Nd isotope mapping of Grenvillian crustal terranes in the vicinity of the Manicouagan Impact Structure |
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| Authors: | Stephanie D Thomson Alan P Dickin John G Spray |
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| Institution: | 1. Endogene Prozesse, Steinmann Institut für Geologie, Mineralogie und Paläeontologie, University of Bonn, Germany;2. Department of Earth Sciences, University of Alberta, Edmonton, Canada;1. School of Earth Sciences, Division of Historical Geology, The Ohio State University, 125 S. Oval Mall, Columbus, OH 43210, USA;2. Department of Geology, Lund University, Sölvegatan 12, SE 223 62 Lund, Sweden;3. Department of Physics, Astrogeobiology Laboratory, Lund University, SE 221 00 Lund, Sweden;4. Department of Earth, Ocean & Atmospheric Science, Florida State University, Tallahassee, FL 32386, USA;1. Key Laboratory of Mineral Resources, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China;2. School of the Earth Sciences and Resources, China University of Geosciences, Beijing 100083, China;3. Department of Geoscience, University of Iowa, Iowa City, IA 52242, USA;4. Institute of Geomechanics, Chinese Academy of Geological Sciences, Beijing 100081, China |
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| Abstract: | Over 70 new Nd isotope analyses are presented for the Manicouagan area of the Grenville Province to estimate the crustal age of target rocks involved in the 214 Ma Manicouagan Impact Structure, and to reconstruct the Precambrian geological evolution of this crustal segment. The rocks fall into two main groups: Samples from the Archean-aged Gagnon Terrane to the north and west of the impact give TDM ages averaging 2.70 Ga. Samples from the Manicouagan Imbricate Zone (MIZ) and other allochthonous lithotectonic domains to the south of the impact yield Paleoproterozoic TDM ages averaging 2.01 Ga for the MIZ and 1.86 Ga for the southern domains. These Paleoproterozoic terranes are correlated with Makkovik-age crust in Labrador that was heavily reworked by Labradorian magmatism that increased in intensity southwards. The target rocks involved in the impact event would have consisted almost entirely of the MIZ, which formed a layer several kilometres thick, overlying Archean crust at depth. |
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