http://www.geologyontario.mndm.gov.on.ca/mndmaccess/mndm_dir.asp?type=pub&id=ofr6350
There are four papers of interest to those in Eastern Ontario, two dealing with Precambrian Geology and two with Paleozoic Geology:
Precambrian Geology – Proterozoic and Grenville Province
14. Project SO-17-001. Precambrian Geology and Mineral Potential of the Carleton Place Area, Grenville Province, by R.M. Easton, pages 14-1 to 14-10
15. Project SO-18-001. Precambrian Geology of the Renfrew Area, Northeastern Central Metasedimentary Belt, Grenville Province, by M. Duguet, pages 15-1 to 15-9
Paleozoic Geology and Energy Studies
22. Project SO-18-006. Paleozoic Geology of Eastern Ontario: Ottawa Area, by C. Béland Otis, pages 22-1 to 22-10
23. Project SO-18-005. Identification and Mapping of Alkali–Carbonate Reactive Layers in the Gull River Formation, Near Kingston, Ontario by K.E. Hahn and C.A. MacDonald, pages 23-1 to 23-8
Below I mention what I found to be the highlights of each report.
Precambrian Geology and Mineral Potential of the Carleton Place Area, Grenville Province
Dr. Michael Easton mentions:
• “Mafic metavolcanic rocks and associated fine- to medium-grained foliated gabbro sills appear to have been deformed and metamorphosed before, rather than during, emplacement of the Lavant gabbro and associated felsic intrusive rocks.”
• Peraluminous sapphirine has been found. “Peraluminous sapphirine is typically associated with ultra-high temperature metamorphism (>1000C, >8 kilobars).” This is the first reported occurrence from the Central Metasedimentary Belt of the Grenville Province.
• “Most of the major faults shown on the Paleozoic geology map of Williams and Wolf (1984) located solely in Precambrian rocks present in the western half of the Carleton Place map area could not be validated by geology or geophysics.”
• The report contains a colourful simplified geological map of the Carleton Place and southern Arnprior map areas.
• “Work in 2018 indicates that clean, high brightness, low silica content calcite and dolomite marbles are not restricted to the lower metamorphic grade portion of Sharbot Lake domain west of the Clayton shear zone, but they also occur at much higher metamorphic grades between the Maberly shear zone and the Wolf Grove structure, and in the area between the Pakenham and the Wolf Grove structures.” In the long term this could be important for Lanark County’s economy as high-purity marble products have been produced from marble mined at Omya Canada Inc.’s quarry at Tatlock and refined at Omya’s plant on Highway 7 just west of Perth for more than 30 years.
Precambrian Geology of the Renfrew Area, Northeastern Central Metasedimentary Belt, Grenville Province
Dr. Manuel Duguet mentions a “newly discovered lithostructural unit, provisionally named the Calabogie klippe, is exposed south of the Madawaska River”, which is “mostly composed of amphibolites and calcite marbles.” His report contains a simplified geological map of the area.
Paleozoic Geology of Eastern Ontario: Ottawa Area
Catherine Béland Otis is continuing her a multi-year project of mapping the Paleozoic geology of eastern Ontario, and addressing the fact that “in the last 3 decades, almost all Cambro-Ordovician stratigraphic units of eastern Ontario have been the focus of academic research. These studies have introduced new stratigraphic units (or re-introduced old terms), revised geological contact definitions and/or proposed the application in Ontario of stratigraphic terminology used in adjacent jurisdictions instead of the current OGS nomenclature.” Her Figure 22.2 deals with competing terminologies for Paleozoic strata in eastern Ontario, with her left Column providing the nomenclature currently used by the Ontario Geological Survey , while the column on the right is the nomenclature proposed in more recent publications.
In the summer of 2018, the OGS started geological mapping of the Ontario portion of the
Ottawa National Topographic Sheet, and Catherine Béland Otis provides a concise summary of each rock unit mapped in the Ottawa area. Based on the terms used in her report it appears that the OGS will adopt Lowe and Arnott’s breakdown of the Potsdam Group into three formations, but may not change Nepean to Keeseville for the uppermost unit.
Identification and Mapping of Alkali–Carbonate Reactive Layers in the Gull River Formation, Near Kingston, Ontario
Katherine E. Hahn and C.A. MacDonald are dealing with an interesting problem. While the Gull River and Bobcaygeon formations are being used as a source of concrete aggregate in Ontario “[b]oth of these units contain lithologies that are known to cause alkali aggregate reaction, a chemical reaction that occurs in either mortar or concrete between the hydroxyl associated with the alkalis sodium and potassium from Portland cement or other sources, with certain mineral phases in the coarse or fine aggregates.” This is a concern because it can cause premature deterioration of concrete.
The two main questions that their project aims to address are :
1. Can alkali–carbonate reaction (‘ACR’) strata be mapped at the regional scale and predicted based on sedimentology and stratigraphy?
2. What are the geological controls on the distribution of ACR strata?
Field activities were conducted in 2018 with visits to 21 quarries (active and inactive) and 135 outcrop localities. They have focused on “a green marker bed in the Gull River Formation (probably stratigraphically equivalent to the middle member in the Kingston area) that is used to constrain where the alkali reactive beds begin; generally, aggregate for concrete purposes is not extracted within 1 m above the green bed and never below it.” Further investigations are planned.
Christopher Brett
Ottawa
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