The formation of Tharsis affected nearly the entire western hemisphere of Mars and had a profound effect on Martian geodynamics. Tharsis-related lithospheric deformation created a variety of tectonic structures that record past stress fields, some of which may still be active today. However, evidence for very recent endogenic activity (<1 Ma) in Tharsis remains limited even after the seismic measurements by the NASA InSight mission. Very few morphologically pristine tectonic structures have been discovered in remote sensing data, limiting our understanding of the current endogenic activity in Tharsis.

Building on our previous research in the southeastern Tharsis region, we focus on the Claritas Fossae region. This area displays several cross-cutting fracture and fault sets, recording a complex history of multiple volcano-tectonic events. Using High Resolution Imaging Science Experiment (HiRISE) images and stereo image-derived Digital Elevation Models (DEMs), we identified uphill-facing scarps on the west-facing Claritas Rupes scarp, which bounds a major N-S-trending extensional structure, informally called the Thaumasia Graben. The two-kilometer-high steep slopes of Claritas Rupes experience intense mass wasting, producing rockfalls (boulders) that accumulate against these uphill-facing scarps. Despite the high boulder fall rates, which over time could fill the accommodation space created by the uphill-facing scarps and mask them, small of these scarps retain a pristine topography. These observations suggest a very young age (<1 Ma) for these scarps. We interpret these scarps as surface expressions of normal faulting linked to Deep-seated Gravitational Slope Deformations (DGSDs), likely caused by seismic activity tied to reactivation of the Claritas Rupes fault associated with Thaumasia Graben subsidence. This indicates neotectonic activity in the region, which is potentially still ongoing.

To better constrain the tectonic processes and the mechanism of the very recent small-scale faulting at the Claritas Rupes scarp, our current structural mapping aims at deciphering the orientations and the spatiotemporal relationships of these scarps. Our approach involves obtaining dip angles through a planar fitting method and quantifying shortening along mapped scarp features. This forms the basis for determining effective stress distribution under isotropic stress conditions with plane strain assumptions, offering insights into the youngest stages of the tectonic evolution of this region. Our satellite image-based morphological investigations focusing on fresh-looking scarps show great advances in tectonic feature mapping, offering valuable insights into inaccessible subsurface endogenic processes in southeastern Tharsis.

How to cite: Pieterek, B., Brož, P., Hauber, E., and Karagoz, O.: Evidence for very recent tectonic activity in southern Tharsis, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-518, https://doi.org/10.5194/egusphere-egu25-518, 2025.

During the ESA funded 4D Dynamic Earth project, different sensitivity studies are performed to understand the applicability of current ground and satellite datasets available to study the dynamical behavior of the solid Earth, in particular the complete mantle. This project is a joint effort between ESA and many European universities and is lead by Delft University of Technology (https://4ddynamicearth.tudelft.nl/). 

The project consists of ten work packages, many of them relying on some form of forward geodynamical modelling. Given the diversity of participants multiple codes are used in the project: a 2D axisymmetric Python code developed by C.T. at the Utrecht University, a 3D Matlab code developed by O.O-G. and the 3D massively parallel C++ community code ASPECT.

One recurring quantity that is of paramount importance for some work packages is dynamic topography, i.e. the outer surface expression to dynamic mantle flow. We have therefore designed a simple isothermal experiment of an anomalous sphere present in the mantle of a planet (the core is ignored as is customary in whole-Earth geodynamic modelling). The sphere itself can be positively or negatively buoyant, and the mantle can be isoviscous or characterized by a radial viscosity profile. Boundary conditions at the core-mantle boundary and at the surface are either no-slip or free-slip. 

Dynamic topography calculations involve the radial stress which is derived from the primitive variables velocity (actually, its gradient) and pressure which are found to be sensitive to mesh size in both radial and lateral directions. We therefore report on the root mean square velocity, the surface strain rate, stress and dynamic topography and the gravity anomaly for a range of experiments. Our objective is two-fold: characterize the accuracy of our codes and provide the community with a benchmark. 

