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

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In Timmins, the first generation of folding and faulting with an associated fabric is a series of stacked, south-over-north D2 thrust faults with hanging wall folds, located north of the PDDZ (Bateman et al. 2005). The D2 event is post-Porcupine assemblage in timing (i.e., 2676 Ma), because the Timiskaming unconformity truncates the D2 folds and thrust faults. Early ductile deformation, which is interpreted to be synchronous with D2, is evident as C-S structures in the PDDZ indicating south-over-north thrusting along a south-dipping zone, which was probably the root zone to the stacked thrusts to the north (Bateman et al. 2005). A post-Porcupine age for early thrusting coincides with the age data from the Duparquet Basin associated with the PDDZ in Quebec (Mueller et al. 1996). Younger syntectonic intrusions (2680–2670 Ma) are small stocks, dikes and sills that are coeval with the Timiskaming assemblage and are spatially associated with the PDDZ and LLCDZ. Broadly synchronous with this magmatic event, syntectonic opening of the Timiskaming half-graben in a dilatational jog, was followed by foliation and folding, only the late stages of which affected the sediments. S3 foliation is strongly developed in Tisdale, Porcupine and Timiskaming assemblage rocks proximal to the PDDZ in the Timmins area, and is axial planar to a series of en échelon folds with curved axial surfaces along the PDDZ. The F3 fold axes do not affect the trace of the PDDZ, and do not extend directly across it to its southern side. These facts are interpreted to indicate development of F3 during leftlateral strike-slip movement along the PDDZ (Bleeker 1995). The magnitude of this sinistral displacement appears to be about 13 km as indicated by the offset of both the Krist formation and the F2 Porcupine syncline in Tisdale Township, eastward into Whitney and Cody townships. Here, the Krist formation underlies the Porcupine assemblage sediments on the western limb of an F2 syncline within the Whitney formation (see Figure 2). Therefore, it is hypothesized that both the Krist and Beatty formations and the F2 Porcupine syncline have been offset across the PDDZ during D3. This D3 event in Timmins may be correlative with early folding observed in Timiskaming assemblage wackes in Gauthier Township where it has been designated as pre-D2 (see “Kirkland Lake–Larder Lake Subproject”). The late tectonic intrusions (2670–2660 Ma) are minor, high crustal level intrusions which occur both within the external batholiths and the supracrustal belt. Possibly synchronous with this magmatic event, D4 folding created a syncline within the Timiskaming assemblage rocks in the Timmins area. Here, S4 foliation crenulates S3 and is axial planar to F4 folds that commonly have Z asymmetry. Minor structures suggest right lateral strike-slip along the PDDZ. The last significant event, D5, consists of an intense constrictional strain seen in Tisdale assemblage pillows, clasts in Krist formation volcaniclastic rocks and cobbles in Timiskaming assemblage conglomerates. The D4–D5 event represents the final stage in transpressional deformation along the PDDZ. This structural event may be correlative with the D2 event identified in the Kirkland Lake–Larder Lake area in which S2 overprints Timiskaming assemblage volcanic rocks with an age of 2670 Ma and is most strongly developed in proximity to the LLCDZ. Kinematic indicators in Gauthier Township suggest a reverse-dextral sense of movement along the LLCDZ during D2. 46
Subproject Results VMS MINERALIZATION SUBPROJECTS Kamiskotia Area Subprojects The main goal of this subproject (Hathway, Hudak and Hamilton 2005) has been to understand the stratigraphy, volcanic facies, alteration and structural style of the Archean Kamiskotia Volcanic Complex, the volcanic succession that hosts copper-zinc volcanogenic massive sulphide (VMS) mineralization in the Kamiskotia area (Abitibi greenstone belt, Timmins region). With this aim, the study area was mapped at regional scale (1:10 000 and 1:20 000 scale), with focussed deposit-scale work on the main pastproducing VMS deposits. 