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Since 1963, the International Heat Flow Commission (IHFC | www.ihfc-iugg.org) has been dedicated to providing standards for heat flow measurements and maintaining the Global Heat Flow Database (GHFDB) — a collection of heat flow data from around the world. The first quality framework for heat-flow-density data was proposed by Jessop et al. (1976), reflecting the state of knowledge, measurement techniques, and technical developments at that time. In 2019, the IHFC initiated a major revision of the GHFDB to develop an authenticated and quality-assessed database. This initiative involved multinational working groups and led to a comprehensive update of key parameters affecting heat-flow calculations. These updates included measurement methods for both temperature and thermal conductivity, as well as metadata structures. The new standard for a revised GHFDB structure was developed through a collaborative community approach and published in 2021 (Fuchs et al., 2021). This standard reflected changes in database technology and scientific documentation and served as a template for users submitting data to the GHFDB. It was further developed into the currently valid data and metadata standard in 2023, which also introduced an enhanced quality evaluation framework (Fuchs et al., 2023). The ongoing assessment work and the latest release of the GHFDB (Global Heat Flow Database Assessment Group et al., 2024), along with its frequent use, revealed the need for additional refinements. These refinements were particularly necessary in aspects related to metadata consistency, measurement techniques, and classification criteria. Consequently, further updates were implemented to improve the reliability and applicability of the dataset, ensuring a more robust evaluation of global heat-flow data. Here, we present the 2026.03 version of the GHFDB Data Template. The previous template introduced by Fuchs et al. (2023) has been improved based on the latest data ass6ssment process. The current version of the template incorporates the advancements in data collection methodologies, the IHFC quality evaluation framework, and metadata management, ensuring that data submitted to the GHFDB follows the IHFC standards for the GHFDB. A changelog is available and a summary of changes is also provided in the data descripton file (PDF). To promote open access, the template is also hosted on the official GitHub repository of the IHFC: https://github.com/ihfc-iugg. Users can download both the original version from 2023 and the revised templates. Version 2025.06 is also available in the previous-versions folder of this data publication. Maintaining the GHFDB Data Template in a version-controlled environment ensures transparency regarding changes over time and fosters a documentation style that sets high standards to support the reproducibility of research results. Moreover, it supports a smooth and fast integration of data from the research community into the Global Heat Flow Database of the IHFC.
Heat Flow Quality Analysis Toolbox hfqa_tool is a Python package containing tools for validating and evaluating the quality of heat flow data. It is designed for researchers and professionals. hfqa_tool simplifies heat flow data analysis by providing standardized and reproducible quality checks. This is developed in compliance with the paper by Fuchs et al. (2023) titled "Quality-assurance of heat-flow data: The new structure and evaluation scheme of the IHFC Global Heat Flow Database," published in Tectonophysics 863: 229976. Also revised for the newer release 2024. There are mainly 2 functions defined in this tool with description as follows: vocabulary_check(): This set of code has been developed to check whether all the values entered in a Heatflow database adhere to a controlled vocabulary and proper structure described in the aforementioned scientific paper. It generates an error message for each entry where the value entered is out of bounds and does not meet the assigned criteria. The code also enables checking the vocabulary for multiple values entered in a single column for a particular Heatflow data entry. It's a recommended prerequisite before calculating 'Quality Scores' for a given Heatflow dataset. quality_scores(): This code has been developed to assess the quality of the Heatflow database in terms of U-score (Uncertainty quantification), M-Score (Methodological quality), and P-Flags (Perturbation effects) adhering to the data structure described in the aforementioned scientific paper.
In diesem Bericht wird die durch das GFZ Potsdam am 18. Juli 2024 durchgeführte bohrlochgeophysikalische Messung in der Bohrung Gt P 14a/23 in Potsdam (Brandenburg) dokumentiert. Die Messung wurde mit dem Ziel der Gewinnung hochaufgelöster und ungestörter Temperatur-Tiefen-Profile durchgeführt. Die Sidetrack-Bohrung der Hauptbohrung Gt P 14 wurde im März 2023 abgeteuft. Anschließend erfolgten Testarbeiten im Mai desselben Jahres. Bis zur Durchführung dieser Messungen erfolgten keine weiteren Aktivitäten in der Bohrung. Die Stillstandszeit (shut-in time) beträgt mind. 14 Monaten für die oberen 1.100 m, weshalb keine thermische Beeinflussung der Temperaturen durch den Bohrprozess mehr erwartet wird. In der Bohrung Gt P 14a/22 wurde bei 1039,9 m Teufe eine Temperatur von 46,07 °C gemessen, welches einem mittleren Temperaturgradienten von 35,6 °C/ km entspricht.
