In April, 2017 the Ontario Geological Survey released the Southern Ontario Regional Resident Geologist Report for 2016 that contains a number of papers of interest for those in Eastern Ontario. See: Open File Report 6329: Report of Activities 2016, Resident Geologist Program, Southern Ontario Regional Resident Geologist Report: Southeastern Ontario and Southwestern Ontario Districts, and Petroleum Operations; by A.C. Tessier, P.S. LeBaron, S.J. Charbonneau, D.A. Laidlaw, A.C. Wilson and L. Fortner. 73p., which includes the papers:
- Union Glory Gold Limited, Addington Property, Kaladar Township, pages 30-36
- Crown William Mining Corporation, Bannockburn Gold Project, Madoc Township, 36-41
- Flake Graphite in the Grenville Province of Southern Ontario, pages 42 - 45
- Nickel-Copper-(Cobalt-Platinum Group Metals) Mineralization in Southeastern Ontario, 46-50
The last two papers were also published in another OGS publication– Recommendations for Exploration 2016–2017. All four are worth a read by anyone with an interest in the gold, graphite or nickel-copper occurrences of Eastern Ontario.
In July, 2017 the Ontario Geological Survey released a new field trip guidebook by Dr. R. M. Easton entitled Insights into the tectonic and metamorphic architecture of the Composite Arc Belt and the Frontenac – Adirondack Belt near Perth, Ontario, Grenville Orogen: A geological guidebook ; Ontario Geological Survey, Open File Report 6330, 54p.
http://www.geologyontario.mndm.gov.on.ca/mndmfiles/pub/data/imaging/OFR6330//OFR6330.pdf
The guide is very informative, has great photos and good directions, will appeal to both academics that work on the Grenville and field naturalists with an interest in geology, and I’ll be using it next summer. Worth mentioning is his Figure 5 which provides a pressure –temperature diagram showing the bathozones defined by Carmichael and the high pressure-temperature conditions of metamorphism in the Wolf Grove and Perth map areas.
This guide repeats part of Dr. Easton’s paper from 2016, and contains information about a number of faults he found, including the one he named the Chaffey’s Lock fault, a “fault that trends north-northeast from Chaffey’s Lock to Portland to Glen Elm just south-southeast of Smiths Falls, herein termed the Chaffey’s Lock fault. In the Perth map area, this fault is downdropped to the east, and places rocks of the Nepean Formation against rocks of the upper March and Oxford formations. This probably indicates no more than 100 m of post -Ordovician displacement across the fault. A difference of 2 kilobars between the Perth and Lyndhurst areas would involve at least a vertical displacement of 7 km (considering a lithostatic pressure for an average crustal density of 2.8×10 3 kg/m 3 ). It is not known if this displacement occurred rapidly during the Proterozoic, or if it occurred in several stages in both the Proterozoic and the Phanerozoic.”
Also worth mentioning is that Dr. Easton describes the granite exposed throughout downtown Perth, Lanark County, and notes that it “was sampled for geochronology and yielded a thermal ionization mass spectrometry U/Pb age on zircon of 1103.5±2.1 Ma with a similar age on titanite of 1090±16 Ma . This age is so far unique in Frontenac terrane. It is 55 million years younger than any known Frontenac suite intrusion, and 10 to 15 million years older than the oldest known Kensington–Skootamatta suite intrusion. As such, it may represent a magmatic event transitional between the 2 suites.”
In December, 2017 the Ontario Geological Survey released the Summary of Field Work and Other Activities, 2017 (Open File Report 6333). This file can be downloaded from:
http://www.geologyontario.mndm.gov.on.ca/mndmfiles/pub/data/imaging/ofr6333//ofr6333.pdf
Two papers in the report deal with the geology of Eastern Ontario:
- first, a paper by Dr. Easton entitled ‘Precambrian and Paleozoic Geology of the Carleton Place Area, Grenville Province’;
- second, a paper by Catherine Béland Otis entitled ‘Paleozoic Mapping of Eastern Ontario’
both of which I discuss further below.
Precambrian and Paleozoic Geology of the Carleton Place Area, Grenville Province by Dr. R. Michael Easton, pages 18-1 to 18-18 (OFR 6333)
In my December 31, 2016 blog posting entitled ‘Ontario Geological Survey Remapping the Perth Map Sheet’ I mentioned that Dr. Michael Easton of the Ontario Geological Survey had been mapping the Precambrian rocks of the Perth Map sheet and briefly summarized parts of his reports for the field seasons of 2015 and 2016. He has extended his mapping north to the Carleton Place map sheet.