All three codes are Finite Element codes and all rely on the Taylor-Hood element but they are also quite different with respect to meshing and solver architecture. Nevertheless we find that all measured quantities converge within approx. 1% for radial resolutions of at least 30km.

How to cite: Thieulot, C., Ortega-Gelabert, O., Root, B., and Conrad, C.: Benchmarking dynamic topography across geodynamical codes, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-8998, https://doi.org/10.5194/egusphere-egu25-8998, 2025.

Observations of several short-period rocky exoplanets (e.g., LHS 3844 b, TRAPPIST-1 b, GJ 367 b) suggest that they do no host substantial secondary atmospheres, which makes their surfaces directly accessible to spectral characterisation. Various minerals and rock types have potentially distinguishable surface reflectance spectra, allowing for observational characterisation of surface geology for such atmosphere-less exoplanets. While extensive surface spectra for Solar System lithologies are available, they may not capture the full range of surface diversity, as rocky exoplanets display a bulk compositional diversity far exceeding that seen in the Solar System. To address this gap, we explore potential surface mineralogies of volatile-free rocky exoplanets, with compositional diversity informed by stellar abundances.
 
We model magma compositions formed from bulk mantle melting in the NCFMASCr system with a Gibbs free energy minimization algorithm, Perple_X. Bulk mantle compositions are systematically varied in terms of relative abundances of Mg, Si, Ca, Al, and Na, informed by stellar abundances, while keeping Fe and Cr constant and equal to the Earth bulk mantle. We then use the same modelling set-up to derive crustal mineralogy for bulk crust compositions based on these magmas. 
 
Surface mineralogy primarily varies with the bulk mantle Mg/Si ratio: Si-rich mantles produce quartz- and plagioclase-dominated crusts, intermediate planets produce pyroxene- and plagioclase-dominated crusts, and Mg-rich planets produce crusts consisting of olivine, spinel, and nepheline. Increasing the abundances of Ca, Al, and Na mainly results in a widening of the clinopyroxene, spinel, and nepheline stability fields. The crusts of Mg-rich planets are experimentally under-explored, while we predict a significant fraction of all rocky exoplanets to form such crusts. Thus, additional surface reflectance spectra measurements are required to fully cover the diversity of potential rocky exoplanet surfaces and to enable accurate interpretation of future observations of their surface geology.

We further show with geodynamical simulations that the high-pressure density contrast between crustal and mantle rocks plays a first-order role in thermal and dynamical evolution of rocky exoplanet interiors. Planets with a greater density contrast tend to stabilize a layered mantle structure, where subducted crust accumulates at the bottom of the mantle, overlain by a cold, depleted, and typically ultramafic upper mantle. Calculating the density contrast between crust and mantle rocks for our sample of exoplanet compositions at a pressure of 140 GPa, we find that most Mg-rich planets form crusts that are significantly denser than the residual mantle, forming such a double-layered mantle structure. Meanwhile, the most Si-rich mantles produce granite-like crusts, which we predict to be too buoyant to subduct. Only planets with intermediate Mg/Si, which includes the solar system planets, have crustal buoyancy that allows for subduction and mixing of subducted crust with the mantle on geological timescales. Thus, constraining rocky exoplanet crust mineralogy and density is essential for understanding their long-term evolution and for interpreting spectroscopic observations of such planets, which is possible with JWST.

How to cite: Spaargaren, R., Manjon Cabeza Cordoba, A., Ballmer, M., and Lichtenberg, T.: Modelling surface mineral diversity of atmosphere-free rocky exoplanets for spectroscopic characterisation, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-18054, https://doi.org/10.5194/egusphere-egu25-18054, 2025.

Three-dimensional (3D) mapping of planetary surfaces is critical for exploration missions and scientific research (Gwinner et al., 2016). Previous research mainly focused on employing rigorous techniques such as photogrammetry and photoclinometry to generate topographic products such as digital elevation models (DEMs). While the integration of these two techniques can yield detailed and precise topographic data, photoclinometric algorithms are heavily dependent on radiometric data and surface reflectance behaviors (Chen, Hu, et al., 2024; Liu and Wu, 2023), which limits their use in different circumstances. This paper undertakes a new endeavor to explore the potential of the emerging 3D Gaussian splatting techniques for a detailed reconstruction of planetary surfaces from orbiter images.

