed to examine the variation of 87Sr/86Sr in wines from Douro Valley taking into account the effects of vineyard location and grape variety. The 87Sr/86Sr of soils and wines from six vineyards were determined by using an ICP-MS based analytical procedure. A total of twenty-two monovarietal wines, obtained at micro vinification scale, from relevant white and red grapevine varieties for Douro region, were analysed. The range of 87Sr/86Sr values observed in soils and wines was of 0.708–0.725 and 0.711–0.717, respectively. The present study updates the scarce knowledge available on strontium isotopic ratios in soils and wines from Douro Valley, and its results will enlarge global databank on wine composition and support comparison with other world regions.
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Zaky, Amir H., Uwe Brand, Dieter Buhl, Nigel Blamey, M. Aleksandra Bitner, Alan Logan, Daniele Gaspard y Alexander Popov. "Strontium isotope geochemistry of modern and ancient archives: tracer of secular change in ocean chemistry". Canadian Journal of Earth Sciences 56, n.º 3 (marzo de 2019): 245–64. http://dx.doi.org/10.1139/cjes-2018-0085.
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Strontium isotopes of marine archives provide a significant means for tracing physical and chemical processes operating over geologic time. Modern articulated brachiopods and halite samples were collected from all depths of the world’s main water bodies. Material from the Arctic, North and South Atlantic, North and South Pacific, Indian and Southern oceans, as well as Caribbean and Mediterranean seas provide baseline parameters for diagenetic screening and reconstruction of seawater curves. The Sr isotopic ratio of modern brachiopods is unobscured by latitude, depth, and biologic factors (Order, valves, and shell segment). However, there is a small but significant impact of external sources reflected by salinity and temperature on the Sr isotope ratio of modern brachiopods. We found a significant difference in 87Sr/86Sr of brachiopods from polar and temperate-tropical habitats (p = 0.001), which should be considered when working with deep-time archives. The average 87Sr/86Sr value of all our modern shells (0.709160 ± 0.000019; N = 95) and halite (0.709153) is similar to values measured for modern seawater (0.710167 ± 0.000009; p = 0.118). The radiogenic Sr content of present-day seawater does not vary significantly, and modern biogenic-calcite 87Sr/86Sr ranges from 0.709126 to 0.709233 with a fluctuation of about ±0.000054. With the most rigorous diagenetic evaluations and stratigraphic assignment of deep-time samples, and applying the Sr isotope fluctuation recorded by modern biogenic calcite to ancient carbonates and a 1 Myr interval, reconstructions resulted in a seawater-87Sr curve with greater details during the Phanerozoic and Neoproterozoic.
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Gabel, B. "Wine origin authentication linked to terroir – wine fingerprint". BIO Web of Conferences 15 (2019): 02033. http://dx.doi.org/10.1051/bioconf/20191502033.
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Global wine and alcohol trade faces a serious economic problem linked to counterfeiting of these commodities. Recently applied authentication methods and techniques pose more difficulties for counterfeiters but they are apparently not effective once we consider economical losses identified by EU legal authorities. The presented solution links isotopic characteristics of the soil, plant, technological intermediate product and the final food product (wine, grapes) on the basis of 87Sr/86Sr isotopes ratios. For the isotopic signature of wines, the average isotope composition of the substrate cannot be a reliable indicator. Only the isotopic composition of pore water can, as it leaches various mineral phases at different stages and passes into vine root system. Instead of complicated sampling of pore water, an original method of preparing and processing soil samples and consequently must & wine samples was developed. Based on both, soil and biological material analysis, we can unquestionably determine not only geographical but also regional and local authenticity of the wine. Determination of red wines isotopic signature is more straightforward process in comparison to white wines, because of technologically different processing of grapes. That is the reason why, in case of white vines, the 87Sr/86Sr ratio of bentonites (natural purifier and absorbent useful in the process of winemaking) must also be taken into consideration. Results of analyses of Slovak wines from geographically diverse regions as well as from sites in close-by distances have clearly established reliability of presented concept, in which the soil is linked to the plant and to the final food product (wine or table grapes).
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Török, Anamaria Iulia, Ana Moldovan, Claudiu Tănăselia, Eniko Kovacs, Ionuț Cornel Mirea, Oana Teodora Moldovan y Erika Andrea Levei. "Sr Isotope, Major, and Trace Element Signatures in Karst Groundwaters". Water 15, n.º 7 (6 de abril de 2023): 1431. http://dx.doi.org/10.3390/w15071431.
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Natural and anthropogenic factors highly influence the concentration of major (Na, Mg, K, Ca) and trace (Sr, Ba, Mn, Li) elements, anions (HCO3−, NO3−, SO42−, Cl−), and Sr isotopic signatures. The current study identified the Sr isotopic signature in groundwaters from the Southern Carpathians and Apuseni Mountains karst areas of Romania and its relation to the water’s chemistry. The Sr concentration ranged between 16.5 and 658 µg/L, but in most groundwaters, it was below 200 µg/L. A considerable spatial variation and a low temporal variation, with a slightly lower Sr concentration in the winter than in spring, were observed. The strong positive correlation of the Sr with Ca, Mg, K, and Na indicated the common source of these elements. The main source of the Sr in groundwaters was the dissolution of carbonates, especially calcite, and dolomite to a lesser extent. The 87Sr/86Sr isotopic ratio ranged between 0.7038 and 0.7158. Generally, waters with a high Sr concentration and moderate 87Sr/86Sr ratios indicated carbonate dissolution, whereas samples with low Sr concentrations and high 87Sr/86Sr ratios suggested the dissolution of silicates.
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Négrel, P., W. Kloppman, M. Garcin y D. Giot. "Strontium isotopic record of signatures of Holocene fluvial sediments in the Loire valley, France". Hydrology and Earth System Sciences 6, n.º 5 (31 de octubre de 2002): 849–58. http://dx.doi.org/10.5194/hess-6-849-2002.
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Abstract. The distribution of Sr contents and isotopes of strontium Sr in the labile fraction of sediments from a channel fillings infill in the Middle Loire alluvial plain is used to highlight aspects of the evolution of the basin over the period from 10 000 yr. BP to the present. The acid extractable matter (AEM) in the sediment samples is variable in amount and in trace element contents. Carbonates and Fe–Mn oxyhydroxides are the principal carrying phases in the labile fraction. The historical record of 87Sr/86Sr ratio variations in AEM shows two components. In the first, the AEM is consistently low (around 10%) and the 87Sr/86Sr ratios range from around 0.7086 to 0.710. This corresponds to the hydrous Fe-Mn oxides endmember. Fe–Mn oxyhydroxides originate from the Massif Central and their 87Sr/86Sr ratios display a larger range than present day Fe–Mn oxides. Furthermore, the mixing proportions between Fe–Mn oxides generated on granitoids and on basalts fluctuated only weakly in the past. The second component has greater AEM (20–50%) and the 87Sr/86Sr ratio is almost constant at 0.709–0.7095. This corresponds to a carbonate endmember, clearly different from present day carbonates and may reflect the influence of both authigenic and detrital origins. The low 87Sr/86Sr ratio suggests a dominantly authigenic source for the carbonate endmember; this may be linked to groundwater inputs, although a minor influence from a secondary detrital source cannot be discounted. This reflects a different functioning of the river between deposition in the channel and the present day. Keywords: River Loire, Holocene, fluvial dynamics, geochemistry, strontium isotopes
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NUNES, Márcia Andréia da Silva, Maria Virginia Alves MARTINS, Armando Dias TAVARES, Igor A. PESSOA, Luiz Felipe Romero SILVA, Marco Helênio de Paula Alves COELHO y Mauro César GERALDES. "Sr ISOTOPES BY LA-MC-ICP-MS PROCEDURES COUPLED WITH THE MACS3 REFERENCE MATERIAL IN A CORAL SAMPLE: A RECORD OF ENVIRONMENTAL CHANGES". Geosciences = Geociências 41, n.º 2 (11 de octubre de 2022): 317–34. http://dx.doi.org/10.5016/geociencias.v41i02.16322.
