School of Engineering and Science - Jacobs University

More documents

Recommendations

Info

For the more recent, full 32 element test of analytical recovery, the 10 μg/kg spike solution was analyzed in the middle of an ICPMS run containing Fe-rich carbonates that had a dilution factor of only 250, and these carbonates displayed extreme IS correction factors as high as 2.0, reflective of the high TDS content of these solutions. In contrast, the analytical recovery as determined from the pre-June 2006 analysis was not included within part of an ICPMS run, and was conducted following routine cleaning and optimization of the ICPMS. It therefore seems that the discrepancy between the two tests of analytical recovery for the HF-HClO 4 decomposition method, one using a 24 element spike and the other a 32 element spike, reflects details of the individual tests, including such factors as sample deposition within the ICPMS interface region affecting signal intensities (i.e., signal suppression or enhancement). Based on the few data, it is therefore concluded that for the HF-HClO 4 decomposition analytical recoveries for the majority of elements are typically within 2-3% of their predicted concentrations, similar to that observed for the carbonate decomposition method. This variability may represent the optimum analytical recovery possible, as it is comparable to the inherent precision of ~2% observed for most element measurements (see above discussion regarding precision). However, in view of the limited data, more tests of analytical recovery are warranted, particularly using the HF-HClO 4 decomposition method and complete, 32 element spike solutions. 7. Analytical accuracy 7.1. Reference values and major element interferences The best measure of the suitability of the analytical methods employed within the JUB Geochemistry Lab is if these methods can accurately (and reproducibly) quantify the elements of interest in certified reference materials. As mentioned previously, the CRMs used as routine quality assurance standards are chosen to match the rock types most commonly analyzed within the JUB Geochemistry Lab. If the measured CRM concentration data for a given sample decomposition is consistent with the certified data, then this provides the best measure of conservative element behavior and overall accuracy for the ICPMS methods employed. The concentration data for CRMs are generally reported as either recommended values or preferable/informational values, with recommended values 27
considered more accurate and possessing lower degrees of uncertainty. Concentration data for most major and some trace elements in CRMs are typically provided by the issuing organization (Table 1). However, for many trace metals (particularly the REE, Nb, Mo, Ta, and W), values are either not provided by the issuing organization or are considered informational or preferred values, indicating that higher degrees of uncertainty surround these data. Therefore, for a significant number of the 32 elements analyzed at JUB, concentration data in CRMs may only be obtained from combinations of separate studies and compilations. One of the most comprehensive and widely referenced compilations of geoanalytical data was assembled by Govindaraju (1994), which combines data produced using different analytical methods from a multitude of sources. However, for the CRMs listed in Table 1 much of the minor and trace metal data in Govindaraju (1994) is highly variable, particularly for the REE and other metals present at low concentrations such as Ti, Nb, Ta, Hf, Th, and U. Additionally, for some of the CRMs data has been published since 1994 using newer analytical methods such as laser ablation and/or high resolution multi-collector ICPMS. A thorough study of numerous CRMs, including the ones relevant to this discussion, was conducted by Dulski (2001), whose data closely match results from this study. Newer data (e.g., Baker et al., 2002; Bohlar et al., 2004) are consistent with the results presented here and the values of Dulski (2001), suggesting that the highly variable trace metal concentrations observed in older compilations of CRM data do not result from sample heterogeneity, but rather from limitations of older analytical methods. The reference values for the CRMs used in this study are presented in Appendix 1, along with average concentration data for these CRMs as measured within the JUB Geochemistry Lab. The literature data presented are not intended to reflect an exhaustive or comprehensive survey of all available data for the various CRMs, and were selected according to three criteria: 1) data published by the CRM issuing organization, which usually are compilations of data produced by different laboratories using different methods; 2) studies that provided data for a large number of the 32 elements considered for this study; and/or 3) work that utilized similar analytical methods, particularly ICPMS techniques. This approach is intended to facilitate comparison between the CRM values measured at JUB with worldwide laboratories using similar analytical methods. Recently, Jochum et al. (2005) produced a thorough compilation of published major element, trace element, and 28
