Aiming to contribute to the energy transition, this study provides an integrated picture of the geothermal system hosted in the West Netherlands Basin and shows how the reconstruction of the basin's geological history can contribute to the correct exploration and exploitation of its geothermal resources. In the West Netherlands Basin, the main geothermal targets are found in the Cretaceous and Jurassic strata that were deposited during the rifting and post-rifting stages and were deformed during the subsequent basin inversion. Despite multiple studies on the tectonic setting, the timing and tectono-stratigraphic architecture of the rift system and its overall control on the development and evolution of geothermal systems are still to be fully deciphered. In this study, a detailed seismo-stratigraphic interpretation of the syn- and post-rift intervals in the West Netherlands Basin will be given within the framework of geothermal exploration. A recently released and reprocessed 3D seismic cube is used, covering a large portion of the onshore section of the basin. We identified two major Jurassic rifting episodes and a Late Cretaceous inversion event. During the Jurassic rifting phases, the compartmentalization of the basin and the creation of accommodation space led to the deposition of the Late Jurassic Nieuwerkerk Formation, which is the main regional geothermal producing target. Within this formation, we individuate growth synclines located in the central portions of the Jurassic half-grabens as sites that show good potential for geothermal exploration.@en

The West Netherlands Basin, which has a long history in exploration as a former prosperous hydrocarbon province, is currently a geothermal hotspot. Being exploited since the 1950’s, most of its oil and gas fields are now in their final phase of production. In the past decade, interest shifted to sustainable energy sources. The geothermal industry in the area is developing quickly, helped by the legacy of the hydrocarbon industry: a wealth of publicly available seismic and well data. Currently, the area has 14 realized, and at least 3 projects in the development phase, with the Late Jurassic Nieuwerkerk Formation being the main target.

Conversely to petroleum systems, in which anticlines are the preferential target for hydrocarbon exploration, synclines are the most suitable sites for geothermal exploration. They offer higher temperatures with respect to the limbs and anticlines, and possible remaining hydrocarbons are not expected to be located inside the central portions of the synclines.

The West Netherlands Basin is a former rift basin that developed during the Mesozoic in the framework of the North Sea rift, and subsequently inverted during the Late Cretaceous. The Nieuwerkerk Formation was deposited during the last major rifting phase. Thus, the thickest packages of its fluvial-deltaic deposits are fault-controlled and commonly located in the synclines. The heterogeneity of fluvial reservoirs causes lateral and vertical quality variations in porosity, permeability and net-to-gross ratios. With the hydrocarbon industry focussing on the stratigraphic highs, there is only limited well data available for the central portions of the synclines.

With reprocessed 3D seismic data, our study uses an image processing approach, coupling traditional amplitude mapping with seismic attributes. This will help to reconstruct the evolution of the fluvial architecture of the Nieuwerkerk Formation over time. By tying the seismic with well data, a better prediction of the quality of the sandy bodies per location can be made. These results can be implemented in de-risking geothermal well planning across fluvial reservoirs in inverted rift basins.@en

Aiming to contribute to the energy transition, this study provides an integrated picture of the geothermal system hosted in the West Netherlands Basin and shows how the reconstruction of the basin's geological history can contribute to the correct exploration and exploitation of its geothermal resources. In the West Netherlands Basin, the main geothermal targets are found in the Cretaceous and Jurassic strata that were deposited during the rifting and post-rifting stages and were deformed during the subsequent basin inversion. Despite multiple studies on the tectonic setting, the timing and tectono-stratigraphic architecture of the rift system and its overall control on the development and evolution of geothermal systems are still to be fully deciphered. In this study, a detailed seismo-stratigraphic interpretation of the syn- and post-rift intervals in the West Netherlands Basin will be given within the framework of geothermal exploration. A recently released and reprocessed 3D seismic cube is used, covering a large portion of the onshore section of the basin. We identified two major Jurassic rifting episodes and a Late Cretaceous inversion event. During the Jurassic rifting phases, the compartmentalization of the basin and the creation of accommodation space led to the deposition of the Late Jurassic Nieuwerkerk Formation, which is the main regional geothermal producing target. Within this formation, we individuate growth synclines located in the central portions of the Jurassic half-grabens as sites that show good potential for geothermal exploration.