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The main aim of this work is to demonstrate that the Laser ablation multi-collector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS) is a powerful tool for the analysis of strontium (Sr) isotopes in corals. This work discusses certification strategies for Sr isotopes determination, using reference material (RM) analyses and the results treatment based on detailed data acquired in biological materials, a coral sample. To obtain reliable results, it is essential to properly adjust the mass spectrometer and laser ablation system. Adjusting the equipment to its maximum intensity does not always result in correct 87Sr/86Sr ratios. Therefore, the optimization of the mass spectrometer was performed using the reference material NIST SRM-987 (solution) and adjusting the correct Sr isotope ratio to the reference material (USGS MACS3 and NIST-612, solids) before each analytical session. The protocol applied the solid reference material USGS MACS3 with an isotopic ratio 87Sr/86Sr of 0.72000. The values obtained for this RM varied between 0.7012 and 0.7014, with a correction factor calculated between 0.990 and 0.988. In order to account for potential drifts in the mass spectrometer during an analytical session, the application of bracketing correction and the use of the most convenient reference material are suggested. The analytical uncertainty of Sr data obtained by LA-MC-ICP-MS is comparable to studies carried out on other carbonate materials. The results of ablation techniques are reproducible within the analytical error, which implies that this technique produces robust results when applied to coral carbonates. In addition, several comparative measurements of different reference materials (e.g. USGS MACS3 and NIST 612) and the comparison of the 87Sr/86Sr ratios highlight the robustness of the method. The results along the coral growth axes showed a decrease in the 87Sr/86Sr ratio from the inner to the outer layer of the coral (from 0.70920 to 0.70627), which indicate variations in the availability of particulate matter during the coral growth, probably related to local marine environmental changes.
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Xu, Jianzhong, Guangming Yu, Shichang Kang, Shugui Hou, Qianggong Zhang, Jiawen Ren y Dahe Qin. "Sr-Nd isotope evidence for modern aeolian dust sources in mountain glaciers of western China". Journal of Glaciology 58, n.º 211 (2012): 859–65. http://dx.doi.org/10.3189/2012jog12j006.
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AbstractIn order to apportion the dust sources of mountain glaciers in western China, the Sr-Nd isotopic compositions of insoluble particles were determined in snow samples collected from 13 sites. The combined plot of 87Sr/86Sr and εNd(0) demonstrates a distinctive geographic pattern over western China, which can be classified into three regions from north to south. Samples from the Altai mountains show the lowest 87Sr/86Sr ratio and the highest εNd(0) value, similar to the data of deserts in the north of China such as the Gurbantunggut desert. Samples from the southern Tibetan Plateau (TP) and Himalaya show the highest 87Sr/86Sr and lowest εNd(0) values, resembling the local and regional dust sources found in the southern TP and Himalaya-India region. Samples from the Tien Shan and northern Tibetan Plateau exhibit intermediate 87Sr/86Sr and εNd(0) values, similar to the data reported for the northern margin of the TP (NM_TP). However, three sampling sites, JMYZ (Jiemayangzong) located in the Himalaya and ZD (Zadang) and YL (Yulong) located in the southeast TP, presented distinctive Sr-Nd isotopic signatures typical of the NM_TP, suggesting potential long-range and high-altitude dust transport across the TP.
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Zhang, Qing, Gang Chen y Chuan Yang Su. "The Strontium Isotopic Chemical Analysis of Geothermal Water in Guihu, Fuzhou". Applied Mechanics and Materials 472 (enero de 2014): 867–73. http://dx.doi.org/10.4028/www.scientific.net/amm.472.867.
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This paper takes Fuzhou Guihu geothermal field as the research object, analyzing its geothermal background of regional tectonic characteristics. With the increase of flow path, contents of carbonate and aluminosilicate minerals both raises, while 87Sr/86Sr goes down gradually. 87Sr/86Sr in discharge regions of geothermal water is the lowest. Analysis of the geothermal water chemistry and isotopic characteristics lead to the conclusion that the underground water circular depth of wells located on the alluvia and proluvial fans in front of mountains is relatively deep, which reaches 500-700m. Average of the mixed ratio is 0.14, which means that 14% cold water is mixed.
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Wickman, F. E. y G. Åberg. "Variations in the 87Sr/86Sr Ratio in Lake Waters from Central Sweden". Hydrology Research 18, n.º 1 (1 de febrero de 1987): 21–32. http://dx.doi.org/10.2166/nh.1987.0002.
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The 87Sr/86Sr ratios of lake waters from eastern Central Sweden, a region consisting mainly of 1.7-2.0 × 109 years old granitoid rocks are reported and discussed. The ratios range from 0.722-0.739, and are similar to lake and stream waters in geologically similar areas. The annual variation of the isotope ratio in two small lakes varied in the range of 0.7323-0.7339 and 0.7313-0.7325 respectively, except at ice clearing in spring when the ratio of surface water was lowered by a contribution from melting snow. Small lateral differences also exist in Lake Mälaren, probably because its complex outline hinders complete mixing of its water. The Sr isotopic ratio variations with respect to bedrock geology suggest that a more important influence on the ratio is the mineralogic composition of the Quaternary deposits (mainly till). The great difference between the ratios of rain water (0.709-0.710) and those of rocks in old Precambrian platforms with granitic rocks (0.720 and greater) results in waters (ground, lake and river) with ratios around 0.720-0.740. This means that the 87Sr/86Sr ratio is an excellent tool in studies of hydrologic processes, such as mixing of waters and exchange reactions between water and mineral matter.
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Nguyen, Minh Quy, Long Hoang, Thi Thu Huong Le, Van Huan Luong y Thi Tuong Hanh Vo. "Identifying the sources of produced water in the oil field by isotopic techniques". Nuclear Science and Technology 4, n.º 2 (30 de junio de 2014): 32–41. http://dx.doi.org/10.53747/jnst.v4i2.226.
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The objective of this study is to identify the sources of the formation water in the Southwest Su Tu Den (STD SW) basement reservoir. To achieve the objective, isotopic techniques along with geochemical analysis for chloride, bromide, strontium dissolved in the water were applied. The isotopic techniques used in this study were the determination of water stable isotopes signatures (δ2H and δ18O) and of the 87Sr/86Sr ratio of strontium in rock cutting sample and that dissolved in the formation water. The obtained results showed that the stable isotopes compositions of water in the Lower Miocene was -3‰ and -23‰ for δ18O and δ2H, respectively indicating the primeval nature of seawater in the reservoir. Meanwhile, the isotopic composition of water in the basement was clustered in a range of alternated freshwater with δ18O and δ2H being –(3-4)‰ and -(54-60)‰, respectively). The strontium isotopes ratio for water in the Lower Miocene reservoir was lower compared to that for water in the basement confirming the different natures of the water in the two reservoirs. The obtained results are assured for the techniques applicability, and it is recommended that studies on identification of the flow-path of the formation water in the STD SW basement reservoir should be continued.
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Stepanyuk, L. M., T. B. Yaskevich y I. M. Kotvitska. "ZIRCON ANATOMY FROM THE ROCKS ASSOCIATION OF THE OSTRIVSKY QUARRY (ROS-TIKYCH MEGABLOCK OF THE UKRAINIAN SHIELD)". Mineralogical Journal 45, n.º 1 (2023): 41–49. http://dx.doi.org/10.15407/mineraljournal.45.01.041.
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Granitoids play a key role in the geological structure of the Ros-Tikych megablock. Supercrustal rocks of the Ros-Tikych series have been preserved in the granitoids only in the form of isolated fragments such as elongated remains, small skialites and even smaller "melted" xenoliths. In particular, in the Ostrivsky quarry, located on the right bank of the Ros River east of Bila Tserkva, granitoids are found (even-grained, porphyry-like granites) among which, as a rule, small bodies of granodiorites, plagiogranites and amphibolites occur. In order to determine the source of the parent magmas of rocks the properties of zircon crystals and the isotopic composition (87Sr/86Sr ratio) of apatite were studied. An analysis of the zircon crystals of the crystalline rocks exposed at the Ostrivsky quarry allows us to propose that the and plagio- and difeldspar granites were formed from one protolith. This is because they contain similar virtually identical zircon relics as nucleus. In addition, none of the granitoids contain zircon crystals whose internal structure is similar to zircon crystals found in amphibolite. This suggests that the granitoids were not derived by melting of amphibolites. Most likely, amphibolites are relicts of the protolith that were not assimilated during granite formation. The occurrence of heterogeneous zircon crystals (relic zircon cores of the protolith) in the protolith of the various studied granitoids indicates that they formed from volcanic-sedimentary rocks. Apatites in plagiogranitoids and porphyry granite contain strontium of similar isotopic composition. Their 87Sr/86Sr isotopic ratio is 0.70680 in apatite granodiorite and 0.70822 in granite. A high ratio of 87Sr/86Sr = 0.77940 was measured for apatite from monazite-bearing granite, thus indicating a different source for its parent magma.
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Alexeev, Sergey, Ludmila Alexeeva y Orfan Shouakar-Stash. "Strontium isotopic ratio in brines from the north-east of the Angara-Lenskiy artesian basin". E3S Web of Conferences 98 (2019): 12001. http://dx.doi.org/10.1051/e3sconf/20199812001.
