Analysis of heat flow data—correlation of thermal resistivity and shock metamorphic grade and its use as evidence for an impact origin of the Brent Crater

1976 ◽  
Vol 13 (7) ◽  
pp. 929-936 ◽  
Author(s):  
A. E. Beck ◽  
V. M. Hamza ◽  
C. C. Chang
Keyword(s):  
Heat Flow ◽  
Heat Production ◽  
Metamorphic Grade ◽  
Stable Region ◽  
Thermal Resistivity ◽  
Deep Borehole ◽  
Meteorite Impact ◽  
Production Values ◽  
Impact Origin ◽  
Impact Hypothesis

Measurements of heat flow and radioactive heat generation values have been made at small intervals using a completely cored, 1 km deep borehole located close to the center of the Brent Crater. A remarkable correlation is observed between the thermal resistivity values and shock metamorphic grade. This is interpreted as due to residual shock effects on the lattice conductivity. These effects are preserved over long periods of time, probably because of rapid cooling that prevented thermal annealing and recrystallization. The highly shock metamorphosed samples also have characteristically low heat production values, resulting from a depletion of thorium and uranium; potassium distribution is fairly uniform except at the boundaries of metamorphic zones, where it is enriched to a considerable degree. These results support the meteorite impact hypothesis for the origin of the crater.Mean heat production and corrected heat flow values obtained for this borehole are 1.51 ± 0.57 μWm−3 (3.6 ± 1.4 HPU) and 41.9 ± 6.3 mWm−2 (1.00 ± 0.15 HFU), respectively. These values indicate that this region may belong or be similar to the Central Stable region heat flow province.

scholarly journals Crustal heat production and estimate of terrestrial heat flow in central East Antarctica, with implications for thermal input to the East Antarctic ice sheet

2018 ◽  
Vol 12 (2) ◽  
pp. 491-504 ◽  
Author(s):  
John W. Goodge
Keyword(s):  
Heat Flow ◽  
Heat Production ◽  
Ice Sheet ◽  
Surface Heat ◽  
East Antarctica ◽  
Antarctic Ice Sheet ◽  
Surface Heat Flow ◽  
Terrestrial Heat Flow ◽  
Production Values ◽  
East Antarctic Ice Sheet

Abstract. Terrestrial heat flow is a critical first-order factor governing the thermal condition and, therefore, mechanical stability of Antarctic ice sheets, yet heat flow across Antarctica is poorly known. Previous estimates of terrestrial heat flow in East Antarctica come from inversion of seismic and magnetic geophysical data, by modeling temperature profiles in ice boreholes, and by calculation from heat production values reported for exposed bedrock. Although accurate estimates of surface heat flow are important as an input parameter for ice-sheet growth and stability models, there are no direct measurements of terrestrial heat flow in East Antarctica coupled to either subglacial sediment or bedrock. As has been done with bedrock exposed along coastal margins and in rare inland outcrops, valuable estimates of heat flow in central East Antarctica can be extrapolated from heat production determined by the geochemical composition of glacial rock clasts eroded from the continental interior. In this study, U, Th, and K concentrations in a suite of Proterozoic (1.2–2.0 Ga) granitoids sourced within the Byrd and Nimrod glacial drainages of central East Antarctica indicate average upper crustal heat production (Ho) of about 2.6  ±  1.9 µW m−3. Assuming typical mantle and lower crustal heat flux for stable continental shields, and a length scale for the distribution of heat production in the upper crust, the heat production values determined for individual samples yield estimates of surface heat flow (qo) ranging from 33 to 84 mW m−2 and an average of 48.0  ±  13.6 mW m−2. Estimates of heat production obtained for this suite of glacially sourced granitoids therefore indicate that the interior of the East Antarctic ice sheet is underlain in part by Proterozoic continental lithosphere with an average surface heat flow, providing constraints on both geodynamic history and ice-sheet stability. The ages and geothermal characteristics of the granites indicate that crust in central East Antarctica resembles that in the Proterozoic Arunta and Tennant Creek inliers of Australia but is dissimilar to other areas like the Central Australian Heat Flow Province that are characterized by anomalously high heat flow. Age variation within the sample suite indicates that central East Antarctic lithosphere is heterogeneous, yet the average heat production and heat flow of four age subgroups cluster around the group mean, indicating minor variation in the thermal contribution to the overlying ice sheet from upper crustal heat production. Despite these minor differences, ice-sheet models may favor a geologically realistic input of crustal heat flow represented by the distribution of ages and geothermal characteristics found in these glacial clasts.

scholarly journals Crustal heat production and estimate of terrestrial heat flow in central East Antarctica, with implications for thermal input to the East Antarctic ice sheet