Gaussian Splatting has demonstrated outstanding performance in 3D applications for close-range scenes and has recently attracted significant attention. The primary challenge in utilizing 3D Gaussian Splatting for the reconstruction of planetary surfaces from orbiter images lies in the complexity of the planetary push-broom camera models. The sophisticated camera model and projection algorithm complicate this optimization approach. To address this, a two-step approach is proposed to transform the planetary push-broom images into frame-like images. First, photogrammetry is applied to push-broom images to extract precise 3D topography, which is then textured using the corresponding textures from the orthoimages. From the textured 3D landscape, frame images are rendered with careful consideration of overlapping and lighting conditions to better support 3D reconstruction tasks. For surface reconstruction, the 2D Gaussian splatting method (Chen., Li., et al., 2024) is selected and implemented in a coarse-to-fine manner, incorporating a smoothness loss to ensure its suitability for textureless planetary surfaces. In addition to utilizing information from the images, the algorithm also takes into account the camera geometry derived from the previous two steps for improved 3D surface reconstruction.

Experiment analysis is conducted using HiRISE images covering the Jezero crater on Mars. The photogrammetric DEM is generated at a resolution of 1 meter per pixel, and the original images are rectified and mosaicked at their native resolution of 0.25 meters per pixel. A total of 421 frame images are rendered, ensuring high overlapping (e.g., one point appears in eight rendered images) coverages. Compared to the photogrammetric DEM, the DEM generated by 3D Gaussian splatting reveals more subtle topographic details and maintains geometric accuracy.

Reference

Chen, D., Li, H., Ye, W., Wang, Y., et al., 2024. PGSR: Planar-based Gaussian Splatting for Efficient and High-Fidelity Surface Reconstruction. arXiv preprint arXiv:2406.06521.

Chen, H., Hu, X., Willner, K., Ye, Z., et al., 2024. Neural implicit shape modeling for small planetary bodies from multi-view images using a mask-based classification sampling strategy. ISPRS Journal of Photogrammetry and Remote Sensing 212, pp. 122-145.

Liu, W.C., Wu, B., 2023. Atmosphere-aware photoclinometry for pixel-wise 3D topographic mapping of Mars. ISPRS Journal of Photogrammetry and Remote Sensing 204, pp. 237-256.

Gwinner, K., Jaumann, R., Hauber, E., Hoffmann, et al., 2016. The High Resolution Stereo Camera (HRSC) of Mars Express and its approach to science analysis and mapping for Mars and its satellites. Planetary and Space Science 126, pp. 93-138.

How to cite: Li, Z., Wu, B., and Chen, S.: 3D Gaussian Splatting for Detailed Reconstruction of Planetary Surfaces from Orbiter Images, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-2216, https://doi.org/10.5194/egusphere-egu25-2216, 2025.

In orbit since the April 2018, the Colour and Stereo Surface Imaging System (CaSSIS) on board of the ExoMars Trace Gas Orbiter (TGO) has recently entered its 6th year of scientific phase. Since then, CaSSIS has provided us with a rich catalog of up to four bands stereo images of the Martian surface. The stereo capability is achieved through an innovative telescope rotation approach composing a convergence angle of almost 22 degrees between the stereo couple. In this way CaSSIS can produce detailed color 3D maps, thus providing crucial data for the analysis of the surfaces and their composition.

The pipeline for three-dimensional modelling is developed and maintained by the INAF team located at the Astronomical Observatory of Padova, making available the Digital Terrain Models (DTMs) and orthorectified images to the entire team and scientific community since the start of the mission.

The 3DPD software (Simioni et al., 2021; Re et al., 2022), at the core of the pipeline, allows the exploitation of data according to the principles of stereogrammetry. The DTMs are produced at 13.5 m ground sample distance from 4.5 m/px images, with an estimated vertical accuracy below 3 pixels size (15 m)  (Fig.1).

