TEXTURAL AND MICROANALYSIS OF IGNEOUS ROCKS: TOOLS ...

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87 Sr/ 86 SrI = 0.705542(8) Ba/Sr = 0.14 Rb/Sr = 0.0008 87 Sr/ 86 SrI = 0.705510(8) Ba/Sr = 0.11 Rb/Sr = 0.0006 2 mm Ba/Sr = 0.15 Rb/Sr = 0.0009 2 mm A) 10-2A-C 10-2A-D 87 Sr/ 86 SrI = 0.705572(10) Ba/Sr = 0.14 Rb/Sr = 0.0007 Figure 4.10. Diagrams of zoning features in the three Unit 10 plagioclase phenocrysts that were subjects of EPMA, LA-ICP-MS and micro Sr isotope analyses. Thin dotted black lines mark the locations of core to rim EPMA transects. 87 Sr/ 86 SrI results are shown for each along with the measured 2σ error in parentheses. Measured Ba/Sr and Rb/Sr ratios are shown for each zone examined. A) Crystal 10-2A-C has an ∼ An60 core bounded by a resorption surface and an An65−66 rim. Both the core and rim were sampled. B) Crystal 10-2A-D has an ∼ An60 core bounded by a dissolution surface and an An65−67 rim. Both the core and rim were sampled. 197 B)
and Rb (Fig. 4.11d,e). 4.4.3.3 Yttrium and the Rare Earth Elements La, Ce, Pr, Nd, Sm, and Eu The highest Y abundances were measured in Unit 4 crystal cores and intermediate zones (Fig. 4.12b). There is no other obvious systematic variation in Y abundance between phenocryst zones in crystals from either Unit. At a given An content, Unit 10 phenocrysts have greater La, Ce, Pr, Nd, Sm, and Eu. Where core and interior sections of Unit 4 phenocrysts overlap, they tend to have lower overall REE abundances relative to the instances where there is no overlap (Fig. 4.12). The opposite relationship holds true or Unit 10 phenocryst zones with overlap- ping An, where core and intermediate zones tend to have greater REE abundances (Fig. 4.12). 4.4.4 Sr Isotope Microdrilling There are subtle variations in 87 Sr/ 86 SrI between crystals zones in Unit 4 and 10 crystals (Figs. 4.13, 4.8, 4.9, and 4.10; Table 4.3). Unit 4 crystals have much less radiogenic 87 Sr/ 86 SrI than Unit 10 crystals (Fig. 4.13). The rim of Unit 4 crystal D bears the most radiogenic 87 Sr/ 86 SrI observed in a Unit 4 crystal and exhibits a higher 87 Sr/ 86 SrI than all Site 1137 upper group whole-rock samples reported by Ingle et al. [75] (Fig. 4.8b). The rim zone of crystal D is bounded by a resorption surface and a change from An67 in the intermediate zone to An64 at the rim. All other Unit 4 plagioclase zones overlap Site 1137 upper group whole-rock 87 Sr/ 86 SrI reported by Ingle et al. [75]. There is little other distinction in terms of 87 Sr/ 86 SrI between core, intermediate, and rim zones (Fig. 4.13). Site 1137 lower group whole-rock samples reported by Ingle et al. [75] extend 198
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TEXTURAL AND MICROANALYSIS OF IGNEO
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TEXTURAL AND MICROANALYSIS OF IGNEO
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DEDICATION This work is dedicated t
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CHAPTER 2: MAGMA EVOLUTION REVEALED
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3.6.3.1 Crystal Population Origins
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FIGURES 1.1 Magma Chambers . . . .
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TABLES 2.1 MAJOR AND TRACE ELEMENT
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thus been debate within the volcano
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Cambrian schist) including a crysta
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explosive eruption vs. mild effusiv
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tiation (e.g., [84, 98]; Fig. 1.3).
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defined as having crystallinities b
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12 Figure 1.4: Large Igneous Provin
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distribution of crystal sizes (e.g.
