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

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Kirkland Lake–Larder Lake Area Hyde (1980) subdivided sedimentary components of the Timiskaming Group in the Kirkland Lake– Larder Lake area into an early non-marine association dominated by conglomerates and sandstone of braided river origin. These are intimately intercalated with alkalic volcanic rocks consisting of pyroclastic and massive trachytic flows. He also interpreted a later re-sedimented association consisting of turbidites, turbiditic conglomerates and oxide-iron formation representing submarine fan deposits. However, the timing of the re-sedimented association is controversial as Jensen and Langford (1985), Corfu, Jackson and Sutcliffe (1991), and Mueller, Donaldson and Doucet (1994) all interpreted the turbidite sequences as part of an older sedimentary association, analogous to the relationship between the Porcupine and Timiskaming assemblages in the Timmins area. Jackson, Fyon and Corfu (1994) interpreted these turbiditic units as structurally overlying the Timiskaming assemblage and identified them as the part of the Hearst assemblage. Figure 17. Backscattered electron images of the cores of inherited zircon and a zircon overgrowth from Timiskaming assemblage volcanic sample 99JAA-0057. The spot locations, numbers and ages correspond with the SHRIMP II analyses in Appendix 2 (Table A2). 36
Corfu, Jackson and Sutcliffe (1991) sampled a number of the non-marine association facies sedimentary rocks in the Kirkland Lake and Larder Lake areas and determined their maximum age of deposition to be about 2679 Ma. More recent geochronology from a turbidite sample interbedded with heterolithic conglomerate beds and minor oxide-iron formation from McVittie Township, east of the town of Larder Lake, yielded detrital zircon ages of 2674.3±3.7 Ma and 2684.9±1.9 Ma (Ayer, Ketchum and Trowell 2002) indicating that at least this part of the re-sedimented association belongs to the Timiskaming assemblage as was originally interpreted by Hyde (1980). New geochronology of a wacke sample from Gauthier Township yielded detrital zircons ranging from the youngest at 2677.7±3.1 Ma, to 2682 Ma and 2770 Ma (#32: Table 1, Figure 7D)and a sample of trachyte flow from this area yielded an even younger zircon age of 2669.6±1.4 Ma with inheritance zircons having ages of 2676.6±4.3 Ma and 2694.2±2.8 Ma (#31: Table 1, Figure 7C). These ages indicate that the upper part of the Timiskaming assemblage in this area is as young as 2670 Ma, similar to the age of the Three Nations formation east of Timmins (see above). Matachewan Area A unit of conglomerate and cross-bedded sandstone, locally associated with turbiditic sedimentary rocks, extends west from Cairo Township to south of Hutt Township (see Figure 2). A number of geochronology samples were analyzed from this unit in order to determine its age and provenance (Ayer, Ketchum and Trowell 2002). The youngest detrital zircon from a sandstone in Powell Township has an age of 2685.8±1.5 Ma, as well as older detrital zircons with ages of 2692.3±2.7 Ma, 2695.2±2.4 Ma and 2757±12 Ma. A second sample was collected from fine-grained wacke interbedded with conglomerate south of Montrose Township. The youngest zircon indicates a maximum deposition age of 2688.5±1.0 Ma, whereas a number of older detrital zircons range from 2690 to 2723 Ma. The youngest detrital zircons, from sandstone interbedded with conglomerate south of Hutt Township, indicate a maximum depositional age of 2690±3.0 Ma also with detrital zircons with ages of 2706 and 2715 Ma (Ayer, Amelin et al. 2002). The above U/Pb zircon data indicate that these sedimentary units were deposited sometime after 2685.8±1.5 Ma and that only Abitibi-age zircons have been detected to date. Thus, they could belong to either the Porcupine or the Timiskaming assemblages given the time limits established for these assemblages as discussed above. However, because of the facies association of localized fluvial conglomerates and cross-bedded sandstones and the strong spatial association with the Larder Lake– Cadillac deformation zone (LLCDZ), the unit is still considered to be part of the Timiskaming assemblage. In contrast with the Porcupine, the Timiskaming assemblage samples (see below) commonly contain detrital zircons with pre-Abitibi ages (i.e., 2860–2790 Ma). These ages indicate a more widespread provenance that included source terrains older than the Abitibi. These sources could have included detritus from the Opatica Subprovince to the north, or unknown older terrains to the south or east which would have been subsequently removed by collision with the Grenville Province during the Proterozoic. However, new evidence of pre-Abitibi U/Pb ages of zircon xenocrysts, and ancient crustally contaminated Nd and Hf isotopes (Ketchum et al., in press) in some volcanic and plutonic samples only found to date in the westernmost part of the SAGB, suggests that pre-Abitibi crust, similar in age to the lowermost part of the Wawa supracrustal sequences, may have underlain the AGB in a wedge extending up to 80 km east of the Kapuskasing Structural Zone (Ketchum et al., in press). This suggests the strong possibility that the Wawa Subprovince may have contributed at least some of this pre-Abitibi detritus to the Timiskaming. 37
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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 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
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,
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
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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
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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
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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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