To date, more than 2100 stereo couples are available on a total of 40.000 images acquired. Of these about 400 stereo pairs have already been processed and available for download at  the OAPD-hosted repository (https://cassis.oapd.inaf.it/archive/).

Since the framework was first founded by Simioni et al., 2021, the pipeline has been continuously developing to improve the performance of the data product generation.

The goal of this work is to present the actual state of the framework and all the improvements made. Recent changes are here described and supported by an assessment of the quality and precision of the generated products and their derivatives.

Recent developments include the integration of the Bundle Block Adjustment, employing the jigsaw routines made available with the USGS ISIS platform (Laura et al., 2023). Thanks to the jigsaw output, we are able to refine the projection matrices affected otherwise by distortions that introduce geometric effects of misalignments between the acquisitions. The misalignments not adequately modelled and resolved by the Bundle Adjustment could otherwise result in steps artefacts that can reach even hundreds of m in the worst cases.

Further important update is given by an innovative approach of aligning DTMs to MOLA-HRSC (Fergason et al., 2018), further improving the surface projection and the absolute elevation, reaching values generally below 50 m/px of standard deviation in comparison with it. This process was also extended to the entire database of DTMs already produced as one major update, bringing similar results (Fig.2).

Fig.1 Comparison between a CaSSIS DTM (MY34_003673_018) and a HiRISE DTM (DTEEC_005533_1975_005388_1975) at 1 m/px, demonstrating a vertical accuracy of about 8m.

Fig.2 The standard deviation on the vertical accuracy, achieved as a result of the recent alignment with the MOLA-HRSC and applied to the entire CaSSIS DTMs database.

How to cite: Tullo, A., Re, C., Simioni, E., Bertoli, S., La Grassa, R., Cremonese, G., and Thomas, N.: Updates to the TGO-CaSSIS Stereo Products Generation and the INAF public catalog of DTMs, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-19966, https://doi.org/10.5194/egusphere-egu25-19966, 2025.

Lunar cold spots are thermal anomalies associated with fresh impact craters and understanding them offers critical insights into the Moon's surface evolution and thermophysical properties. Traditionally, their detection has relied on manual methods, which are labor-intensive and time-consuming. This study evaluates the performance of two advanced deep learning-based object detection models, YOLOv8 and YOLOv11, for automating lunar cold spot detection using Diviner radiometer data. The training dataset was generated from 128-pixel-per-degree (ppd) rock-free nighttime regolith temperature maps covering latitudes up to ±60°. The dataset included 384 lunar images with 652 annotated cold spots for model training. For testing, the 2023 High-Resolution Nighttime Temperature dataset was cropped into 512×512-pixel sub-images (~4×4 degrees) with a 20% overlap to capture edge cold spots. This process generated 4,816 sub-images, ensuring comprehensive coverage and minimizing missed detections.

The experimental design included two strategies: a straightforward train-test split and a more robust 5-fold cross-validation approach. The models were assessed using key performance metrics: precision, recall, F1 score, and mean Average Precision (mAP). YOLOv11 consistently outperformed YOLOv8 across most metrics, achieving a precision of 0.85, recall of 0.78, F1 score of 0.81, and mAP-50 of 0.79 with K-fold cross-validation. Both models demonstrated superior performance in detecting faint thermal anomalies, showcasing their capability to identify subtle features often overlooked by manual methods.

Hyperparameter tuning and robust preprocessing techniques, including overlapping sub-image and data augmentation, contributed significantly to the models' performance. YOLOv11's higher selectivity resulted in fewer false positives and greater reliability, whereas YOLOv8 identified a larger number of cold spots, though with a higher false positive rate. Both models significantly outperformed manual detection methods, demonstrating their ability to expand the catalog of lunar cold spots efficiently and accurately with precision of 78% and 89% for YOLOv8 and Yolov11, respectively. This automated approach identified previously undetected cold spots, providing a more comprehensive understanding of lunar thermal anomalies and their spatial distribution.