156 samples were analyzed for major oxides and selected trace elements in order to characterize the volcanic rock units of the mapped area, and 7 new U/Pb zircon ages were acquired. A detailed subproject by Hocker focussed on the Genex deposit and is discussed below. KIDD–MUNRO ASSEMBLAGE New U/Pb ages of 2714.6±1.2 and 2712.3±2.8 Ma indicate that the northeast-facing succession in the northern part of the study area (Loveland, Macdiarmid and Thorburn townships) forms part of the Kidd– Munro assemblage (2719–2710 Ma: Ayer, Amelin et al. 2002). A west-northwest-trending faulted contact is inferred between this older succession and the Kamiskotia Volcanic Complex to the south (Figure 20). The lower part of the Kidd–Munro assemblage, in south-central Loveland and northernmost Robb townships, consists of high-silica FIIIb rhyolites with consistent, relatively flat REE patterns with strong negative Eu anomalies. All outcrops appear to consist of quartz- and feldspar-phyric, typically flowbanded coherent rhyolite. Minor felsic volcaniclastic intervals within the rhyolite succession have been intersected by drilling. The rhyolites are overlain by a thick succession of massive to pillowed, sparsely plagioclase-phyric mafic volcanic rocks. Pillow facing directions are to the east-northeast or northeast. These rocks largely plot in the calc-alkaline basalt and andesite fields on the Jensen cation plot. Chondrite-normalized REE patterns for most samples are similar, and distinct from other groups, with a flat pattern in the middle and heavy REE, a moderately steep negative slope in the light REE, and a slight negative Eu anomaly. Lenses of re-deposited felsic volcaniclastic rocks occur within the mafic volcanic succession. In northwestern Macdiarmid Township, northeast Loveland Township, and on the southern boundary of Thorburn Township, the mafic lavas are overlain by a thicker felsic to intermediate volcaniclastic succession. Here, exposed rocks are largely massive, poorly sorted breccias and tuff breccias, although thick sections of tuffaceous sandstone and graphitic argillite are seen in drill core. Sharp-based graded beds at several locations indicate facing to the north-northeast. KAMISKOTIA VOLCANIC COMPLEX The Archean volcanic rocks in the southern part of the study area are assigned to the Kamiskotia Volcanic Complex (KVC: Figure 20). The known VMS deposits in the study area occur within a restricted, eastfacing stratigraphic interval in the upper part of the KVC. New U/Pb ages for this interval, ranging from 2701.1±1.4 to 2698.6±1.3 Ma, and an age of 2703.1±1.2 Ma from the lower part of the KVC, indicate that the KVC may better be regarded as part of the Blake River assemblage (2701–2697 Ma: Ayer, Amelin et al. 2002), rather than the Tisdale assemblage (2710–2703 Ma). Facing directions through most of the 47
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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 74 and 75: Figure 20. Geological sketch map of
Page 76 and 77: from Halfmoon Lake, only 2 km to th
Page 78 and 79: The Blake River Group is divided in
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.,
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Bleeker, W., Parrish, R.R. and Sage
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Galley, A.G., Pilote, P. and Davis,
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Heather, K.B., Percival, J.A., Mose
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Lesher, C.M., 1989. Komatiite-assoc
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Péloquin, A.S., Verpaelst, P., and
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Stern, R.A. 1997. The GSC sensitive
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108 This page left blank intentiona
Page 136 and 137:
THERMAL IONIZATION MASS SPECTROMETR
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04BHA-0462 Granophyre, Kamiskotia G
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contrastingly have been dated near
Page 142 and 143:
The revised age of 2672.8±1.1 Ma f
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fraction (A1a) also overlaps concor
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04JAA-0010 Albitite dike cutting Ti
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Therefore, on geochronological grou
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Three individual grains were analyz
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03VOI-0422-1 Trachytic lava, Timisk
Page 154 and 155:
03SJP-115-1 Monzonite, Clifford sto
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the original Corfu (1993) age, only
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Table A1. U/Pb isotopic data for zi
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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
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Table A2. continued 204 U Th Pb* Pb
Page 170 and 171:
Table A2. continued 204 U Th Pb* Pb
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Metric Conversion Table Conversion
Page 175 and 176:
Chart A. Magnetic and Gravity Three
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Overview of Results from the Greenstone ... - Geology Ontario

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