Heat flow and deep thermal structure near the southeastern edge of the Canadian Shield

2000 ◽  
Vol 37 (2-3) ◽  
pp. 399-414 ◽  
Author(s):  
J C Mareschal ◽  
C Jaupart ◽  
C Gariépy ◽  
L Z Cheng ◽  
L Guillou-Frottier ◽  
...  
Keyword(s):  
Heat Flow ◽  
Heat Production ◽  
Thermal Structure ◽  
Canadian Shield ◽  
Eastern Canada ◽  
Data Set ◽  
Grenville Province ◽  
Average Heat ◽  
Crustal Composition ◽  
Abitibi Subprovince

Five new heat-flow and heat-production measurements in the Archean Superior Province are presented. These measurements include the first heat-flow values to be reported for the Opatica subprovince and the Otish basin. These new data complete the data set acquired in the eastern Canadian Shield during the Abitibi-Grenville Lithoprobe transect. The data set now available in eastern Canada, covering geological provinces ranging in age from 2700 to 400 Ma, achieves sufficient sampling to define the deep thermal structure of a continent near the edge of the craton. It shows that, for the Canadian Shield, there is no simple relation between heat flow and the age of tectonic provinces. The map of heat flow in eastern Canada demonstrates that there is no significant difference in heat flow between the Abitibi subprovince and the Grenville Province (including the Adirondacks) where the area-weighted average heat flow is the same (39 vs. 38 mW·m-2, respectively). Outside the Abitibi, the Superior Province is characterized by a higher heat flow (45 mW·m-2). Heat-flow and gravity data are used together to determine changes in crustal composition and thickness. The analysis of these data and constraints from seismology support the view that the variations in surface heat flow can be entirely accounted for by changes in crustal composition. Heat-flow variations across the Abitibi subprovince indicate that there are significant differences in crustal composition that reflect the complex assemblages that make up the Archean crust. The heat-flow map shows a sharp transition between the Grenville Province and the Appalachians, where the average heat flow is significantly higher (57 mW·m-2). This difference is due to higher heat production in the Appalachian upper crust with the same mantle heat flow as in the shield (~12 mW·m-2 throughout eastern Canada). Lower crustal and upper mantle temperatures are typically low, which might explain the preservation of irregular crustal thickness over several billion years.

scholarly journals Adjoint inversion of the thermal structure of Southeastern Australia

2019 ◽  
Vol 219 (3) ◽  
pp. 1648-1659 ◽  
Author(s):  
B Mather ◽  
L Moresi ◽  
P Rayner
Keyword(s):  
Thermal Properties ◽  
Heat Flow ◽  
Heat Production ◽  
Thermal Structure ◽  
Surface Heat ◽  
Flow Data ◽  
Data Set ◽  
Surface Heat Flow ◽  
Southeastern Australia ◽  
Curie Depth

SUMMARY The variation of temperature in the crust is difficult to quantify due to the sparsity of surface heat flow observations and lack of measurements on the thermal properties of rocks at depth. We examine the degree to which the thermal structure of the crust can be constrained from the Curie depth and surface heat flow data in Southeastern Australia. We cast the inverse problem of heat conduction within a Bayesian framework and derive its adjoint so that we can efficiently find the optimal model that best reproduces the data and prior information on the thermal properties of the crust. Efficiency gains obtained from the adjoint method facilitate a detailed exploration of thermal structure in SE Australia, where we predict high temperatures within Precambrian rocks of 650 °C due to relatively high rates of heat production (0.9–1.4 μW m−3). In contrast, temperatures within dominantly Phanerozoic crust reach only 520 °C at the Moho due to the low rates of heat production in Cambrian mafic volcanics. A combination of the Curie depth and heat flow data is required to constrain the uncertainty of lower crustal temperatures to ±73 °C. We also show that parts of the crust are unconstrained if either data set is omitted from the inversion.