These findings highlight the transformative potential of convolutional neural networks (CNNs) in planetary science, particularly in automating complex and data-intensive tasks like lunar cold spot detection. The scalability and precision of YOLOv11, combined with YOLOv8's sensitivity to faint anomalies, underscore the value of integrating deep learning techniques into planetary exploration and research.

How to cite: Weil Zattelman, S. and Kizel, F.: COMPARATIVE ANALYSIS OF YOLOv8 AND YOLOv11 FOR COLD SPOT DETECTION ON THE LUNAR SURFACE, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12535, https://doi.org/10.5194/egusphere-egu25-12535, 2025.

The island of Lanzarote (Canary Islands) is widely recognized as a terrestrial analog for planetary science due to its geological and environmental characteristics. This island hosts numerous lava tubes, including the 7.6-km-long La Corona tube, one of Earth’s largest. Detecting lava tubes and other subsurface cavities is crucial for planetary exploration, as they may be used as safe shelters in future planetary missions. 

Magnetic data, including scalar and vector magnetometer data as well as magnetic susceptibility measurements, were collected during the NASA Goddard GeoLife expedition in May 2023 to study three lava tubes of different morphometry, age, and geological features: La Corona, Los Naturalistas, and Tahiche. This study focuses on analyzing vector magnetometer measurements over La Corona tube. We rotate and process the vector magnetic measurements to derive magnetic anomalies of both the total magnetic field and the individual vector components. To identify, delineate, and characterize the lava tube, we apply various enhancement techniques such as calculating the reduction to the pole or the lateral derivatives.

Our findings reveal the feasibility of using vector magnetometer data to detect lava tubes. Additionally, we show that our magnetic anomaly values derived from vector magnetometer data are comparable to those obtained from scalar magnetometer data. Lastly, we illustrate that we can extract valuable information from each of the vector magnetic field components and use them together with the total field values to identify and interpret magnetic subsurface features.

How to cite: Martin de Blas, J., Martos, Y. M., Espley, J., Richardson, J., Sheppard, D., and Connerney, J.: Magnetic signature of La Corona lava tube (Lanzarote, Canary Islands) as a planetary analog, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-6513, https://doi.org/10.5194/egusphere-egu25-6513, 2025.

Hydromagmatic eruptions are of particular importance for the search of extraterrestrial life since they require the presence of water. Phreatomagmatic volcanoes on Mars shall resemble those of the Earth and thus, terrestrial analogues of Mars, such as Lanzarote in the Canary Islands, are a good reference for further studies of the Martian volcanoes.

In this study we present our drone-based magnetic survey results combined with a morphometric analysis of Caldereta horse-shoe shaped volcano in Lanzarote, catalogued as a phreatomagmatic tuff for its similarity and proximity to Caldera Blanca, a well-known hydromagmatic edifice (Barrera Morate et al., 2011; Carracedo and Day, 2002; Romero et al., 2007; Kervyn et al., 2012; Brož and Hauber, 2013). On Mars, the chosen edifice is C27 volcano, a horse-shoe shaped cone in the Nephentes/Amenthes region, whose pitted cones were suggested to be of phreatomagmatic origin by Brož and Hauber (2013).

Our morphometric analyses allowed us to classify both Caldereta and C27 edifices as tuff rings, specifically maars. With the drone-based survey performed in Caldereta we demonstrate how more insights could be gained from Martian volcanos when combining magnetic surveys using helicopters on Mars (Mittelholz et al., 2023) with morphometric analyses using satellite data and high-resolution near surface geophysical studies.

Keywords

Magnetometry, Mars, planetary magnetism, crustal magnetism, Mars hydromagmatism, planetary science, space magnetometers.

References:

Barrera Morate J.L., García Moral R., 2011. Mapa geológico de Canarias. GRAFCAN.  https://www.idecanarias.es/resources/GEOLOGICO/LZ_LITO_unidades_geologicas.pdf

Brož, P., Hauber, E., 2013. Hydrovolcanic tuff rings and cones as indicators for phreatomagmatic explosive eruptions on Mars. J. of Geophys. Res.: Planets 118, 1656–1675. doi: 10.1002/jgre.20120.

