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Ontario Geological Survey Precambrian Geoscience Section Geoneutrino Conference, Sudbury, September 17-19, 2008 GEOLOGY DISCUSSION R.M. Easton.

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Presentation on theme: "Ontario Geological Survey Precambrian Geoscience Section Geoneutrino Conference, Sudbury, September 17-19, 2008 GEOLOGY DISCUSSION R.M. Easton."— Presentation transcript:

1 Ontario Geological Survey Precambrian Geoscience Section Geoneutrino Conference, Sudbury, September 17-19, 2008 GEOLOGY DISCUSSION R.M. Easton

2 Ontario Geological Survey Precambrian Geoscience Section Geoneutrino Conference, Sudbury, September 17-19, 2008 ~300 km radius ~500 km radius

3 Ontario Geological Survey Precambrian Geoscience Section Geoneutrino Conference, Sudbury, September 17-19, 2008 Chalk River ~290 km Bruce ~260 km Darlington ~340 km Pickering~330 km Elliot Lake mines extracted 350 million tonnes of ore with an average grade of 765 ppm U, roughly equal Th (0.09% U 3 O 8 or 1.8 lbs/ton or 136,000 tonnes of uranium metal) Pele Mtn. Pecors Lake prospect 2008 estimate 30 million tonnes at 425 ppm U

4 Ontario Geological Survey Precambrian Geoscience Section Geoneutrino Conference, Sudbury, September 17-19, 2008 DATA SETS CURRENTLY AVAILABLE RELEVANT TO ESTIMATING HPE IN THE CRUST IN THE SUDBURY AREA 1.Determine crustal thickness, estimates of lower, middle, upper crust thickness, depth to Moho –Seismic reflection and refraction data on land and in Great Lakes, for Superior and Grenville Provinces, under Southern Province east of Sudbury (Wanapitei magnetic anomaly) (GLIMPCE, COCRUST, LITHOPROBE)

5 Inferred crustal levels Sudbury region

6 Cross-section through the Sudbury region

7 Ontario Geological Survey Precambrian Geoscience Section Geoneutrino Conference, Sudbury, September 17-19, 2008 2.Ground gravity data good for Sudbury and parts of Abitibi, gravity models for Sudbury, Killarney, various parts of the Grenville Province 3.Actual heat flow measurements and HPE determinations –Data of Jean-Claude Mareschal and co-workers 4.Regional geology well known, with one exception (crust beneath Manitoulin Island and northern Lake Huron)

8 Ontario Geological Survey Precambrian Geoscience Section Geoneutrino Conference, Sudbury, September 17-19, 2008 Grenville KNOWN UNKNOWNS Paleozoic atop Grenville Superior Midcontinent Rift axis unknown KMB

9 Ontario Geological Survey Precambrian Geoscience Section Geoneutrino Conference, Sudbury, September 17-19, 2008 5.Upper crustal compositional data –Whole-rock geochemical data (modern, high-quality data for Abitibi, Sudbury structure, more limited high- quality data for parts of Huronian, Grenville, Killarney) –Airborne gamma-ray surveys (both low and high- resolution over land) –Ground gamma-ray data in some areas in the Huronian (assay mode K, U, Th) collected in conjunction with a more limited whole-rock geochemistry data set –OGS Meridian 80 surface water and sediment geochemical data along 80W from Lake Erie to James Bay

10 Examples of K, U, Th data for Sudbury area rocks UnitKUThmethod Pecors (mudstone) FELSIC 3.1 2.73 7.3 5.9 13.9 13.8 Scintillometer XRF-F/ICP-MS Lower Matinenda Upper Matinenda McKim Ramsey Lake Espanola (FELSIC) 4.5 3.3 2.7 1.6 0.1 8.5 1.9 4.3 5.9 1.2 38.3 9.9 13.2 14.4 5.9 Scintillometer, n=15 Scintillometer, n=15 Scintillometer, n=15 Scintillometer, n=5 Scintillometer, n=10 Birch Lake granite 2651 Ma FELSIC 4.5 4.4 5.2 6.8 9.9 6.1 29.1 88.8 34.7 Scintillometer, n=13 highest scint XRF-F/ICP-MS Nipissing gabbro MAFIC 1.01 1.66 2.1 2.6 6.9 7.6 (P) XRF-F/ICP-MS (M) XRF-F/ICP-MS East Bull Lake suite MAFIC 0.40.10.5Huronian volcanics are similar (Espanola)

11 Ontario Geological Survey Precambrian Geoscience Section Geoneutrino Conference, Sudbury, September 17-19, 2008

12 Ontario Geological Survey Precambrian Geoscience Section Geoneutrino Conference, Sudbury, September 17-19, 2008 6.Paleozoic data –OPG Bruce Nuclear diamond drill program collecting core through the Paleozoic from surface to Grenville basement beneath the Bruce site, core is accessible to OGS if we needed to collect K, U, Th data on main Paleozoic units –OPG making 3-D crustal model of Paleozoic for much of southwestern Ontario as part of their nuclear waste management program –Paleozoic stratigraphy well-known –Map of Grenville basement exists based on examining all basement-penetrating exploration holes

13 Ontario Geological Survey Precambrian Geoscience Section Geoneutrino Conference, Sudbury, September 17-19, 2008 Extensional Events (± plume) EventAge (Ma)Intrusions/Mineralization EBLI suite NA + Europe 2480-2445 layered intrusions, dikes PGE-Cu-Ni, contact style, reef? Nipissing~2220 sills, contact style, skarn Ni-Cu-PGE, 5-element veins, Cu veins Sudbury impact 1850 Ni-Cu-PGE (not plume but mantle input/reworking of existing deposits?) Sudbury swarm ~1250 layered intrusions, dikes Fe-Ti oxides, Cu?, potential unknown MCR1140-1080 layered intrusions, sills, contact style, reef Ni-Cu-PGE Grenville~590 dikes only, Cu?, potential unknown


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