2017 ◽  
Author(s):  
John W. Goodge
Keyword(s):  
Heat Flow ◽  
Heat Production ◽  
Ice Sheet ◽  
Surface Heat ◽  
East Antarctica ◽  
Antarctic Ice Sheet ◽  
Surface Heat Flow ◽  
Terrestrial Heat Flow ◽  
Production Values ◽  
East Antarctic Ice Sheet

Abstract. Terrestrial heat flow is a critical first-order factor governing the thermal condition and, therefore, mechanical stability of Antarctic ice sheets, yet heat flow across Antarctica is poorly known. Previous estimates of terrestrial heat flow come from inversion of seismic and magnetic geophysical data, by modeling temperature profiles in ice boreholes, and by calculation from heat production values reported for exposed bedrock. Although accurate estimates of surface heat flow are important as an input parameter for ice-sheet growth and stability models, there are no direct measurements of terrestrial heat flow in East Antarctica coupled to either subglacial sediment or bedrock. Bedrock outcrop is limited to coastal margins and rare inland exposures, yet valuable estimates of heat flow in central East Antarctica can be extrapolated from heat production determined by the geochemical composition of glacial rock clasts eroded from the continental interior. In this study, U, Th and K concentrations in a suite of Proterozoic (1.2–2.0 Ga) granitoids sourced within the Byrd and Nimrod glacial drainages of central East Antarctica indicate average upper crustal heat production (Ho) of about 2.6 ± 1.9 μW m-3. Assuming typical mantle and lower crustal heat flux for stable continental shields, and a length scale for the distribution of heat production in the upper crust, the heat production values determined for individual samples yield estimates of surface heat flow (qo) ranging from 33–84 mW m-2 and an average of 48.0 ± 13.6 mW m-2. Estimates of heat production obtained for this suite of glacially-sourced granitoids therefore indicate that the interior of the East Antarctic ice sheet is underlain in part by Proterozoic continental lithosphere with average surface heat flow, providing constraints on both geodynamic history and ice-sheet stability. The ages and geothermal characteristics of the granites indicate that crust in central East Antarctica resembles that in the Proterozoic Arunta and Tenant Creek inliers of Australia, but is dissimilar to other areas characterized by anomalously high heat flow in the Central Australian Heat Flow Province. Age variation within the sample suite indicates that central East Antarctic lithosphere is heterogeneous, yet the average heat production and heat flow of four age subgroups cluster around the group mean, indicating minor variation in thermal contribution to the overlying ice sheet from upper crustal heat production. Despite their minor differences, ice-sheet models may favor a geologically realistic model of crustal heat flow represented by such a distribution of ages and geothermal characteristics.

Analysis of Heat Flow Data–Vertical Variations of Heat Flow and Heat Producing Elements in Sediments

1975 ◽  
Vol 12 (6) ◽  
pp. 996-1005 ◽  
Author(s):  
V. M. Hamza ◽  
A. E. Beck
Keyword(s):  
Heat Flow ◽  
Heat Production ◽  
Gamma Ray ◽  
Detailed Examination ◽  
Uranium Content ◽  
Thermal Resistivity ◽  
Geochemical Reactions ◽  
Vertical Variations ◽  
Heat Flow Variations

Gamma ray spectrometric techniques have been used for the determination of uranium, thorium and potassium contents from cores selected at 3 to 4 m intervals from a 600 m deep borehole in sedimentary formations and the results compared with a similarly detailed examination of heat flow, and some physical properties, from the same borehole.The results indicate a broad positive correlation between thermal resistivity and some of the radio-element parameters and between heat flow and heat production. The heat production variations down the borehole are not quantitatively sufficient to explain the observed heat flow variations. The uranium series appears to be in radioactive equilibrium even in those sections where the uranium content is low, the porosity relatively high and the heat flow low; it is therefore concluded that the depletion of uranium is due to an ancient rather than a recent leaching process and that it is unlikely that the heat flow variations along the borehole are due to existing or recent underground waterflows. Long term geochemical reactions are now thought to be the most likely explanation of the heat flow variations.

