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

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

A dense event cluster occurs in the vicinity of the 461 orebody (orebody shown in Fig. 2.4A, B), which is hosted in the 461 Splay that connects the 402 and Return Air Raise shear zones. This is represented by clustering about the 461 Orebody on the 7530 level and is also reflected on the 7400 Level (Fig. 3.7). 461-related seismicity does not cluster temporally but occurs sporadically throughout the 2006-2007 time interval, contemporaneously with events to the east in the active zone. Seismicity in this vicinity has also intensified from 2002-2007. This cluster is discussed in the following sections. 3.2.3 Cluster Analysis for the 7400 Level The degree of damage in a rock mass can have a dramatic effect on the properties of the seismic waves emitted from microseismic sources, notably on wave velocity and attenuation (Feustel, 1998). Such changes have been used to describe the rock mass character. Lower velocity and higher attenuation is recorded in a heavily fractured rock mass as compared to a homogeneous and unfractured rock mass (Feustel, 1998). Given this, it is expected that the state of damage in the rock mass would also have a noticeable effect on source parameters, most of which are calculated directly or indirectly from the recorded waveforms. Temporal trends in seismic event parameters can approximate loading curves similar to those traced in acoustic emission tests (Coulson and Bawden, 2008). Such curves indicate that at the point of fracture initiation, the moment magnitude, seismic moment, seismic energy and apparent stress increase until the point of yield, at which point fractures coalesce and there is a significant drop in parameter values (Coulson and Bawden, 2008). The source radius and source complexity (ratio of dynamic stress drop to static stress drop) show a decrease in parameter values during loading and a sudden increase as the rock mass yields. Following this, characteristics of events in an intact and fractured rockmass are summarized in Table 3.1. 52
Table 3.1: Event characteristics in an intact and fractured rock mass Events in intact rock mass (loading) • High moment magnitude, M • Low M • High seismic energy, E o • Low E o • High seismic moment, M o • Low M o • High apparent stresses, σ a • Low σ a • Low source radius, R o • High R o • Comparable dynamic and static stress drop values (low complexity) Events in yielded rock mass (post-peak) • High dynamic stress drop as compared to static stress drop (high complexity) Spatial and temporal analysis of microseismic event parameters was conducted to identify trends and assess rockmass properties on levels 7200, 7400 and 7530. Temporal analysis of levels and clustered events on the 7400 Level did not reveal any significant trends (temporal parameter results can be found in Appendix B) but did reveal comparable spatial event distributions: dense seismicity extends from the southeastern corner of the excavation to an area southwest of the excavation (Fig. 3.7). Events in this area occur sporadically during the two-year time period. It is postulated that in the Creighton Deep the microseismic event distribution as well as the event parameters reflect both local stress conditions and the physical state of the rock mass; heavily damaged rock is expected to be aseismic, whereas a actively yielding rock mass will result in denser seismic activity. Seismicity on 7400 Level is separated into three distinct clusters (Table 3.2, Fig. 3.8). The first cluster (Cluster 1) is located to the southwest of the excavation. Cluster 1 is the densest cluster and has a markedly different seismic character from the other clusters. Cluster 1 contains elevated source parameter values for seismic moment, energy, apparent stress, stress drop as well as particle motion parameters that are well above background levels (Table 3.3). 53
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THE INFLUENCES OF STRESS AND STRUCT
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esulting in increased stress to the
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Table of Contents Abstract.........
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4.6.1 Fracture Reactivation........
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List of Figures Figure 1.1: Locatio
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Figure 3.23: Preliminary stress inv
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Figure B11: Events between Jan 1, 2
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List of Tables Table 2.1: Geologica
Page 17 and 18: Chapter 1 Introduction 1.1 Backgrou
Page 19 and 20: Figure 1.1: Location of Sudbury and
Page 21 and 22: Chapter 2 Geological Assessment of
Page 23 and 24: ack breccia and sediments later dep
Page 25 and 26: Murray Fault, the principal fault o
Page 27 and 28: 2.2 Local Geology of Creighton Mine
Page 29 and 30: B West East B’ Figure 2.4B: Longi
Page 31 and 32: Table 2.2: Fault systems within the
Page 33 and 34: Table 2.3: Summary of Fault Charact
Page 35 and 36: Figure 2.6: (A) Damage to shotcrete
Page 37 and 38: Figure 2.7: (A) The 1290 Shear Zone
Page 39 and 40: Figure 2.8: Images of (A) the 400-E
Page 41 and 42: Figure 2.9: (A) Photograph of the c
Page 43 and 44: Figure 2.10 (A) Shear foliation, in
Page 45 and 46: Figure 2.11: Thin sections of the F
Page 47 and 48: (Fig. 2.12B). Reduction of quartz g
Page 49 and 50: 2.3.11 Late-Stage Fractures The you
Page 51 and 52: overprinting (Cochrane, 1991; Couls
Page 53 and 54: Table 2.4: Summary of Proterozoic t
Page 55 and 56: Both of these inferred stress direc
Page 57 and 58: are, at this time, in the process o
Page 59 and 60: Microseismic events of this subset
Page 61 and 62: 3.2.1.2 Seismic Energy (E o ) and S
Page 63 and 64: 3.2.1.4 Stress Parameters Stress pa