In diesem Bericht wird die durch das GFZ Potsdam am 9. September 2020 durchgeführte bohrlochgeophysikalische Messung in der Bohrungen Ug Wsbg 10/76 in Wesenberg (Mecklenburg-Vorpommern) dokumentiert. Die Messung wurde mit dem Ziel der Gewinnung eines hochaufgelösten und ungestörten Temperatur-Tiefen-Profils durchgeführt. Die Untergrundspeicherbohrung wurde 1976 am Salzstock Wesenberg abgeteuft und lange als Sole-Verpressbohrung genutzt. Die Stillstandszeit nach letzter Nutzung liegt bei mind. 44 Monaten, weshalb von hydraulisch ungestörten Gebirgstemperaturen ausgegangen wird. In der Bohrung Ug Wsbg 10/76 wurde bei 1784,3 m Teufe eine Temperatur von 72.70 °C ermittelt, welches einem mittleren Temperaturgradienten von 36,0 °C/ km entspricht.
In diesem Bericht werden die durch das GFZ Potsdam am 29. und 30. November 2023 durchgeführte bohrlochgeophysikalische Messungen in den Bohrungen Gt Khn 1/88 und Gt Khn 2/87 in Karlshagen (Mecklenburg-Vorpommern) dokumen-tiert. Die Messungen wurden mit dem Ziel der Gewinnung hochaufgelöster und un-gestörter Temperatur-Tiefen-Profile durchgeführt. Die Stillstandszeiten seit Erstel-lung liegen bei mehreren Jahrzehnten; jene seit letzter Befahrung bei fünfzehn Jahren, weshalb von ungestörten Gebirgstemperaturen ausgegangen werden kann. In der Bohrung Gt Khn 2/87 wurde bei 1786,5 m Teufe eine Temperatur von 57,8 °C, welches einem mittleren Temperaturgradienten von 27,8 °C/km entspricht, ge-messen. Die Bohrung Gt Khn 1/88 konnte bis zu einer Teufe von 325,1 m befahren werden, die gemessene Temperatur betrug 16,2 °C, der entsprechende mittlere ge-othermische Gradient beträgt ca. 23,6 °C/km. This report documents the borehole geophysical logging performed by GFZ Potsdam in the Gt Khn 1/88 and Gt Khn 2/87 boreholes in Karlshagen (Mecklenburg-Western Pomerania) on the 29th and 30th of November 2023. The measurements were conducted to achieve high-resolution and undisturbed temperature-depth pro-files. The shut-in times since the boreholes were drilled are several decades; the shut-in time since last activities in the boreholes are in the order of 15 years. There-fore, undisturbed formation temperatures can be expected in the boreholes. In the Gt Khn 2/87 borehole, a temperature of 57.8 °C was measured at a depth of 1786.5 m, which corresponds to an average temperature gradient of 27.8 °C/km. The Gt Khn 1/88 borehole could be logged to a depth of 325.1 m and the measured temperature at this depth was 16.2 °C, corresponding to an average geothermal gradient of approx. 23.6 °C/km.
This report summarizes the measurements carried out by the GFZ Potsdam on the boreholes Gt S 6/17 and Gt S 7/20 in Schwerin (Mecklenburg-Western Pomerania). The first part of the report describes the borehole measurements of the unperturbed temperature profiles. The second part describes the compilation of the thermal-hydraulic rock properties (thermal conductivity, porosity, permeability, density, etc.) measured on drill-core material. The shut-in time since the drilling is around 4 years for Gt S 6/17 and around 21 months for Gt S 7/20. Hence, unperturbed borehole temperatures are assumed at the time of temperature logging.
This data set compiles the raw data used to evaluate the performance of the Goto & Matsubayashi model for continental sedimentary rocks ( Goto & Matsubayashi, 2009). It reports thermal diffusivity (α) and porosity (φ) data for two suites of rock, quartz sandstones of varying porosity and clastic and carbonate lithologies of variable porosity and modal mineralogy.The rock collection involves roughly 120 samples (from boreholes and outcrops) with porosities between 0 and 35%, on which the operability of the Goto & Matsubayashi modified geometric mean model (mGM) was evaluated and quantified.Our study confirms the operability of the mGM for consolidated quartz-rich sandstones and implies a reasonably good performance of this model also for mineralogically more complex sedimentary rocks. This model was also proven to be an appropriate tool to convert thermal diffusivity data obtained on air-saturated samples into such reflecting water-saturated conditions. Altogether, our study suggests that the mGM is suited to model thermal-diffusivity data of all types of sedimentary rock of whatever porosity and chemistry of the pore fluid.The data reported in this data publication are the basis for tables and plots published by Fuchs et al. (2020). Data are provided in tab-delimited text format and described in detail in the associated data description.