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investigating magmatic evolution us
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length dispersive spectroscopy(WDS)
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microdrilling, a pre-cleaned square
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1.7.2 Detroit Seamount, Part of the
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lations. Reprocessing of intrusive
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nucleated homogenously and grew thr
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With accurate partition coefficient
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uniform composition of large volume
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Figure 2.2. Hand sample and thin se
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2.3.1 A Cogenetic Relationship Betw
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Figure 2.4. Stratigraphic section o
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Figure 2.5. Backscatter electron im
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studies of Kwaimbaita basalt by San
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42 Crystal Zone An (mol%) TABLE 2.1
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44 Crystal Zone An (mol%) 63R2 phen
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along the xenolith margins (e.g., F
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are more abundant in phenocrysts fr
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54 Crystal Zone 5 ML-X1 xenolith TA
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56 TABLE 2.2 Continued Crystal Zone
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Figure 2.7. Measured major and trac
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2.5.3.2 Trace Elements It is diffic
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Figure 2.9. Trace element ratio plo
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2.5.4 Resorption Features in Site 1
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should, however, be noted that in t
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2.6.1.2 An-rich OJP Plagioclase: In
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equivocally the roles of H2O, press
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ent magma requires significant clin
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tion driven plumes, or stirring by
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Yamashita, [123], and thus did not
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erally extensive crystal-mush netwo
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asalt at Site 1185 of ODP Leg 192 [
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CHAPTER 3 SHALLOW MAGMA EVOLUTION D
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magma compositions [23, 39, 98]. A
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Figure 3.2. Stratigraphy of basalts
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[118]. No volcaniclastic rocks were
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magmatic crystallization. Using the
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Figure 3.3. A cross polarized light
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3.4.5 Major and Trace Element Data
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3.4.6.1 Partition coefficients for
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3.5.1.2 Site 884 CSDs I measured pl
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Figure 3.5. Plagioclase CSDs of ODP
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106 TABLE 3.2 CSD RESULTS Sample OD
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ln (n) [mm -4 ] ln (n) [mm -4 ] 10
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ulation A crystals are unzoned (An6
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Figure 3.8. a) The majority of Site
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3.5.4.3 Site 1203 Unit 31 and Site
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3.5.5 Trace Elements 3.5.5.1 Measur
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Unit 31 > Site 884 Unit 8 (Table 3.
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3.6 Discussion 3.6.1 Evidence of Cr
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3.6.1.1 Site 1203 Alkalic Basalts a
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etween the different crystal popula
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Unit 14 and 31 magmas accumulated o
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sition is similar to parent magmas
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Sr - low La/Ce population A parent
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The Unit 31 plagioclase CSD is kink
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was dominated by late stage clinopy
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pressure, and growth of An-rich pla
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138 TABLE 3.3 PLAGIOCLASE PHENOCRYS
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140 TABLE 3.3 Continued Sample Zone
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Page 159 and 160: 146 TABLE 3.3 Continued Sample Zone
Page 187 and 188: KP has been done via drilling at 11
Page 189 and 190: and over time crustal wall-rocks be
Page 191 and 192: flow [33]. I selected a single samp
Page 193 and 194: 4.3.4 Major and Trace Element Data
Page 195 and 196: B) C) parafilm splash guard A) tape
Page 197 and 198: of these elements are the better co
Page 199 and 200: 5 mm 5 mm Figure 4.4. Cross polariz
Page 201 and 202: 4.4.2 Electron Probe Microanalysis
Page 203 and 204: An (mol %) An (mol %) An (mol %) An
Page 205 and 206: study exhibit their highest An at t
Page 207 and 208: 4.4.3 LA-ICP-MS - Trace Elements An
Page 209: 87 86 Sr/ SrI = 0.705722(8) Ba/Sr =
Page 213 and 214: Sr (ppm) Y (ppm) La (ppm) Ce (ppm)
Page 215 and 216: Unit 4 plagioclase rims plagioclase
Page 217 and 218: 204 TABLE 4.4 UNIT 4 PLAGIOCLASE PA
Page 219 and 220: 4.5 Discussion 4.5.0.1 Origin of Ma
Page 221 and 222: 4.5.0.2 Insights from Trace Element
Page 223 and 224: that other factors influenced the a
Page 225 and 226: C A/B / D A/B C A/B / D A/B Unit 4
Page 227 and 228: Magma chambers tend to form at hori
Page 229 and 230: whole-rock basalt data. Cumulate xe
Page 231 and 232: over short time spans but may be ea
Page 233 and 234: lowing initial Elan Bank magma empl
Page 235 and 236: BIBLIOGRAPHY 1. C. Allegre, A. Prov
Page 237 and 238: 22. B. Charlier, J. Davidson, O. Ba
Page 239 and 240: 46. J. Fitton and M. Godard, Origin
Page 241 and 242: 68. M. Higgins, Measurement of crys
Page 243 and 244: 89. J. Longhi, D. Walker and J. Hay
Page 245 and 246: 100 of Geophysical Monograph, pages
Page 247 and 248: 129. J. Tarduno, W. Sliter, L. Kroe
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