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High-Resolution, Ultra-Trace and Major Element Chemical Stratigraphy of A Goldschmidt Conference Abstracts 465 High-resolution, ultra-trace and The volcanic-plutonic connection major element chemical stratigraphy O. BACHMANN1, C. DEERING1, J. DUFEK2 AND C. HUBER2 of a new Paleoproterozoic weathering 1Departement of Earth and Space Sciences, University of profile Washington, Seattle, USA 2School of Earth and Atmospheric Sciences, Georgia Institute M.G. BABECHUK* AND B.S. KAMBER of Technology, Atlanta, USA Laurentian University, Sudbury, ON, Canada (*correspondance: [email protected]) The broad similarities in age and compositonal range found in plutonic and volcanic exposures from a given Paleosols contain information about ancient atmospheric magmatic province clearly indicate that these rocks types are and climate conditions, as well as the secular change in supply closely related genetically. However, to which extent plutons of nutrients to the ocean. A newly exposed, ~5 meters deep (particularly the ones with intermediate to silicic 1.85 Ga weathering profile is described. It developed on compositions) are former magma reservoirs that have lost melt pillowed metabasalt (Flin Flon, Manitoba, Canada) and was remains controversial. Recent work using both geochemical sampled (~120 samples) and analyzed at much higher spatial and physical modeling provides new avenues to explore these resolution (>50 samples) than previous such profiles for ultra- issues that are fundamental to our understanding of crustal trace, major element, and ferrous iron. evolution. First, mechanical constraints on rates of crystal- Consistent with previous studies on nearby paleosol liquid separation indicate that most chemical differentiation is exposures [1,2], the examined weathering profile is likely to occur within an melt extraction window located characterized by a spectacularly preserved, coherent upward between 50 and 80 vol% crystals across the whole range of Fe enrichment, accompanied by loss of Fe2+ and the magma composition (from mafic to silicic). This extraction development of a positive Ce anomaly, implying weathering window will lead to compositional gaps in extracted liquids, in an oxic atmsophere. The new, high-precision trace element as observed in numerous volcanic series around the world. In data collected reveal enrichment of several alkali (Cs, Rb, in contrast, plutonic exposures will span a range of compositions addition to K, Na) and alkaline earth (Be, Sr, Ba) elements that will vary continously as a function of how much melt was upward towards the paleosol contact with overlying sandstone. lost at a given location. Trace element modelling suggest that By contrast, the HFSE remained largely immobile in the variable degrees of crystal accumulations are common in all profile which is evident through the highly consistent Zr/Hf, plutonic sequences, including in intermediate to silicic Th/Nb, and Nb/Ta ratios. compositions (tonalites - granodiorites). We also report This presentation will discuss the distinction of original erupted crystal cumulates, excavated from shallow magma chemical features preserved in the profile, for example those chambers during large explosive eruptions. Such findings, inherited from the separate pillow basalt flows, versus those alongside with thermal models of magma-crust interaction, superimposed by weathering, water table fluctuation and suggest that crystal fractionation occurring by melt extraction possible extraneous sediment input. in mush zones, and accompanied by a limited amount of crustal assimilation, is the dominant differentiation process in the Earth’s crust. In this framework, volcanic rocks mostly represent liquids extracted from different reservoirs while plutons typically correspond to the left-overs crystal mushes that have been periodically stripped from a fraction of their interstitial melts. [1] Holland et al. (1989) Am. J. Sci. 289, 362-389. [2] Pan & Stauffer (2000) Am. Mineral. 85, 898-911. Mineralogical Magazine www.minersoc.org Downloaded from http://pubs.geoscienceworld.org/minmag/article-pdf/75/3/465/2918804/gsminmag.75.3.02-B.pdf by guest on 24 September 2021 466 Goldschmidt Conference Abstracts Enhancing the accuracy of the Distribution of rare elements in environmental monitoring systems in mineral-forming environments of mining areas rare-metal granites CALIN BACIU, DAN COSTIN*, CRISTIAN POP AND E.V. BADANINA1, A.Y. BORISOVA2, R. THOMAS3 AND LAURA LAZAR L.F. SYRITSO1 Babes-Bolyai University, Faculty of Environmental Science 1St.Petersburg State University, St.Petersburg, Russia and Engineering, Fantanele 30, 400294 Cluj-Napoca, ([email protected]) Romania (correspondence: [email protected]) 2University of Toulouse III – CNRS – IRD – OMP, France ([email protected]) Mining operations