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The Sr isotopic composition was measured in a number of samples of highly concentrated oil-field brines from the Angara-Lenskiy artesian basin. The brines are contained in the salt-bearing and subsalt-bearing hydrogeological formations at a depth of 1,500-3,000 m. They have high salinity (385-530 g/L) and high Sr content (2.3-7.0 mg/L). The 87Sr/86Sr ratio ranges from 0.70800 to 0.713062. Most brine samples exhibit an isotopic composition similar to Vendian-Cambrian paleoocean water, however several samples from the Yaraktinskiy horizon are significantly more radiogenic than others. It suggests that a considerable amount of 87Sr is likely to have been carried from terrigenous sediments due to a water-rock interaction.
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Kaya, Ayse D., Raúl Bruno de Sousa, António S. Curvelo-Garcia, Jorge M. Ricardo-da-Silva y Sofia Catarino. "Effect of Wood Aging on Wine Mineral Composition and 87Sr/86Sr Isotopic Ratio". Journal of Agricultural and Food Chemistry 65, n.º 23 (junio de 2017): 4766–76. http://dx.doi.org/10.1021/acs.jafc.7b01510.
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de Caritat, Patrice, Anthony Dosseto y Florian Dux. "A strontium isoscape of northern Australia". Earth System Science Data 15, n.º 4 (14 de abril de 2023): 1655–73. http://dx.doi.org/10.5194/essd-15-1655-2023.
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Abstract. Strontium isotopes (87Sr/86Sr) are useful to trace processes in the Earth sciences as well as in forensic, archaeological, palaeontological, and ecological sciences. As very few large-scale Sr isoscapes exist in Australia, we have identified an opportunity to determine 87Sr/86Sr ratios on archived fluvial sediment samples from the low-density National Geochemical Survey of Australia. The present study targeted the northern parts of Western Australia, the Northern Territory, and Queensland, north of 21.5∘ S. The samples were taken mostly from a depth of ∼60–80 cm in floodplain deposits at or near the outlet of large catchments (drainage basins). A coarse (<2 mm) grain-size fraction was air-dried, sieved, milled, and digested (hydrofluoric acid + nitric acid followed by aqua regia) to release total Sr. The Sr was then separated by chromatography, and the 87Sr/86Sr ratio was determined by multicollector inductively coupled plasma mass spectrometry. The results demonstrate a wide range of Sr isotopic values (0.7048 to 1.0330) over the survey area, reflecting a large diversity of source rock lithologies, geological processes, and bedrock ages. The spatial distribution of 87Sr/86Sr shows coherent (multi-point anomalies and smooth gradients), large-scale (>100 km) patterns that appear to be broadly consistent with surface geology, regolith/soil type, and/or nearby outcropping bedrock. For instance, the extensive black clay soils of the Barkly Tableland define a >500 km long northwest–southeast-trending unradiogenic anomaly (87Sr/86Sr <0.7182). Where sedimentary carbonate or mafic/ultramafic igneous rocks dominate, low to moderate 87Sr/86Sr values are generally recorded (medians of 0.7387 and 0.7422, respectively). Conversely, In proximity to the outcropping Proterozoic metamorphic basement of the Tennant, McArthur, Murphy, and Mount Isa geological regions, radiogenic 87Sr/86Sr values (>0.7655) are observed. A potential correlation between mineralization and elevated 87Sr/86Sr values in these regions needs to be investigated in greater detail. Our results to date indicate that incorporating soil/regolith Sr isotopes in regional, exploratory geoscience investigations can help identify basement rock types under (shallow) cover, constrain surface processes (e.g. weathering and dispersion), and, potentially, recognize components of mineral systems. Furthermore, the resulting Sr isoscape and future models derived therefrom can also be utilized in forensic, archaeological, palaeontological, and ecological studies that aim to investigate, for example, past and modern animal (including humans) dietary habits and migrations. The new spatial Sr isotope dataset for the northern Australia region is publicly available (de Caritat et al., 2022a; https://doi.org/10.26186/147473).
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Soloshenko, N. G., M. V. Streletskaya, M. V. Chervyakovskaya y D. V. Kiseleva. "Implementation and experience of using methods for analyzing the isotopic composition of Sm and Nd, Rb and Sr in rock samples at the Geoanalitik Center for Collective Use". LITHOSPHERE (Russia) 24, n.º 2 (7 de mayo de 2024): 364–75. http://dx.doi.org/10.24930/1681-9004-2024-24-2-364-375.
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Research subject. AGV-2 and BHVO-2 geochemical reference materials for studying the Sm, Nd and Rb, Sr isotope systems along with various rocks and mineral samples. Materials and Methods. An analysis of the isotopic composition of Sm, Nd and Rb, Sr was carried out using Neptune Plus and Triton Plus mass spectrometers. Aim. To implement analytical techniques for the isotopic composition of Sm and Nd, Rb, and Sr in various rock and mineral samples using two types of multicollector mass spectrometers – inductively coupled plasma NeptunePlus and thermal ionization TritonPlus (Thermo-Fisher), as well as a description of the procedure of processing experimental data and the experience in using techniques at the “Geoanalitik” shared research facilities of the IGG UB RAS for the period 2015-2023. Results. The analytical techniques implemented included (1) column chromatography using various ion-exchange resins, optimised for the ratio of labour costs/quality of analytical results; (2) the measurement of isotope ratios using two types of mass spectrometers; (3) the correction of mass bias of isotope ratios and the determination of Sm and Nd, Rb, and Sr concentrations by the isotope dilution method using 149Sm+150Nd and 85Rb+84Sr spikes. Testing of the techniques was carried out using the AGV-2 and BHVO-2 geochemical reference materials; their metrological characteristics were presented. When using TritonPlus, the reproducibility (BHVO-2, n=60) of measurements of 143Nd/144Nd, 147Sm/144Nd isotope ratios and Sm and Nd concentrations are ±0.000020, ±0.0004, ±1.3 and ±0.4, respectively; indicators of correctness of determining the ratios 143Nd/144Nd and 147Sm/144Nd – 0.001 and 0.25% and concentrations of Sm and Nd – 2%; the reproducibility (BHVO-2, n=63) of measurements of 87Sr/86Sr, 87Rb/86Sr isotope ratios and concentrations (Rb and Sr) are ±0.0025%, ±1.5%, ±2%, respectively. The uncertainty of a single measurement of the 143Nd/144Nd and 87Sr/86Sr isotope ratio, represented by the standard error of the average single measurement in the sample, does not exceed 0.0025%. Conclusions: the results obtained for the geochemical reference materials are in satisfactory agreement with those provided in the GeoReM database, as well as with the certified values provided by the United States Geological Survey (USGS). The described analytical techniques are used at the “Geoanalitik” shared research facilities of the IGG UB RAS to analyse various rock and mineral samples. The work presents a number of experimental results obtained, which are subsequently used in geochronological applications.
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Spišiak, Ján, Anna Vozárová, Jozef Vozár, Štefan Ferenc, Viera Šimonová y Juraj Butek. "Implication of Mineralogy and Isotope Data on the Origin of the Permian Basic Volcanic Rocks of the Hronicum (Slovakia, Western Carpathians)". Minerals 11, n.º 8 (4 de agosto de 2021): 841. http://dx.doi.org/10.3390/min11080841.
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The paper presents new geochemical data of the basic to intermediate volcanic rocks from the Hronic unit. The studied rocks are strongly altered and the primary mineral composition (clinopyroxenes, amphiboles, spinels, biotites, and plagioclases) is preserved only in some localities. The clinopyroxene corresponds to augite and primary amphiboles to pargasites. Spinels have a chemical composition similar to spinels from volcanic rocks. According to chemical composition, the studied basalts correspond to rift-related continental tholeiites. 143Nd/144Nd vs. 87Sr/86Sr isotopic ratios of the basalts are scattered around the value of 143Nd/144Nd for CHUR, where 143Nd/144Nd ratios are relatively stable and 87Sr/86Sr values are relatively varied. According to isotopic ratio of 207Pb/204Pb vs. 206Pb/204Pb, the basalt analyses lie in the field of EMII (mantle source enriched with crustal materials). The new results of U-Pb LA-ICP-MS dating of apatite point to an age 254 ± 23 Ma (Lopingian).
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Chen, Song y Herong Gui. "Isotopic characteristics of D, 18O, 13Cdic, 18Odic, 87Sr/86Sr and their application in coal mine water: a case study". Water Practice and Technology 12, n.º 1 (1 de marzo de 2017): 97–103. http://dx.doi.org/10.2166/wpt.2017.017.
