Porphyritic Volcanic Rock - When the Comment is More Interesting than the Original Post

Henri Lessard, who writes the  Géo-Outaouais blog covering the geology of the Outaouais and Ottawa area, left me a very interesting comment, that I’ve reproduced below (as I suspect most people don’t read the comments):

“A pyroxenite seems to have already been discovered in the Ordovician limestone at Hull (Gatineau), Qc....
      Drilling reports dating from 1998 for the construction of Boulevard des Allumettières at Hull (now Gatineau) reports a mafic intrusive rock (a pyroxenite) in Ordovician limestone.
     The "greenish intrusive" encountered in the upper part of a borehole, between 1.25 m and 1.50 m deep. The intrusive-limestone contact is well defined, however, the orientation of the contact is undefined.
      Drilling was carried out at the corner of Demontigny and Laramée streets (the latter today under boulevard des Allumettières). In thin section, the intrusive is equigranular (grains 0.5-1.0 mm), and consists of 75% orthopyroxene (hypersthene) and clinopyroxene (augite) in equal proportions. The remaining 25% is composed of quartz, calcite and clay minerals [weathered?] "So we are dealing with pyroxenite. (P.13)
      Link toward my blog (in french) :
http://geo-outaouais.blogspot.com/2018/06/roche-intrusive-pyroxenite-dans-le.html
Thank You,
Henri Lessard”

On his blog page he references:
Les Laboratoires Gatineau, 1998. Étude de caractérisation des sols et du roc : boulevard St-Laurent - Laramée, Hull - secteur DeMontigny au Lac-des-Fées. Projet 20-6672-8385-A - Rapport final. Gouvernement du Québec, Ministère des Transports.

Other interesting posts from Henri Lessard’s blog, in a similar vein, is his post from Wednesday, December 12, 2018 entitled “Roche porphyrique à l'Ange-Gardien, QC”   where he includes photographs of a rock rich in feldspar phenocrysts, and his post from Thursday, November 16, 2017 entitled ‘Volcanisme à L'Ange-Gardien, QC”, both of which discuss the Mesoproterozoic Robitaille igneous suite which has been assigned an age of 1060 Ma (Hogarth, 2007).   L'Ange-Gardien is a municipality in the Outaouais region of Quebec.    The Mesoproterozoic Robitaille igneous suite is found on both sides of the Rivière du Lièvre at L'Ange-Gardien.



I decided to highlight Henri Lessard's comment because it is more interesting than my original post, and the pyroxenite he mentions is worth further investigation.

Christopher Brett
Ottawa

Suggested Readings:

Hogarth, Donald D., 2007 (or more recent)
GM 63238: Rocks of the Mason -Buckingham - Mayo area, with emphasis on Mesoproterozoic Igneous Types. Ministère de l’Énergie et des Resources naturelles, Québec
http://gq.mines.gouv.qc.ca/documents/examine/GM63238/GM63238.pdf

Hogarth, Donald D., 2016
Chemical trends in the Meech Lake, Québec, carbonatites and fenites.   The Canadian Mineralogist 54(5):1105-1128  September 2016
https://www.researchgate.net/publication/318091132_Chemical_trends_in_the_Meech_Lake_Quebec_carbonatites_and_fenites

Hogarth,  Donald D.  and  van Breemen, O.,   1996:
Geology  and  age  of  the Lac  a  la Perdrix  fenite,  southern Gatineau district, Quebec; in Radiogenic Age and Isotopic Studies: Report 9; Geological Survey of Canada, Current Research  1995-F, p.  33-41
https://inis.iaea.org/collection/NCLCollectionStore/_Public/28/056/28056346.pdf

Hogarth, Donald D.  And Robin, Michel J.L., 2007
Strontium in Feldspars of High-K Proterozoic Igneous Rocks of the Robitaille Suite, Buckingham, Québec. The Canadian Mineralogist, vol. 45, p. 1293-1306.
http://dx.doi.org/10.2113/gscanmin.45.5.1293
https://pubs.geoscienceworld.org/canmin/article-abstract/45/5/1293/13682/STRONTIUM-IN-FELDSPARS-OF-HIGH-K-PROTEROZOIC?redirectedFrom=fulltext

Lafleur, Jean and Hogarth, Donald D., 1981
Cambro-Proterozoic volcanism near Buckingham, Quebec. [trachyandesit 573 +-32 Ma]  Canadian Journal of Earth Sciences, 1981, 18(12): 1817-1823,
https://doi.org/10.1139/e81-169

Sinaei-Esfahani, Fahimeh,  2013
Localized metasomatism of Grenvillian marble leading to its melting,  Autoroute 5  near  Old  Chelsea, Quebec.  Thesis submitted for the degree of Masters of Science. Department of Earth and Planetary Sciences, McGill University, Montreal, 133 pages     digitool.library.mcgill.ca › thesisfile117148
 [ Local metasomatism of regional marble by an alkaline fluid of mixed crust + mantle derivation, possibly at the end of the Ottawan orogenic phase, at approximately 1020 m.y., or the Rigolet orogenic phase, at approximately 980 m.y.]