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.

scholarly journals Heat flow, seismic cut-off depth and thermal modeling of the Fennoscandian Shield

2017 ◽  
Vol 211 (3) ◽  
pp. 1414-1427 ◽  
Author(s):  
Toni Veikkolainen ◽  
Ilmo T Kukkonen ◽  
Timo Tiira
Keyword(s):  
Heat Flow ◽  
Heat Production ◽  
Focal Depth ◽  
Fennoscandian Shield ◽  
Plate Boundaries ◽  
Finnish Lapland ◽  
Brittle Ductile Transition ◽  
Production Values ◽  
Gulf Of Bothnia ◽  
Mantle Heat Flow

Summary Being far from plate boundaries but covered with seismograph networks, the Fennoscandian Shield features an ideal test laboratory for studies of intraplate seismicity. For this purpose, this study applies 4190 earthquake events from years 2000–2015 with magnitudes ranging from 0.10 to 5.22 in Finnish and Swedish national catalogues. In addition, 223 heat flow determinations from both countries and their immediate vicinity were used to analyse the potential correlation of earthquake focal depths and the spatially interpolated heat flow field. Separate subset analyses were performed for five areas of notable seismic activity: the southern Gulf of Bothnia coast of Sweden (area 1), the northern Gulf of Bothnia coast of Sweden (area 2), the Swedish Norrbotten and western Finnish Lapland (area 3), the Kuusamo region of Finland (area 4) and the southernmost Sweden (area 5). In total, our subsets incorporated 3619 earthquake events. No obvious relation of heat flow and focal depth exists, implying that variations of heat flow are primarily caused by shallow lying heat producing units instead of deeper sources. This allows for construction of generic geotherms for the range of representative palaeoclimatically corrected (steady-state) surface heat flow values (40–60 mW m−2). The 1-D geotherms constructed for a three-layer crust and lithospheric upper mantle are based on mantle heat flow constrained with the aid of mantle xenolith thermobarometry (9–15 mW m−2), upper crustal heat production values (3.3–1.1 μWm−3) and the brittle-ductile transition temperature (350 °C) assigned to the cut-off depth of seismicity (28 ± 4 km). For the middle and lower crust heat production values of 0.6 and 0.2 μWm−3 were assigned, respectively. The models suggest a Moho temperature range of 460–500 °C.

scholarly journals The impact of natural fractures on heat extraction from tight Triassic sandstones in the West Netherlands Basin: a case study combining well, seismic and numerical data

2021 ◽  
Vol 100 ◽  
Author(s):  
Quinten D. Boersma ◽  
Pierre Olivier Bruna ◽  
Stephan de Hoop ◽  
Francesco Vinci ◽  
Ali Moradi Tehrani ◽  
...  
Keyword(s):  
Fluid Flow ◽  
Heat Production ◽  
Positive Impact ◽  
Heat Extraction ◽  
Natural Fractures ◽  
Negative Power ◽  
Petrophysical Analysis ◽  
Production Values ◽  
Geostatistical Inversion ◽  
The Impact

Abstract The positive impact that natural fractures can have on geothermal heat production from low-permeability reservoirs has become increasingly recognised and proven by subsurface case studies. In this study, we assess the potential impact of natural fractures on heat extraction from the tight Lower Buntsandstein Subgroup targeted by the recently drilled NLW-GT-01 well (West Netherlands Basin (WNB)). We integrate: (1) reservoir property characterisation using petrophysical analysis and geostatistical inversion, (2) image-log and core interpretation, (3) large-scale seismic fault extraction and characterisation, (4) Discrete Fracture Network (DFN) modelling and permeability upscaling, and (5) fluid-flow and temperature modelling. First, the results of the petrophysical analysis and geostatistical inversion indicate that the Volpriehausen has almost no intrinsic porosity or permeability in the rock volume surrounding the NLW-GT-01 well. The Detfurth and Hardegsen sandstones show better reservoir properties. Second, the image-log interpretation shows predominately NW–SE-orientated fractures, which are hydraulically conductive and show log-normal and negative-power-law behaviour for their length and aperture, respectively. Third, the faults extracted from the seismic data have four different orientations: NW–SE, N–S, NE–SW and E–W, with faults in proximity to the NLW-GT-01 having a similar strike to the observed fractures. Fourth, inspection of the reservoir-scale 2D DFNs, upscaled permeability models and fluid-flow/temperature simulations indicates that these potentially open natural fractures significantly enhance the effective permeability and heat production of the normally tight reservoir volume. However, our modelling results also show that when the natural fractures are closed, production values are negligible. Furthermore, because active well tests were not performed prior to the abandonment of the Triassic formations targeted by the NLW-GT-01, no conclusive data exist on whether the observed natural fractures are connected and hydraulically conductive under subsurface conditions. Therefore, based on the presented findings and remaining uncertainties, we propose that measures which can test the potential of fracture-enhanced permeability under subsurface conditions should become standard procedure in projects targeting deep and potentially fractured geothermal reservoirs.