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In order to understand the isotopic characteristics of coal mine water in diverse aquifers, ten groundwater samples were collected from three aquifers – Quaternary (QA), Coal-bearing (CA), and Limestone (LA) – in Xutuan coal mine, Anhui Province, China. The geochemical characteristics of major ions and isotopes were determined, and the results showed that all of the groundwater samples are HCO3-Na·K or Cl-Na·K types. The concentrations of Na+ + K+ decreased in the order CA > QA > LA, whereas the content of Ca2+ and Mg2+ increased from CA to LA. Groundwater in LA is meteoric in origin, while that in QA is clearly influenced by surface water. The δ13Cdic and δ18Odic in groundwater samples from LA, QA and CA are influenced by the surrounding strata, CO2 and microorganism activity, respectively. The strontium concentration decreases in the sequence LA > CA > QA, but water samples from CA give the highest value of 87Sr/86Sr. Strontium is released by dissolution from the surrounding rock, and the 87Sr/86Sr ratio could be used to identify the groundwater source.
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Blum, Joel D. "A petrologic and Rb–Sr isotopic study of intrusive rocks near Fairbanks, Alaska". Canadian Journal of Earth Sciences 22, n.º 9 (1 de septiembre de 1985): 1314–21. http://dx.doi.org/10.1139/e85-135.
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Epizonal granodiorite and granite plutons intrude the northwestern portion of the Yukon Crystalline Terrane near Fairbanks, Alaska. Mineralogic, major-oxide, and trace-element studies indicate that the plutons represent a comagmatic fractionation suite. A Rb–Sr whole-rock isochron for one pluton yields an age of 90.9 ± 0.9 Ma, in agreement with previous K–Ar dating of biotite and hornblende and an initial 87Sr/86Sr ratio of 0.71238 ± 0.00014. The elevated initial 87Sr/86Sr ratio suggests that the plutons may have had a different source from that of the belt of subduction-related, mid-Cretaceous plutonic rocks found farther to the southeast in the Yukon Crystalline Terrane. In contrast, they appear to have been formed at least in part by anatectic melting of Late Proterozoic or early Paleozoic crustal rocks. Comparison of aplite dike compositions with the synthetic granite system, estimates of average uplift rate, and K–Ar cooling ages of surrounding schists all indicate that the magmas that formed the plutons near Fairbanks intruded much higher into the crust after anatectic melting and crystallized at a relatively shallow depth of 3–5 km.
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Sitkina, D. R., A. B. Kuznetsov, G. V. Konstantinova y T. L. Turchenko. "The Isotopic Age and Correlation of Carbonate Rocks of the Ara-Oshei Formation (Tunka Ridge, East Sayan)". Russian Geology and Geophysics 63, n.º 8 (1 de agosto de 2022): 901–14. http://dx.doi.org/10.2113/rgg20214378.
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Abstract —We present results of Pb–Pb geochronology and Sr- and C- chemostratigraphic study of limestones and dolomites of the Ara-Oshei Formation of the Tunka ridge in East Sayan. The δ13C value of the limestones varies from –0.6 to 2.3‰ PDB, the 87Sr/86Sr ratio is within 0.70851–0.70864, and the Pb–Pb age is 521 ± 21 Ma (MSWD = 0.9). The δ13C value of the dolomites varies from –3.9 to 0.5‰ PDB, the 87Sr/86Sr ratio is 0.70844–0.70882, and the Pb–Pb age is 417 ± 8 Ma (MSWD = 2.5). The U–Pb isotope system of the dolomites was disturbed during the geologic evolution of the region, which led to the rejuvenation of their Pb–Pb age in the Early Devonian. The obtained Sr-chemostratigraphic and Pb–Pb data show that the limestones of the Ara-Oshei Formation accumulated in the early Cambrian. This provides a reliable proof that the limestones are part of the Vendian–Cambrian sedimentary cover of the Tuva–Mongolian massif.
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Munro, Andrew R., Bronwyn M. Gillanders, Travis S. Elsdon, David A. Crook y Andrew C. Sanger. "Enriched stable isotope marking of juvenile golden perch (Macquaria ambigua) otoliths". Canadian Journal of Fisheries and Aquatic Sciences 65, n.º 2 (1 de febrero de 2008): 276–85. http://dx.doi.org/10.1139/f08-010.
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Stocking of native fish is a standard practice to aid in the recovery and enhancement of depleted populations. However, evaluating the effectiveness of these stocking programs has been hindered because of difficulty in distinguishing hatchery from wild fish, especially for species that are stocked as small, fragile fingerlings. Stable isotopes offer the potential to chemically mark fish with multiple marks that are distinct from each other and from natural signatures. Golden perch (Macquaria ambigua) fingerlings were reared in water enriched in 137Ba and combinations of 137Ba and 86Sr for various lengths of time. Ba and Sr isotopic ratios in the otoliths were determined using laser ablation inductively coupled plasma-mass spectrometry. Fish exposed to increased levels of 137Ba had lower 138Ba/137Ba ratios in their otoliths relative to the natural ratio of control fish and were significantly different in fish exposed to at least 5 µg·L-1 for 8 days or to 15 µg·L-1 for 4 days. Furthermore, eight unique signatures were produced in fish reared in combinations of 137Ba (0–5 µg·L-1) and 86Sr (0–100 µg·L-1) for 24 days. Our results suggest that immersion in water enriched in specific stable isotopes could be an effective means of marking hatchery-reared fish for stock enhancement.
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Vetrova, N. I., E. V. Vetrov y E. F. Letnikova. "СHEMOSTRATIGRAPHY OF THE CARBONATE DEPOSITS OF THE KINTEREP FORMATION IN NORTHWESTERN SALAIR: FIRST DATA". Geology and mineral resources of Siberia, n.º 2 (junio de 2022): 10–23. http://dx.doi.org/10.20403/2078-0575-2022-2-10-23.
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The results of geochemical, isotope-geochemical (Sr, C, O) surveys of the Kinterep Formation carbonate deposits of Northwestern Salair and U-Pb dating (LA-ICP-MS) of zircons were given. Carbonate rocks represented by pure limestones are characterized by normal values of δ18OSMOW from 19.8 to 23.8 ‰ and δ13 CPDB from –0.7 to +0.9, the isotopic composition of Sr (87Sr/86Sr ratio) varies in a narrow range from 0.708486 to 0.708582.Using Sr and C isotope chemostratigraphy and U-Pb dating of zircons, age limits (525-510 Ma) were determined for the formation time of carbonate deposits of the Kinterep Formation. The first data of isotope chemostratigraphy in combination with the results of geochronological studies made it possible to compare the limestones of the Kinterep Formation of Northwestern Salair with carbonate sections of Siberia and Central Asia.
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CORDANI, UMBERTO G., ANA M. MIZUSAKI, KOJI KAWASHITA y ANTONIO THOMAZ-FILHO. "Rb–Sr systematics of Holocene pelitic sediments and their bearing on whole-rock dating". Geological Magazine 141, n.º 2 (marzo de 2004): 233–44. http://dx.doi.org/10.1017/s0016756803008616.
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In many cases, when dealing with argillaceous fine-grained sedimentary rocks, the isotopic ages obtained from Rb–Sr whole-rock isochron calculations are of geological significance, despite the fact that the initial conditions of Sr isotopic homogenization are not fulfilled. To explain this, a mechanical mixing during deposition has been suggested, leading to an aggregate of mixed material with fairly uniform 87Sr/86Sr values, whatever Rb/Sr ratio is found in the analysed samples. This investigation of the behaviour of Rb and Sr during sedimentation and early diagenesis, involves study of more than 60 samples of fine-grained recent sediments from selected coastal localities of Brazil. The results indicate that pelitic samples from some recent to present-day transitional or shallow marine environments, such as the Jacarepaguá tidal flat and the Amazonas River mouth, where halmirolysis could have occurred, may produce nearly horizontal best-fit lines in a Rb–Sr isochron diagram. Moreover, the initial isotopic 87Sr/86Sr ratios appear to be well above 0.710. In open marine environments, such as the Campos Basin, where sampling was spread over more than 100 metres, exchanges between the argillaceous sediments and seawater potentially happen at low temperature, inducing a reduction of the 87Sr/86Sr isotopic composition of the sediments to nearly 0.710. An almost horizontal best-fit line is produced for the entire stratigraphic section, independent of the sedimentation age. We believe that in similar environments such ‘zero age isochrons’ are maintained for some time, testifying to exchanges between the sediment and the interstitial fluids, before the onset of burial diagenesis. The above described studies on fine-grained and recent argillaceous sediments seem to confirm the production of horizontal best-fit lines in isochron diagrams, justifying the application of the Rb–Sr whole-rock method to pelitic sedimentary rocks. The nature of the material is critical. The pelitic sediments to be analysed should contain only very limited amounts of coarse clastic material (especially feldspars and mica fragments) and consist mainly of fine clay minerals in which smectites, illite and mixed layers illite–smectite largely predominate.
