Labrador Trough

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The Labrador Trough or the New Quebec Orogen is a 1,600 km (994 mi) long and 160 km (99 mi) wide geologic belt in Canada, extending south-southeast from Ungava Bay through Quebec and Labrador.

The trough is a linear belt of sedimentary and volcanic rocks which developed in an Early Proterozoic rift basin. To the west is the Archean Superior Craton. To the east are the rocks of the Archean Rae Craton. The sedimentary rocks and volcanics of the Labrador Trough were intensely deformed and subjected to high grade metamorphism along with the Churchill terrain during the Trans-Hudson orogeny.[1] It is a northeast extension of the Circum-Superior Belt and is terminated to the south by the Grenville Front Tectonic Zone.[2]

Radiometric dates of 1883-1870 Ma are reported for mafic, ultramafic, carbonatite and lamprophyre intrusions within the Trough.[3]

It is a large iron ore belt developed on banded iron formations and has had mining operations since 1954.[4]

At least two large magmatic events occurred in the Labrador Trough. The first event 2,170 million years ago engulfed an area of 30,000 km2 (12,000 sq mi) and the second 1,880 million years ago covered a similar area of 30,000 km2 (12,000 sq mi).[5]

See also[edit]

References[edit]

  1. ^ Kearey, Philip and Frederick Vine, Global Tectonics, Wiley-Blackwell, 2nd ed., 1996, pp. 279-281 ISBN 978-0-86542-924-6
  2. ^ Green, J. C., Proterozoic Rifts, in Condie, K. C., ed., Proterozoic Crustal Evolution, Elsevier, 1993, Ch. 3, pp. 102-104 ISBN 978-0-444-88782-5
  3. ^ "Ca. 1880 Ma Circum-Superior LIP". Ernst, Richard E. Retrieved 2010-01-10. 
  4. ^ Iron Deposits of the Labrador Trough
  5. ^ "Large Igneous Provinces in Canada Through Time and Their Metallogenic Potential Appendix 1". Mineral Deposits of Canada. Geological Survey of Canada. 2008-09-24. Retrieved 2010-06-14. 

Coordinates: 56°00′N 67°30′W / 56.0°N 67.5°W / 56.0; -67.5