Meguma terrane

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Map of Nova Scotia, showing how the Meguma terrane forms the southern portion.

The Meguma terrane, also known as Megumia, is a terrane exposed in southern Nova Scotia, that became joined to the present North American landmass as part of the Appalachian orogeny.

The exposed part of the Meguma terrane, the , is largely composed of c. 10 km (6.2 mi) thick Cambrian to Ordovician turbidites that have been interpreted as submarine fan deposits.[1] The Meguma terrane is joined to the Avalon terrane along the Minas Fault Zone, which runs east–west from Chedabucto Bay to Cobequid Bay and the Minas Basin.[2] The Meguma Group is intruded by numerous Devonian and Carboniferous plutons.[3]

The extent of the formation is unclear; some geologists believe that a magnetic anomaly along the coast of Cape Cod may represent a suture between the Meguma and Avalon terranes in that region.[4] Unlike the Avalon terrane, the Meguma terrane has not been definitely associated with a territory on the other side of the Atlantic. It may be represented in either the Galicia-Tras-Os-Montes Zone in Spain and Portugal;[citation needed] the West African Craton in Morocco; or the Amazonian Craton.[5] Meguma was, nevertheless, part of Gondwana during the Cambrian, and possibly formed a single peri-Gondwanan fragment together with Avalon. Meguma then became shortened during the Acadian orogeny but Avalon somehow escaped those Acadian deformations.[6]

Geologically this area is of interest not only to students of geological history, but because metamorphism produced gold deposits which were mined extensively (up to 30,000 ozt/a (930 kg/a)) in the latter half of the 19th century, and which remain potentially exploitable today during periods of higher gold prices.[7]

See also[]

  • Ganderia, also known as Gander terrane – Terrane in the northern Appalachians which broke off the supercontinent Gondwana
  • Rheic Ocean – Ancient ocean which separated two major palaeocontinents, Gondwana and Laurussia

References[]

Notes
  1. ^ Waldron et al. 2005, Maguma Terrane in Nova Scotia, p. 4
  2. ^ Sangster & Smith 2007, Regional Geology and Tectonic Setting, pp. 724–725
  3. ^ Horne et al. 2007
  4. ^ Hallett et al. 2003, Geologic setting
  5. ^ Nance et al. 2010, p. 211
  6. ^ Waldron et al. 2005, History of the Avalon-Meguma Boundary, p. 5
  7. ^ Sangster & Smith 2007, Introduction and history, pp. 723–724
Sources
  • Hallett, B. W.; Paskevich, V. F.; Poppe, L. J.; Brand, S. G.; Blackwood, D. S. (2003). "A Pictorial Survey of the Bedrock beneath Western Cape Cod, Massachusetts". Open-File Report OF-2003-221. United States Geological Survey. Retrieved 3 February 2018.
  • Horne, R. J.; Culshaw, N.; White, C. E.; Kontak, D. (2007). Neoacadian deformation within the Meguma terrane. Northeastern Section - 42nd Annual Meeting. 39. Geological Society of America. p. 69. Retrieved 3 February 2018.
  • Nance, R. D.; Gutiérrez-Alonso, G.; Keppie, J. D.; Linnemann, U.; Murphy, J. B.; Quesada, C.; Strachan, R. A.; Woodcock, N. H. (2010). "Evolution of the Rheic ocean". Gondwana Research. 17 (2–3): 194–222. Bibcode:2010GondR..17..194N. doi:10.1016/j.gr.2009.08.001. Retrieved 3 February 2018.
  • Sangster, A. L.; Smith, P. K. (2007). "Metallogenic summary of the Meguma gold deposits, Nova Scotia" (PDF). In Goodfellow, W. D. (ed.). Mineral deposits of Canada: a synthesis of major deposit-types, district metallogeny, the evolution of geological provinces, and exploration methods. Special Publication. 5. Geological Association of Canada, Mineral Deposits Division. pp. 723–732. Retrieved 3 February 2018.
  • Waldron, J. W.; White, J. C.; MacInnes, E.; Roselli, C. G. (2005). Field Trip B7: Transpression and transtension along a continental transform fault: Minas Fault Zone, Nova Scotia (PDF). AGS Special Publication. 33. Atlantic Geoscience Society. hdl:10222/53771. ISBN 9780973798227.

Coordinates: 44°30′00″N 65°00′00″W / 44.50000°N 65.00000°W / 44.50000; -65.00000


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