DISCLAIMER: This English version is translated from the original French. In case of any discrepancy, the French version shall prevail.
|Author:||Clark and Globensky, 1975|
|Stratotype:||Type section described by Clark and Globensky (1975) from drilling Gauthier No. 2 at the Gauthier Quarry, Saint-Marc-des-Carrières (46.6764º N, 72.0569º E)|
|Type area:||Saint-Marc-des Carrières area (NTS sheet 31I09)|
|Geological province:||St. Lawrence Platform|
|Geological subdivision:||St. Lawrence Lowlands Platform|
Two diamond drillings in the Gauthier Quarry (in Saint-Marc-des-Carrières) crossed, under limestone of the Deschambault Formation, 8.8 and 11.3 m of quartzitic sandstone overlying gneiss. Although not outcropping and likely not widespread, Clark and Globensky (1975) considered it of sufficient importance to define the Saint-Marc Formation. The name refers to the town of Saint-Marc-des-Carrières (sheet 31I09) where drillings were conducted.
The Saint-Marc Formation consists of a light, almost pure, well-sorted quartzitic sandstone (Clark and Globensky, 1975; Harland and Pickerill, 1982; Globensky, 1993). It contains limestone interbeds of the Deschambault Formation. This sandstone is interpreted as a shallow, subtidal, clastic sedimentary deposit from a local shoreline or near an island (Harland and Pickerill, 1982). The type section described below is taken from the bottom 11.3 m of driling Gauthier No. 2, in Saint-Marc-des-Carrières (Clark and Globensky, 1975):
In the two Gauthier Quarry drillings, the Saint-Marc Formation is 8.8 and 11.3 m thick (Clark and Globensky, 1975). This sandstone does not outcrop and has not been observed elsewhere.
The Saint-Marc Formation lies on Precambrian bedrock and contains interbeds of the Deschambault Formation, which relates it to the Lower Trenton Group (Clark and Globensky, 1975). In terms of its lithology and stratigraphic position, Saint-Marc Formation sandstone is very similar to that of the La Gabelle Formation, belonging to the Black River Group, underlying the Trenton Group.
No fossil was observed in the sandstone. However, in drilling Gauthier No. 1, typical bryozoans of the Deschambault Formation were observed in limestone interbeds (Clark and Globensky, 1975).
CLARK, T H., GLOBENSKY, Y. 1975. REGION DE GRONDINES. MRN. RG 154, 171 pages and 1 plan.
GLOBENSKY, Y. 1993. LEXIQUE STRATIGRAPHIQUE CANADIEN – VOLUME V-B – REGION DES APPALACHES, DES BASSES-TERRES DU SAINT-LAURENT ET DES ILES DE LA MADELEINE. MRN. DV 91-23, 336 pages.
HARLAND, T.L., PICKERILL, R.K. 1982. A review of Middle Ordovician sedimentation in the St. Lawrence Lowland, eastern Canada. Geological Journal; volume 17, pages 135-156. https://doi.org/10.1002/gj.3350170205