generally have a significant impact on 3German Research Centre for Geosciences GFZ Potsdam, the environment. Traditional monitoring by periodically Germany performing field measurements, sampling, and lab analyses is laborious, costly, and not always reproducible and reliable. The composition of melt and its evolution in space and Abundant series of monitoring data may be obtained by time is traced at formation of ore-bearing Li-F granites and installing continuous measuring devices in selected points. In them sub-effusive analogs (ongonites, rhyolites, felsit- most of the mining areas, the number of such monitoring porphyries) from Orlovka, Etyka and Sherlovaja Gora in points is rather limited. The data series provided by such Transbaikalia (Russia) on the basis of melt inclusions study in systems are usually interpreted as averages of the measured quartz [1]. It is established that process of fractional parameters for a certain area. Very often, this is not the case, crystallization is not the unique mechanism of concentration either due to the limited representativity of the selected points, of LILE (Li, Rb, Cs) and HFSE (Nb, Ta, Zr, REE, W, Sn). A or because of the high dynamic of the environmental role of various mechanisms of concentration (fractionation, parameters. The environmental issues related to mining have liquid immiscibility, metasomatism) estimate by calculation of become an ever increasing concern all over the world, with a distribution coefficients and saturation degree of melt for ore direct impact on the prices of commodities, as opening a new minerals. Contrast behavior of various rare elements is mine is getting more and more difficult. A cost-effective and established at different stages of melt evolution [1]. High precise monitoring system is essential in the management of concentration of Li, B, Ta, Zn are found out in hydrosaline the environmental problems. Providing accurate monitoring and fluid inclusions of Orlovka [2]. High concentration of data may also increase the confidence and acceptance of the some rare elements are found out in fluid inclusions (FI) in communities and other stakeholders towards the mining quartz from Sn-bearing rhyolites of Sherlovaya Gora by LA- activity. New methods and tools are needed for accomplishing ICP-MS. So, the Sn concentration varies from 1864 to 5879 this goal. ppm that explains formation of large tin deposit with finely The EU-funded project ImpactMin (www.impactmin.eu) dispersed cassiterite at a hydrothermal stage. High develops a combination of satellite remote sensing and aerial concentration of Zr in a fluid (to 1,5 wt %) from ultrapotassic lightweight measurements for obtaining new methods of felsite-porphyriy explains the formation here saturation zones environmental monitoring in mining areas. Four test-sites of fine crystalline zircon in a topaz from famous a topaz- were selected for calibrating and demonstrating the new aquamarine greisen of Sherlovaya Gora and confirms toolset. Rosia Montana test-site (Romania) has a particular probability of its crystallization at a hydrothermal stage. High position in this context, as the cumulated impact of almost uranium concentration in melt of rhyolites (up to 42 ppm U) 2,000 years of gold mining can be observed. Currently the exceed those in rhyolites of a Streltsovsky deposit. Sharp mine is inactive, the operations ceased in 2006 due to increase of U in FI up to 116 ppm unequivocally testifies to a economic reasons. A new mining project is proposed on the potential role of rhyolites in genesis of uranium deposits of same location, intending to implement a large scale open pit Transbaikalia that closes discussion about a source of uranium operation. The newly developed monitoring methods may for them. represent an important contribution to the proper definition of the environmental baseline conditions, should the mining [1] Badanina et al. (2010) Petrology. 18. 139-167. [2] Thomas operations re-start. et al. (2009) Min Petrol. 96. 129-140. Acknowledgements: The present work was financially supported by the FP7-ENV-2009-1 project 244166 – ImpactMin. Mineralogical Magazine www.minersoc.org Downloaded from http://pubs.geoscienceworld.org/minmag/article-pdf/75/3/465/2918804/gsminmag.75.3.02-B.pdf by guest on 24 September 2021 Goldschmidt Conference Abstracts 467 Orbital scale alkenone based CO2 A multidisciplinary study of core records across the Pliocene composition intensification of Northern JAMES BADRO hemisphere glaciation Institut de Physique du Globe de Paris, France. 1 1 2 ([email protected]) M.P.S. BADGER *, G.C. BOWLER , C. DAVIS , 1 2 2 A.C. HULL , M.D.A. POTTS , D.N. SCHMIDT AND 1 Planetary cores form as a results of the major chemical R.D. PANCOST differentiation even on a terrestrial planet; the melting of 1Organic
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