In Haeger et al. (2022), we created a three dimensional model of the temperature distribution and the geothermal heat flow of the Antarctic lithosphere as well as a new model of the lithosphere-asthenosphere boundary (LAB). The models were obtained in a three-step approach: First, we calculate the initial temperature distribution in the upper mantle by iteratively combining seismic tomography (An et al., 2015; Schaeffer & Lebedev, 2013) and gravity data (Förste et al., 2014; Scheinert et al., 2016) considering composition and density variations self-consistently (Haeger et al., 2019). Second, we define the lithosphere-asthenosphere boundary in a thermal sense based on the resulting geotherm by assuming it corresponds to the 1300°C isotherm. Third, we solve the steady-state heat equation to obtain the temperature distribution and the geothermal heat flow in the lithosphere. One crucial yet still largely unknown factor in the model is the parametrization of the crust. In order to overcome this, we calculated thermal models for a range of crustal properties that are described in detail in Haeger et al. (2022) and the related supplementary material. Here, we only share the conductive temperature and the geothermal heat flow model for the preferred model (n° 29 in the supplementary) in binary netCDF files. Additionally, we present the depth to LAB and surface and mantle heat flow maps, the latter represents the heat flow at the depth of the Moho discontinuity (Haeger et al., 2019) as .txt ascii tables. As a measure of uncertainty of the preferred surface heat flow model, the standard deviation of all calculated models is additionally given. The models are presented in polar stereographic projections with true scale at 71° South (Snyder, 1987) and span ±3700 km with a 10 km spacing in x- and y-direction, respectively. For the netCDF files, the depth ranges from the bedrock surface (BedMachine, Morlighem et al., 2020) which is defined as the 0 level to the LAB in a 1 km spacing. The depths to the Moho and the LAB are given relative to sea level.
Carbon dioxide is the most abundant, non-condensable gas in volcanic systems, released into the atmosphere through either diffuse or advective fluid flow. The emission of substantial amounts of CO2 at Earth’s surface is not only controlled by volcanic plumes during periods of eruptive activity or fumaroles, but also by soil degassing along permeable structures in the subsurface. Monitoring of these processes is of utmost importance for volcanic hazard analyses, and is also relevant for managing geothermal resources. Fluid-bearing faults are key elements of economic value for geothermal power generation. Here, we describe for the first time how sensitively and quickly natural gas emissions react to changes within a deep hydrothermal system due to geothermal fluid reinjection. For this purpose, we deployed an automated, multi-chamber CO2 flux monitoring system within the damage zone of a deep-rooted major normal fault in the Los Humeros Volcanic Complex (LHVC) in Mexico and recorded data over a period of five months. After removing the atmospheric effects on variations in CO2 flux, we calculated correlation coefficients between residual CO2 emissions and reinjection rates, identifying an inverse correlation of ρ = -0.51 to -0.66. Our results indicate that gas emissions respond to changes in reinjection rates within 24 hours, proving an active hydraulic communication between the hydrothermal system and Earth’s surface. This finding is a promising indication not only for geothermal reservoir monitoring but also for advanced long-term volcanic risk analysis. Response times allow for estimation of fluid migration velocities, which is a key constraint for conceptual and numerical modelling of fluid flow in fracture-dominated systems.
KTB Borehole Measurements Data - Data collection This data collection compiles the KTB Borehole Measurements Data of the German Continental Deep Drilling Program operated by the GFZ - German Research Centre for Geosciences. Extensive borehole measurements were performed during the active drilling phase of the KTB pilot and main hole. All KTB borehole measurements are described in detail in the Scientific Technical Report - Data 21/03 "KTB Borehole Logging Data" (Kück et al. 2021). The terms borehole measurements, downhole logging, and logging are used synonymously here. The KTB logging data files contain the final processed versions of the geoscientific borehole logging data from logs in the two KTB boreholes: • KTB-Oberpfalz VB (KTB Vorbohrung/Pilot Hole or KTB-VB) • KTB-Oberpfalz HB (KTB Hauptbohrung/Main Hole or KTB-HB). Here only the acronyms KTB-VB and KTB-HB are used. In total there are 145 logging data files from the KTB-VB and 239 logging data files from the KTB-HB. The data compilation comprises the following measurements: • Borehole geometry and orientation logs • Composite logs (compilation of standard logs of resistivity, gamma spectrum, density, neutron porosity, sonic) • Geochemical logs • Gravimetry logs • Magnetic susceptibility and field logs • Spontaneous potential and induced polarization (SP and IP) logs • Structures from borehole images, foliation, fracs, faults, joints • Temperature logs The maximum logging depth was 4001 m in the KTB-VB and 9085 m in the KTB-HB. There is no sonic waveform data available. There is no electrical or acoustic borehole wall image data available. However, the spatial orientation of planar structures (foliation, faults, fractures, joints) gained by manual sinus structure picking from these electrical images are included.
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