Some new measurements of heat flow in the Superior Province of the Canadian Shield

1987 ◽  
Vol 24 (7) ◽  
pp. 1486-1489 ◽  
Author(s):  
Malcolm Drury ◽  
Alan Taylor
Keyword(s):  
Standard Deviation ◽  
Heat Flow ◽  
Canadian Shield ◽  
Superior Province ◽  
Flow Measurements ◽  
Radiogenic Heat ◽  
Radiogenic Heat Production ◽  
Climatic Variations ◽  
The Mean ◽  
A Site

Borehole heat-flow measurements are reported from six new sites in the Superior Province of the Canadian Shield. Values adjusted for glaciation effects, but not for Holocene climatic variations, range from 42 to 56 mW/m2. When these new values are combined with 21 previously published borehole values the mean is 42 mW/m2 with a standard deviation of 11 mW/m2. The data for a site on the Lac du Bonnet batholith suggest that the batholith has a thin veneer, less than 3 km, of rock of high radiogenic heat production at the surface.

New heat flow density and radiogenic heat production data in the Canadian Shield and the Quebec Appalachians

1989 ◽  
Vol 26 (4) ◽  
pp. 845-852 ◽  
Author(s):  
J. C. Mareschal ◽  
C. Pinet ◽  
C. Gariépy ◽  
C. Jaupart ◽  
G. Bienfait ◽  
...  
Keyword(s):  
Heat Flow ◽  
Heat Production ◽  
Flow Density ◽  
Superior Province ◽  
Heat Flow Density ◽  
Grenville Province ◽  
Radiogenic Heat ◽  
Radiogenic Heat Production ◽  
Sedimentary Sequences ◽  
Reduced Heat Flow

New heat flow density (HFD) measurements were performed at 10 sites in Quebec. For five of the sites located in the Superior Province, the heat flow density varies between 24 and 35 mW/m2 (26 and 37 mW/m2 after adjustment for Pleistocene climatic variations). In the Grenville Province, the values obtained range between 25 and 28 mW/m2 (29 and 31 mW/m2 after adjustment). For two nearby sites in the Gaspé region (Appalachians), the heat flow density is 47 mW/m2 (48 mW/m2 after adjustment). Radiogenic heat production was also measured. At the sites located in the meta-volcano-sedimentary sequences of the Superior Province, the heat production is low (0.1–0.6 μW/m3) and it does not always correlate with the surface heat flow. In the Grenville Province, the HFD is close to (slightly higher than) the reduced heat flow of the Superior. The higher HFD in the Appalachians is partly explained by the higher crustal heat production, and partly by higher deep heat flow.

Thermal regime of the lithosphere in the Canadian ShieldThis article is one of a series of papers published in this Special Issue on the theme Lithoprobe — parameters, processes, and the evolution of a continent.

2010 ◽  
Vol 47 (4) ◽  
pp. 389-408 ◽  
Author(s):  
Claire Perry ◽  
Carmen Rosieanu ◽  
Jean-Claude Mareschal ◽  
Claude Jaupart
Keyword(s):  
Heat Flow ◽  
Heat Generation ◽  
Seismic Refraction ◽  
Surface Heat ◽  
Canadian Shield ◽  
P Wave ◽  
Seismic Velocities ◽  
Flow Measurements ◽  
Surface Heat Flow ◽  
Mantle Heat Flow

Geothermal studies were conducted within the framework of Lithoprobe to systematically document variations of heat flow and surface heat production in the major geological provinces of the Canadian Shield. One of the main conclusions is that in the Shield the variations in surface heat flow are dominated by the crustal heat generation. Horizontal variations in mantle heat flow are too small to be resolved by heat flow measurements. Different methods constrain the mantle heat flow to be in the range of 12–18 mW·m–2. Most of the heat flow anomalies (high and low) are due to variations in crustal composition and structure. The vertical distribution of radioelements is characterized by a differentiation index (DI) that measures the ratio of the surface to the average crustal heat generation in a province. Determination of mantle temperatures requires the knowledge of both the surface heat flow and DI. Mantle temperatures increase with an increase in surface heat flow but decrease with an increase in DI. Stabilization of the crust is achieved by crustal differentiation that results in decreasing temperatures in the lower crust. Present mantle temperatures inferred from xenolith studies and variations in mantle seismic P-wave velocity (Pn) from seismic refraction surveys are consistent with geotherms calculated from heat flow. These results emphasize that deep lithospheric temperatures do not always increase with an increase in the surface heat flow. The dense data coverage that has been achieved in the Canadian Shield allows some discrimination between temperature and composition effects on seismic velocities in the lithospheric mantle.

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