western quebec and southern ontario - Department of Geology

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

CHAPTER 5ANALYSIS AND DISCUSSION5.1 IntroductionPrevious studies have attempted to discern trends in seismicity and relate them to regionalgeology or tectonics, which led to increased efforts to map basement fault zones and tore-evaluate seismic hazard in many areas of Eastern North America which were formerlyregarded as low risk areas (Barosh, 1986; Jacobi and Fountain, 1993; Seeber andArmbruster, 1993; Talwani, 1999). Sbar and Sykes (1973) proposed that earthquakes inEastern North America occur in areas of high stress along existing fault zones of latePaleozoic or younger age. Yang and Aggarwal (1981) distinguished two seismogenicprovinces, that is, the Adirondack–western Quebec province and the Appalachianprovince, using the locations of 364 earthquakes of magnitude 2 to 5, and 22 focalmechanism solutions. Adams and Basham (1989) defined four seismic zones insoutheastern Canada and argued that most of the events were associated with thereactivation of late Proterozoic to Paleozoic rift system along the St. Lawrence andOttawa Rivers. In this chapter seismic source parameters (focal depth strike orientation,plunging angle P-axes and T-axes) determined in the present study are combined with the59
esults from other similar studies, and analysed and compared with tectonic features ofthe study area.5.2 Focal DepthsDepth is one of the main parameters considered in the seismic hazard. It plays animportant role in determination of the seismogenic layer in earthquake zones. Figure 5.1shows the distribution of studied earthquakes with their focal depth. There is obviously adistinct geographic difference in the depths of the seismic events in western Quebec andsouthern Ontario.The southern Ontario events and the events and south of Lake Erie occur at shallowdepths between 4 and 20 km (Figure 5.1) but most of them are with hypocentres around10 km. The depth range of these events is similar to the range of depths suggested byWhite et al. (2000) for the Grenville province in southern Ontario (possibly Grenvillerocks under Palaeozoic cover).The western Quebec events are generally deeper – between 12 to 30 km but mostof them are around 18 - 20 km. The hypocentres around 18 km and deeper are restrictedmostly in the eastern part of Western Quebec Seismic Zone. Considering a felsiccomposition of rock types at depths lower than 18 km and the temperature in such depths(≥350ºC) (Mareschal et al., 2000) the state of the crust in this zone seems to be close tothe ductile/brittle transition. The depth interval for the hypocentres in western Quebecseems to be consistent with the depth of the Mesoproterozoic shear zone on theLlTHOPROBE seismic profile (Figure 5.2a). Based on this correlation, it may beconcluded that the distribution of earthquakes in the WQSZ may be locally influenced by60
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FOCAL MECHANISMS AND VARIATIONS IN
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Acknowledgements:I would like to ex
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Figure 5.12: Summary of the focal m
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AbbreviationsCNSN: Canadian Nationa
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Earthquakes in western Quebec and s
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1.2 Organization of ThesisChapter 1
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eastern Canada each year, of which
Page 19 and 20: Metasedimentary Belt boundary tecto
Page 21 and 22: The Grenville Front tectonic zone (
Page 23 and 24: Figure 2.3: Seismicity in the study
Page 25 and 26: oadly similar continent-continent c
Page 27 and 28: Figure 2.4: Historical earthquakes
Page 29 and 30: earthquakes have occurred within th
Page 31 and 32: cluster, which is considered part o
Page 33 and 34: 2001. All events seemed to occur in
Page 35 and 36: CHAPTER 3DATA SET AND METHODS3.1 In
Page 37 and 38: Fig. 3.1: Locations of seismic stat
Page 39 and 40: Figure 3.2: Number of stations used
Page 41 and 42: the strongest recorded event in the
Page 43 and 44: Figure 3.5: Earthquake source param
Page 45 and 46: The amplitudes of the seismic waves
Page 47 and 48: Figure 3.7: Vertical component wave
Page 49 and 50: HYPOCENTER programThe HYPOCENTER pr
Page 51 and 52: wave - e.g. Pg or Pn, Sg or Sn), th
Page 53 and 54: model for P-wave velocity with mult
Page 55 and 56: CHAPTER 4RESULTSIn this chapter the
Page 57 and 58: Figure 4.1: Distribution of RMS of
Page 59 and 60: Table 4.2: Earthquake parameters (h
Page 61 and 62: The focal depth calculated here is
Page 63 and 64: focal mechanism beach-ball diagrams
Page 65 and 66: some spatial variability of the ori
Page 67 and 68: 22 20001006 50 ±3 134 ±10 90 ±0
Page 69: a)b)c)d)Western QuebecSouthern Onta
Page 73 and 74: source region (e.g. Chen and Molnar
Page 75 and 76: estimate using a stress inversion t
Page 77 and 78: Figure 5.3: Stress pattern for all
Page 79 and 80: oundaries of the Central Metasedime
Page 81 and 82: In Western Quebec Seizmic Zone (WQS
Page 83 and 84: deeper than 20 km (20 km to 26 km).
Page 85 and 86: Figure 5.7: Geologic features of WQ
Page 87 and 88: 2009). The Mont-Laurier earthquake
Page 89 and 90: a) b)c) d)Figure 5.9: Summary of th
Page 91 and 92: 5.4.3 Adirondack Clusters (WQ4 and
Page 93 and 94: WQ5 is located in the southern part
Page 95 and 96: Figure 5.13: Geological features of
Page 97 and 98: consistent with regional fault map
Page 99 and 100: WQ8 is locatedin the north-western
Page 101 and 102: 5.4.5 Timiskaming Cluster (WQ9)The
Page 103 and 104: The known faults in WQ9 cluster are
Page 105 and 106: a) b)c) d)Figure 5.19: Summary of t
Page 107 and 108: ecorded within this cluster. As it
Page 109 and 110: Figure 5.22: Nodal plane strike for
Page 111 and 112: estricted to western Lake Ontario o
Page 113 and 114: More detailed look at the relations
Page 115 and 116: Baird, W.A. F., and McKinnon, S. D.
Page 117 and 118: Easton, R. M. (1986). Geochronology
Page 119 and 120: Havskov, J., and Ottemöller, L. (2
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Ma, S., and Adams, J. (2002). Estim
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Rimando, R. E., and Benn, K. (2005)
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Wahlstrom, R. (1987) Focal mechanis
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APPENDIX A: Examples of Input and O
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SUNO BZ SN 3 141 15.29SADO BZ SG 4
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EEO BZ SG 4 140 48.02 91 0.09 0 315
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PAL BZ PN 2 D 140 33.20 53 -0.21 1
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APPENDIX C: Faults Plane Solutions
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Appendix D: Focal Mechanisms From P
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19810707 -74.6 45.1 13.0 1.9 304.0
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19950603 -76.4 47.1 18.0 3.9 100.1
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20060225 -75.2 45.7 18.7 4.5 125.8
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western quebec and southern ontario - Department of Geology

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