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Armstrong, Richard Lee y Paul Ramaekers. "Sr isotopic study of Helikian sediment and diabase dikes in the Athabasca Basin, northern Saskatchewan". Canadian Journal of Earth Sciences 22, n.º 3 (1 de marzo de 1985): 399–407. http://dx.doi.org/10.1139/e85-038.
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The Athabasca Group overlies 1.8 Ga or older basement of the Churchill Province and predates uranium mineralization at 1.3 Ga. Cross-cutting diabase dikes have been dated by Rb–Sr mineral isochrons at 1.31 ± 0.07 Ga at Diabase Peninsula, Cree Lake, and 1.16 ± 0.04 Ga at Lazy Edward Bay, Cree Lake. Initial 87Sr/86Sr ratios for these dikes are 0.7040 ± 0.0005 and 0.7036 ± 0.002, respectively. Clastic sedimentary rocks of the Athabasca Group normally show limited variation in Rb/Sr and variable initial 87Sr/86Sr. Sedimentary rocks in two areas near the northern margin of the Athabasca Basin scatter about isochrons of 2.6 Ga, reflecting Archean provenance of detrital material and lack of Sr isotopic homogenization since deposition. Sediment of the tuffaceous Wolverine Point Formation, near Rumpel Lake, is much more variable in Rb/Sr and enriched in Rb relative to Sr and defines a 1.43 ± 0.03 Ga isochron with a 0.7057 ± 0.0005 initial ratio. This is possibly the age of deposition of the Athabasca Group.
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Gorokhov, I. M., T. S. Zaitseva, A. B. Kuznetsov, G. V. Ovchinnikova, M. M. Arakelyants, V. P. Kovach, G. V. Konstantinova, T. L. Turchenko y I. M. Vasil’eva. "Isotope Systematics and the Age of Authigenic Minerals in Shales of the Inzer Formation, the Southern Urals". Стратиграфия 27, n.º 2 (25 de marzo de 2019): 3–30. http://dx.doi.org/10.31857/s0869-592x2723-30.
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The 2–5, 0.6–2, 0.3–0.6, 0.2–0.3 and 0.1–0.2 µm clay subfractions (SFs) separated from two shale samples of the Upper Riphean Inzer Formation, the southern Urals, were studied by the TEM, XRD, and U–Pb, Sm–Nd, Rb–Sr and K–Ar isotopic methods. All the SFs consist of the low-temperature 1Md illite; admixtures of quartz, chlorite and 2M1 illite occur only in the coarsest SFs. The clay particles are isometric, regardless of their size. The CIS (Crystallinity Index Standard) illite values for the all SFs are typical for the dia(kata)genetic zone. As the size of particles in the SF decreases from 2–5 to 0.1–0.2 µm, the CIS rises, the I002/I001 ratio on the XRD diagrams decreases, and the K content and the K/Rb ratio increase.
Leaching with 1N HCl and 1N ammonium acetate (NH4OAc) and subsequent U–Pb, Sm–Nd and Rb–Sr analyses of the untreated SF, acid (acetate) leachate and residue made possible to study the mixing systematics in mobile and silicate materials of the shales. The 238U/204Pb and 87Rb/86Sr ratios in the acid and acetate leachates are below, and the 147Sm/144Nd ratio is above those in the residues. Less radiogenic Pb and Sr and more radiogenic Nd are also common for the leachates compared to the residues. As the size of particles in the SFs decreases, the U, Pb, Sm, Nd and Sr contents in the residues are smoothly reduced, whereas the Rb content shows an increase. The 87Rb/86Sr and 87Sr/86Sr values in the residues for fine-grained SFs are well above, and the 238U/204Pb value is well below those for coarse-grained SFs. What is more, in the 87Rb/86Sr–87Sr/86Sr and 1/86Sr–87Sr/86Sr diagrams, data points for the residues of variable size are arranged on the mixing lines. The data points of respective acid and acetate leachates also form linear trends in the 238U/204Pb–206Pb/204Pb, 206Pb/204Pb–207Pb/204Pb, 147Sm/144Nd–143Nd/144Nd, and 87Rb/86Sr–87Sr/86Sr coordinates. The apparent Rb–Sr age values, calculated from the slopes of “inner isochrons” (“leachochrons”), along with the K–Ar ages are smoothly lowered from 835–836 and 721–773 m.y. for the 2–5 µm SF to 572–580 and 555–580 m.y. for the 0.1–0.2 µm SF. Hence the XRD and isotopic data testify that the clay as well as the mobile material of the shale represent the mixtures of at least two components, the silicate phase containing authigenic illites of different ages. The first illite generation enriched in coarse-grained 2–5 and 0.6–2 µm SFs was formed shortly after deposition of the Inzer sediments, and its age of 803–836 m.y. is in agreement with the stratigraphic age of the formation. Simple lithostatic burial or intensive lateral fluid flow induced by tectonic inversion in the eastern regions of the Urals paleobasin may be considered as the geological processes responsible for the forming of this illite. The second illite generation was formed 572–580 m.y. ago. As the starting points for its formation, alternatively, may be concerned either vertical tectonics or renewal of pore fluid compositions during deformations and metamorphism on the southern Urals area related to evolution of the Beloretsk metamorphic complex.
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Jiao, He, Guo-Biao Huang, Wei Ma, Qiang-Qiang Cui, Wei-Hu Wang, Qing-Feng Ding, Xuan Zhou y Rui-Zhe Wu. "Geochemical and Isotopic Compositions of Fluorites from the Yama Fluorite Deposit in the Qilian Orogen in Northwest China, and Their Metallogenic Implications". Minerals 14, n.º 1 (28 de diciembre de 2023): 37. http://dx.doi.org/10.3390/min14010037.
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The Yama area is characterized by numerous large-scale fluorite–quartz veins that are located along faults within the widespread Late Devonian–Late Silurian syenogranites in the Tataleng granitic batholith, Qilian Orogen, Northwest China. These fluorite–quartz veins contribute to an important fluorite reserve, but their ore genesis remains unresolved so far. In this study, trace elements, rare earth elements (REEs), and hydrogen, oxygen, and strontium isotopic compositions of fluorites are analyzed. The studied fluorite samples have similar chondrite-normalized REEs, including Y patterns, with relatively strong enrichment in heavy REEs, negative Eu anomalies, strongly positive Y anomalies, and comparably invariable Y/Ho ratios of 41.43–73.79, suggesting a unique hydrothermal genesis. The relatively variable values of δD and δ18O are −77.4‰ to −102.4‰ and −12.7‰ to −4.3‰, respectively, close to the meteoric water line. These fluorites yield relatively invariable analytical 87Sr/86Sr ratios of 0.749089−0.756628 (except for an anomalously high ratio), and their calculated initial 87Sr/86Sr ratios, based on the ore-forming ages provided, are apparently higher than the calculated initial 87Sr/86Sr ratios of syenogranite wall rocks. Collectively, the geochemistry of trace elements, REEs, and stable isotopes (H, O, and Sr) suggests that the ore-forming fluids were of meteoric origin and that the Sr sources were directly derived from the ore-forming fluids themselves rather than syenogranite wall rocks. Finally, it was considered that the Yama fluorite deposit is a fault-controlled hydrothermal vein-type deposit which was possibly related to the evolution of the Paleo-Tethys Ocean in the Permian–Triassic.
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Négrel, P., E. Petelet-Giraud y D. Widory. "Strontium isotope geochemistry of alluvial groundwater: a tracer for groundwater resources characterisation". Hydrology and Earth System Sciences 8, n.º 5 (31 de octubre de 2004): 959–72. http://dx.doi.org/10.5194/hess-8-959-2004.
