sgr ms thesis - University of Maine

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achieve supersolidus temperatures. For example, volcanic tuff, quartzite, or calcsilicate layers would not melt with the pelitic layers, leaving a preference to preserve the clasts produced from the higher melting temperature layers. This means that not all clasts would follow the same trend of melting, and could explain why not all Bar Harbor Formation clasts completely melted in Type 3 Shatter Zone. For the 900°C intrusion model, the clasts and matrix reach equilibrium at a temperature well above Cadillac Mountain Granite feldspar crystallization temperatures (Wiebe et al., 1997a), but the 800°C intrusion model is well below the 825°C feldspar crystallization of the Cadillac mountain Granite (Wiebe et al., 1997). Although the temperature remains above the Bar Harbor Formation solidus for a relatively long time, feldspar crystallization would significantly increase viscosity (e.g. Baker, 1996; Bea, 2010). If magma partially solidifies around a clast, there is a reduced chance for disaggregation (e.g. Beard and Ragland, 2005). For the 900°C intrusion model, the equilibrium temperature is too high for a viscosity increase, but for the 800°C intrusion model, magma crystallization may have been able to protect clasts from disaggregation with an envelope of more viscous material. The initial temperature and volume fraction of wall rock and magma determine the equilibrium temperature. As seen in Figure 7.4, a lower magma matrix percent by volume would cause less clast melting. Several initial intrusion and clast temperatures are used to replicate potential magma temperatures and wall rock temperatures with distance from the reservoir. Type 1 and 2 Shatter 105
Zone experienced a relatively weaker thermal pulse and therefore would have experienced less melt as compared to Type 3. It is likely that Type 3 Shatter Zone initially had a lower matrix volume percent, but continued melt and disaggregation of clasts allowed greater accommodation of granitic magma. Type 3 Shatter Zone may originally have looked similar to Type 2 because of this, and clast melt may have followed the conditions used for Figure 7.4.B. For a Type 2 geometry, small clasts entrained in the magma channels surrounding larger clasts would also experience a greater than average exposure to magma. Melt of small clasts in these channels would be preferred, while the surrounding larger clasts could not melt under the conditions. The characteristics of CSD evolution with partial clast melt are visible in figure 7.5. D s decreases over time with the loss of small clasts and generally no change in large clast populations. Starting with a fractal distribution at time zero, as small clasts quickly disaggregate, a bifractal trend appears to develop. Eventually, the slope changes completely to a trend that can be better defined by an exponential size distribution. This model can explain the progression of D s from Type 2 to Type 3 in Bar Harbor Formation clasts. Type 3 Bar Harbor Formation size distributions have the most evolved slope and the greatest thermal exposure. I cannot assume that the Bar Harbor Formation clasts completely followed this migrating CSD trend because of the compositional differences between layers. CSD for Bar Harbor Formation clasts therefore reflect the trend of partial melt in most of the clasts and the remnant clasts that did not attain melting temperatures. 106
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FRACTAL ANALYSIS AND THERMAL-ELASTI
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LIBRARY RIGHTS STATEMENT In present
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emplacement of mafic magma, resulti
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© 2011 Samuel Geoffrey Roy All Rig
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TABLE OF CONTENTS ACKNOWLEDGEMENTS
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5.3.5. Clast Circularity Analysis .
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LIST OF FIGURES Figure 2.1. Figure
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LIST OF TABLES Table 6.1. Table 7.1
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subvolcanic magmatic systems, the l
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Chapter 2 GEOLOGIC SETTING 2.1. Reg
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Somesville granite suite to the wes
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Biotite is metamorphic in origin, a
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Chapter 3 PHYSICAL DESCRIPTION OF S
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thinned lithosphere allows for part
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A B C Figure 3.1. Formation of a la
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1997; Branney and Kokelaar, 1998; J
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Effusive-Type Eruption max 10 0 - 1
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magma quickly intrudes the develope
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Piston Downsag Piecemeal Funnel Tra
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fragmentation, and thermal energy h
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Chapter 4 THERMAL FRAMEWORK FOR CON
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contrast, conduction is heat transf
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A B Grt C Grt D Crd Crd E 1 mm F Cr
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! ! ! ! Biotite Zone Garnet Zone !
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4.3.1. Model Setup The model is use
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to make a “hockey puck” style g
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t = 0s t = 1E11 t = 1E12s t = 1E13s
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850 750 650 550 450 400m Into Chamb
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approximately 140m thinner. The Sha
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Chapter 5 ROCK MECHANICS AND THE FR
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A β δ σ 1 σ 3 σ t c a σ 1 σ
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friction along the closed crack sur
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h h/2 h/4 Figure 5.2. A cube displa
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where N (≥r) is the count of clas
Page 69 and 70: to place a minimum size limit when
Page 71 and 72: moment of sudden fracture tip failu
Page 73 and 74: produced results in a self-similar
Page 75 and 76: 13 ln(area) (pixels) 12 11 10 9 ln(
Page 77 and 78: eaction processes were involved in
Page 79 and 80: Chapter 6 ANALYSIS AND RESULTS The
Page 81 and 82: Type 1 Type 2 500 m N Type 1 Type 2
Page 83 and 84: A B Figure 6.3. Type 2 Shatter Zone
Page 85 and 86: A B Figure 6.5. Centimeter-scale bo
Page 87 and 88: A B Figure 6.6. Brecciation texture
Page 89 and 90: The final breccia classified in thi
Page 91 and 92: esolution images of each box were s
Page 93 and 94: Clast circularity data were produce
Page 95 and 96: A 1000 Clast Size Distribu on: Type
Page 97 and 98: diorite dike with D s = 2.62 and R
Page 99 and 100: 6.3.3. Clast Circularity Analysis (
Page 101 and 102: with decreasing clast size in all T
Page 103 and 104: possibilities as postulated previou
Page 105 and 106: Chapter 7 MECHANISMS FOR SECONDARY
Page 107 and 108: magma. To prove the viability of th
Page 109 and 110: mesh to better evaluate large therm
Page 111 and 112: consistent with Type 3 breccias. Th
Page 113 and 114: A temperature versus time plot was
Page 115 and 116: Dimensionless time 0 0.05 0.1 0.15
Page 117 and 118: Figure 7.4 displays model results f
Page 119: thermal model ignores advection of
Page 123 and 124: 7.4. Thermal-Induced Fracture Field
Page 125 and 126: Metapelite/hornfels Diorite dike E
Page 127 and 128: 7.4.2. Results and Discussion COMSO
Page 129 and 130: This thermal fracture model explain
Page 131 and 132: disaggregation of Bar Harbor clasts
Page 133 and 134: REFERENCES Acocella, V. (2007). Und
Page 135 and 136: Billen, M.I. and Gurnis, M. (2001).
Page 137 and 138: Clarke, D. B. (2007). Assimilation
Page 139 and 140: Fisher, R.V. (1960). Classification
Page 141 and 142: Hartmann, W.K. (1969). Terrestrial,
Page 143 and 144: Johnson, S.E.; Paterson, S.R.; Tate
Page 145 and 146: Mandelbrot, B.B. (1967). How long i
Page 147 and 148: Oliver, N.H.S.; Rubenach, M.J.; Fu,
Page 149 and 150: Schoutens, J.E. (1979). Empirical A
Page 151 and 152: Wiebe, R.; Holden, J.; Coombs, M.;
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