Downward continuation of heat flow data: Method and examples from the western United States

Geophysics ◽  
1985 ◽  
Vol 50 (5) ◽  
pp. 846-851 ◽  
Author(s):  
Jean‐Claude Mareschal ◽  
James P. Cunningham ◽  
Robert P. Lowell
Keyword(s):  
United States ◽  
Heat Flow ◽  
Active Regions ◽  
Basin And Range ◽  
Surface Heat ◽  
Western United States ◽  
Rio Grande Rift ◽  
Heat Sources ◽  
Surface Heat Flow ◽  
Tectonically Active

We outline a method to determine, directly from the data, a subsurface temperature distribution which is compatible with the surface heat flow and takes into consideration the effect of the shallow heat sources. The analysis assumes that (1) the crust is in conductive equilibrium, (2) the lateral changes in thermal conductivity can be neglected, and (3) the depth of the heat sources is proportional to the wavelength of the variations in surface heat flow. We apply the technique to determine the crustal temperatures in two tectonically active regions of the western United States. In the Rio Grande rift, temperatures higher than 1 100°C are predicted at a depth of 20 km. In the transition region between the Colorado Plateau and the Basin and Range, the variability in surface heat flow is partially accounted for by shallow heat sources; however, the increase in heat flow toward the Basin and Range seems associated with deep seated (i.e., lower crust or upper mantle) variations in the thermal regime.

Maintenance of permeable habitable subsurface environments by earthquakes and tidal stresses

2012 ◽  
Vol 11 (4) ◽  
pp. 257-268 ◽  
Author(s):  
Norman H. Sleep
Keyword(s):  
Heat Flow ◽  
Active Regions ◽  
Surface Heat ◽  
Surface Gravity ◽  
Plate Boundaries ◽  
Surface Heat Flow ◽  
The Earth ◽  
Subsurface Environments ◽  
Water Saturated ◽  
Rocky Planets

AbstractLife inhabits the subsurface of the Earth down to depths where temperature precludes it. Similar conditions are likely to exist within the traditional habitable zone for objects between 0.1 Earth mass (Mars) and 10 Earth masses (superearth). Long-term cooling and internal radioactivity maintain surface heat flow on the Earth. These heat sources are comparable and likely to be comparable in general within old rocky planets. Surface heat flow scales with mass divided by surface area and hence with surface gravity. The average absolute habitable subsurface thickness scales inversely with heat flow and gravity. Surface gravity varies by only 0.4 g for Mars to 3.15 g for a superearth. This range is less than the regional variation of heat flow on the Earth. Still ocean-boiling asteroid impacts (if they occur) are more likely to sterilize the thin habitable subsurface of large objects than thick habitable subsurface of small ones. Tectonics self-organizes to maintain subsurface permeability and habitability within both stable and active regions on the Earth. Small earthquakes within stable regions allow sudden mixing of water masses. Large earthquakes at plate boundaries allow surface water to descend to great habitable depths. Seismic shaking near major faults cracks shallow rock forming permeable regolith. Strong tidal strains form a similar porous regolith on small bodies such as Enceladus with weak stellar heating. This regolith may be water-saturated within rocky bodies and thus habitable.

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.

scholarly journals Estimation of Curie-point depths, geothermal gradients and near-surface heat flow from spectral analysis of aeromagnetic data in the Loum – Minta area (Centre-East Cameroon)

2018 ◽  
Vol 27 (4) ◽  
pp. 1291-1299
Author(s):  
Jean Aimé Mono ◽  
Théophile Ndougsa-Mbarga ◽  
Yara Tarek ◽  
Jean Daniel Ngoh ◽  
Olivier Ulrich Igor Owono Amougou
Keyword(s):  
Spectral Analysis ◽  
Heat Flow ◽  
Curie Point ◽  
Surface Heat ◽  
Aeromagnetic Data ◽  
Near Surface ◽  
Geothermal Gradients ◽  
Surface Heat Flow

scholarly journals Surface heat flow and lithosphere thermal structure of the Rhenohercynian Zone in the greater Luxembourg region

Geothermics ◽  
2015 ◽  
Vol 56 ◽  
pp. 93-109 ◽  
Author(s):  
Tom Schintgen ◽  
Andrea Förster ◽  
Hans-Jürgen Förster ◽  
Ben Norden
Keyword(s):  
Heat Flow ◽  
Thermal Structure ◽  
Surface Heat ◽  
Surface Heat Flow ◽  
Rhenohercynian Zone

Deep temperatures and surface heat flow distribution

2001 ◽  
pp. 65-76 ◽  
Author(s):  
Bruno Della Vedova ◽  
Stefano Bellani ◽  
Giulio Pellis ◽  
Paolo Squarci
Keyword(s):  
Heat Flow ◽  
Flow Distribution ◽  
Surface Heat ◽  
Surface Heat Flow
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