Carracedo, J.C., Day, S., 2002. Canary Islands, in: Classic Geology in Europe Series 4. Terra Publishing, Harpenden, Hertfordshire, p. 294.

Kervyn, M., Ernst, G.G.J., Carracedo, J.C., Jacobs, P., 2012. Geomorphometric variability of “monogenetic” volcanic cones: Evidence from Mauna Kea, Lanzarote and experimental cones. J. Geomorphol. 136, 59-75. https://doi.org/10.1016/j.geomorph.2011.04.009

Mittelholz, A., Heagy, L., Johnson, C. L., Fraeman, A. A., Langlais, B., Lillis, R. J., and Rapin, W.: Helicopter Magnetic Field Surveys for Future Mars Missions, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-11186, https://doi.org/10.5194/egusphere-egu23-11186, 2023.Romero, C., Dóniz, J., García Cacho, L., Guillén, C., Coello, E., 2007. Nuevas evidencias acerca del origen hidromagmático del conjunto volcánico Caldera Blanca/Risco Quebrado (Lanzarote, Islas Canarias). Resúmenes XII Reunión Nacional de Cuaternario, Ávila.

How to cite: Díaz-Michelena, M., Losantos, E., Rivero, M. Á., Oliveira, J. S., García Monasterio1, Ó., Mansilla, F., Melguizo, Á., García Bueno, J. L., Salamanca, D., and Fernández Romero, S.: Geophysical investigation of the terrestrial analogue, Caldereta volcano, in Lanzarote, the Canary Islands as a precursory study to mars phreatomagmatic volcanoes, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-10842, https://doi.org/10.5194/egusphere-egu25-10842, 2025.

Extensive physical and chemical evidence from orbiter, lander, and rover data show that surface water was widespread on Mars into the Amazonian. Alluvial fans are geologic landforms on Mars that preserve evidence of this late-stage aqueous activity in the geologic record. The composition and distribution materials in an alluvial fan, either in the catchment (source) and/or the fan (sink), help inform our understanding of the origin and extent of aqueous alteration, either in the source rocks prior to deposition or after, in the fan itself. However, the geochemical and mineralogical properties of martian alluvial fans, and how these properties vary from the catchment to the fan, are not well constrained. 

The work presented here characterizes the geochemistry and mineralogy of two alluvial fans and their associated catchments at sites in Iceland—Fjallabak and near Hoffellsjökull—which serve as close compositional analogs for Mars. These results can help us to understand the aqueous alteration that formed similar deposits on Mars while placing constraints on martian geologic history and paleoclimate.

We utilize a suite of complementary laboratory techniques: Raman spectroscopy, scanning electron microscopy with an energy dispersive X-ray detector (SEM/EDS), and X-ray diffraction (XRD). Raman spectroscopy qualitatively maps spectral properties to confirm existing mineral identification and spectra are processed to determine the relative abundance materials; this technique is of particular use to identify amorphous glass. SEM/EDS is used to quantitatively map elemental compositions, and XRD with Rietveld refinement can identify the type and abundance of crystalline minerals. Raman and XRD both have in situ instrument analogs on the surface of Mars: the Scanning Habitable Environments with Raman and Luminescence for Organics and Chemicals (SHERLOC) on the Perseverance rover, and Chemistry and Mineralogy (CheMin) instrument on the Curiosity rover, respectively. SEM/EDS techniques are also likely to be applied to samples returned from Mars.

At Fjallabak, source rocks are primarily a combination of hyaloclastite (a product of subglacial volcanism) and rhyolite. At Hoffellsjökull, the rocks are mostly basalt with evidence of minor hydrothermal alteration. Rocks and sediments do not appear to be heavily altered upon deposition into the alluvial fan, although some authigenic alteration may have occurred in the catchment itself.

