Overview of Results from the Greenstone ... - Geology Ontario

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The Blake River Group is divided into 3 subgroups: the Garrison, the Misema and the Noranda. The volcanic rocks of Katrine, Ben Nevis and Clifford townships belong to the Misema subgroup. The Misema subgroup in Ben Nevis Township has a U/Pb age of 2696.6±1.3 Ma. This is younger than the pre-cauldron phase of the Noranda subgroup (2701±1 Ma: Mortensen 1993b), younger than the Misema subgroup in Pontiac Township (2701±2 Ma: Corfu et al. 1989), and of the same age as the post-cauldron phase of the Noranda subgroup (the Reneault–Dufresnoy formation: 2697.9+1.3/–0.7 (Mortensen 1993b) and 2696±1.1 Ma (Lafrance, Moorhead and Davis 2003), and the Bousquet formation: 2698.6±1.5 Ma, 2698.0±1.5 Ma and 2694±2 Ma (Lafrance, Moorhead and Davis 2003)). Thus, the Ben Nevis–Clifford volcanic complex formed late in the Blake River Group volcanic event. The Noranda cauldron sequence of the Noranda subgroup hosts the majority of VMS deposits in the Blake River Group (Gibson, Watkinson and Comba 1989; Gibson and Watkinson 1990). The volcanism in the Noranda cauldron is flow dominated (de Rosen-Spence 1976; Gibson, Watkinson and Comba 1989; Paradis 1990), as is the pre-cauldron volcanism (Péloquin, Verpaelst and Gaulin 1989a; Péloquin et al. 1989b; Péloquin 2000). However, pyroclastic rocks form an important part of the post-cauldron volcanism (Trudel 1978, 1979; Goutier 1997; Lafrance, Moorhead and Davis 2003). The Ben Nevis–Clifford volcanic centre has a large pyroclastic component. Subaqueous andesite flows are the dominant rock type in the study area. In Katrine Township, pyroclastic rocks are rare, and felsic volcanic rocks even rarer. In Ben Nevis and Clifford townships, there is a spectrum of subaqueous volcanic rocks from basalt to rhyolite. Both flow and pyroclastic facies occur in all rock types, but the felsic volcanic rocks are dominantly pyroclastic with rare flow or dome facies. The large pyroclastic component of the Ben Nevis–Clifford volcanic centre suggests that it may be a subaqueous composite stratovolcano constructed on a mafic to intermediate volcanic “floor” represented by the Misema subgroup mafic to intermediate volcanic rocks in Katrine Township. The increase in pyroclastic rocks, and the pumiceous and scoriaceous nature of some of the fragments, indicates shallow depth of emplacement for the Ben Nevis–Clifford volcano. The geochemistry of the Ben Nevis–Clifford volcanic centre also differs from the Noranda volcanism. Noranda has long been known to be bimodal (andesite–rhyolite) and to have 2 end-member andesite affinities: tholeiitic and calc-alkalic (or LREE-enriched) (e.g., Goodwin 1977; Gélinas et al. 1977; Laflèche, Dupuy and Bougault 1992; Péloquin 2000; Péloquin et al. 2001). In contrast, the Misema subgroup in the study area is unimodal (andesite dominant) with no silica gap, and there are no true tholeiites in the area. Volcanogenic massive sulphide (VMS)-style alteration and mineralization occur in the study area indicating that a synvolcanic hydrothermal system existed. However, the mineralization is concentrated in synvolcanic dikes as veins or in the multiple injection margins, suggesting that the fluids were channelized within the dikes. This indicates that the present exposure may represent the feeder zone of the hydrothermal system. The area is structurally complex and the influence of faults and deformation zones on the stratigraphy of the area must be determined, as should the effect of possible folding. High-level synvolcanic dikes, which can only be distinguished from extrusive rocks by their crosscutting relationships, occur in all rock types throughout the study area, as do mafic to intermediate dikes and irregular masses, which are comagmatic with the Blake River Group volcanism. The differences between the Ben Nevis–Clifford volcanic centre and the Noranda cauldron indicate that mineral exploration in Ben Nevis and Clifford townships should not be limited strictly to Norandatype Cu-Zn VMS deposits. The presence of VMS-style alteration and mineralization in the area indicates that a synvolcanic hydrothermal system existed. However, the apparent concentration of the mineralization in the synvolcanic dikes, as veins or in the multiple injection margins, suggests that the 52
fluids were channelized within the dikes. Thus, the present exposure may represent the feeder zone of the hydrothermal system (Figure 21). The structural complexity of the area must first be unravelled. The influence of faulting and the iron-carbonatized deformation zones on the stratigraphy of the area should be determined, and the possibility that the area is affected by complex folding examined. The recognition of a porphyry system related to the Clifford stock in Clifford Township by Piercey (Piercey et al. 2004: MacDonald, Piercey and Hamilton 2005) opens up a new avenue for exploration. A gravity low in Ben Nevis Township, which is similar to that corresponding to the Clifford stock in Clifford Township, suggests a “Clifford-type” intrusion at depth. The occurrence of Clifford-event porphyry dikes in Ben Nevis Township confirms that the Clifford intrusive event extends south of the Murdoch Creek–Kennedy Lake fault. Figure 21. Schematic diagrams (not to scale) of a) the Ben Nevis–Clifford stratovolcano in relationship to the Misema mafic lava plain (Katrine township and western Quebec) and the Noranda cauldron, indicating possible areas of present exposure, b) the Ben Nevis–Clifford stratovolcano indicating the possible area of present exposure, and c) the Noranda cauldron indicating the possible area of present exposure (from Péloquin and Piercey 2005, p.47). 53
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ISBN 0-7794-8652-8 THESE TERMS GOVE
Page 5:
ONTARIO GEOLOGICAL SURVEY Open File
Page 9:
Contents Abstract .................