@en

Sedimentary injectites are increasingly doc-umented in many hydrocarbon plays at various scales, either interpreted as potential risks (e.g., top-seal bypass, a drilling hazard) or benefits (e.g., reservoir interconnection, increased hydro-carbon volumes) for production operations. As such, they have potential critical implications for the assessment of suitability for CO ₂ injection and sequestration. Detailed characterization of such units, especially in terms of diagenesis and (paleo) fluid flow, is directly achievable at outcrop scale, overcoming dimensional and time constraints oth-erwise unresolvable at seismic scale. Two sedimentary injection complexes have been recognized in the succession of the Middle Jurassic-Lower Cretaceous Agardhfjellet Forma-tion exposed at Deltaneset, central Spitsbergen, Norway, at different stratigraphic levels. The upper complex comprises two main clastic dikes charac-terized by different orientation and consolidation, tapering out vertically (upward and downward) within a stratigraphic thickness and lateral extent of more than 50 m and 200 m, respectively. The lower complex is coarser grained, made up by a network of interconnected dikes and sills, shooting off from isolated lenticular and morphologically articulated bodies, interpreted as sedimentary intrusions linked to seafloor extrusion (sand volcano). Petrographic and micromorphological analyses were used to identify the underlying lithologies of the Late Triassic to Middle Jurassic Wilhelm⊘ya Subgroup as the possible source of this remobilized material for both the upper and lower complexes. This subsurface remobilization and consequent intrusion were first achieved in the lower complex during the Late Jurassic at shallow burial conditions, and then at higher confinement pressure for the upper complex, probably during the Late Cretaceous. These results highlight how field data can be used to constrain long-lived spatiotemporal relationships of sedimentary intru-sions, allowing a finely tuned upscaling of seismic data and interpretations.

@en

Meso-scale (sub-seismic) sedimentary injectites are inferred to play an important role in controlling subsurface fluid flow as documented in many hydrocarbon plays at various scales. Detailed characterisation of such units, usually unresolvable at the seismic scale, can be directly achieved at outcrop scale. In this framework, two sedimentary injection complexes have been analysed in the middle Jurassic-lower Cretaceous Agardhfjellet Formation exposed at Deltaneset (central Spitsbergen) at different stratigraphic levels. The upper complex comprises two main isolated, decimetres-thick clastic dykes characterized by different orientation and consolidation, tapering out vertically (up- and downward) within a stratigraphic thickness and a lateral extension of more than 50 m and 200 m, respectively. The lower complex is coarser-grained, made up by a network of interconnected dykes and sills, branching off from isolated lenticular bodies, interpreted to be linked to seafloor extrusion structures (sand volcano). Petrographic and micromorphologic analysis were used to identify the possible source of the remobilized material for both the upper and lower complexes within the over- and under-burden formations. Our results reveal that such granular material is likely sourced by the underlying coarse-grained lithologies of the late Triassic to middle Jurassic Wilhelmøya Subgroup. The lower complex was firstly emplaced during the Late Jurassic at shallow burial conditions, while the upper complex developed at higher confinement pressure, probably during the Late Cretaceous, with the progressive reworking of the same granular material. Field data allow detailed characterisation of complex structural-stratigraphic architectures of sedimentary intrusions, which can be used to constrain their spatial-temporal relationships with subsurface fluid flow.@en

In rift basins, the spatial arrangement of extensional faults can influence the facies and the thickness distribution of the syn- and post-sedimentary infill, which can harbour good potential for geothermal systems. In this framework, unravelling the tectono-stratigraphic evolution of a rift basin is decisive, as it can influence one of the key parameters for planning geothermal doublets: aquifer thickness.

In our study, the West Netherlands Basin, located in one of the Netherlands most densely populated areas, is used as a case study. Up to 2022, 14 geothermal doublets were realized in the area, with the main target being the syn-rift deposits of the Late Jurassic Nieuwerkerk Formation. As a NW-SE oriented transtensional basin, the West Netherlands Basin developed as consequence of Mesozoic extensional tectonics, after which it became inverted during the Late Cretaceous and Cenozoic. Using publicly available seismic 3D and well data, our renewed interpretation of the study area shows two important rift events. The first one during the Early-Mid Jurassic and the second one, partly controlled by structures of the former, during the Late Jurassic, coinciding with the deposition of the Nieuwerkerk Formation.