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Abstract. This study presents strontium isotope and major ion data of shallow groundwater and river water from the Ile du Chambon catchment, located on the Allier river in the Massif Central (France). There are large variations in the major-element contents in the surface- and groundwater. Plotting of Na vs. Cl contents and Ca, Mg, NO3, K, SO4, HCO3, Sr concentrations reflect water–rock interaction (carbonate dissolution for Ca, Mg, HCO3 and Sr because the bedrock contains marly limestones), agricultural input (farming and fertilising) and sewage effluents (for NO3, K, SO4), although some water samples are unpolluted. Sr contents and isotope ratios (87Sr/86Sr vary from 0.70892 to 0.71180 along the hydrological cycle) in the groundwater agree with previous work on groundwater in alluvial aquifers in the Loire catchment. The data plot along three directions in a 87Sr/86Sr v. 1/Sr diagram as a result of mixing, involving at least three geochemical signatures–Allier river water, and two distinct signatures that might be related to different water-rock interactions in the catchment. Mixing proportions are calculated and discussed. The alluvial aquifer of the Ile du Chambon catchment is considered, within the Sr isotope systematic, in a larger scheme that includes several alluvial aquifers of the Loire Allier catchment. Keywords: : Loire river, major and trace elements, Sr isotopic ratio, alluvial aquifer, hydrology
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Boschetti, Tiziano, Mohamed Awaleh y Maurizio Barbieri. "Waters from the Djiboutian Afar: A Review of Strontium Isotopic Composition and a Comparison with Ethiopian Waters and Red Sea Brines". Water 10, n.º 11 (21 de noviembre de 2018): 1700. http://dx.doi.org/10.3390/w10111700.
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Drinking water is scarce in Djibouti because of the hot desert climate. Moreover, seawater intrusion or fossil saltwater contamination of the limited number of freshwater aquifers due to groundwater overexploitation affect those who live close to the coastline (~80% of the population). Despite this, the geothermal potential of the country’s plentiful hot springs could resolve the increasing electricity demand. Strontium isotopes (87Sr/86Sr) are routinely used to determine sources and mixing relationships in geochemical studies. They have proven to be useful in determining weathering processes and quantifying endmember mixing processes. In this study, we summarise and reinterpret the 87Sr/86Sr ratio and Sr concentration data of the groundwater collected to date in the different regions of the Djibouti country, trying to discriminate between the different water sources, to evaluate the water/rock ratio and to compare the data with those coming from the groundwater in the neighbouring Main Ethiopian Rift and the Red Sea bottom brine. New preliminary data from the groundwater of the Hanlé-Gaggadé plains are also presented.
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Brombin, Valentina, Claudio Natali, Gianluca Frijia, Katharina Schmitt, Martina Casalini y Gianluca Bianchini. "Isotope Geochemistry for Seafood Traceability and Authentication: The Northern Adriatic Manila Clams Case Study". Foods 11, n.º 19 (1 de octubre de 2022): 3054. http://dx.doi.org/10.3390/foods11193054.
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In Italy, the production of manila clams (Ruditapes philippinarum, Adams and Reeve, 1850) is mainly localized in northern Adriatic lagoons in the Po River delta, where shellfish farming provides important socio-economic revenue. However, in our globalized world, the seafood market is threated by fraudulent activities, in which agri-food products whose provenance is not certified are sold, posing a risk to consumer health. Multi-isotope ratio analysis is commonly used to trace the provenance of goods produced in different countries with different climatic and environmental conditions. Here, we investigated the reliability of this approach in terms of tracing the exact provenance of manila clams harvested in three Adriatic northern lagoons that are close to each other. We also verified the origin of samples bought at a local supermarket with a certificate of provenance. We carried out elemental analyses of carbon (C), nitrogen (N), and sulfur (S) and the respective isotopic ratios (13C/12C; 15N/14N; 34S/32S) on manila clam tissues, plus isotopic analyses of carbon (13C/12C), oxygen (18O/16O), and strontium (87Sr/86Sr) on manila clam shells. Each isotopic parameter can be used to identify the marine and continental contributions of water and/or nutrient supplies occurring in the lagoons. Therefore, the combination of isotopic parameters in a linear discriminant analysis (LDA) allowed for the identification of the lagoons in which the manila clams were produced.
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Mancini, Marco, Elisabetta D'Anastasio, Mario Barbieri y Paolo Marco De Martini. "Geomorphological, paleontological and 87Sr/86Sr isotope analyses of early Pleistocene paleoshorelines to define the uplift of Central Apennines (Italy)". Quaternary Research 67, n.º 3 (mayo de 2007): 487–501. http://dx.doi.org/10.1016/j.yqres.2007.01.005.
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AbstractThe eastern border of the Middle Valley of the Tiber River is characterized by several Plio-Pleistocene paleoshorelines, which extend for about 100 km along the western margin of the Central Apennines (Italy). We studied these paleoshorelines by the means of geological and paleontological analyses and new 87Sr/86Sr isotope analyses. The youngest and uppermost paleoshorelines have been detected and mapped through detailed geologic and stratigraphic surveys, which led to the recognition of nearshore deposits, cliff breccias, alignments of Lithophaga borings, fossil abrasion notches and wave-cut platforms. The altitude of these paleoshorelines decreases almost regularly in the NNW–SSE direction from 480 to 220 m a.s.l. Measurements of the 87Sr/86Sr isotope ratio have been conducted on corals and mollusks collected from sediments outcropping close to the paleoshorelines. The isotopic dating results indicate numerical values that range between 0.70907 and 0.70910 all over the 100-km outcrop. These results, together with biostratigraphic data, constrain the age of the youngest paleoshorelines to 1.65–1.50 Ma. These paleoshorelines are thus considered almost isochronous, giving an estimated uplift rate of 0.34–0.17±0.03 mm/a moving from NNW to SSE. Shape, length and continuity of the 100-km-long observed movements indicate that the studied paleoshorelines are an important marker of the Quaternary uplift of the Central Apennines.
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Tinoco, Rachel Lima Ribeiro, Murilo Quitans Ribeiro Bastos, Carlos Eduardo Palhares Machado, Roberto Ventura Santos y Claudia Rodrigues-Carvalho. "Isotopic analysis in teeth of contemporary brazilians with known diet and geolocation and its forensic value for human identification". Research, Society and Development 10, n.º 12 (19 de septiembre de 2021): e238101220243. http://dx.doi.org/10.33448/rsd-v10i12.20243.
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Dental anthropological data may provide valuable information about an individual's life, including age at death, health, signs of violence, ancestry, diet features, intentional modifications, and geographic origin. These pieces of information may be further detailed by diet and residential mobility estimates provided by isotopic analyses. The use of isotope data in the modern population is strongly dependent on the diverse origin of food supply, thus requiring an updated and location-specific database. In this study, we have analyzed the isotopic ratio of strontium, carbon, and nitrogen in enamel and dentin collagen of third molars individuals from three main cities in Brazil. Besides the isotope data, we have also surveyed their diet in adolescence habits to develop models to be applied for forensic studies in the Brazilian territory. We show that the forensic value of the place of origin estimation based 87Sr/86Sr levels is reduced in these highly urbanized samples. Among the outliers, most individuals are older than the mean age (25.1) or had water from wells in childhood. The sample's diet has a robust C4 presence and mean trophic levels consistent with the declared high frequency of chicken, meat, and dairy products, also compatible with the high consumption of sugar, rice, and beans in the local culture. Individuals with special diets, either by choice or therapeutic needs, were potential outliers among the group. Our results also contribute to the international human tissues isotopic database and can contribute for human identification of Brazilians or foreigners with distinct isotopic signatures.
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Karasinski, Jakub, Ewa Bulska, Marcin Wojciechowski, Agnieszka Anna Krata y Ludwik Halicz. "On-line separation of strontium from a matrix and determination of the 87Sr/86Sr ratio by Ion Chromatography/Multicollector-ICPMS". Journal of Analytical Atomic Spectrometry 31, n.º 7 (2016): 1459–63. http://dx.doi.org/10.1039/c6ja00109b.
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In this work a high throughput, robust and sensitive method for the precise isotopic analysis of 87Sr/86Sr by coupling Ion Chromatography (IC) and Multicollector Inductively Coupled Plasma Mass Spectrometry (MC-ICPMS) is presented.
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Clark, G. S. y D. C. P. Schledewitz. "Rubidium–strontium ages of Archean and Proterozoic rocks in the Nejanilini and Great Island domains, Churchill Province, northern Manitoba, Canada". Canadian Journal of Earth Sciences 25, n.º 2 (1 de febrero de 1988): 246–54. http://dx.doi.org/10.1139/e88-027.