Page 13:
Appendix 1. Thermal Ionization Mass
Page 17:
Miscellaneous Release—Data 155 Di
Page 21:
The Timmins area and Kirkland Lake-
Page 25:
Overview of Results from the Greens
Page 28 and 29: 3. The geophysical subproject funct
Page 30 and 31: The following Preliminary Maps have
Page 32 and 33: Samples with zircons analyzed by SH
Page 34 and 35: Figure 4. U/Pb concordia plots of T
Page 36 and 37: Figure 6. U/Pb concordia plot of TI
Page 38 and 39: Targeting of several of these overg
Page 40 and 41: Figure 10. U/Pb SHRIMP results from
Page 42 and 43: In northwest Cleaver Township, a fe
Page 44 and 45: SHRIMP U/Pb dating was carried out
Page 46 and 47: Stratigraphic Framework In this sec
Page 48 and 49: PACAUD ASSEMBLAGE The 2750 to 2735
Page 50 and 51: The iron formation and chert brecci
Page 52 and 53: (thickness) of banded iron-poor iro
Page 54 and 55: clast conglomerates at the top of t
Page 56 and 57: BLAKE RIVER ASSEMBLAGE Lower Part T
Page 58 and 59: The Krist formation consists of cal
Page 60 and 61: Timmins Area In the Timmins area, t
Page 62 and 63: Kirkland Lake-Larder Lake Area Hyde
Page 64 and 65: Intrusion Framework The plutonic ro
Page 66 and 67: The youngest dated synvolcanic mafi
Page 68 and 69: Albitite dikes are crosscut by gold
Page 70 and 71: Worming Geophysical Data Treatment
Page 72 and 73: In Timmins, the first generation of
Page 74 and 75: Figure 20. Geological sketch map of
Page 76 and 77: from Halfmoon Lake, only 2 km to th
Page 80 and 81: Figure 22. Geological map of Munro
Page 82 and 83: Mine stratigraphic succession, have
Page 84 and 85: Figure 24. Geological map of Currie
Page 86 and 87: Table 5. Simplified classification
Page 88 and 89: mesocumulate). The Stoughton-Roquem
Page 90 and 91: Shaw Dome Area GEOLOGICAL SETTING T
Page 92 and 93: 66 Figure 26. A generalized map of
Page 94 and 95: 1999) in their REE patterns and oth
Page 96 and 97: plumbing system geometrically stabl
Page 98 and 99: GOLD MINERALIZATION Production comm
Page 100 and 101: The Narrows Break mineralized zone,
Page 102 and 103: Table 7. Diagnostic mineral assembl
Page 104 and 105: anomaly and the Dome Mine (Figures
Page 106 and 107: Recommendations • Further testing
Page 108 and 109: of the inversion product. (Recent a
Page 110 and 111: the evidence for pre-Pacaud strata
Page 112 and 113: plutonism suggests the onset of reg
Page 114 and 115: Watkinson and Comba 1989; Gibson an
Page 116 and 117: The Kirkland Lake giant gold deposi
Page 118 and 119: The Timmins and Kirkland Lake-Larde
Page 120 and 121: References Ames, D.E., Bleeker, W.,
Page 122 and 123: Bleeker, W., Parrish, R.R. and Sage
Page 124 and 125: Galley, A.G., Pilote, P. and Davis,
Page 126 and 127: Heather, K.B., Percival, J.A., Mose
Page 128 and 129:
Lesher, C.M., 1989. Komatiite-assoc
Page 130 and 131:
Péloquin, A.S., Verpaelst, P., and
Page 132 and 133:
Stern, R.A. 1997. The GSC sensitive
Page 134 and 135:
108 This page left blank intentiona
Page 136 and 137:
THERMAL IONIZATION MASS SPECTROMETR
Page 138 and 139:
04BHA-0462 Granophyre, Kamiskotia G
Page 140 and 141:
contrastingly have been dated near
Page 142 and 143:
The revised age of 2672.8±1.1 Ma f
Page 144 and 145:
fraction (A1a) also overlaps concor
Page 146 and 147:
04JAA-0010 Albitite dike cutting Ti
Page 148 and 149:
Therefore, on geochronological grou
Page 150 and 151:
Three individual grains were analyz
Page 152 and 153:
03VOI-0422-1 Trachytic lava, Timisk
Page 154 and 155:
03SJP-115-1 Monzonite, Clifford sto
Page 156 and 157:
the original Corfu (1993) age, only
Page 158 and 159:
Table A1. U/Pb isotopic data for zi
Page 160 and 161:
206 Sample Analysis Description Wei
Page 162 and 163:
Appendix 2 Sensitive High-Resolutio
Page 164 and 165:
Table A2. Ion microprobe (SHRIMP II
Page 166 and 167:
Table A2. continued Struct. U Th Pb
Page 168 and 169:
Table A2. continued 204 U Th Pb* Pb
Page 170 and 171:
Table A2. continued 204 U Th Pb* Pb
Page 172:
Metric Conversion Table Conversion
Page 175 and 176:
Chart A. Magnetic and Gravity Three
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