Abstract
Geysers are among the most fascinating geological features on Earth. Yet, little is still known about their hydrogeological structure at depth. To shed light on the spatial relationships between the vertical conduits and the aquifers feeding them, we conducted a 3D geoelectrical campaign in the Haukadalur hydrothermal field, Iceland. We deployed 24 Iris Fullwavers across the hydrothermal field and inverted resistivity and chargeability measurements. Additionally, we measured temperature variations inside Strokkur and Great Geysir geysers showing temperature fluctuations pointing out the oscillatory behaviour that characterises the geysering cycle of the geysers. By combining a semi-quantitative temperature distribution of the thermal springs across the hydrothermal field with the inversion of the geoelectrical data, we highlight the control that extensional tectonics have on the distribution of fluids across the hydrothermal field. We also point out the occurrence of a common deep groundwater reservoir feeding the hydrothermal centres. Induced polarization data show that the geysers are fed by sub-vertical water-filled fracture zones. The geysers are found at the margins of highly resistive regions where we speculate boiling groundwater and vapour is found. Our proposed model suggests that local waters feeding the main groundwater reservoir downwell from the nearby region and then convect upwards, phase transitioning into vapour at about 200 m depth. From here, fluids flow towards the surface through pipes cutting a highly pressurised and hot system. This study shows to the best of our knowledge the first full 3D tomographic image of a hydrothermal field hosting geysers.
Original language | English (US) |
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Journal | Journal of Geophysical Research: Solid Earth |
DOIs | |
State | Published - Oct 19 2022 |
Bibliographical note
KAUST Repository Item: Exported on 2022-10-21Acknowledgements: This study was partially funded by the Augustin Lombard Scholarship for Sebastian Mueller, that is thanked385for the support in the field. Marine Collignon was funded by a Marie Skłodowska-Curie Individual Fellowship386(NERUDA 793662). Laura Pioli was funded by the Fond National Suisse Project 200021-162439. We thank the387Umhverfisstofnun, Environment Agency of Iceland for facilitating the access to the field and for the support of the388rangers. All the data generated or analysed during this study are stored under the DOI 10.5281/zenodo.5850495389with an embargo until the 12.06.2023. The embargo can be lifted and data shared upon request for collaborative390projects. We also thank very much the Associated editor and two anonymous Reviewers that very much helped391improving the content of this manuscript.392–12–