Temperature structure of the Andean subduction zone as derived from the 3D geometry of crustal and upper mantle discontinuities

2020 ◽  
Author(s):  
Andres Tassara ◽  
Joaquín Julve ◽  
Iñigo Echeverría ◽  
Ingo Stotz
Keyword(s):  
Heat Flow ◽  
Heat Production ◽  
Thermal Structure ◽  
Surface Heat ◽  
Thermal Parameters ◽  
Continental Lithosphere ◽  
Flow Measurements ◽  
Study Region ◽  
Surface Heat Flow ◽  
Input Model

<p>The distribution of temperature inside active continental margins plays a fundamental role on regulating first order geodynamic processes as the isostatic balance, rheologic behavior of crust and mantle, magmagenesis, volcanism and seismogenesis. In spite of these major implications, well-constrained 3D thermal models are known for few regions of the world (Europe, Western USA, China) where large geophysical databases have been integrated into compositional and structural models of crust and lithospheric mantle from which a thermal model is derived. Here we present a three-dimensional representation of the distribution of temperature underneath the Andean active margin of South America (10°-45°S) that is based on a geophysically-constrained model for the geometry of the subducted slab, continental lithosphere-asthenosphere boundary (LAB), Moho discontinuity and an intracrustal discontinuity (ICD). This input model was constructed by forward modelling the satellite gravity anomaly under the constraint of most of the seismic information published for this region. We use analytical expressions of 1D conductive continental geotherms with adequate boundary conditions that consider the compositional stratification of crust and mantle included in the input model, and the advective thermal effect of slab subduction. The 1D geotherms are assembled into a 3D volume defining the thermal structure of the study region. We test the influence of several thermal parameters and structural configurations of the Andean lithosphere by comparing the resulting surface heat flow distribution of these different models against a database containing heat flow measurements that we compile from the literature. Our results show that the thermal structure and derived surface heat flow is dominantly controlled by the geometry of the thermal boundary layer at the base of the lithosphere, i.e. the slab upper surface below the forearc and LAB inland. Variations on the modeled configuration of the continental lithosphere (i.e. the way on which the geometry of the continental Moho and ICD are considered into the definition of a space-variable thermal conductivity or the length scale for radiogenic heat production) have an effect on surface heat flow that is lower than the average uncertainty of the measurements and therefore can be considered as second-order. The simplicity of our analytical approach allows us to compute hundreds of different models in order to test the sensitivity of results to changes on thermal parameters (conductivity, heat production, mantle potential temperature, etc), which provides a tool for discussing their possible range of values in the context of a subduction margin. We will also show how variations of these models impact on the Moho temperature and therefore in the expected mechanical behavior of crust and mantle in this geotectonic context</p>

Heat flow, thermal regime, and elastic thickness of the lithosphere in the Trans-Hudson Orogen

2005 ◽  
Vol 42 (4) ◽  
pp. 517-532 ◽  
Author(s):  
J C Mareschal ◽  
C Jaupart ◽  
F Rolandone ◽  
C Gariépy ◽  
C MR Fowler ◽  
...  
Keyword(s):  
Heat Flow ◽  
Heat Production ◽  
Large Fraction ◽  
Flow Region ◽  
Canadian Shield ◽  
Poor Correlation ◽  
Cold Spot ◽  
The South ◽  
Effective Elastic Thickness ◽  
Lynn Lake

