Rencontre Formation

Rencontre Formation
Stratigraphic range:
Outcrops of the Rencontre Formation in Rencontre, NL.
TypeFormation
Unit of(Long Harbour Group, in some schemes - e.g. NL GeoAtlas)
UnderliesChapel Island Fm[2]
OverliesLong Harbour Group - volcanics - in Rencontre, Mooring Cove Formation
ThicknessHundreds of metres[2]
Location
RegionNewfoundland
CountryCanada

Outcrop distribution

The Rencontre Formation (locally pronounced Rown-Counter) is a geological formation just below the Cambrian-Ediacaran boundary in Newfoundland, deposited in a fault-bounded enclosed basin. U-Pb dates obtained just below its base give a maximum age of 552 ± 3 million years ago.

It is subdivided into five depositional phases, with two subsequent phases in a seven-phase series corresponding to the overlying Chapel Island Formation (900 m thick in this basin) and Random Formation (250 m thick in this basin).[2]

  1. Phase one - 300 m - conglomerate dominated, some sandstone and minor siltstones
  2. Phase 2 - 150 m - sands and silts
  3. Phase 3 - 180 m - silts and minor sands; lower silts are grey-green, glauconitic, wave-rippled and mud-cracked; upper silts becoming red
  4. Phase 4 - 200 m - coarse sands
  5. Phase 5 - greater than 200 m - arenites and red silts.

References

  1. ^ Myrow, P. M. 1995. Neoproterozoic rocks of the Newfoundland Avalon Zone. Precambrian Research, 73:123–136.
  2. ^ a b c S. A. Smith, R. N. Hiscott, Can. J. Earth Sci. 21, 1379–1392 (1987).
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