Page 65 and 66: located events were removed from cl
Page 67: Figure 3.7: Detected seismicity cor
Page 71 and 72: Table 3.3: Summary of relevant para
Page 73 and 74: ) Damage Zone The rock mass in the
Page 75 and 76: quadrants of dilatation and compres
Page 77 and 78: Figure 3.12: Lower hemisphere equal
Page 79 and 80: mechanism shows that over 57% of th
Page 81 and 82: Figure 3.16: Classification of prin
Page 83 and 84: Figure 3.18: Contoured P-axis, B-ax
Page 85 and 86: Figure 3.20: Distribution of double
Page 87 and 88: This parameter reflects the magnitu
Page 89 and 90: Figure 3.23: Preliminary stress inv
Page 91 and 92: Figure 3.25: Equal area stereonet s
Page 93 and 94: Figure 3.27: (A) Maximum principal
Page 95 and 96: 4.2 Numerical Methods Phase 2 and U
Page 97 and 98: Stress-strain relationships are use
Page 99 and 100: Rock mass failure is governed by th
Page 101 and 102: Figure 4.5: (A) Model for tectonic
Page 103 and 104: The zero cohesion and low friction
Page 105 and 106: Figure 4.9: Model of yielding for C
Page 107 and 108: Figure 4.11: Model of differential
Page 109 and 110: Figure 4.14: Model of maximum stres
Page 111 and 112: stress field model. There is little
Page 113 and 114: clustering are indications of rock
Page 115 and 116: Figure 4.23: Contoured domains of s
Page 117 and 118: Figure 4.24: Fracture initiation th
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seismic Cluster 1, which correspond
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contains energetic events and is no
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preferentially oriented fracture pl
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methodologies employed are of value
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References Alcott, J. M., Kaiser, P
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Galkin, V., Mungall, J. (2005). Str
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Mungall, J. E., & Hanley, J. J. (20
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Appendix A Geological Maps and Samp
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A.2 Level Plans with Sample Locatio
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Figure A3: 7400 Level, modified for
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Figure A5: 7680 Level, modified for
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Figure A7: 7940 Ramp, modified from
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MICROSEISMIC EVENTS Source Radius A
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2006 Event Frequency with Depth 600
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B.2 Spatial Distribution of Seismic
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Cluster 1 Source Radius Asp. Radius
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Seismic Moment 10.0 9.5 9.0 8.5 8.0
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143 Peak Velocity Parameter -2.5 -2
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B.4.2 Temporal Distribution of Clus
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147 Static Stress Drop 5.0 5.5 6.0
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B.4.3 Temporal Distribution of Clus
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151 Static Stress Drop 4.0 4.5 5.0
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Frequency-Magnitude Relation for Cl
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P-axis B-axis T-axis 155 Fault Plan
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P-axis B-axis T-axis Fault Plane 1
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D.1.1: Case 1 Models Figure D1: Cas
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Figure D3: Case 1, elastic models s
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A B C D Figure D5: Case 1, plastic
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A B C D Figure D7: Case 1, plastic
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D.1.2: Case 2 Models A B C D Figure
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D.1.3: Case 3 Models A B C Figure D
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D1.4 Tectonic Loading Models Figure
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D.2 Discussion of Phase 2 Models El
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Staged models were created in which
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Figure D17 (A) Elastic model showin
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Figure D19 (A) Elastic model showin
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• Similar damage zones surroundin
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; ;================================
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change jmat=1 range 0,1564.64 0,156
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crack (845.579,718.676) (787.063,57
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;===plum=== crack (0,355.2371429) (
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crack (866.14,726.44) (838.2,737.61
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crack (838.2,737.616) (815.848,771.
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crack (815.848,771.144) (815.848,78
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;===== define sub block ===========
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E.9 S3:S1 Model for fracture reacti
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yval= abs(z_syy(zi)) xyval= abs(z_s
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and rearranged to , (Equation F4) .
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Such that , (Equation F19) I is the
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title of the thesis - Department of Geology - Queen's University

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