Heat flow studies on the exposed part of the Trans-Hudson Orogen (THO) in northern Manitoba and Saskatchewan allow constraints on crustal composition and lithosphere structure. The average of all heat flow values in the THO is the same as in other geological provinces of the Canadian Shield. However, where juvenile crust is exposed, heat flow is on average lower than in the Superior and Grenville provinces (37 vs. 41 mW m–2). Heat flow increases towards the surrounding Archean provinces, Rae–Hearne to the west, Sask to the south, and Superior to the east. There are strong differences in heat flow within and between the belts of the THO. The poor correlation between heat flow and heat production in the rocks exposed at the surface implies that these differences involve a large fraction of the crustal column. One new heat flow determination confirms the existence of a ``cold spot'' around the town of Lynn Lake in the northern part of the THO. Heat flow data in the Kisseynew and Glennie domains remain sparse, but they indicate that this low heat flow region extends as far south as the Flin Flon – Snow Lake Belt. The Lynn Lake Belt is underlain by poorly radiogenic rocks, possibly Kisseynew-type crust with oceanic basement. Northward increase in heat flow along the Thompson Belt is consistent with the view that the belt is thrust over Kisseynew-type basement only in the south. Heat flow increases southward in the Paleozoic basin because of higher heat production in basement rocks, probably from the Sask craton. We used the low heat flow regions to obtain an upper bound of 15 mW m–2 for the mantle heat flow in the THO. The effective elastic thickness of the lithosphere can be determined from the coherence between the topography and the Bouguer gravity. The effective elastic thickness is high (>40 km) thoughout the Canadian Shield and is highest in the central part of the shield, in particular in the Lynn Lake region. There seems to be a negative correlation between elastic thickness and heat flow in the central and western Canadian Shield. This indicates that, even in stable continents, the elastic thickness is largely controlled by the lithospheric temperatures that depend strongly on crustal heat generation and hence crustal structure.

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.

Heat flow and heat production in the canadian shield

Geothermics ◽  
1972 ◽  
Vol 1 (2) ◽  
pp. 70-72
Author(s):  
V. Cermák ◽  
A.M. Jessop ◽  
M.L. Gupta
Keyword(s):  
Heat Flow ◽  
Heat Production ◽  
Canadian Shield

Heat production and thermal conductivity of rocks from the Pikwitonei–Sachigo continental cross section, central Manitoba: implications for the thermal structure of Archean crust

1987 ◽  
Vol 24 (8) ◽  
pp. 1583-1594 ◽  
Author(s):  
David M. Fountain ◽  
Matthew H. Salisbury ◽  
Kevin P. Furlong
Keyword(s):  
Thermal Conductivity ◽  
Heat Flow ◽  
Cross Section ◽  
Heat Production ◽  
Thermal Structure ◽  
Granulite Facies ◽  
Surface Heat ◽  
Gamma Ray Spectrometry ◽  
Surface Heat Flow ◽  
Greenstone Belts

The Pikwitonei and Sachigo subprovinces of central Manitoba provide a cross-sectional view of the Superior Province crust. In cross section, the upper to mid-level crust is composed of synformal greenstone belts surrounded by tonalitic gneisses, both of which are intruded by granitoid plutons. This crustal structure persists downward into the granulite facies, where keels of the greenstone belts can be found. To constrain thermal models of the crust, we measured heat production and thermal conductivity in 60 rocks from this terrain using standard gamma-ray spectrometry and divided bar techniques. Large vertical and lateral heterogeneities in heat production in the upper crust are evident; heat production is high in granites and metasedimentary rocks, intermediate in tonalite gneisses, and low in the portions of greenstone belts dominated by mafic meta-igneous rocks. In the deeper granulite facies rocks, heat production decreases by a factor of two in the tonalitic gneisses and remains low in the high-grade mafic rocks. When applied to the Pikwitonei–Sachigo crust cross section, the laboratory data here do not support step function or exponential models of the variation of heat production with depth. However, estimates of surface heat flow and surface heat production for various sites in the crustal model yield the well-known linear relationship between surface heat production and surface heat flow observed for heat-flow provinces for both one- and two-dimensional models. This demonstrates that determinations of heat production with depth based on inversion of the linear heat-production–heat-flow relationship are nonunique.

