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Home , Boudinage, Grenville orogeny, Lithology

Data Collection: Recording and Lithology at the Grenville Front along the Georgian Bay Michelle M. LaBelle 1Department of Earth Sciences, University of South Alabama, Mobile, AL; 2Geology Program, University of South Alabama, Mobile, AL

Abstract Methods Hypothesis During the Mesoproterozoic, the first , , was formed. The Data collection was based on cluster samples tracing the Georgian Bay from result was a major mountain-building event that occurred due to the collision of Parry Sound to Killarney, Ontario. Samples chosen for data collection were Abundant mafic intrusions and mineral assemblages identified within the the Laurentian and South American plate. That long lived event was the part of the exposed bedrock and maintained the alignment of the source tectonic zone show evidence of possible of a mafic composition Grenville . A field study was organized to collect and catalog data bedrock. Each specimen was recorded with north facing alignment, angle of plate, or impact with a volcanic system along the ancient Laurentian pertaining to the country and metamorphic composition as well as the dip, and elevation. Specimens were separated from the bedrock by utilizing continental margin. Evidence of exotic terrain of intermediate composition tectonic environment that shaped the study area within the Grenville Front Zone. pre-existing cracks in the bedrock. A hand lens evaluation of each specimen suggests that the Grundy Lake area (site 3) may have been from the exotic Lithology and deformation of crust within the Grenville tectonic zone from the was made to determine a mineral assemblage, and each specimen was terrain overriding the Laurentian land mass. area of Parry Sound tracing the Georgian Bay to Killarney was recorded using a photographed against a white background on site with markers illustrating the It is suggested by this author that the amount of mafic deposits are a result of cluster analysis based on access. Limited tectonic activity in the area allowed azimuth and dip. The specimens chosen for study were based on access, the thickening of the felsic composition land mass that allows the magmatic for a more accurate study of the Grenville metamorphism. The most recent study area representation, and duration of field work. Equipment used to intrusions to have a more mafic composition, and thus contain more favorable glacial recession had exposed the existing bedrock of the orogeny in the study collect data on the specimens were a pocket transit with level, tape measure, resources. area. The study of this area provided a base compilation of data for future hand lens, GPS handheld device, a magnet, paper denoting north facing, and studies. Initial analysis has found granitic samples with a low percentage of camera. Specimens suspected of having a composition were tested potassium in a localized area (Grundy Lake). This suggests with diluted HCl. Specimens were assigned a designation based on the camp hydrothermal processes in the area. Several Sturgeon Bay site samples showed location in the vicinity (i.e. C1S03 = Campsite 1, Specimen 03). boudinage characteristics that may indicate post orogenic deformation. The A photographic and written observation of the surrounding bedrock was literary research gathered herein is to provide a basic knowledge regarding this recorded to compare the specimen analysis with the overall topographic study, and a basis in which to compare this study’s findings. formation. A photographic record was made of the exposed outcrops along highway 401 from the Sudbury District moving southeasterly to the suspected Figure 1. Drawing of the supercontinent zone at kilometer marker 152. Rodinia. The Grenville Orogeny is The latitude and longitude of each specimen was plotted on Google Earth to represented by the shaded area that spans demonstrate the cluster areas that were studied. Any specimen in which across Rodinia. identification of assemblage was uncertain was examined by Dr. David Allison The North American land mass () is through photographs of specimens and locations. shown here positioned against the South American land mass (Amazonia). Prior to this , exotic terrain of possible volcanic arc origin impacted the Laurentian continental margin. (Levin, 2013) Figure 4. Folded and tilted banded iron formations at Parry Sound show strong deformation in high pressure and temperature conditions. Background Figure 5. Mafic intrusions in white bedrock. The photograph was taken in Lake George. The Grenville Orogeny Between 1.2 and 1.0 billion years ago a long lasting mountain building event Conclusions occurred along the eastern of North America (Laurentia)and the western South America (Amazonia). It was part of the assemblage of the first • The Grundy Lake Cluster collection shows indications of hydrothermal supercontinent, Rodinia (Fig 1). (Levin, 2013) . The continental margin processes due to the lack of potassium feldspar in the bedrock composition. impacted the eastern edge of the continent with an unknown exotic terrain. Extension deformation is suspected at the Sturgeon Bay site. Several of the Figure 2. Google Earth image showing the locations of the cluster studies. The • Widespread deformation and metamorphism of the margin created large specimens studied had boudinage characteristics that could indicate the second regions of to . Deep plastic deformation at the front data collection sites followed along the Georgian Bay in Ontario, Canada from Parry Sound, in the southeast, to Killarney in the northwest. The information deformation after the orogeny. as well as substantial faulting has been mapped extensively within the study •The number four and five sites (Lake George and Killarney) show less folding; area by Brett. Brett’s study examines the zones along the Georgian Bay to derived from these sites were performed on site. (Google Earth) Figure 3. The general lithology of the study area (Culshaw et al., 2004) however, mafic dike intrusions and mid-grade metamorphism are prevalent. (Brett, 1960). Ancient rocks were thrust up into a vast . Evidence suggests additional metamorphism occurred after the Grenville Orogeny at this Literature Cited margin during the expansion of the front as a result of the breakup of Rodinia. Results (Streepey et al., 2004) Over millions of years the mountains that were up thrust Using available outcrops and exposed areas of rock along highway 400 in Anovitz, Lawrence and Essene, Eric J. Thermobarometry and Pressure-Temperature Paths in the by tectonic and magmatic influences eroded away down to their roots. Both Grenville Province of Ontario*. Oxford University Press. 