TEXTURAL AND MICROANALYSIS OF IGNEOUS ROCKS: TOOLS ...

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TABLE 4.3 UNIT 4 <strong>AND</strong> 10 87 Sr/ 86 Sr DATA Sample Zone Site 1137 Unit 4 Plagioclase 87 Sr/ 86 SrM Rb/Sr 87 Sr/ 86 SrI J C rep1 0.704940(12) – 0.704939 J C rep2 0.704965(14) – 0.704964 J C avg 0.704953(13) 0.0003 0.70495 J I 0.704903(10) 0.0003 0.704902 D C 0.704850(12) 0.0002 0.704849 D R 0.704987(68) 0.0004 0.704985 A C rep1 0.704941(12) – 0.704939 A C rep2 0.704936(8) – 0.704934 A C avg 0.704939(10) 0.0004 0.704937 A R 0.704847(6) 0.0004 0.704845 Site 1137 Unit 10 Plagioclase 10-1C-A C 0.705738(10) 0.0008 0.705735 10-1C-A I 0.705725(8) 0.0007 0.705722 10-1C-A I 0.705689(6) 0.0009 0.705685 10-2A-D C 0.705575(10) 0.0007 0.705572 10-2A-D R 0.705513(8) 0.0006 0.705510 10-2A-C C 0.705545(8) 0.0008 0.705542 10-1C-D I 0.705577(10) 0.0009 0.705575 10-1C-D I 0.705623(10) 0.0010 0.705620 10-1D-A I 0.705640(12) 0.0010 0.705637 10-1D-A R 0.705539(8) 0.0006 0.705536 1 A 107.7 Ma age of Site 1137 basalts from [42] was used to correct Sr isotope ratios for in-situ decay. I subscript denotes initial 87 Sr/ 86 Sr ratio. 2 values in parentheses are errors reported as measured 2σ in the last two decimal places of 87 Sr/ 86 SrM. 3 C = core, I = intermediate zone, R = rim. 4 Rb/Sr measured at coincident microdrill site by LA-ICP-MS. 201
Unit 4 plagioclase rims plagioclase intermediate zones plagioclase cores Site 1137 Upper Group whole-rock Unit 10 plagioclase rims plagioclase intermediate zones plagioclase cores Site 1137 Lower Group whole-rock 0.704500 0.705000 0.705500 0.706000 0.706500 Figure 4.13. The range of 87 Sr/ 86 SrI of Unit 4 and Unit 10 phenocrysts are shown relative to their respective host basalt groups as defined by Ingle et al. [75]. Note that plagioclase phenocrysts from each unit are similar to whole-rock 87 Sr/ 86 SrI reported by Ingle et al. [75]. Unit 10 plagioclase rims are less radiogenic but still overlap intermediate and rim zones. to more radiogenic 87 Sr/ 86 SrI than any Unit 10 plagioclase zone sampled in this study (Fig. 4.13). Unit 10 plagioclase rims exhibit the least radiogenic 87 Sr/ 86 SrI of the three zones (Fig. 4.13). The core of crystal 10-1C-A has the most radiogenic 87 Sr/ 86 SrI any Unit 10 crystal zone sampled (Fig. 4.9a), and the rim of crystal 10- 2A-D has the least 87 Sr/ 86 SrI of any Unit 10 crystal zone (Fig. 4.10b). In summary, crystals from both Units 4 and 10 have 87 Sr/ 86 SrI similar to Site 1137 upper group (less radiogenic) and lower group (more radiogenic) whole-rock samples (i.e., their host basalts) reported by Ingle et al. [75]. 4.4.5 Inferred Parent Magma Compositions Plagioclase parent magmas from Units 4 and 10 have Ba/Sr ratios and Rb abundances that overlap Site 1137 upper group and lower group basalts. (Fig. 4.14), although this overlap is less apparent when a smaller subset of Site 1137 basalts 202
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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 163 and 164: 150 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 and 210: 87 86 Sr/ SrI = 0.705722(8) Ba/Sr =
Page 211 and 212: and Rb (Fig. 4.11d,e). 4.4.3.3 Yttr
Page 213: Sr (ppm) Y (ppm) La (ppm) Ce (ppm)
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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