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Rubidium–strontium whole-rock ages are reported from the Nejanilini – Great Island area in northeastern Manitoba. This area is part of an extensive zone of Archean basement that was metamorphosed and intruded by granitic magma during the Proterozoic; it extends into Saskatchewan and southern District of Keewatin, Northwest Tertitories. An age of 2577 ± 42 Ma (1σ error) for the extensive Nejanilini granulite massif (Nejanilini domain), considered one of the oldest rock units in the area, is interpreted as a minimum age for late Archean granulite-facies metamorphism. A minimum age of 2052 ± 41 Ma (initial ratio 0.7150) for quartz–feldspar porphyry that intrudes the Seal River volcanic suite constrains the age of these volcanics and could represent a partially reset Archean age. Early Proterozoic quartzite and metagreywacke of the Great Island Group unconformably overlies the quartz–feldspar porphyry. These metasedimentary rocks, which are probably correlative with the Daly Lake Group (Saskatchewan) or the Hurwitz Group (southern District of Keewatin), give an age of 1885 ± 85 Ma, with an initial ratio of 0.7093. The age records the time of closure of the Rb–Sr isotopic system subsequent to early Proterozoic metamorphism. The age and initial ratio are consistent with published results for other, possibly correlative, metasedimentary rocks in this zone. Modelling the Rb–Sr isotopic data constrains the time of sedimentation to between ca. 2100 and 2000 Ma ago. Syn- to late-kinematic, early Proterozoic granite to granodiorite batholiths, which intruded metasedimentary rocks of the Great Island Group, may largely be the product of melting of Archean basement, based on field evidence and high initial 87Sr/86Sr ratios. The Caribou Lake porphyritic quartz monzonite gives an age of 1795 ± 35 Ma, with an initial 87Sr/86Sr ratio of 0.7084. High initial ratios seem to typify early Proterozoic granitic rocks in this remobilized craton.
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Pereira, Luciana A., Roberto V. Santos, Marília Hauser, Fabrice Duponchelle, Fernando Carvajal, Christophe Pecheyran, Sylvain Bérail y Marc Pouilly. "Commercial traceability of <i>Arapaima</i> spp. fisheries in the Amazon basin: can biogeochemical tags be useful?" Biogeosciences 16, n.º 8 (26 de abril de 2019): 1781–97. http://dx.doi.org/10.5194/bg-16-1781-2019.
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Abstract. The development of analytical tools to determine the origin of fishes is useful to better understand patterns of habitat use and to monitor, manage, and control fisheries, including certification of food origin. The application of isotopic analyses to study calcified structures of fishes (scales, vertebrae, and otoliths) may provide robust information about the fish geographic origin and environmental living conditions. In this study, we used Sr and C isotopic markers recorded in otoliths of wild and farmed commercialized pirarucu (Arapaima spp.) to evaluate their prediction potential to trace the fishes origin. Wild and farmed fish specimens, as well as food used for feeding pirarucu in captivity, were collected from different sites. Isotope composition of otoliths performed by isotope-ratio mass spectrometry (IRMS; δ13C) and femtosecond laser ablation multi-collector inductively coupled plasma mass spectrometry (LAfs-MC-ICPMS; 87Sr∕86Sr) were compared to the isotopic composition of water and of the food given to the fishes in the farms. Wild fish specimens that lived in environments with the largest fluctuation of river water Sr isotope ratios over time presented the largest Sr isotope variations in otoliths. A quadratic discriminant analysis on otolith isotopic composition provided 58 % of correct classification for fish production (wild and farmed) and 76 % of correct classification for the fish region. Classification accuracy for region varied between 100 % and 29 % for the Madeira and the Lower Amazon fishes, respectively. Overall, this preliminary trial is not yet fully developed to be applied as a commercial traceability tool. However, given the importance of Arapaima spp. for food security and the generation of economic resources for millions of people in the Amazon basin, further analyses are needed to increase the discrimination performance of these biogeographical tags.
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Lilov, Petar. "Rb-Sr and K-Ar dating of Sakar granitoid pluton". Geologica Balcanica 20, n.º 6 (30 de diciembre de 1990): 53–60. http://dx.doi.org/10.52321/geolbalc.20.6.53.
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Rb-Sr isotopic data have been obtained for 9 wholerock samples from equigranular and porphyroid granitoids from Sakar pluton. A reliable isochron is based upon 7 of them, the corresponding age being 500±70 Ma, and the initial (87Sr/86Sr)i ratio of 0.70279±0.00149. The low initial strontium ratio indicates a mantle origin for the primary magma, and presumably acid magmas formed by differentiation and fractioning without contamination with old crustal material. It is supposed that the intrusion was simultaneous with a metamorphic event during the Assyntian (550-500 Ma) orogenesis. K-Ar data (within the range 106-120 Ma) reflect argon migration from the minerals due to a Late Cretaceous tectonothermal event.
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Porru, Maria Chiara, Claudio Arras, Riccardo Biddau, Rosa Cidu, Francesca Lobina, Francesca Podda, Richard Wanty y Stefania Da Pelo. "Assessing Recharge Sources and Seawater Intrusion in Coastal Groundwater: A Hydrogeological and Multi-Isotopic Approach". Water 16, n.º 8 (12 de abril de 2024): 1106. http://dx.doi.org/10.3390/w16081106.
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One of the crucial challenges of our time is climate change. The consequences of rising sea levels and drought greatly impact water resources, potentially worsening seawater intrusion. Characterizing coastal aquifers is an essential step in devising strategies to address these phenomena. Seawater intrusion poses a critical socio-economic and environmental issue in the coastal plain of Muravera, southeastern Sardinia (Italy). This coastal plain is an important agricultural area in Sardinia, and the health of the crops is compromised by the increasing salinization of shallow groundwater. To enhance our understanding of the hydrogeological conceptual model, which is essential for a sustainable resource management system, hydrogeological investigations were conducted and complemented by the chemical and multi-isotopic analyses of groundwater. The main objectives of this study were to identify groundwater recharge areas, understand salinization mechanisms and trace the evolution of water chemistry. Within this framework, a monthly survey monitoring piezometric level and electrical conductivity was carried out for one year. This survey was integrated with chemical and isotope analyses, including δ18OH2O and δ2HH2O, δ11B, δ18OSO4, δ34SSO4, and 87Sr/86Sr. Hydrochemistry analysis results revealed the occurrence of seawater–freshwater mixing, extending up to 4 km inland. H2O isotope analysis confirmed the mixing processes and indicated the meteoric origin of recharge waters for both shallow and semi-confined aquifers. The strontium isotopes ratio facilitated the identification of four main groundwater flow paths, confirmed by the SIAR model. The results of this combined hydrogeological–geochemical–isotopic survey provide essential elements for the future implementation of an integrated and sustainable management system. These findings enable interventions to slow the process of seawater intrusion and meet the economic needs for the development of local communities.
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Zhong, Yun, Xu Zhang, Zhilei Sun, Jinnan Liu, Wei Li, Yaoliang Ma, Weiliang Liu, Bin Xia y Yao Guan. "Sr–Nd–Pb–Hf Isotopic Constraints on the Mantle Heterogeneities beneath the South Mid-Atlantic Ridge at 18–21°S". Minerals 10, n.º 11 (13 de noviembre de 2020): 1010. http://dx.doi.org/10.3390/min10111010.
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In an attempt to investigate the nature and origin of mantle heterogeneities beneath the South Mid-Atlantic Ridge (SMAR), we report new whole-rock Sr, Nd, Pb, and Hf isotopic data from eight basalt samples at four dredge stations along the SMAR between 18°S and 21°S. Sr, Nd, and Pb isotopic data from SMAR mid-ocean ridge basalts (MORBs) at 18–21°S published by other researchers were also utilized in this study. The SMAR MORBs at 18–21°S feature the following ratio ranges: 87Sr/86Sr = 0.70212 to 0.70410, 143Nd/144Nd = 0.512893 to 0.513177, 206Pb/204Pb = 18.05 to 19.50, 207Pb/204Pb = 15.47 to 15.71, 208Pb/204Pb = 37.87 to 38.64, and 176Hf/177Hf = 0.283001 to 0.283175. The 87Sr/86Sr, 143Nd/144Nd, 206Pb/204Pb, and 176Hf/177Hf ratios of these MORBs varied considerably along the SMAR axis. The variable compositions of the Sr–Nd–Pb–Hf isotopes, combined with the corresponding whole-rock major and trace elemental abundances reported in previous studies, suggest that the SMAR MORBs at 18–21°S were probably derived from a heterogeneous mantle substrate related to a mixture of depleted mantle (DM) materials with a small amount (but variable input) of HIMU (high-μ, where μ = 238U/204Pb)- and enriched (EMII)-type materials. The HIMU-type materials likely originated from the proximal St. Helena plume and may have been transported through “pipe-like inclined sublithospheric channels” into the SMAR axial zone. The EMII-type materials possibly originated from a recycled metasomatized oceanic crust that may have been derived from the early dispersion of other plume heads into the subcontinental asthenosphere prior to the opening of the South Atlantic Ocean. In addition, the contributions of subducted sediments, continental crust, and subcontinental lithospheric mantle components to the formation of the SMAR MORBs at 18–21°S may be nonexistent or negligible.