Our study adds to the understanding of a multiple stage rifting history in the West Netherlands Basin. This is important, as the process influences reservoir thicknesses and with that, the amount of MW that can be extracted from geothermal aquifers. Therefore, this study forms a bridge between providing an integrated picture of the West Netherlands Basin and how the basins geological history affects its geothermal resources.@en

Future human space exploration of the Moon and Mars could lead to the study of processes on the surface and subsurface of these planetary bodies in more detail. Nowadays, analogue space missions on Earth are used to prepare humanity for the challenges that will need to be overcome in order to settle on the Moon or Mars. The Hawaii - Space Exploration Analog and Simulation (HI-SEAS) habitat, is one of the places where these types of missions are performed. The habitat is located on the volcano Mauna Loa (Hawaii). Currently, operations of simulated missions at HI-SEAS are coordinated by the International MoonBase Alliance (IMA), an organization dedicated to building a Moon base prototype in Hawaii and ultimately a real settlement on the Moon. During the EMMIHS-1 campaign, a two week analog mission to the Moon was performed from the 20th of February till the 6th of March 2019. EMMIHS-1 was the first of a series of analogue Moon missions at the HI-SEAS habitat, as part of the EuroMoonMars program. Results of the simulated missions contribute to the understanding of how to properly build a Moon base on the lunar surface in the near future and what research still needs to be performed in order for humans to return to the Moon. Part of the lunar simulation was focused on how to do geological fieldwork despite the limitations of the analog spacesuits. This included the field research of secondary mineralization inside lava tubes and the hydrous alteration of lava flows. The research was conducted wearing analog spacesuits during extra vehicular activities (EVAs) with basic geological equipment and a drone. Infrared spectroscopy was applied on all collected samples, as an easy and quick tool for mineral identification. Furthermore, lab-measurements will deliver a better characterization of the mineralogical and elemental content of the samples. Another type of geological research that was performed during the mission was the study of the alteration of the lava flows on Mauna Loa, which can be used as an analogue for the hydrous alteration of basaltic rocks on Mars. Its goal was to help understand the surface processes on the red planet. Furthermore, the samples collected from within the lava tubes can help determine the impact of biogeological activity on secondary mineralization within those environments. As lava tubes mimic subsurface conditions of other planetary bodies, the results can be used to help find microbial extraterrestrial life on other planets.@en

Over the past decades, due to an increasing number of successful orbiter and lander space missions, interest in planet Mars experienced an enormous growth. To complement Mars missions, studies using samples from Earth as analogue for Mars contribute to the increasing knowledge about Mars. This study is the first to use basaltic rock samples from the shield volcano Mauna Loa (Hawaii) as Martian analogue for a hydrous alteration study.

First, samples from differently aged lava flows were collected during the EMMIHS-I simulated Moon mission at the HI-SEAS habitat. The HISEAS habitat is situated on the north-eastern flank of the shield volcano Mauna Loa (Big Island, Hawaii). In order to obtain the most representative samples, only the top 10 cm of horizontally emplaced pahoehoe lava flows were sampled in a radius of 6 km around the HISEAS habitat. From the samples, thin sections were analysed using petrographic microscopy, SEM-EDS and SWIR hyperspectral imagery. Combining the datasets from these three methods made it possible to estimate the chemical composition of the present hydrated minerals. Additionally, XRF was used to study the elemental changes along the depth profiles through the samples and calculate geochemical weathering indices. The Hawaiian rocks were then compared to datasets from Mars. The Hawaiian XRF dataset was compared with calibrated APXS data from the Mars Exploration Rovers (MER). Hawaiian mineral spectra obtained using SWIR hyperspectral imagery were compared with remote sensing data from Mars Orbital spacecrafts.

In the field, hydrous alteration can be recognized by the removal of metallic surface layers, presence of brown horizontal surface layers and horizons enriched in ferric iron. The main detected alteration products include Fe,Mg-smectites, hydrated silica, Al-silicates, Al-hydroxide and palagonite. These products formed due to the interaction between meteoric water and basaltic rocks. The calculated geochemical weathering indices indicate alteration and weathering processes acting on the top 2-3 cm of the rock samples from lava flows with ages >400 years. The values indicate the alteration products formed in an arid to semi-arid environment at cold to moderate temperatures.

Comparisons between the Hawaiian datasets and the Martian datasets mentioned in the Methods section [5,6,7,8], show that the alteration products on Mars are similar to the hydrous alteration products found on Mauna Loa. When calculating the already mentioned geochemical weathering indices for the MER datasets, the Martian values indicate a low degree of weathering and alteration processes, similar to the values of the Hawaiian rocks. This suggests that the Martian alteration products formed in a similar environment as the Hawaiian alteration products. These observations are consistent with the assumption of a present active hydrosphere on an early Mars.

This study shows analogies between rock samples from the Hawaiian shield volcano Mauna Loa and Martian datasets in terms of mineralogy and alteration environments. The study suggests the same type of clay minerals as identified on Mauna Loa have formed in an arid to semi-arid environment at cold to moderate temperatures on an early Mars. These findings add to the assumption that Mars once had a more Earth-like climate with an active hydrosphere and relatively thick atmosphere.@en