Properties and Processes of Earth's Lower Crust

Properties and Processesof Earth\'s Lower Crust......Page 1
Geophysical Monograph Series......Page 2
GEOPHYSICAL MONOGRAPH SERIES......Page 3
Properties and Processes of Earth\'s Lower Crust......Page 5
CONTENTS......Page 7
PREFACE......Page 9
Introduction......Page 10
Geological Summary......Page 11
Seismic Data Acquisition and Processing......Page 13
Mid-crustal Velocity Increase......Page 15
Barcoo Trough......Page 16
BMR Line 1......Page 17
Sub-Moho Reflections......Page 18
Discussion......Page 19
Conclusions......Page 21
References......Page 22
Introduction......Page 24
Geological Framework......Page 25
The Layering of the Lower Crust and the Moho......Page 26
Other Seismic Events......Page 30
Constraints on the Timing......Page 32
Causes of the Layering in the Lower Crust......Page 34
Significance of the Seismic Moho andits Relation with the Upper Mantle......Page 35
References......Page 36
Comparative Geology of Newfoundland and the British Isles......Page 39
Seismic Images across Strike-Slip Faults......Page 41
Seismic Images in Overthrust Terranes......Page 42
Lower Crustal \'Wedges\' and the Iapetus Suture......Page 46
Discussion......Page 47
References......Page 48
The Grenville Block......Page 50
Discussion......Page 53
Conclusion......Page 56
References......Page 57
Nevada......Page 58
Minnesota......Page 62
Discussion......Page 63
References......Page 67
Penokean Orogen......Page 69
Midcontinent Keweenawan Rift System MRS......Page 71
Results From the Grenville Front and Adjacent Terranes -Profile J......Page 72
Geometry of Structures Beneath Profile C -A North-Dipping Mega-Half-Graben......Page 75
Geometry of Structures Beneath Profile A -A South-Dipping Mega-Half-Graben......Page 77
Segmentation of the MRS......Page 78
Conclusions......Page 81
References......Page 82
Rift Basin Reflections......Page 85
Lower Crust and Moho Reflections......Page 89
Model for Rift Magmatism......Page 92
References......Page 93
Introduction......Page 94
Geology of the Area......Page 95
Previous Geophysical Work......Page 96
Experimental Results and Interpretation......Page 97
Conclusions......Page 99
References......Page 101
Introduction......Page 103
Discussion......Page 111
References......Page 117
Reflectivity Modeling of the Laminated Lower Crust......Page 120
References......Page 123
Introduction......Page 125
DSS and Other Geophysical Studies in the Area......Page 127
Crustal Velocity Functions......Page 129
Velocity Models for the Lower Crust......Page 130
Two Dimensional Travel Times Modeling......Page 131
Interpretation and Discussion of  Results......Page 136
References......Page 138
Introduction......Page 140
Digitization and Presentation of the Record Sections......Page 141
Upper Crustal  Model......Page 144
The Moho Boundary......Page 146
Discussion......Page 150
References......Page 153
Data Acquisition Method......Page 155
The Main Results of  DSS......Page 157
Comparison of  DSS Results......Page 159
References......Page 163
A SEISMIC REFRACTION STUDY OF THE CRUSTAL STRUCTURE OF THE SOUTH KENYA RIFT......Page 165
References......Page 168
SEISMICITY NEAR LAKE BOGORIA IN THE KENYA RIFT VALLEY......Page 169
References......Page 171
The Single Source-Single Station Multimode Method......Page 172
Data Processing for the Determination of Q Models......Page 175
Modeling......Page 177
Analysis of  Factor R......Page 186
Conclusions......Page 188
References......Page 189
Introduction......Page 190
Tectonic Setting and Instrumentation......Page 191
Focal Depths......Page 192
Compressional Wave Velocities......Page 193
Focal Mechanisms......Page 197
Crustal Temperatures......Page 199
Discussion......Page 202
References......Page 204
Introduction......Page 207
Temperature Measurements......Page 208
Corrections......Page 209
Thermal Conductivity......Page 210
Geothermal Models......Page 211
Discussion......Page 213
Electrical Conductivity......Page 215
Seismicity......Page 221
References......Page 222
Introduction......Page 225
Conversion Technique......Page 226
D-parameter Variation with Depth......Page 227
Moho Heat Flow......Page 228
Discussion and Conclusions......Page 230
References......Page 231
Experimental Data......Page 233
Interpretation......Page 234
Discussion......Page 235
References......Page 236
Interpretation of  Magnetic Anomalies in Particular Regions......Page 237
Model of the Earth\'s Crust as a Whole Compared with Magsat Data......Page 238
Estimations from Rock Magnetics......Page 239
Conclusions......Page 241
References......Page 242
Introduction......Page 244
Magnetization of the Crust off Canada\'s East Coast......Page 246
Submerged Continental Area......Page 253
Rift Basins and Ocean Continent Boundary OCB......Page 256
Oceanic Areas......Page 255
References......Page 257
Introduction......Page 260
The Method......Page 261
Results and Discussion......Page 263
References......Page 265
GRAVITY FIELD, DEEP SEISMIC SOUNDING AND NATURE OF CONTINENTAL CRUST UNDERNEATH NW HIMALAYAS......Page 267
References......Page 272
Thermal-Mechanical Models of Extension......Page 273
Extension with Distributed Magmatism......Page 274
Volume of Undernlated Material......Page 275
Metamorphism in the Lower Crust......Page 277
Rheologv and Deformation of Extensional Lower Crust......Page 278
An Example of Extensional Lower Crust......Page 279
References......Page 282
Granulites and the Lower Crust......Page 286
English River Subprovince......Page 288
Kapuskasing Uplift......Page 289
Lower Crust?......Page 291
References......Page 292
Composition and Thermodynamic Stateof the Lower Crustal Rocks......Page 296
Equilibrium Phase Diagrams......Page 298
Kinetic  Model......Page 299
Lower Crust  Models......Page 301
References......Page 304
Island Arc Processes......Page 306
Sediment Subduction......Page 307
Isotopic Constraints......Page 308
Delamination......Page 310
References......Page 312
Major Elements......Page 315
Rb, Sr and Their Isotopes......Page 316
Origin of Olivine Tholeiitic Magma......Page 319
Formation of Alkaline Olivine Basalt......Page 320
References......Page 322