Joint Inversion for Surface Accumulation and Geothermal Heat Flow from Ice-Penetrating Radar Observations at Dome A, East Antarctica. 

2021 ◽  
Author(s):  
Michael Wolovick ◽  
John Moore ◽  
Liyun Zhao
Keyword(s):  
Heat Flow ◽  
Accumulation Rate ◽  
Joint Inversion ◽  
Observational Constraints ◽  
Dome A ◽  
Glacial Cycles ◽  
Geothermal Heat ◽  
Hydrological System ◽  
And Storage ◽  
Best Fit

<p>Dome A is the summit of the East Antarctic Ice Sheet (EAIS), underlain by the rugged Gamburtsev Subglacial Mountains (GSM).  The rugged basal topography produces a complex hydrological system featuring basal melt, water transport and storage, and freeze-on.  Here, we present the results of an inverse model used to infer the spatial distributions of geothermal heat flow (GHF) and accumulation rate that best fit a variety of observational constraints.  Our model agrees well with the observed water bodies and freeze-on structures, while also predicting a significant amount of unobserved water and suggesting a change in stratigraphic interpretation that reduces the volume of the freeze-on units.  Our model stratigraphy agrees well with observations, and we predict that there will be two distinct patches of ice up to 1.5 Ma suitable for ice coring underneath the divide.  Past divide migration could have interrupted stratigraphic continuity at the old ice patches, but various indirect lines of evidence suggest that the divide has been stable for about the last one and a half glacial cycles, which is a hopeful but by no means definitive sign for stability in the longer term.  Finally, our GHF estimate is higher than previous estimates for this region, but consistent with possible heterogeneity in crustal heat production.     </p>

scholarly journals Critical Tectonic Limits for Geothermal Aquifer Use: Case Study from the East Slovakian Basin Rim

Resources ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 31
Author(s):  
Stanislav Jacko ◽  
Roman Farkašovský ◽  
Igor Ďuriška ◽  
Barbora Ščerbáková ◽  
Kristína Bátorová
Keyword(s):  
Heat Flow ◽  
Pannonian Basin ◽  
Open Fractures ◽  
Water Type ◽  
Geothermal Heat ◽  
The North ◽  
Heat System ◽  
Volcanic Chain ◽  
Saline Solutions

The Pannonian basin is a major geothermal heat system in Central Europe. Its peripheral basin, the East Slovakian basin, is an example of a geothermal structure with a linear, directed heat flow ranging from 90 to 100 mW/m2 from west to east. However, the use of the geothermal source is limited by several critical tectono-geologic factors: (a) Tectonics, and the associated disintegration of the aquifer block by multiple deformations during the pre-Paleogene, mainly Miocene, period. The main discontinuities of NW-SE and N-S direction negatively affect the permeability of the aquifer environment. For utilization, minor NE-SW dilatation open fractures are important, which have been developed by sinistral transtension on N–S faults and accelerated normal movements to the southeast. (b) Hydrogeologically, the geothermal structure is accommodated by three water types, namely, Na-HCO3 with 10.9 g·L−1 mineralization (in the north), the Ca-Mg-HCO3 with 0.5–4.5 g·L−1 mineralization (in the west), and Na-Cl water type containing 26.8–33.4 g·L−1 mineralization (in the southwest). The chemical composition of the water is influenced by the Middle Triassic dolomite aquifer, as well as by infiltration of saline solutions and meteoric waters along with open fractures/faults. (c) Geothermally anomalous heat flow of 123–129 °C with 170 L/s total flow near the Slanské vchy volcanic chain seems to be the perspective for heat production.

