ABSTRACT
Chagnon Mountain is located near the southern end of the Baie
Verte-Brompton Line in the Eastern Townships of southern Quebec.
The lithologic units in the area of study, from west to east and
going up structure, are: gabbro, quartz-diorite, diabase,
volcanics, the St. Daniel Formation and the Peasley Pond
Conglomerate of the Glenbrooke Group. All these rocks have been
metamorphosed to the greenschist facies. Contacts between the
plutonic rocks are irregular and gradational indicating only one
parent magma. Diabase dikes are present in the diabase unit and in
the volcanics indicating the dikes acted as feeders to the
volcanics. Geochemical analyses on several samples supports a
tholeiitic origin for the mafic rocks and infer this magma to be
from an ocean floor setting.
The St. Daniel Formation lies structurally above the volcanics
with the contact in some places conformable and in others,
unconformable. The contact between the two could be a normal fault
or set of faults which would give rise to a situation where
sedimentation of muds would occur onto surfaces existing before
faulting in some places and onto degrading fault scarps in others.
The Peasley Pond Conglomerate was deposited after emplacement of
the Baldface-Orford-Chagnon (BOC) ophiolites. It is a basal
conglomerate which unconformably overlies the volcanic rocks and
the St. Daniel Formation in the Chagnon Mountain area. The
sediments of this unit contain chromite grains and silicic
volcanic clasts indicating sources both the northeast (BOC source)
and southwest (Ascot-Weedon source).
Harris, J.M., 1984. The geology of ophiolitic and adjoining rocks
of Chagnon Mountain, southern Quebec. Unpublished MSc. thesis,
State University of New York at Albany. 113 pp., +xi; 1 folded
plate (map)
University at Albany Science Library call number: SCIENCE
Oversize (*) QE 40 Z899 1984 H37
MS thesis scanned
text pdf (7MB);
Plate 1 - Geological
Map
of
Chagnon
Mountain,
southern
half; Eastern Townships, Quebec, Canada
(coloured outcrop map, scale ~1: 7,800) - pdf file 3.6 MB
Return to MS Theses completed in the
Geological Sciences Program, University at Albany