Heat flow variations in 2 km deep borehole Litoměřice, Czechia
The result's identifiers
Result code in IS VaVaI
<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F67985530%3A_____%2F23%3A00570575" target="_blank" >RIV/67985530:_____/23:00570575 - isvavai.cz</a>
Result on the web
<a href="https://www.sciencedirect.com/science/article/pii/S0375650523000627" target="_blank" >https://www.sciencedirect.com/science/article/pii/S0375650523000627</a>
DOI - Digital Object Identifier
<a href="http://dx.doi.org/10.1016/j.geothermics.2023.102708" target="_blank" >10.1016/j.geothermics.2023.102708</a>
Alternative languages
Result language
angličtina
Original language name
Heat flow variations in 2 km deep borehole Litoměřice, Czechia
Original language description
Temperature in 2 km deep borehole Litoměřice, drilled in 2007, was repeatedly logged down to 1700 m in the period 2007 – 2020. We were able to monitor a return of the temperature to the equilibrium temperature-depth profile undisturbed by drilling. The uppermost part of the profile contains signal of the recent warming manifested by a negative temperature gradient close to the surface and a temperature minimum at a depth of about 40 m. The minimum has been migrating downward at a rate of 1.5 – 2 m per year in the period 2015 – 2020. A detailed knowledge of temperature gradient together with thermal conductivity, diffusivity and heat production measurements on the drill-core samples of mica-schist that occurs below 900 m depth enabled us to analyze the heat flow vertical variations in the lithologically homogeneous depth section 900 – 1700 m. We came to the conclusion that temperature-depth profile in this section contains a robust climate signal of the last glacial cycle. The reconstructed ground surface temperature history indicates the magnitude of the last glacial – Holocene warming 13 -15 K and existence of a minimum 15 – 20 ka. The long-term mean ground surface temperature +1 - +2 °C suggests that the borehole site was permafrost free for most of the glacial cycle. Existence of about 100 m deep permafrost is possible in the coldest part of the last glacial. The steady-state surface heat flow has been estimated at 88 mW/m2. The reconstructed ground surface temperature history used as a surface forcing function in a numerical solution of the transient heat conduction equation provided an estimate of the present-day heat flow in the well. The estimate is practically independent from the poorly constrained conductivity of the 900 m thick sedimentary cover. According to it the present-day heat flow is lower than the steady-state one by 20 - 30 mW/m2 in the first hundreds of meters below the surface and still by about 10 mW/m2 at a depth of 1 km.
Czech name
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Czech description
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Classification
Type
J<sub>imp</sub> - Article in a specialist periodical, which is included in the Web of Science database
CEP classification
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OECD FORD branch
10507 - Volcanology
Result continuities
Project
<a href="/en/project/GA21-23196S" target="_blank" >GA21-23196S: Distribution, Thickness and Evolution of Permafrost in Central Europe in Late Quaternary</a><br>
Continuities
I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace
Others
Publication year
2023
Confidentiality
S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů
Data specific for result type
Name of the periodical
Geothermics
ISSN
0375-6505
e-ISSN
1879-3576
Volume of the periodical
111
Issue of the periodical within the volume
June
Country of publishing house
GB - UNITED KINGDOM
Number of pages
11
Pages from-to
102708
UT code for WoS article
000959610700001
EID of the result in the Scopus database
2-s2.0-85150457260