Heat flow, heat production and thermo-tectonic setting in mainland UK

1987 ◽  
Vol 144 (1) ◽  
pp. 35-42 ◽  
Author(s):  
M. K. LEE ◽  
G. C. BROWN ◽  
P. C. WEBB ◽  
J. WHEILDON ◽  
K. E. ROLLIN
Keyword(s):  
Heat Flow ◽  
Heat Production ◽  
Tectonic Setting ◽  
Flow Heat

The Deeper the Better? A Thermogeological Analysis of Medium-deep Borehole Heat Exchanger Efficiency in Crystalline Rocks

2022 ◽  
Author(s):  
Kaiu Piipponen ◽  
Annu Martinkauppi ◽  
Sami Vallin ◽  
Teppo Arola ◽  
Nina Leppäharju ◽  
...  
Keyword(s):  
Fluid Flow ◽  
Heat Exchanger ◽  
Thermal Energy ◽  
Heat Production ◽  
Heat Exchangers ◽  
Energy Production ◽  
Crystalline Rocks ◽  
Deep Borehole ◽  
Deep Well ◽  
Borehole Heat Exchangers

Abstract The energy sector is undergoing a fundamental transformation, with significant investment in low-carbon technologies to replace fossil-based systems. In densely populated urban areas, deep boreholes offer an alternative over shallow geothermal systems, which demand extensive surface area to attain large-scale heat production. This paper presents numerical calculations of the thermal energy that can be extracted from the medium-deep borehole heat exchangers of depths ranging from 600-3000 m. We applied the thermogeological parameters of three locations across Finland and tested two types of coaxial borehole heat exchangers to understand better the variables that affect heat production in low permeability crystalline rocks. For each depth, location, and heat collector type, we used a range of fluid flow rates to examine the correlation between thermal energy production and resulting outlet temperature. Our results indicate a trade-off between thermal energy production and outlet fluid temperature depending on the fluid flow rate, and that the vacuum-insulated tubing outperforms high-density polyethylene pipe in energy and temperature production. In addition, the results suggest that the local thermogeological factors impact heat production. Maximum energy production from a 600-m-deep well achieved 170 MWh/a, increasing to 330 MWh/a from a 1000-m-deep well, 980 MWh/a from a 2-km-deep well, and up to 1880 MWh/a from a 3-km-deep well. We demonstrate that understanding the interplay of the local geology, heat exchanger materials, and fluid circulation rates is necessary to maximize the potential of medium-deep geothermal boreholes as a reliable long-term baseload energy source.

scholarly journals Julius Kaljuvee, Ivan Reinwald, and Estonian pioneering ideas on meteorite impacts and cosmic neocatastrophism in the early 20th century

2018 ◽  
Vol 189 (3) ◽  
pp. 11 ◽  
Author(s):  
Grzegorz Racki ◽  
Tõnu Viik ◽  
Väino Puura
Keyword(s):  
Large Body ◽  
Rare Event ◽  
Continental Drift ◽  
Meteorite Impact ◽  
Mining Engineer ◽  
Meteorite Impacts ◽  
Event Theory ◽  
Geological Past ◽  
The Impact ◽  
Impact Origin

The article comprehensively presents little known Estonian contribution to the recognition of first meteorite impact structures in Europe, related to works of Julius Kaljuvee (Kalkun; 1869–1940) and Ivan Reinwald (Reinwaldt; 1878–1941). As an active educator specialized in geoscience, Kaljuvee was the first to hypothesize in 1922 that Kaali lake cirque in Saaremaa Island, Estonia, was created by meteorite impact. Thanks to mining engineer Reinwald, this assumption was accepted since 1928 due to the exhaustive field and borehole works of the latter (also as a result of exploration by several German scholars, including renowned Alfred Wegener). The impact origin of Kaali structure was proved finally in 1937 by finding of meteoritic iron splinters (as the first European site). Reinwald was not only outstanding investigator of meteorite cratering process, but also successful propagator of the Estonian discoveries in Anglophone mainstream science in 1930s. In addition, in his 1933 book, Kaljuvee first highlighted an impact explanation of enigmatic Ries structure in Bavaria, as well as probable magmatic activation in distant regions due to “the impulse of a giant meteorite”. He also outlined ideas of the inevitable periodic cosmic collisions in geological past (“rare event” theory nowadays), and resulting biotic crises. In a general conceptual context, the ideas of Kaljuvee were in noteworthy direct or indirect link with concepts of the great French naturalists – Laplace, Cuvier and Élie de Beaumont. However, some other Kaljuvee’s notions, albeit recurrent also later in geoscientific literature, are queer at the present time (e.g., the large-body impact as a driving force of continental drift and change the Earth axis, resulting in the Pleistocene glaciation). Thus, the Kaljuvee thought-provocative but premature dissertation is rather a record of distinguishing erudite activity, but not a real neocatastrophic landmark in geosciences history. Nevertheless, several concepts of Kaljuvee were revived as the key elements in the current geological paradigm.

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