sgr ms thesis - University of Maine

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t = 0 t = 10 t = 100 t = 1500 % Clast partial melt by area 100 90 80 70 60 50 40 30 20 10 0 ΔT=150°C ΔT=250°C 0 1000 2000 3000 4000 5000 6000 7000 8000 9000 Time (seconds) Figure 7.3. A plot displaying clast melt over time. The total area of clast material below the 720°C isograd decreases quickly as small clasts melt, then progresses more slowly when few large clasts remain. 101
Figure 7.4 displays model results from the transient temperature path for points within the spherical clast model with ΔT = 150°C and ΔT = 250°C runs. The ΔT = 250°C results show that, for a magmatic breccia with 75% matrix, homogenization temperature is reached by = 1.6. For this model, clast centers achieve supersolidus temperatures by = 0.2 for T i = 900°C and = 0.3 for T i = 800°C. Equilibrium temperature is 840°C (θ = 0.76) and 770°C (θ = 0.48) respectively. Results from the 34% magma by volume model show a constant intrusion temperature of 900°C for T c = 650°C with = 0.24 and 450°C, which does not reach the solidus temperature at the clast center. Results from the 16% magma by volume model show a constant intrusion temperature of 900°C for T c = 650°C and 400°C, both of which do not reach the solidus temperature at the clast center. 7.3.1. Discussion Based on thermal modeling results and the calculated solidus temperature of 720°C, All Bar Harbor Formation clasts with the average bulk chemistry (Metzger, 1959) achieved supersolidus temperatures with 75% magma matrix by volume, allowing partial melt to occur. Small, noncircular clasts melt first, and because there is such a large population of small clasts, there is a rapid increase in percent partial melt seen in Figure 7.3. The melt percent by area slope decreases when only larger clasts remain. An order of magnitude change in clast radius will cause two orders of magnitude change in the amount of time for the clast to achieve supersolidus temperatures (Okaya et al., in press). Although the 102
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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
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 and 114: A temperature versus time plot was
Page 115: Dimensionless time 0 0.05 0.1 0.15
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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