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

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The Krist formation consists of calc-alkaline felsic fragmental volcanic rocks locally unconformably overlying the Tisdale assemblage. Recent geochronology has provided crystallization ages of 2687.5±1.3 Ma and 2687.3±1.6 Ma for samples in the Kayorum syncline and the nose of the Porcupine syncline in Timmins, and an age of 2691±1.5 Ma, south of the PDF in Whitney Township (Ayer, Barr et al. 2003). The ages and geochemical signatures of the Krist formation volcanic rocks, which are indistinguishable from those of the porphyry intrusions in the Timmins region, indicate that the abundant porphyry intrusions in the Timmins area represent subvolcanic intrusions coeval with Krist formation volcanism (see “Intrusion Subproject”). The Hoyle formation is a widespread unit of turbiditic sedimentary rocks with minor conglomerate restricted to north side of the PDDZ. It extend east as far as Guibord Township, and west as far as Denton Township. It unconformably overlies a number of older volcanic assemblages including the Tisdale and Blake River assemblages and is separated from the Kidd–Munro assemblage to the north by the Pipestone fault. Previous geochronology of detrital zircons from clastic samples indicate maximum depositional ages of 2684.7±6.3 Ma in Kidd Township (Bleeker, Parrish and Sager-Kinsman 1999) and 2691.3±1.5 Ma in Mountjoy Township (Bleeker 1999). New samples from Tisdale and Whitney townships, analyzed by TIMS, indicate maximum depositional ages of
Porcupine assemblage (Ayer, Amelin et al. 2002). The southern margin of this unit occurs in Wesley and Moody townships within the study area. The youngest detrital zircons from sandstone in Purvis Township (just north of the study area) yielded a maximum age of deposition of 2698±2.4 Ma. Older detrital zircons from this sample yield ages of 2745 Ma, 2725 Ma and 2715 Ma suggesting provenance from the Pacaud, Deloro and Kidd–Munro assemblages, respectively. A significantly older detrital zircon with an age of 2825 Ma may have been derived from pre-Abitibi rocks of the Opatica Subprovince. All three of these sedimentary units are included within the Porcupine assemblage and are interpreted to have had unconformable basal contacts with older volcanic assemblages, but the contacts have been modified by subsequent deformation and many are now the locus of regional deformation zones (see “Structural Framework”). Larder Lake South Area A unit interpreted to be part of the Porcupine assemblage occurs in the southeast corner of the study area. It was previously identified as part of the Hearst assemblage (Jackson, Fyon and Corfu 1994) and consists of turbidites and heterolithic conglomerate. It unconformably overlies, and is complexly infolded with the Larder Lake group volcanic rocks of the Tisdale assemblage. Two samples (a turbidite and a conglomerate) were analyzed from northern Skead Township (see Figure 2) and the youngest detrital zircon age detected was 2695.6±3.0 Ma with older detrital zircons at 2703 Ma, 2708 Ma, 2715 Ma and 2718 Ma (Ayer, Barr et al. 2003). Thus, the unit was deposited sometime after 2695.6±3.0 Ma. It is, therefore, interpreted to be part of Porcupine assemblage, but, unlike the samples from the Timmins area, the unit was lacking in a source for detrital zircons closer to the actual age of deposition (i.e.,
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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 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 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
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Watkinson and Comba 1989; Gibson an
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The Kirkland Lake giant gold deposi
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The Timmins and Kirkland Lake-Larde
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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
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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
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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
Page 172:
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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