Français
 
Saint-Marc Formation
Stratigraphic label: [ordm]na
Map symbol: Omna

First published: 14 June 2019
Last modified:

 

 

 

  DISCLAIMER: This English version is translated from the original French. In case of any discrepancy, the French version shall prevail. 

Informal subdivision(s)
Numbering does not necessarily reflect the stratigraphic position.
 
None
 
Author: Clark and Globensky, 1975
Age: Middle Ordovician
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
Lithology: Quartzitic sandstone
Category: Lithostratigraphic
Rank: Formation
Status: Formal
Use: Active

Background

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.

 

Description

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):

Deschambault Formation Coarse, medium and fine-grained Deschambault-type crystalline limestone.  
Saint-Marc Formation Sandstone 0.3 m
Dark, dense, sublithographic limestone 0.03 m
Sandstone 2.5 m
Dark, dense, sublithographic limestone 0.1 m
Sandstone 8.5 m
Precambrian bedrock Gneiss  

 

Thickness and distribution

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.

 

Dating

None.

Stratigraphic Relationship(s)

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.

 

Paleontology

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).

References

 

Publications Available Through SIGÉOM Examine

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.

 

Other Publications

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

 

20 mai 2020