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
Page 10 and 11:
viii
Page 12 and 13:
goal of the research is to discern
Page 14 and 15:
Figure 1. Map of southern Africa sh
Page 16 and 17:
appropriate to briefly discuss: 1)
Page 18 and 19:
100 10 MORB 1 0.1 raw data (mg/kg)
Page 20 and 21:
10 -2 hydrothermal fluid 10 -3 10 -
Page 22 and 23:
seawater and returned to the sedime
Page 24 and 25:
100 MCO + 3 + M(CO 3 )- 2 rare eart
Page 26 and 27:
net effect of carbonate complexatio
Page 28 and 29:
feature was not recognized in early
Page 30 and 31:
sound geochemical basis for anomalo
Page 32 and 33: deviation of the 143 Nd/ 144 Nd rat
Page 34 and 35: available, it should be possible to
Page 36 and 37: modern and Archean oceans, as well
Page 38 and 39: Bau M., Möller P., and Dulski P. (
Page 40 and 41: Elderfield H. and Greaves M.J. (198
Page 42 and 43: Haley B.A., Klinkhammer G.P. (2003)
Page 44 and 45: Lee J.H. and Byrne R.H. (1993) Comp
Page 46 and 47: Piepgras D.J. and Wasserburg G.J. (
Page 48 and 49: Tosiani T., Loubet M., Viers J., Va
Page 50 and 51: THIS PAGE INTENTIONALLY LEFT BLANK
Page 52 and 53: Abstract The benefits of inductivel
Page 54 and 55: List of Figures Figure 1. Sample de
Page 56 and 57: 1. Introduction The advent of induc
Page 58 and 59: Figure 1. Flow-chart diagram of the
Page 60 and 61: during decomposition (SiF 4 and CO
Page 62 and 63: Fractionation between the three iso
Page 64 and 65: cps, then 3000 cps must be subtract
Page 66 and 67: variety of ways. These range from r
Page 68 and 69: Table 3. Change in HFSE concentrati
Page 70 and 71: 0.90, corresponding to an anomalous
Page 72 and 73: 10 2 JDo-1 reference values 10 1 IF
Page 74 and 75: Figure 5. Diagram depicting various
Page 76 and 77: 20 18 basalt BHVO-2 (n=5) run preci
Page 78 and 79: The method precision for elements p
Page 80 and 81: Two approaches may be utilized to d
Page 84 and 85: isotopic data for geologic CRMs, av
Page 86 and 87: Table 4. Interferences observed for
Page 88 and 89: value uncertainty (as %RSD) is repr
Page 90 and 91: 1.50 FeR-4 (n=2) 1.25 JUB / referen
Page 92 and 93: 1 IF-G/shale 0.1 0.01 La Ce Pr Nd P
Page 94 and 95: consistent (App. 1), and similar to
Page 96 and 97: 1.50 SGR-1b (n=3) 1.25 JUB / refere
Page 98 and 99: 1.50 JCh-1 (n=3) 1.25 JUB / referen
Page 100 and 101: 1.50 JDo-1 (n=5) 1.25 JUB / referen
Page 102 and 103: determinations in carbonate rocks r
Page 104 and 105: 1.50 JMn-1 (n=4) 1.25 JUB / referen
Page 106 and 107: eference value. The result is that
Page 108 and 109: eference value and the measured JUB
Page 110 and 111: the 32 analyzed elements, with Ti b
Page 112 and 113: Govindaraju K. (1995) 1995 working
Page 114 and 115: Appendix 1. Analytical data Appendi
Page 116 and 117: Appendix 1. Literature reference va
Page 118 and 119: Appendix 1 continued. Data in mg/kg
Page 120 and 121: the concentration of the major elem
Page 122 and 123: Potential interferences on monoisot
Page 124 and 125: 1500 0.5 M HCl 4.0 interference on
Page 126 and 127: 4000 0.40 0.20 3500 0.17 mg/kg 0.18
Page 128 and 129: interference on 95 Mo in sample sol
Page 130 and 131: THIS PAGE INTENTIONALLY LEFT BLANK
Page 132 and 133:
Nd isotopes in 2.9 Ga Archean surfa
Page 134 and 135:
Page 136 and 137:
Table 2 Trace element concentration
Page 138 and 139:
Page 140 and 141:
Page 142 and 143:
Page 144 and 145:
Page 146 and 147:
Page 148 and 149:
THIS PAGE INTENTIONALLY LEFT BLANK
Page 150 and 151:
Page 152 and 153:
Author's personal copy B.W. Alexand
Page 154 and 155:
Page 156 and 157:
Page 158 and 159:
Page 160 and 161:
Page 162 and 163:
Page 164 and 165:
Page 166 and 167:
and preservation of oxide-facies IF
Page 168 and 169:
TOP relative stratigraphic position
Page 170 and 171:
The mechanism by which the alkali m
Page 172 and 173:
6. Widdel, F. et al. Ferrous iron o
Page 174 and 175:
Page 176 and 177:
Page 178 and 179:
82 PRESERVATION OF PRIMARY REE PATT
Page 180 and 181:
Page 182 and 183:
Page 184:
ulk, open ocean seawater tended to
show all

School of Engineering and Science - Jacobs University

Create successful ePaper yourself

Delete template?

Save as template?