TEXTURAL AND MICROANALYSIS OF IGNEOUS ROCKS: TOOLS ...

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187 TABLE 4.1 UNIT 4 PLAGIOCLASE MAJOR <strong>AND</strong> TRACE ELEMENT ABUNDANCES Sample Zone An FeOT P2O5 K2O TiO2 Na2O CaO MgO SiO2 Al2O3 Total Sc Ti V Rb Sr Y Ba La Ce Pr Nd Sm Eu Pb (mol%) K C 69 0.62 0.12 0.18 0.05 3.47 14.29 0.16 51 31 100.95 2 642 3.5 0.37 829 0.33 99 0.92 2.2 0.21 0.77 0.07 0.59 0.76 K I 71 0.67 0.08 0.17 0.04 3.17 14.78 0.18 50.6 31.2 100.91 1.4 522 3.3 0.22 850 0.27 81 1.07 2.4 0.23 1.03 0.15 0.61 0.67 K R 66 0.67 0.05 0.21 0.09 3.78 13.7 0.18 51.5 30.8 100.99 1.9 565 3.1 0.17 839 0.17 79 0.95 2 0.2 0.68 0.09 0.59 0.6 L C 61 0.63 0.1 0.25 0.09 4.23 12.41 0.19 52.9 29.9 100.73 1.2 566 2.8 0.30 797 0.07 73 0.94 1.7 0.18 0.52 0.14 0.52 0.55 L I 62 0.68 0.1 0.27 0.1 4.23 12.8 0.2 52.7 29.7 100.84 1.4 630 3.4 0.42 804 0.33 84 0.77 1.7 0.16 0.48 0.14 0.63 0.67 L R 68 0.65 0.09 0.18 0.08 3.55 14.17 0.17 50.9 31 100.79 1.1 481 3.8 0.23 803 0.23 68 0.84 1.8 0.18 0.67 0.16 0.53 0.71 Q C 66 0.6 0.07 0.24 0.07 3.7 13.68 0.18 52 30.1 100.59 1.5 478 5.1 0.34 852 0.12 70 0.74 1.8 0.16 0.48 0.1 0.63 0.86 Q I 65 0.65 0.08 0.22 0.03 3.9 13.37 0.18 52.5 29.5 100.49 1.6 483 4 0.24 882 0.13 69 0.87 1.8 0.17 0.7 0.05 0.55 0.7 Q R 60 0.73 0.05 0.26 0.08 4.34 12.47 0.16 53.4 28.9 100.39 2.8 581 3.4 – 922 0.08 91 1.01 2 0.23 0.73 0.12 0.59 0.78 P C 66 0.65 0.1 0.21 0 3.63 13.34 0.18 52.1 30.2 100.48 2.1 445 3.8 0.34 856 0.14 68 0.69 1.5 0.16 0.48 0.07 0.51 0.89 P I 65 0.08 0.21 0 3.82 13.04 0.15 53 29.9 100.17 1.4 462 4.6 0.35 825 0.13 67 0.78 1.8 0.17 0.69 0.07 0.56 0.65 J C 68 0.6 0.04 0.2 0.08 3.6 14.43 0.2 51.3 30.4 100.92 1.5 499 4.4 0.30 924 0.09 71 0.86 1.8 0.2 0.61 0.08 0.58 0.44 J I 68 0.62 0.09 0.19 0.08 3.66 14.26 0.17 51.4 30.7 101.21 1.6 479 4.2 0.29 909 0.1 72 0.9 1.9 0.17 0.57 0.12 0.55 0.48 J R 62 0.79 0.08 0.25 0.07 4.23 12.91 0.19 53 29.4 100.9 1.8 580 3.9 0.34 925 0.09 98 1.05 1.9 0.2 0.68 0.05 0.73 0.64 N C 64 0.65 0.08 0.2 0.28 3.92 13.22 0.19 52.4 30 100.94 1.7 501 3.3 0.26 849 0.1 70 0.84 1.7 0.18 0.66 0.14 0.57 0.63 N R 61 0.8 0.06 0.26 0 4.23 12.71 0.19 52.9 29.7 100.88 1.5 845 6.9 0.59 1040 0.21 132 1.53 2.8 0.26 1.22 0.21 1.33 0.97 O C 67 1.24 0.07 0.2 0 3.57 13.57 0.18 51.1 31 100.97 1.2 429 3.8 0.31 874 0.13 69 0.84 1.8 0.14 0.68 0.1 0.61 0.54 O I 67 0.68 0.11 0.2 0.04 3.58 13.43 0.16 51.9 30.7 100.72 2.2 535 4.1 0.40 934 0.11 92 0.96 1.9 0.19 0.73 0.1 0.72 0.82 O I 57 0.71 0.06 0.3 0.09 4.6 11.6 0.16 54.2 29.1 100.73 1.5 660 3.5 0.51 905 0.1 91 0.92 2.1 0.21 0.8 0.1 0.55 0.53 O I 62 0.73 0.1 0.25 0.11 4.09 12.56 0.16 53 29.6 100.62 1.2 713 4.9 0.48 983 0.1 116 1.26 2.3 0.2 0.93 0.2 0.9 0.67 O R 54 0.87 0.09 0.33 0.13 4.83 10.67 0.38 55.2 28 100.46 2 785 7.2 0.69 917 0.13 125 1.15 2.1 0.2 0.72 0.15 0.98 0.69 D C 67 0.67 0.1 0.2 0 3.65 13.98 0.17 51.6 30.3 100.7 1.1 522 4 0.18 929 0.13 69 0.88 1.7 0.18 0.77 0.12 0.59 0.46 D R 64 0.6 0.08 0.21 0.07 3.96 12.9 0.19 52.1 30 100.13 1.5 534 4.5 0.34 906 0.12 71 0.88 1.6 0.17 0.56 0.1 0.64 0.48 A C 63 0.6 0.08 0.22 0.09 4.1 12.83 0.19 53 29.2 100.21 1.7 492 3 0.36 949 0.08 77 0.87 1.8 0.19 0.64 0.1 0.44 1.21 A I 64 0.65 0.06 0.22 0.08 4.07 