TEXTURAL AND MICROANALYSIS OF IGNEOUS ROCKS: TOOLS ...

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will change composition reflecting such resorption. If entrained crystals survive they may be deposited by sedimentation elsewhere in the magmatic system ef- fectively fractionating the residual magma, a process referred to as punctuated differentiation by Marsh [98]. Shallow magma evolution in basaltic systems on Earth (LIPs) is thus influenced by a balance of several processes that include: 1) Formation of evolved melts within crystal-mush regions due to partial crystallization and the return of these melts to the main magma body by buoyancy driven flow or solidification front erosion; 2) Flushing of variably evolved melts from the crystal-mush interstitial spaces (i.e, filter pressing mechanism); 3) Entrainment of phenocrysts and other crystal debris during magma recharge; 4) Resorption; 5) Crystal settling and solidification front capture of crystals leading to magma fractionation [84, 85, 98, 101]; 6) Assimilation; and 7) Magma mixing. 1.3 The Global Significance of Large Igneous Provinces (LIPs) Large igneous provinces or LIPs are massive crustal emplacements of mafic magma unrelated to normal ocean floor spreading [31] (Fig. 1.4). Magmas from LIPs provide insight into regions of the mantle untapped during normal sea-floor spreading [32]. Understanding LIP magma dynamics is important, particularly in light of recent debate regarding the existence of mantle plumes and their common association with LIPS (e.g., [48, 124]). Plume based models generally favor deep mantle source regions for LIPS (e.g., [17]), possibly at the core mantle boundary (e.g., [14, 31]), whereas alternative, non-plume models favor shallow fertile upper mantle source regions referred to as “perisphere” [81]. Resolution of this debate must first begin with a better understanding of primitive LIP magmas, including their volatile content, temperature, and most importantly - the extent to which 11
12 Figure 1.4: Large Igneous Provinces around the globe; The three LIPs at the focus of this study are labeled: Hawaiian- Emperor Chain, Ontong Java Plateau, and the Kerguelen Plateau. Map is adapted from [32].
Page 1 and 2: TEXTURAL AND MICROANALYSIS OF IGNEO
Page 3 and 4: TEXTURAL AND MICROANALYSIS OF IGNEO
Page 5 and 6: DEDICATION This work is dedicated t
Page 7 and 8: CHAPTER 2: MAGMA EVOLUTION REVEALED
Page 9 and 10: 3.6.3.1 Crystal Population Origins
Page 11 and 12: FIGURES 1.1 Magma Chambers . . . .
Page 13 and 14: TABLES 2.1 MAJOR AND TRACE ELEMENT
Page 15 and 16: thus been debate within the volcano
Page 17 and 18: Cambrian schist) including a crysta
Page 19 and 20: explosive eruption vs. mild effusiv
Page 21 and 22: tiation (e.g., [84, 98]; Fig. 1.3).
Page 23: defined as having crystallinities b
Page 27 and 28: distribution of crystal sizes (e.g.
Page 29 and 30: investigating magmatic evolution us
Page 31 and 32: length dispersive spectroscopy(WDS)
Page 33 and 34: microdrilling, a pre-cleaned square
Page 35 and 36: 1.7.2 Detroit Seamount, Part of the
Page 37 and 38: lations. Reprocessing of intrusive
Page 39 and 40: nucleated homogenously and grew thr
Page 41 and 42: With accurate partition coefficient
Page 43 and 44: uniform composition of large volume
Page 45 and 46: Figure 2.2. Hand sample and thin se
Page 47 and 48: 2.3.1 A Cogenetic Relationship Betw
Page 49 and 50: Figure 2.4. Stratigraphic section o
Page 51 and 52: Figure 2.5. Backscatter electron im
Page 53 and 54: studies of Kwaimbaita basalt by San
Page 55 and 56: 42 Crystal Zone An (mol%) TABLE 2.1
Page 57 and 58: 44 Crystal Zone An (mol%) 63R2 phen
Page 63 and 64: along the xenolith margins (e.g., F
Page 65 and 66: are more abundant in phenocrysts fr
Page 67 and 68: 54 Crystal Zone 5 ML-X1 xenolith TA
Page 69 and 70: 56 TABLE 2.2 Continued Crystal Zone
Page 75 and 76:
Figure 2.7. Measured major and trac
Page 77 and 78:
2.5.3.2 Trace Elements It is diffic
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Figure 2.9. Trace element ratio plo
Page 81 and 82:
2.5.4 Resorption Features in Site 1
Page 83 and 84:
should, however, be noted that in t
Page 85 and 86:
2.6.1.2 An-rich OJP Plagioclase: In
Page 87 and 88:
equivocally the roles of H2O, press
Page 89 and 90:
ent magma requires significant clin
Page 91 and 92:
tion driven plumes, or stirring by
Page 93 and 94:
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 [
Page 99 and 100:
CHAPTER 3 SHALLOW MAGMA EVOLUTION D
Page 101 and 102:
magma compositions [23, 39, 98]. A
Page 103 and 104:
Figure 3.2. Stratigraphy of basalts
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[118]. No volcaniclastic rocks were
Page 107 and 108:
magmatic crystallization. Using the
Page 109 and 110:
Figure 3.3. A cross polarized light
Page 111 and 112:
3.4.5 Major and Trace Element Data
Page 113 and 114:
3.4.6.1 Partition coefficients for
Page 115 and 116:
3.5.1.2 Site 884 CSDs I measured pl
Page 117 and 118:
Figure 3.5. Plagioclase CSDs of ODP
Page 119 and 120:
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
Page 125 and 126:
Figure 3.8. a) The majority of Site
Page 127 and 128:
3.5.4.3 Site 1203 Unit 31 and Site
Page 129 and 130:
3.5.5 Trace Elements 3.5.5.1 Measur
Page 131 and 132:
Unit 31 > Site 884 Unit 8 (Table 3.
Page 133 and 134:
3.6 Discussion 3.6.1 Evidence of Cr
Page 135 and 136:
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
Page 145 and 146:
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
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Page 157 and 158:
Page 159 and 160:
Page 161 and 162:
Page 163 and 164:
Page 165 and 166:
Page 167 and 168:
Page 169 and 170:
Page 171 and 172:
Page 173 and 174:
Page 175 and 176:
Page 177 and 178:
Page 179 and 180:
Page 181 and 182:
Page 183 and 184:
Page 185 and 186:
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
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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
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4.5 Discussion 4.5.0.1 Origin of Ma
Page 221 and 222:
4.5.0.2 Insights from Trace Element
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that other factors influenced the a
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C A/B / D A/B C A/B / D A/B Unit 4
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Magma chambers tend to form at hori
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whole-rock basalt data. Cumulate xe
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over short time spans but may be ea
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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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