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Lee, Hyo Min, Seung-Gu Lee, Hyeoncheol Kim, Jong Ik Lee y Mi Jung Lee. "REE Tetrad Effect and Sr-Nd Isotope Systematics of A-Type Pirrit Hills Granite from West Antarctica". Minerals 11, n.º 8 (22 de julio de 2021): 792. http://dx.doi.org/10.3390/min11080792.
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The Pirrit Hills are located in the Ellsworth–Whitmore Mountains of West Antarctica. The Pirrit Hills granite exhibits significant negative Eu anomalies (Eu/Eu* = 0.01~0.25) and a REE tetrad effect indicating intensive magmatic differentiation. Whole-rock Rb-Sr and Sm-Nd geochronologic analysis of the Pirrit Hills granite gave respective ages of 172.8 ± 2.4 Ma with initial 87Sr/86Sr = 0.7065 ± 0.0087 Ma and 169 ± 12 Ma with initial 144Nd/143Nd = 0.512207 ± 0.000017. The isotopic ratio data indicate that the Pirrit Hills granite formed by the remelting of Mesoproterozoic mantle-derived crustal materials. Both chondrite-normalized REE patterns and Sr-Nd isotopic data indicate that the Pirrit Hills granite has geochemical features of chondrite-normalized REE patterns indicating that REE tetrad effects and negative Eu anomalies in the highly fractionated granites were produced from magmatic differentiation under the magmatic-hydrothermal transition system.
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Watters, B. R. y R. L. Armstrong. "Rb–Sr study of metavolcanic rocks from the La Ronge and Flin Flon domains, northern Saskatchewan". Canadian Journal of Earth Sciences 22, n.º 3 (1 de marzo de 1985): 452–63. http://dx.doi.org/10.1139/e85-044.
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Two whole-rock suites of metavolcanic rocks from separate volcanic belts of the Churchill Province in northern Saskatchewan have been dated by Rb–Sr. Samples from the Amisk Group of the Flin Flon – Snow Lake domain provide an isochron date of 1784 ± 44 Ma; suites from the Waddy Lake and Devil Lake areas of the La Ronge (–Lynn Lake) domain yield isochron dates of 1814 ± 26 and 1854 ± 100 Ma, respectively. All are regarded as minima for, but close approximations to, emplacement ages. The maximum crustal age of any suite cannot greatly exceed 1850 Ma.Previous Rb–Sr and U–Pb isotopic dates together with these new determinations confirm the contemporaneous existence of two volcanic arcs, active during the late Aphebian (1875–1784 Ma) in the Churchill Province.Low initial 87Sr/86Sr ratios (0.7017–0.7022) are consistent with a petrochemically inferred subduction-related origin for the volcanic rocks with no closed-system reworking of Archean crust, and a linear evolution of 87Sr/86Sr ratio in the magmatic-arc mantle source region from 4.55 Ga to the present.
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Barrett, T. J. y H. Friedrichsen. "Oxygen-isotopic composition of basalts from young spreading axes in the eastern Pacific". Canadian Journal of Earth Sciences 24, n.º 11 (1 de noviembre de 1987): 2105–17. http://dx.doi.org/10.1139/e87-201.
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Oxygen-isotopic composition data are reported for young oceanic basalts from two different tectonic settings in the eastern Pacific: (1) the uppermost basement on the Galapagos Rift (< 1 Ma old), and (2) subbasement depths up to ≈150 m in the Gulf of California (≤ 3.5 Ma old). In the Galapagos area, whole-rock δ18O values exhibit a narrow range of 5.7–6.6‰, consistent with minimal to slight low-temperature alteration. Limited alteration probably reflects a combination of young basement age, low temperatures for solutions in the uppermost basement, and confinement of solutions mainly to discrete fractures. In the Gulf of California, by contrast, high whole-rock values are found at site 474A, near the Baja margin, where the greatest range in δ18O also occurs, from 2.5 to 12.5‰. This indicates considerable variation in both the temperature and degree of alteration at this site, probably a consequence of the heterogeneous basement sequence (intercalated pillow lavas, sills, and wet sediments). Differences in δ18O of up to 6‰ can exist over several metres, implying sharp changes in temperature or local water/rock ratio. The development of low-temperature alteration is more pronounced at site 474A (≈3.5 Ma) than at the several other (younger) crustal locations drilled in the Gulf of California, presumably because of longer exposure to seawater during recession of site 474A from the spreading axis.Analysis of primary magmatic phases at all sites yield 18O fractionations between plagioclase, clinopyroxene, and magnetite consistent with crystallization in a closed system and without high-temperature subsolidus reaction with seawater oxygen (even where sediments are intercalated within the basement). At site 485 in the Gulf of California, a thick basaltic sill yielded the lowest calculated crystallization temperatures (920 ± 50 °C) on the basis of plagioclase–magnetite fractionations; this agrees reasonably with groundmass quartz estimated to have formed at 860 ± 40 °C. Two vein carbonates from the uppermost part of the igneous sequence at this site were formed at temperatures of less than a few tens of degrees.We also report high-precision strontium- and oxygen-isotopic data on mineral separates from four basalts recovered at site 504B (6 Ma old). The most striking feature of these data is very substantial contamination of most mineral phases by seawater Sr, even though the same splits have typical primary magmatic oxygen-isotopic values. Relative to an unaltered mid-ocean ridge basalt 87Sr/86Sr value of 0.70265 ± 0.0001, 87Sr/86Sr ratios of plagioclase range from 0.70270 to 0.70359 (for apparently primary δ18O values of 5.35–5.75‰); for clinopyroxene, 87Sr/86Sr ratios range from 0.70309 to a very enriched value of 0.70695 (δ18O values of 4.97–5.30‰, with one value of 6.05‰). These results indicate that young basalts may have experienced significant interaction with seawater, which is not recorded in terms of oxygen-isotope exchange.
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Gorokhov, I. M., I. M. Vasil'eva, A. B. Kuznetsov, N. G. Rizvanova y G. V. Konstantinova. "A Stepwise Dissolution Method Applied to Isotopic Chemostratigraphic and Geochronological Studies of Riphean Carbonate Rocks of the Baykit Uplift". Геохимия 68, n.º 7 (1 de julio de 2023): 669–86. http://dx.doi.org/10.31857/s0016752523070038.
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The potential of the stepwise dissolution analytical procedure to obtain chemostratigraphic and geochronological information is demonstrated by a case study of Riphean carbonate rocks of the Kamovskaya Group of the Baykit Uplift (Eastern Siberia). The procedures suggested for studying Rb–Sr and U–Pb systems in carbonate rocks included (1) selection of samples with the lowest 87Sr/86Sr ratio on the basis of preliminary Rb–Sr analysis of the collection using the routine procedure of bulk leaching in 0.1N CH3COOH; (2) detailed study of the Rb–Sr system in selected samples using two-step dissolution in 0.2N CH3COOH and derivation of L(Rb–Sr)1 and L(Rb–Sr)2 fractions; (3) analysis of Pb isotope composition of the selected samples to derive the preliminary value of their age; (4) detailed study of U–Pb system of carbonate rocks using the stepwise dissolution in 0.5N HBr, resulting in six dissolved fractions L(U–Pb)1–L(U–Pb)6 for each of the selected samples; and (5) a final calculation of the Pb–Pb age of the studied rocks, based on the results from the obtained fractions, with the exclusion from the calculation of the initial fractions of this dissolution containing epigenetically altered carbonate material. The values of the primary 87Sr/86Sr ratio in L(Rb–Sr)2 fractions of carbonate rocks of the Kamovskaya Group are as follows: limestone of the Madrinskaya Formation, 0.70490; dolomites of the Yurubchenskaya Formation, 0.70495–0.70503; and dolomites of the Kuyumbinskaya and Vingoldinskaya formations, 0.70580 and 0.70521, respectively. These values characterizing the least altered carbonate material correspond to 87Sr/86Sr ratios in the Early Archean and can be used for chemostratigraphic calculations. Taking into account the Rb–Sr data, the U–Pb age of the Yurubchenskaya Formation carbonate rocks dissolved in six steps was calculated, starting from L(U–Pb)3. The slope of the resulting isochron in the coordinates 206Pb/204Pb–207Pb/204Pb corresponds to 1501 ± 23 Ma, which supports the conclusion that the carbonate rocks of the lower part of the Kamovskaya Group of the Baykit Uplift were formed in the Early Riphean.