|
In:
Clastic Tidal Sedimentology, D.G. Smith, G.E. Reinson, B.A. Zaitlin and R. A.
Rahmani (eds) Canadian Society of Petroleum Geologists Memoir 16(1991), 301-312
SEDIMENTOLOGY OF
SUBARCTIC TIDAL FLATS OF WESTERN JAMES BAY AND HUDSON BAY, ONTARIO, CANADA
I.P. MARTINI
Department of Land Resource
Science University of Guelph, Guelph, Ontario, Canada N1G 2W1
¡¡
 The 3 to 5 m thick muddy
and sandy tidal flats on the western and southwestern shores of marine,
mesotidal, subarctic, locally brackish, intracratonic basins of James Bay and
Hudson Bay, resemble those of other basins, except they do not contain major
tidal channels and they display characteristic features that reflect their cold
setting. These features include the following: I) surficial scours caused by ice
floes or ice-pushed boulders and filled with poorly sorted, polymictic sand and
gravel; 2) scattered, frost-resistant, subrounded, igneous and metamorphic
glacial erratics locally reworked by sea ice; 3) frost-shattered, angular
pebbles of limestone and dolostone; and 4) coarse, ice-rafted material enclosed
in fine grained, waterlaid deposits. The macro-infauna is restricted in numbers
of species (primarily Macoma balthica and Hydrobia minuta) and
locally in numbers of individuals (along brackish coasts).
The coastal marshes are
dominated by Puccinellia phryganodes, Carex subspathacea, and Hyppuris
tetraphilla, and the marsh deposits develop diagnostic laminae reflecting
either mat root structure of Puccinellia phryganodes, or buried, discretely
spaced hollow stems of Hippuris tetraphilla. The marshes grade landward
into extensive emerging peatlands (fens and bogs), where, 100 km inland, 3 to 4
m of peat have accumulated in the last 3500 to 4000 years. Cryoturbation and
other pedogenic processes imprint emerged suquences with convolutions and
gleysolic characteristics.
|