13.28 0.19 52.7 29 100.24 2 519 3.6 0.40 929 0.09 84 0.82 2.1 0.2 0.64 0.07 0.57 0.53 A I 64 0.68 0.07 0.22 0.08 4.01 13.3 0.21 52.9 28.8 100.23 2.4 525 3.4 0.36 942 0.11 80 0.88 2.1 0.22 0.73 0.1 0.6 0.46 A R 64 0.71 0.08 0.23 0.09 3.85 12.84 0.17 52.8 28.9 99.66 2.2 474 3.9 0.33 836 0.1 73 0.74 1.8 0.16 0.6 0.12 0.6 0.46 C C 71 0.65 0.08 0.18 0.04 3.24 15.04 0.14 50.5 30.3 100.16 1.2 447 3.2 0.27 945 0.21 89 1.05 2.2 0.22 0.87 0.09 0.59 0.67 C I 66 0.6 0.07 0.2 0.09 3.8 13.78 0.18 52.3 29.2 100.15 1.5 502 3.5 0.31 904 0.15 74 0.99 1.9 0.18 0.78 0.11 0.55 0.64 C R 59 0.69 0.05 0.28 0.07 4.58 12.52 0.17 53.7 28.3 100.31 2.4 594 3.8 0.60 904 0.09 97 1 2 0.21 0.61 0.08 0.65 0.68 1 C = core; I = Intermediate Zone; R = rim 2 total Fe as FeO 3 [An = Ca / (Ca+Na+K)]*100
4.4.2 Electron Probe Microanalysis (EPMA) - Major Elements The An-Ab-Or compositions of zones within Unit 4 and 10 plagioclase phenocrysts that were targeted for trace element microanalysis are shown in figure 4.5. The An content of Unit 4 plagioclase zones range from An54 to An71, and Unit 10 crystals span a narrower An57 to An67 range. Unit 4 plagioclase cores trend to higher An content, and rims trend to lower An content and greater Or content (Fig. 4.5a). Intermediate zones are nearly identical to Unit 4 cores in terms of An-Ab-Or composition (Fig. 4.5b). The lowest An zone sampled in a Unit 4 plagioclase was An54 along a crystal rim, whereas the highest An zones are an An71 intermediate zone near a crystal core and an An71 core. Unit 10 plagioclase cores and intermediate zones trend to lower An content than rim zones (Fig. 4.5b). The highest An zones sampled in Unit 10 plagioclase phenocrysts are an An67 rim zone and an An67 intermediate zone that is adjacent to a crystal rim, and the lowest An zones sampled include two near-core An57 zones and an An58 crystal core (Fig. 4.5b). Core-to-rim EPMA point traverses reveal that each of the Unit 4 and 10 plagioclase crystals analyzed in this study contain major element oscillations, which is consistent with oscillatory zoning apparent in cross polarized light and backscatter electron images (e.g., Figs. 4.9b,c). Half of the Unit 4 plagioclase phenocrysts examined exhibit normal zoning patterns (Fig. 4.6b,d,g,h,j). Crystals from Units 4 and 10 have ubiquitous thin (5-10 µm thick) low An rims that are not obvious for each crystal in figures 4.6 and 4.7. One Unit 4 crystal examined in this study exhibits little significant core to rim change in An content (Fig. 4.6c). Four of the ten Unit 4 plagioclase phenocrysts examined in this study exhibit reverse zoning (Fig. 4.6a,e,f,i). Each of the Unit 10 plagioclase phenocrysts examined in this 188
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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
Page 149 and 150: pressure, and growth of An-rich pla
Page 151 and 152: 138 TABLE 3.3 PLAGIOCLASE PHENOCRYS
Page 153 and 154: 140 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: 5 mm 5 mm Figure 4.4. Cross polariz
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 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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