$50.00
Devonian Carbonate Rocks of the Dundee and Lucas Formations at the St Mary’s Quarry
Leader: Terry Carter
This half day trip takes participants into the St Mary’s Quarry, located on the edge of the small town of St Mary’s on the northwest bank of the Thames River. The quarry supplies limestone for a large cement plant located on the opposite side of the river. The St Mary’s Cement Company was established at this site in 1912 by John Lind and Alfred Rogers who led a small group of local investors in building a 2 kiln, 180 tonne per day cement plant. The plant has been subsequently expanded and modernised and today is part of the worldwide operations of Votorantim Cimentos, a Brazilian company, based in Sao Paulo, Brazil.
The quarry exposes up to 20 metres of carbonate rocks of the Middle Devonian Dundee and Lucas formations. The Lucas is comprised of non-fossiliferous, stromatolitic, laminated, restricted marine limestones and dolomitic limestones and comprises the lowermost 6 to 8 metres of the quarry. It is overlain by thin to thick-bedded, fossiliferous, bioclastic, open marine limestones of the Dundee Formation with abundant crinoids and brachiopods, scattered colonial coral heads, rare trilobites, and the algal cyst Tasminites. Many of the large corals are very porous and contain liquid crude oil. Fresh crude oil also coats the sides of partially-sealed vertical fractures in the Dundee. The contact between the two formations is sharp and unconformable and is underlain by a rusty-weathering porous dolomitic limestone bed.
The Lucas and Dundee Formations form the reservoir rocks at most of the shallow Devonian oil fields in southern Ontario, including the Oil Springs Field, the first commercial oil field in North America. The Lucas Formation forms southern Ontario’s most extensive regional sulphur water aquifer. Sulphur water inflows can be observed in the floor of the quarry. The bedrock is overlain by coarse-grained glacial tills and it is possible to view fresh water seepage into the quarry from the contact aquifer at the interface between the bedrock and the till.
Itinerary
12:00 noon Meet in front lobby, DoubleTree by Hilton, 300 King Street, London
12:15 pm Depart from front entrance, Hilton Hotel
1:00 pm Arrive St Mary’s Quarry
4:00 pm Depart quarry.
4:45 pm Arrive Hilton Hotel
5:30 pm Conference Welcoming Cocktail Reception
*Note, lunch is not provided so either eat before or bring a lunch along.