Implications for the lithospheric structure of Greenland by applying different heat flow models

2021 ◽  
Author(s):  
Agnes Wansing ◽  
Jörg Ebbing ◽  
Mareen Lösing ◽  
Sergei Lebedev ◽  
Nicolas Celli ◽  
...  
Keyword(s):  
Heat Flow ◽  
Heat Dissipation ◽  
Ice Sheet ◽  
Magnetic Data ◽  
Similarity Function ◽  
Lithospheric Structure ◽  
Temperature Structure ◽  
Geothermal Heat ◽  
Flow Models ◽  
Ice Sheet Dynamics

<p>The lithospheric structure of Greenland is still poorly known due to its thick ice sheet, the sparseness of seismological stations, and the limitation of geological outcrops near coastal areas. As only a few geothermal measurements are available for Greenland, one must rely on geophysical models. Such models of Moho and LAB depths and sub-ice geothermal heat-flow vary largely.</p><p>Our approach is to model the lithospheric architecture by geophysical-petrological modelling with LitMod3D. The model is built to reproduce gravity observations, the observed elevation with isostasy assumptions and the velocities from a tomography model. Furthermore, we adjust the thermal parameters and the temperature structure of the model to agree with different geothermal heat flow models. We use three different heat flow models, one from machine learning, one from a spectral analysis of magnetic data and another one which is compiled from a similarity study with tomography data.</p><p>For the latter, a new shear wave tomography model of Greenland is used. Vs-depth profiles from Greenland are compared with velocity profiles from the US Array, where a statistical link between Vs profiles and surface heat flow has been established. A similarity function determines the most similar areas in the U.S. and assigns the mean heat-flow from these areas to the corresponding area in Greenland.</p><p>The geothermal heat flow models will be further used to discuss the influence on ice sheet dynamics by comparison to friction heat and viscous heat dissipation from surface meltwater.</p>

ADDITIONAL HEAT FLOW DETERMINATIONS IN THE AREA OF MOULD BAY, ARCTIC CANADA

1966 ◽  
Vol 3 (2) ◽  
pp. 237-246 ◽  
Author(s):  
W. S. B. Paterson ◽  
L. K. Law
Keyword(s):  
Heat Flow ◽  
Canadian Arctic ◽  
The Arctic ◽  
Canadian Arctic Archipelago ◽  
General Area ◽  
Geothermal Heat ◽  
Field Methods ◽  
The Mean ◽  
Water Depths ◽  
Made In

Seven determinations of geothermal heat flow were made in the general area of southern Prince Patrick Island in the Canadian Arctic Archipelago. Measurements were made from sea ice in water depths of between 200 and 600 m. The mean heat flow for the two stations on the continental shelf in the Arctic Ocean was 0.46 ± 0.08 μcal cm−2 s−1. The mean heat flow for the five stations in the channels to the east of Mould Bay was 1.46 ± 0.16 μcal cm−2 s−1. The instrument and field methods are described. Errors due to the instrument and to the environment are discussed.

Sequence stratigraphy of the late Desmoinesian to early Missourian (Pennsylvanian) succession of southern Illinois: Insights into controls on stratal architecture in an icehouse period of Earth history

2020 ◽  
Vol 90 (2) ◽  
pp. 200-227 ◽  
Author(s):  
Christopher R. Fielding ◽  
W. John Nelson ◽  
Scott D. Elrick
Keyword(s):  
Accumulation Rate ◽  
Sediment Accumulation ◽  
External Control ◽  
Illinois Basin ◽  
Carbonate Sediments ◽  
Glacial Cycles ◽  
Southern Illinois ◽  
Sequence Stratigraphic ◽  
Stratal Architecture ◽  
The Individual

