title of the thesis - Department of Geology - Queen's University

More documents

Recommendations

Info

$Fayek & Kyser 2000 uraninite fractionations.pdf - Queen's University$

al., 1986; Mainprice et al., 1986). This texture corresponds to deformation temperatures in excess of ~630°C (Stipp et al., 2002). Along the deepest structural level observed, ~10 km below the GHS-TSS interface, initial stages of diatexis are seen, in which biotite- and feldspar-rich rafts and leucosome form intermerging schlieren and nebulitic structures. Throughout the migmatitic GHS, macroscale anastomosing leucosome and melanosome define a weakly developed south-dipping foliation. At these structural levels, no mineral lineations are observed. 2.5 Microstructural analyses 2.5.1 Crystallographic preferred orientation of quartz Quartz crystallographic preferred orientations (CPOs) are the result of deformation temperature, strain rate, non-coaxiality of flow, and distortional strain geometry (Sullivan and Beane, 2010 and references therein). Consequently, the analysis of quartz CPOs has become a powerful tool in characterizing high-strain zones and exhumed metamorphic terranes, such as the GHS and its bounding faults (Bouchez & Pêcher, 1976; Brunel and Kienast, 1986; Grujic et al., 1996; Grasemann et al., 1999; Bhattacharya and Weber, 2004; Law et al., 2004; Larson and Godin, 2009; Larson et al., 2010a; Yakymchuk and Godin, 2012). Historically, quartz CPO analysis has been focused on c-axis fabrics due to analytical limitations. However, development of the Electron Back Scatter Diffraction (EBSD) technique has provided an alternative methodology whereby complete crystallographic orientations of all lattice planes and axes can be determined (Prior et al., 1999). This allows for evaluation of both the quartz c- and a- axes. The analysis of a-axis fabrics provides an independent assessment of plane strain, flattening, and constriction (Passchier and Trouw, 2005). Furthermore, Sullivan and 35
Beane (2010) demonstrated that for deformation at high temperatures with non-coaxial flow, a- axis fabrics provide a more accurate representation of strain geometry. We therefore follow the recommendation of the aforementioned study and record c- and a- axes for all samples. Additionally, c-axis fabrics of four samples were measured via a universal stage mounted on an optical microscope for comparative purposes with EBSD-derived data. 2.5.1.1 Methodology Complete crystallographic orientation data of quartz for all samples were obtained using the EBSD method. Data were collected through an HKL EBSD detector installed on a JEOL JSM636OLV Scanning Electron Microscope (SEM) at Colgate University, located in Hamilton, New York, USA. Oxford Instruments HKL Channel 5.0 software was used for acquisition and processing of data. The following SEM conditions were used: high-vacuum mode, accelerating voltage of 20kV and a working distance of 12-20mm (optimal at 15-20mm). Samples were initially polished to a standard probe polish then subsequently polished on a vibrating table for 4- 6 hours using a slightly basic solution to ensure both a mechanical and chemical final polish. Following this process, samples were mounted uncoated within the SEM. EBSD analyses were collected using automated mapping where individual point data for quartz were measured at established intervals (step sizes) and automatically indexed to determine crystallographic orientations. Step sizes were set at increments smaller than the smallest grain size in a given sample to ensure sampling of all grains. Following data acquisition, wild data spikes were extrapolated and clusters of proximal point data with crystallographic misorientations less than 10° were grouped and filled in using a nearest-neighbor algorithm (Fig. 2.9). This eliminated any erratic or misindexed crystallographic orientations. Following this, crystallographic misorientations greater than 10° were defined as grain boundaries; clusters of 36
Page 1 and 2: FROM CESSATION OF SOUTH-DIRECTED MI
Page 3 and 4: Abstract Field mapping and, structu
Page 5 and 6: Co-Authorship This thesis is my own
Page 7 and 8: Table of Contents Abstract ........
Page 9 and 10: 4.1 Introduction ..................
Page 11 and 12: Figure 4.3 Microscale CPO variabili
Page 13 and 14: Abbreviations Mineral Biotite Calci
Page 15 and 16: Figure 1.1 Color relief map of the
Page 17 and 18: 1.2 Evolution of the Himalayan-Tibe
Page 19 and 20: Figure 1.3 Structures in the Himala
Page 21 and 22: the various models. However, this a
Page 23 and 24: of shear (Murphy and Copeland, 2005
Page 25 and 26: Chapter 4 outlines proposed future
Page 27 and 28: indicated by symmetric high-tempera
Page 29 and 30: The second phase of middle Miocene
Page 31 and 32: 2.3 Geologic Setting 2.3.1 Himalaya
Page 33 and 34: 2.4 Geology of the upper Karnali Va
Page 36 and 37: Figure 2.3 Lithotectonic map and si
Page 38 and 39: the main shear zone fabric. The lit
