sgr ms thesis - University of Maine

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characteristic length and it refers to the clast’s radius in this study. Because is normalized time with respect to the diffusivity and clast radius ratio, migration of a phase change through any size clast would show similar results. This allows easy comparison in a breccia with clast sizes spanning more than three orders of magnitude. 7.3. Clast Melt Results Figure 7.2 displays phase boundary migration for the three-dimensional ideal model. The additional curve is formulated from Turcotte and Schubert (1982), and defines phase migration in a semi-infinite slab from an infinite heat source. The time it takes for the ideal clast to completely reach its solidus is = 0.2 (about 15 seconds for a 1 cm radius clast, 150,000 seconds or almost 2 days for a 1m radius clast). Results (Figure 7.3) from the outcrop model show trends for 800°C (ΔT = 150°C) and 900°C (ΔT = 250°C) intruding magma. For the ΔT = 250°C model, clasts with radii below 1cm completely reach solidus within 4 seconds, and all clasts with radii below 5cm reach solidus before 300 seconds. The partially melted area at 300 seconds is equal to 35% of the initial bulk clast area. Approximately 50% of clast area achieves solidus by 900 seconds, and all clast area achieves solidus by 5800 seconds. For the ΔT = 150°C model, solidus temperatures are achieved later and all clast area achieves solidus by 9000 seconds. Both models achieve equilibrium temperature within approximately 2 days. 99
Dimensionless time 0 0.05 0.1 0.15 R 0 0.2 0.4 0.6 0.8 1 2D clast Stefan curve (Turco e and Schubert, 1982) 0.2 Figure 7.2. Solidus migration trend for a spherical clast. The blue curve is the Stefan analytical solution for a half-infinite block exposed to an infinite heat source. Red dots mark the position of the 720°C isotherm as it migrates through the clast over time. 100
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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
Page 63 and 64: friction along the closed crack sur
Page 65 and 66: h h/2 h/4 Figure 5.2. A cube displa
Page 67 and 68: 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: A temperature versus time plot was
Page 117 and 118: Figure 7.4 displays model results f
Page 119 and 120: thermal model ignores advection of
Page 121 and 122: Zone experienced a relatively weake
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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