ABSTRACT Uncertainty persists over whether repetitive stratal rhythms in the Pennsylvanian of Euramerica (so-called “cyclothems”) were externally forced, in all likelihood by waxing and waning of glacial ice centers on Gondwana, or were controlled by autogenic processes. A key to resolving this dispute is the lateral extent of the individual cyclothems, with broad regional extent (beyond the plausible breadth and length of individual depositional systems such as deltas) arguing in favor of an external forcing control. This study provides a sedimentological and sequence stratigraphic analysis of the middle Pennsylvanian (Desmoinesian to early Missourian in North American stratigraphic terminology, Moscovian to early Kasimovian in the terms of the global stratigraphic nomenclature) succession of the southern Illinois Basin in Illinois, Indiana, and Kentucky, eastern USA. An array of eleven lithofacies is recognized, recording deposition of clastic, humic organic, and bioclastic carbonate sediments on a broad, low-gradient, low-paleolatitude shelf and coastal plain that were undersupplied by sediment. These facies are arranged into thirteen repetitive vertical cycles (sequences), each of which can be traced across the entire basin west to east (perpendicular to the paleoslope direction) across a distance of 250 km. Sequences are bounded by erosion surfaces that define 1–4 km-wide, deeply incised valley-fills (IVFs) that are mostly elongate towards the south-southwest, the dominant direction of paleoflow. In the west–east direction, valley erosion surfaces pass laterally into well-developed paleosols, incised locally by smaller channels. Each of these surfaces is laterally persistent across the basin. IVFs comprise multi-story bodies of conglomerate–breccia and sandstone, passing upward into heterolithic sandstone–mudrock associations, recording fluvial and later estuarine environments. Coal bodies typically occur at the tops of IVFs and are interbedded with heterolithic facies recording tidal influence, indicative of initial flooding by the sea. They are in turn overlain by estuarine and marine mudrocks and bioclastic carbonates, recording the maximum extent of marine flooding in a cycle. Each sequence is completed by heterolithic to sandstone-dominated facies of deltaic aspect that are typically truncated by the next erosion surface (sequence boundary). Plausible modern analogs suggest that sea-level excursions were of the order of 20–40 m. The great lateral persistence of not only the thirteen sequences, but also many of their component beds, argues strongly for an external control on sediment accumulation. Eccentricity-paced glacial cycles in Gondwana are invoked as the most likely cause of the cyclicity. The low-accommodation context of the Illinois Basin (average accumulation rate 6 cm/ky) contributed to the incomplete, condensed, and strongly top-truncated nature of preserved sequences.

Low geothermal heat flow of the Urals fold belt — implication of low heat production, fluid circulation or palaeoclimate?

1997 ◽  
Vol 276 (1-4) ◽  
pp. 63-85 ◽  
Author(s):  
I.T. Kukkonen ◽  
I.V. Golovanova ◽  
Yu.V. Khachay ◽  
V.S. Druzhinin ◽  
A.M. Kosarev ◽  
...  
Keyword(s):  
Heat Flow ◽  
Heat Production ◽  
Fluid Circulation ◽  
Fold Belt ◽  
The Urals ◽  
Geothermal Heat

Observational constraints on reheating in braneworld inflation

2019 ◽  
Vol 34 (27) ◽  
pp. 1950152
Author(s):  
Z. Sakhi ◽  
A. Safsafi ◽  
M. Ferricha-Alami ◽  
H. Chakir ◽  
M. Bennai
Keyword(s):  
Cosmological Parameters ◽  
High Energy ◽  
Observational Constraints ◽  
Brane Tension ◽  
Energy Limit ◽  
Polynomial Potential ◽  
High Energy Limit ◽  
Slow Roll ◽  
Braneworld Inflation ◽  
Best Fit

The reheating era after inflation is analyzed in the framework of the braneworld models. We study reheating by calculating the reheating temperature in a braneworld inflation for various cosmological parameters. The variation of reheating [Formula: see text]-folding number and reheating temperature were obtained and analyzed as function of a spectrum of perturbation for a polynomial potential [Formula: see text]. We have applied the slow-roll approximation in the high energy limit to constraint the parameter potentials by confronting our results to recent Planck 2018 observations. We have shown that in general the best values of the predicted reheating temperature is of the order [Formula: see text] GeV, with a brane tension [Formula: see text] GeV4. We have also shown that the polynomial potential in the case [Formula: see text] provides the best fit results with recent observational constraints.

scholarly journals Temperature profiles for the barnes ice cap surge zone

1977 ◽  
Vol 18 (80) ◽  
pp. 391-405 ◽  
Author(s):  
D. F. Classen
Keyword(s):  
Heat Flow ◽  
Flow Line ◽  
Temperature Measurements ◽  
Temperature Profiles ◽  
Baffin Island ◽  
Geothermal Heat ◽  
Ice Cap ◽  
Marginal Areas ◽  
Thermal Drilling

AbstractThermal drilling and deep ice-temperature measurements along a flow line in a surge area of the Barnes Ice Cap, Baffin Island, N.W.T., Canada revealed a layer of basal temperate ice 30 m thick. Marginal areas were determined to be frozen to bedrock and geothermal heat flow estimated to be 1.02 μcal/cm2s (42 mW/m2).

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