Page 40 and 41: South of the interface, the TSS is
Page 42 and 43: WNW Figure 2.6 Representative struc
Page 44 and 45: Figure 2.7 Representative structure
Page 46 and 47: distribution of dextral and sinistr
Page 50 and 51: Figure 2.9 Summary of CPO post-acqu
Page 52: a c a c Figure 2.10 Summary of quar
Page 56 and 57: Sample HK131A is a high-strain quar
Page 58 and 59: constriction, where rhomb slip domi
Page 60 and 61: ± 50°C (Law et al., 2004). Furthe
Page 62 and 63: Figure 2.14 (a) Photomicrograph of
Page 64 and 65: Figure 2.15 Summary of lithotectoni
Page 66 and 67: elationships, these data constrain
Page 68 and 69: primary reference material, “4409
Page 70 and 71: Figure 2.16 - continued. 57
Page 72: monazite grains are aligned paralle
Page 75 and 76: Analysis Position Pb U Th Th/U 207
Page 79 and 80: Analysis Position HK117A Pb U Th Th
Page 83 and 84: are derived from intensely deformed
Page 85 and 86: Samples KH10, HK102a, HK105, HK115,
Page 87 and 88: the intralaboratory standard (MAC-8
Page 89 and 90: Figure 2.18 - continued. 76
Page 91 and 92: espectively. Note that the plateaus
Page 93 and 94: Figure 2.19 Plots of muscovite cool
Page 95 and 96: Figure 2.20 Summary of results from
Page 97 and 98: (2) Previously published chronologi
Page 99 and 100:
Figs. 2.7b,d, 2.15) is locally over
Page 101 and 102:
Thermochronology of muscovite grain
Page 103 and 104:
Figure 2.21 - continued - Box (3) r
Page 105 and 106:
92 Figure 2.22 (a) Location of stud
Page 107 and 108:
is little data to support both afor
Page 109 and 110:
Figure 2.23 Numerical model of modi
Page 111 and 112:
The second phase is associated with
Page 113 and 114:
yr Figure 3.1 Numerical model of Co
Page 115 and 116:
phenomena are consistent with ongoi
Page 117 and 118:
towards the topographic front of th
Page 119 and 120:
Chapter 4 Microstructural analyses:
Page 121 and 122:
a c a c Figure 4.1 Summary of quart
Page 123 and 124:
Figure 4.2 Results of study by Toy
Page 125 and 126:
factors on the formation of differe
Page 127 and 128:
1987; Simpson and De Paor, 1993, 19
Page 129 and 130:
2009). Furthermore, there is rising
Page 131 and 132:
Figure 4.5 Simplified set up of ana
Page 133 and 134:
Appendix A Station locations and st
Page 135 and 136:
Station Latitude Longitude Elevatio
Page 137 and 138:
Station Latitude Longitude KH019 KH
Page 139 and 140:
HK 140 - Non-processed EBSD data 12
Page 141 and 142:
HK 131A - U-Stage data 128
Page 143 and 144:
HK 131A - Non-processed EBSD data 1
Page 145 and 146:
HK 139D - Non-processed EBSD data 1
Page 147 and 148:
HK 105A - U-Stage data 134
Page 149 and 150:
HK 105A - Processed EBSD data (e.g.
Page 151 and 152:
Page 153 and 154:
Page 155 and 156:
HK 125 - Processed EBSD data (e.g.
Page 157 and 158:
Page 159 and 160:
Page 161 and 162:
HK 124B2 - Processed EBSD data (e.g
Page 163 and 164:
KH18a - Monazite 1 150
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:
HK109 - Thin section * For HK109_mo
Page 181 and 182:
U Th 4 3 2 1 5 10 9 11 7 8 6 Nd Y 1
Page 183 and 184:
HK109 - Monazite 3 170
Page 185 and 186:
U SL CP 172
Page 187 and 188:
U Th SL 174
Page 189 and 190:
Page 191 and 192:
U Nd CP 178
Page 193 and 194:
U Nd Th 180
Page 195 and 196:
Page 197 and 198:
Y Nd U Th 184
Page 199 and 200:
U Th SL 186
Page 201 and 202:
Page 203 and 204:
CP Nd 2 3 4 6 5 1 Y P 190
Page 205 and 206:
U Th SL 192
Page 207 and 208:
Page 209 and 210:
CP Nd Y P 196
Page 211 and 212:
U Th SL 198
Page 213 and 214:
HK117a - Thin section 200
Page 215 and 216:
11 12 10 8 9 13 14 15 7 6 4 2 5 3 1
Page 217 and 218:
4 1 5 9 10 2 11 6 16 3 7 17 14 8 18
Page 219 and 220:
9 8 7 10 6 5 4 3 2 1 206
Page 221 and 222:
7 6 8 9 13 14 15 4 5 1 2 3 10 11 12
Page 223 and 224:
210
Page 225 and 226:
5 4 9 6 7 8 3 2 1 10 212
Page 227 and 228:
2 3 4 1 6 7 8 9 10 5 214
Page 229 and 230:
216
Page 231 and 232:
6 5 12 11 10 9 8 7 1 2 3 4 218
Page 233 and 234:
220
Page 235 and 236:
222
Page 237 and 238:
224
Page 239 and 240:
226
Page 241 and 242:
228
Page 243 and 244:
230
Page 245 and 246:
232
Page 247 and 248:
234
Page 249 and 250:
236
Page 251 and 252:
238
Page 253 and 254:
240
Page 255 and 256:
242
Page 257 and 258:
244
Page 259 and 260:
246
Page 261 and 262:
248
Page 263 and 264:
250
Page 265 and 266:
252
Page 267 and 268:
254
Page 269 and 270:
256
Page 271 and 272:
258
Page 273 and 274:
260
Page 275 and 276:
262
Page 277 and 278:
Holdsworth, R.E., McCaffrey, K.J.W.
Page 279 and 280:
Cottle, J. M., Jessup, M. J., Newel
Page 281 and 282:
Ghosh, S.K., and Ramberg, H. 1976.
Page 283 and 284:
Hodges, K.V., and Silverberg, D.S.
Page 285 and 286:
Kohn, M.J. 2008. P-T-t data from ce
Page 287 and 288:
Means, W. D., Hobbs, B. E., Lister,
Page 289 and 290:
Prior, D.J. 2009. EBSD in the earth
Page 291 and 292:
Caledonides. In, S. Sengupta (Ed.),
Page 293:
Yakymchuck, C., 2010. Tectonometamo
show all

title of the thesis - Department of Geology - Queen's University

Create successful ePaper yourself

Delete template?

Save as template?