1990. Abs. basement rocks and sedimentary rocks underwent intense metamorphism and Ontario, it was noted that there was a visible change in lithology around km Brett, Brian Dudley. The Grenville Front of Ontario and Quebec. McGill University, Montreal. 1960. Pp. deformation due to the heat and pressure from the collision. Magmatic marker 152 in which the southeast general lithology appeared to be andesitic in 1-113. nature; whereas the northwest lithology appeared to contain substantial Culshaw, N.G., Corrigan, D., Ketchum, J.W.F., Wallace, P., Wodicka, N. and Easton, R.M. 2004. intrusions of primarily magnesium and iron-rich formed dikes that cut Georgian Bay geological synthesis, Grenville Province: Explanatory notes for Preliminary Maps P.3548 through the pre-existing rock. Whole-rock rubidium – strontium and uranium – with abundant mafic dike intrusions. to P.3552; Ontario Geological Survey, Open File Report 6143, 28p. lead dating suggest that these events first began occurring around 2.4 billion The felsic bedrocks within 50 km to the north west of km marker 152 Levin, Harold L. The Earth Through Time, Tenth Edition. Courier Kenallville. 2013. p.258-260. demonstrated joint frost weathering as well as sheeting. The Parry Sound (C1) Marshak, Stephen. Essentials of Geology, fourth edition. W.W.Norton * Company. 2013. p.335. years ago. (Seyfert, Sirkin, 1973) The temperatures at the tectonic zone of this Postlethwaite, Ben. Seismic velocities and composition of the Canadian crust. B.Sc., The University of collision were estimated to be approximately 850 degrees at central Grenville site showed with calsilicate lenses, foliated , boudinage British Columbia, 2014. Province. ( et al, 2002) The Parry Sound area was estimated to have with magnetite crossbedding, and mafic source rocks. The Rose Rivers, T. et al. "Assembly and Preservation of lower, mid, and upper orogenic crust in the Grenville Trail site (C2)was found to have foliated granites, amphibolites, and megacrystic Province-Implications for the evolution of large hot long-duration orogens". Precambrian Research 167 temperatures up to 800 degrees and decreasing to 650 in the Sudbury district. (3–4). 2008. p 237–259. Pressure changes from the 11 kb to 4 kb exist along the front area though there granites. At Grundy Lake (C3) there was a noticeable absence of k-feldspar in Rivers, Toby, Ketchumb, John, Indares, Aphrodite, and Hynes, Andrew. The High Pressure belt in the are small areas of discontinuity regarding pressure-temperature. (Anovitz, the phaneritic rock. Specimens that were studied at this site were identified as Greenville Province: architecture, timing, and exhumation. NRC Canada. 2002. Abs. diorite, amphibolite, and possibly tronjamite. George Lake and Killarney (C4 and Rivers, T. Testing and refining a tectonic model for the Grenville orogeny. Geophysical Research Essene, 1990) Abstracts Vol. 15, EGU2013-3455, 2013. EGU General Assembly 2013. Glaciation C5) showed signs of a zone by the presence of specimens and Seyfert, Carl K. and Sirkin, Leslie A. Earth History and : An Introduction to Geology. boudinage prophyroclast containing quartzite. Banded iron formations Harper & Row, Publishers, Inc. 1973. p.149-150 During the Pleistocene Epoch, the last glaciation, the Wisconsinan Glaciation, containing magnetite along bedded planes indicated a metasediment Streepey, M.M., Lithgow-Bertelloni, C., van der Pluijm, B.A., Essene, E.J., and Magloughlin, J.F., 2004, (0.08 to 0.02 MA) receded. The northward moving glaciers removed the Exhumation of a collisional orogen: A perspective from the North American Grenville Province, in Tollo, environment. Mafic dikes also showed metamorphism as greenstones. that covered the Grenville Front in the Georgian Bay area. The R.P., Corriveau, L., McLelland, J., and Bartholomew, M.J., eds., Proterozoic tectonic evolution of the Much of the specimens that were studied had iron staining. A specimen was Grenville orogen in North America: Boulder, Colorado, Geological Society of America Memoir 197, p. bedrock was scrapped clean and scored as the glaciers retreated. (Rutter et al, observed in the Sudbury District. It was identified as a mafic gabbro containing 391–410. 2004. 2012) Rocks broken from the bedrock were transported great distances and Woodruff,Lauren G., Nicholson, Suzanne W., and Fey, David L. A Deposit Model for Magmatic Iron- and sodium . redeposited hundreds of miles away. The weight of the continental ice sheet Titanium-Oxide Deposits Related to Proterozoic Massif Plutonic Suites. Chapter K of 36 specimens were studied, recorded, and photographed . Their locations, Mineral Deposit Models for Resource Assessment Scientific Investigations Report 2010–5070–K. U.S. depressed the surrounding area and created the great lake region. Thousands lithology, and alignment have been recorded on a data sheet and will be used in Department of the Interior U.S. Geological Survey. 2013. of bedrock micro islands exist in the Georgian Bay area that show the roots of Nat Rutter, Andrea Coronato, Karin Helmens, Jorge Rabassa, Marcelo Zárate. Glaciations in North and future research. South America from the Miocene to the Last Glacial Maximum: Comparisons, Linkages and the ancient orogenic event. Uncertainties. Springer Science & Business Media, Jun 30, 2012. P.55