Parts of his current paper that I liked are Figure 18.1 which is a Simplified geology map of the Central Metasedimentary Belt in eastern Ontario; Figure 18.2, a Simplified geology map of the western two-thirds of the Carleton Place map area, showing the location of the Pakenham and Wolf Grove structures and the Maberly shear zone; and Photo 18.1 A, a photograph of a pillowed lava unit in the Sharbot Lake domain, on the east side of Lanark County Road 8 south of Middleville. Unfortunately, Dr. Easton states that “Photograph was taken by the author in 1997 soon after the outcrop was exposed during road construction. Pillows are less well exposed today.”
In my previous blog posting I mentioned that Dr. Easton had found a number of previously unknown exposures of Potsdam Group sandstone and conglomerate (both Covey Hill and Nepean formations). In his latest report he mentions that “a previously undocumented inlier of Nepean Formation rocks occurs at Gillies Corners (UTM 413795E 4984105N), 4.3 km southwest of Frankto[w]n, immediately south of the northwestern boundary of the geophysical anomaly (see Figure 18.3A).” Dr. Easton adds that “ This sudden appearance of a stratigraphically lower unit in an area underlain by rocks of the stratigraphically higher March Formation, suggests that if a fault is present, it is down-dropped to the north. Further study of the Paleozoic rocks in the area of the Smiths Falls geophysical anomaly is warranted because, in addition to causing changes in the thickness and distribution of Paleozoic strata, the bounding faults may have also served as post-depositional fluid conduits.”
In previous reports Dr. Easton (2016, OFR 6323, p. 17-11 and 18-1 to 18-9) has reported on mica-apatite veins in the Bancroft and Frontenac terranes of the Central Metasedimentary Belt, has linked these metasomatic deposits with syenite intrusions, has reported rare earth element mineralization in association with those metasomatic deposits, and has suggested that “the carbonate rocks at some mica-apatite occurrences may be potential sources of extractable rare earth element minerals.” In OFR 6333 Dr. Easton mentions finding three additional mica-apatite veins in the Carleton Place area:
- “One ... dominated by fine- to-medium-grained diopside and mica (UTM 406485E 4990485N).
- The second is exposed on Highway 7 (UTM 403285E 4995170N), ....
- The third is exposed on Wolf Grove road east of Taylor Lake (UTM 395220 4998260;...) ”
Paleozoic Mapping of Eastern Ontario by Catherine Béland Otis, pages 22-1 to 22-11 (OFR 6333)
Catherine Béland Otis starts off her report by mentioning that the Ontario Geological Survey has “initiated a multi-year project focussing on the Paleozoic geology of eastern Ontario ... [The OGS intends] to map all of eastern Ontario underlain by Paleozoic rocks and to evaluate and refine the structural framework affecting those same rocks.” She notes 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 names used in adjacent jurisdictions instead of the current OGS nomenclature.” She promises that those stratigraphic units proposed since the last OGS mapping in the 1980s “will be evaluated and may be incorporated in a newly revised OGS stratigraphic framework for the area.”
Catherine Béland Otis’ Figure 22.3 provides the terminology for Paleozoic strata for eastern Ontario, and compares (A) the stratigraphic nomenclature for eastern Ontario currently used by the OGS with (B) the nomenclature in use or proposed in more recent publications. Much of her report summarizes the stratigraphic names proposed over the last three decades, including (A) Lowe et al.’s (2017) division of the Potsdam Group into the Ausable, Hannawa Falls and Keeseville formations; and (B) Salad Hersi and Dix’s (1997, 1999) suggested revision for the Rockcliffe Formation and the Ottawa Group.
One of her objectives for the year 2017–2018 is to gather additional geological information from cores drilled in the study area. She notes that “Geological mapping will be undertaken in subsequent field seasons, beginning in the summer of 2018.” Catherine Béland Otis promises that “A structural framework of the basin will also be developed as the mapping progresses in the region. Depending upon the results and if the data warrant it, a compilation map of the Ottawa Embayment may be produced near the end of the project. Regional stratigraphic correlation with other jurisdictions is another goal of this project.”
She also reports that she has been looking at ages determined from zircons found in bentonite beds in Eastern Ontario and hopes to correlate strata in Eastern Ontario with adjacent jurisdictions. Interestingly, “The bentonite beds represent Late Ordovician volcanic ash deposits from a volcanic arc, now disappeared, located hundreds of kilometres to the east.”
Christopher Brett
Ottawa
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