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TitleGravity measurements in Quebec (south of latitude 52° N.)
AuthorThompson, L G D; Garland, G D
SourcePublications of the Dominion Observatory vol. 19, no. 4, 1957, 57 pages (1 sheet), (Open Access)
PublisherCanada Department of Mines and Technical Surveys
MapsPublication contains 1 map
Map Info.geophysical, gravity anomalies, 1:1,520,640
Mediapaper; on-line; digital
File formatpdf
ProvinceQuebec; New Brunswick
NTS21E; 21K; 21L; 21M; 21N; 21O; 21P; 22; 31F; 31G; 31H; 31I; 31J; 31K; 31L; 31M; 31N; 31O; 31P; 32
Lat/Long WENS -80.0000 -64.0000 52.0000 45.0000
Subjectsgeophysics; regional geology; geophysical interpretations; gravity interpretations; gravity surveys; bouguer gravity; gravity anomalies; bedrock geology; lithology; ultrabasic rocks; igneous rocks; intrusive rocks; anorthosites; granites; gabbros; syenites; volcanic rocks; metamorphic rocks; gneisses; structural features; faults, thrust; Canadian Shield; Grenville Province; Huron-Mistassini thrust fault; Appalachian Province; Keewatin Volcanics; Morin Anorthosite; Logan Fault; Richmond Fault; St. Francis Fault; Phanerozoic; Paleozoic; Precambrian
Illustrationslocation maps; gravity profiles; cross-sections; geoscientific sketch maps; tables
Released1957 01 01; 2018 11 13
AbstractThe results of gravity measurements in Quebec, south of latitude 52°N. and west longitude 64°W., which have been adjusted to the common datum of the primary base network established in Canada in 1952, are presented in this report. While the data include measurements taken during the period 1945 to 1954, observations made on an air survey in 1951 cover the greater part of the area under consideration. The gravity information is presented in the form of tables of principal facts and a preliminary Bouguer anomaly map. Descriptions of primary bases in Quebec are also included.
The general anomaly pattern is discussed and an interpretation is presented. It is believed that the major anomaly trends over the Canadian Shield are caused by systematic differences in density of the Precambrian rocks. There appear to be no gravitational features along the northern boundary of the Grenville sub-province which could be related to the presence of the presumed Huron-Mistassini thrust fault. Large anorthosite bodies in the area are characterized by negative gravity anomalies, which together with the determinations of density show that these rocks are less dense than the surrounding granitic rocks. The positive anomalies in the Eastern Townships and Gaspe are believed to be associated with a belt of ultrabasic rock at moderate depth which surfaces in the Richmond-Thetford and Gaspe districts.