Geothermal regime in the Qaidam basin, northeast Qinghai–Tibet Plateau

2003 ◽  
Vol 140 (6) ◽  
pp. 707-719 ◽  
Author(s):  
QIU NANSHENG
Keyword(s):  
Heat Flow ◽  
Heat Production ◽  
Thermal State ◽  
Qaidam Basin ◽  
Thermal Structure ◽  
Flow Distribution ◽  
Tibet Plateau ◽  
Upper Crust ◽  
Production Values ◽  
Qinghai Tibet Plateau

The thermal properties of rocks in the upper crust of the Qaidam basin are given based on measurements of 98 thermal conductivities and 50 heat production values. Nineteen new measured heat flow data were obtained from thermal conductivity data and systematic steady-state temperature data. This paper contributes 28 calculated heat flow values for the basin for the first time. Examination of 47 heat flow values, ranging from 31.3 to 70.4 mW/m2 with an average value of 52.6±9.6 mW/m2, gives the heat flow distribution character of the basin: high heat flows over 60 mW/m2 are distributed in the western and central parts of the basin. Lower heat flow values are found in the eastern part and north marginal area of the basin, with values less 40 mW/m2. The Qaidam basin heatflow data show a linear relationship between heatflow and heat production, based on thermal structure analysis. The thermal structure of the lithosphere is characterized as having a ‘hot crust’ but ‘cold mantle’. Heat production in the upper crust is a significant source of heat in the basin and contributes up to 56.8% of the surface heat flow. The heat flow province is of great geophysical significance, and the thermal structure of the area gives clues about the regional geodynamics. Study of the Qaidam basin thermal structure shows that the crust has been highly active, particularly during its most recent geological evolution. This corresponds to Himalayan tectonic movements during latest Eocene to Quaternary times in the region of the Qinghai–Tibet Plateau. Since the Qaidam basin is in the northeastern area of the Qinghai–Tibet Plateau, the heat flow values and the thermal structure of the basin may give some insight into the thermal state of the plateau, and study of thermal regime of the Qaidam basin could in turn provide useful information about the tectonics of the Qinghai–Tibet Plateau.

Three measurements of heat flow in Eastern Canada

1968 ◽  
Vol 5 (1) ◽  
pp. 61-68 ◽  
Author(s):  
Alan M. Jessop
Keyword(s):  
Heat Flow ◽  
Superior Province ◽  
Geochemical Analysis ◽  
Eastern Canada ◽  
Flow Measurements ◽  
Grenville Province ◽  
World Average ◽  
Average Value ◽  
The World

Heat flow measurements, with appropriate corrections for the effects of Wisconsin glaciation, from three widely separated locations in eastern Canada are reported. One value in the Grenville rocks of Ontario agrees with earlier published values, but, when corrected for the effects of glaciation, becomes close to the world average value. The heat flow found in the New Quebec part of the Superior Province is significantly lower than is found in the Grenville Province. This can be explained by a hypothesis based on geochemical analysis of the surface rocks.

scholarly journals Update of Brazilian Heat Flow Data, within the framework of a multiprong referencing system

2020 ◽  
Vol 3 (1) ◽  
pp. 45-72 ◽  
Author(s):  
Valiya Hamza ◽  
Fabio Vieira ◽  
Jorge Luiz dos Santos Gomes ◽  
Suze Guimaraes ◽  
Carlos Alexandrino ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Heat Flow ◽  
Heat Production ◽  
Underground Mines ◽  
Data Sets ◽  
Data Set ◽  
Radiogenic Heat ◽  
Radiogenic Heat Production ◽  
Water Wells ◽  
Flow Map

An updated heat-flow database for Brazil is presented providing details of measurements carried out at 406 sites. It has been organized as per the scheme proposed by the International Heat Flow Commission. The data sets refer to results obtained using methods referred to as interval temperature logs (ITL), underground mines (UMM), bottom-hole temperatures (BHT), stable bottom temperatures (SBT) and water wells (AQT). The compilation provides information on depths of temperature logs, gradient determinations, measurements of thermal conductivity and radiogenic heat production. Also included is information on the methods employed and error estimates of the main parameters. A new heat flow map of Brazil has been derived based on the updated data set. A multipronged system has been employed in citing references, where the indexing scheme adopted follows chronological order. It provides information not only on the primary work concerning heat flow determination but also later improvements in measurements of main parameters (temperature gradients, thermal conductivity and radiogenic heat production) as well as techniques employed in data analysis.

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