Preliminary Raman spectral analyses support our initial field interpretations of the rocks and minerals observed at both field sites. To date, we have analyzed hyaloclastite source rocks and confirmed the presence of obsidian and/or albite glass, along with signs of aqueous alteration indicated by Fe-oxides (i.e., goethite) at Fjallabak. We have also identified diopside (Ca-Mg clinopyroxene) and actinolite (a low-grade metamorphic mineral) in inferred hydrothermally altered basalt, along possible Fe-oxide-hydroxides (i.e., lepidocrocite) that indicate aqueous alteration in the Hoffellsjökull fan. Initial results suggest aqueous alteration of materials at both field sites but the distribution of primary versus secondary materials has yet to be constrained. 

Our results will include the laboratory analysis that characterize these Iceland fans that will help determine the extent and distribution of alteration products in alluvial fans at Mars compositional analog sites.

How to cite: Rudolph, A., Haber, J., Wilson, S., Irwin, R., Morgan, A., Horgan, B., Rose, T., and Wardell, R.: Geochemical and Mineralogical Signatures of Alluvial Fans in Iceland and their Implications for Late Stage Aqueous Activity on Mars, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-13284, https://doi.org/10.5194/egusphere-egu25-13284, 2025.

Fan-shaped deposits, including alluvial fans and deltas, are abundant on Mars. They preserve evidence of episodic running water and potentially habitable environments into the early Amazonian. Most alluvial fan analog studies have focused on depositional processes, rather than the composition of fan materials. In particular, it is unclear if the composition of fan deposits represents alteration during transport/deposition or the composition of the watershed in a cold environment.

In this study, we use a suite of remote sensing techniques to characterize mineralogy of rocks and sediments in alluvial fans in Iceland to understand any distinct trends within this tundra climate. This work helps fill a knowledge gap for understanding alluvial fans on Mars through the novel analog study in a cold climate on Earth. Iceland has been widely studied as a Mars analog because of its dominant basaltic composition, general lack of vegetation, and tundra climate. We analyze several alluvial fans of variable morphology, location, and composition to understand how these factors might affect the alteration of fan sediments.

Prior to fieldwork, we analyzed high-resolution orbital images (15 m/pixel) from the World Imagery ESRI Basemap and spectral data (10-60 m/pixel) from the SENTINEL-2 MultiSpectral Instrument in the visible to near infrared (VNIR) range (13 bands; 0.443-2.190 μm) to characterize decameter-scale compositional variability. 

During our July 2024 field season, we imaged fans and their watersheds using a DJI Mavic Pro 2 drone at the meter- to decameter-scale. We used a portable ASD QualitySpec Trek spectrometer to collect VNIR (0.35-2.5 μm) reflectance spectra and identify minerals along transects from the fan apex to toe to capture compositional variability in the fan deposits and their watersheds.

Our results focus on two alluvial fans and their watersheds: one dominated by rhyolite and hyaloclastite in Fjallabak Nature Reserve in the Icelandic highlands and another dominated by basalt near Hoffellsjökull in eastern Iceland. In VNIR spectra from Fjallbak, we observe absorption bands due to hydration (1.4 and 1.9 μm), Fe-oxides (0.53 and ~0.9 μm), and hydrated silica (2.2 μm). At Hoffellsjökull, we also observe kaolinite (2.2 μm doublet) in tan rocks and calcite (2.338 μm) in veins and vesicles within basalt. We also observe broad absorptions near 1 and 2 μm likely due to primary mafic minerals such as olivine, pyroxene, or volcanic glass.

Our results indicate that rocks in the alluvial fans were sourced from a variety of lithologies, which we are able to identify in the watershed using drone and orbiter images. Overall, we do not observe major differences in composition between the fan deposits and their watersheds, suggesting that there is minimal alteration during transport and deposition. Ongoing work includes detailed spectral analyses of sediments along fan transects and comparisons to the watershed to determine how the rocks and sediments vary across the fan deposit. Additionally, comparisons to similar alluvial fans on Mars will improve our understanding of how these features may have formed in a cold climate.

How to cite: Haber, J., Rudolph, A., Irwin, R., Morgan, A., Horgan, B., and Wilson, S.: Using Remote Sensing to Understand Icelandic Alluvial Fan Composition as an Analog for a Cold and Wet Ancient Mars, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-13316, https://doi.org/10.5194/egusphere-egu25-13316, 2025.