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100 10 MORB 1 0.1 raw data (mg/kg) chondrite-normalized La Ce Pr Nd Sm Eu Gd Tb Dy Y Ho Er Tm Yb Lu Figure 3. Typical rare earth element plot where lanthanide elements are arranged in order of increasing atomic mass and decreasing ionic radii, with yttrium inserted between Dy and Ho in accordance with its ionic radius. Normalizing produces smooth REY patterns if none of the REY exhibit anomalous behavior. Mid-ocean ridge basalt (MORB) data from Niu et al. (1999). Some of the rare earth elements may be fractionated from neighboring REY as the result of natural geochemical processes, with Ce and Eu offering the best known examples. The fractionation of Ce and Eu from the other REY is primarily a consequence of the different valence states that these elements can possess. Cerium is readily oxidized from Ce 3+ to Ce 4+ at the Earth’s surface and in the oxic marine environment, fractionating it from the other REY by forming Ce(IV) compounds of low solubility. At elevated temperatures (>200 °C) europium can fractionate from the other REY when Eu is reduced from Eu 3+ to Eu 2+ , e.g., during igneous or hydrothermal processes, with Eu fractionation occuring due to the different charge and significantly larger ionic radius of the Eu 2+ ion (Fig. 2). Examples of Ce and Eu fractionation are presented in Figure 4. The fractionation of Ce from the neighboring elements La and Pr is shown for average world seawater, and Eu fractionation as observed in high 8
10 -2 360 °C hydrothermal fluid 10 -3 10 -4 sample/PAAS 10 -5 10 -6 10 -7 10 -8 10 -9 average world seawater La Ce Pr Nd PmSm Eu Gd Tb Dy Y Ho Er Tm Yb Lu Figure 4. REY distributions in average world seawater and high-T hydrothermal fluid from the mid- Atlantic ridge normalized to continental crust as represented by PAAS (McLennan, 1989). Seawater data are the average of 172 worldwide analyses of all depths (average depth 1560 m) for which complete REY datasets are available (Zhang and Nozaki, 1996; Alibo and Nozaki, 1999; Bau et al., 1997b; Nozaki et al., 1999; Nozaki and Alibo, 2003). Hydrothermal fluid data for sample BS-07-3/3 of Bau and Dulski (1999). Note strong negative Ce anomaly in seawater and strong positive Eu anomaly in high-T hydrothermal fluid. temperature (T= 360 °C) hydrothermal fluids emanating from the mid-Atlantic oceanic ridge (MAR). 1.5.2. Rare earth elements in seawater The abundances of the REY in seawater are extremely low relative to their crustal averages, with world seawater concentrations ~10 -7 of the levels found in upper continental crust (see Figure 4). Higher REY abundances are typically found in river waters and pore waters of marine sediments, though not as high as the concentrations observed for high-T hydrothermal fluids (Figure 5). It is reasonable that these fluids (river water, pore water, and hydrothermal fluid) represent the primary dissolved REY sources for the oceans of the world, and assuming this is true, it is notable that each of these REY sources contains several times the total REY concentration that exists in 9
Page 1: Iron sedimentation and the neodymiu
Page 4 and 5: The process(es) by which IFs were d
Page 7: This thesis represents original and
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Page 12 and 13: goal of the research is to discern
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Page 52 and 53: Abstract The benefits of inductivel
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Table 3. Change in HFSE concentrati
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0.90, corresponding to an anomalous
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10 2 JDo-1 reference values 10 1 IF
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Figure 5. Diagram depicting various
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20 18 basalt BHVO-2 (n=5) run preci
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The method precision for elements p
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Two approaches may be utilized to d
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For the more recent, full 32 elemen
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isotopic data for geologic CRMs, av
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Table 4. Interferences observed for
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value uncertainty (as %RSD) is repr
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1.50 FeR-4 (n=2) 1.25 JUB / referen
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1 IF-G/shale 0.1 0.01 La Ce Pr Nd P
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consistent (App. 1), and similar to
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1.50 SGR-1b (n=3) 1.25 JUB / refere
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1.50 JCh-1 (n=3) 1.25 JUB / referen
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1.50 JDo-1 (n=5) 1.25 JUB / referen
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determinations in carbonate rocks r
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1.50 JMn-1 (n=4) 1.25 JUB / referen
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eference value. The result is that
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eference value and the measured JUB
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the 32 analyzed elements, with Ti b
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Govindaraju K. (1995) 1995 working
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Appendix 1. Analytical data Appendi
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Appendix 1. Literature reference va
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Appendix 1 continued. Data in mg/kg
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the concentration of the major elem
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Potential interferences on monoisot
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1500 0.5 M HCl 4.0 interference on
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4000 0.40 0.20 3500 0.17 mg/kg 0.18
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interference on 95 Mo in sample sol
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Nd isotopes in 2.9 Ga Archean surfa
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Table 2 Trace element concentration
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Author's personal copy B.W. Alexand
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and preservation of oxide-facies IF
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TOP relative stratigraphic position
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The mechanism by which the alkali m
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6. Widdel, F. et al. Ferrous iron o
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82 PRESERVATION OF PRIMARY REE PATT
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ulk, open ocean seawater tended to
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