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The central sector of the Carnic Alps spans the border between Austria and Italy and consists of a succession ranging from the Upper Ordovician to the lowermost part of the upper Carboniferous that has been recently revised in order to formalize the stratigraphic units. Although this area was mapped both on the Austrian and Italian side, the presence of different units with different stratigraphic boundaries prevented from a complete representation of the stratigraphic relationships and the lateral geometrical variability within the basin. We focused mainly on the Devonian ‘transitional facies’ that indirectly reflect the establishment and the demise of a platform. The basin shows a transition from a ramp-type to a rimmed shelf- type profile that occurred between the upper part of the Pragian to the lower Emsian that is constrained by the increasing abundance of reef-derived gravity-driven rudstone deposits. The platform system reached its maximum expansion around the end of the Eifelian and the beginning of the Givetian when the largest debris deposits have been shown to accumulate. Although less productive, the platform system appears to persist until roughly the lower part of the upper Frasnian when the rudstone deposits become depleted of platform- derived clasts and interbedded with microbial limestone. This evolution might have been caused by a sea-level drop event.

Astrobiology is an interdisciplinary science involving many different sources, and disciplines including geology. Biosignature identification on Earth is consequential and strictly linked with the definition of a solid geological context in order to recognize the present and past processes, environments, controls, and their potential to host life. In planetary settings, that can be studied only (or mostly) remotely, the comparative geological analysis with Earth potential analogue is essential. Despite that, the importance of geology is often understated. We stress the importance of geological analyses in association and support of astrobiological investigations in the selection, understanding, and analyses of the study areas and in bridging the gap between the different observation scales on Earth and planets, also in the process of mission planning of remote and in situ missions. Effective comparative studies are possible because of data acquired in the last decades on many planetary surfaces that allow Earth-like field geological investigations: this is especially true on Mars but increasingly important in all of the other planetary bodies, including the icy satellites. In order for a mission to be effective, as an example, the collected samples must be representative of a larger body and reflect some specific feature of variation of it. This implies that the sample representativity is largely dependent on the accuracy of the geological observations that precede sampling. In particular, planning a sampling mission aimed at testing the astrobiological potential of a given target on a planetary surface, is based on the understanding of where to focus (depositional environment), which tools are needed (instruments), and finally to set the precise place where to sample within the selected environment with the ultimate goal to collect a significant sample and not just a stone. Accordingly, the knowledge derived from Earth analogues represents the base to plan the exploration of planetary settings, in order to on one side select the right science target to look for fossil or present life traces and on the other side to test the proper techniques, that should be effective and at the same time low invasive/destructive to be suitable for planetary exploration. Protocols for the sampling (i.e., collection, preservation, and treatment) and for the data analyses (i.e., facies analysis, instruments, combination of instruments) phases are needed both in the field and in the laboratory in order to identify the presence of biosignatures. Still, biosignatures in the rock record include many different organic or organically mediated structures and biochemical signals, which occurrence and evolution are controlled by the specific geological conditions. As a consequence, different types of biosignatures depend on different geological conditions and consequently necessitate different analytical approaches (e.g., Cavalazzi et al., 2019). In turn, this implies that different protocols depend on different geological conditions. Several problems may hamper the possibility to constrain the analogy between Earth and planetary settings, the main issues being the problems of scale and of equifinality (Baker, 2014). The regional analyses to constrain the geological context on Earth and in the planetary settings occur at similar scales, but the scales of the observations and measurements even in the most favorable condition on Mars cannot exceed the meter scale, while on Earth even singe grains or crystals can be recognized and described already in the field. In addition to that, the problem of equifinality arises from similar effects that may be generated by different combinations of causative processes (Baker, 2014), which implies that single morphologies (landforms) can be rarely unequivocally interpreted from remote sensing analysis in terms of genetic origin. To face these issues, the reconstruction of a broader geological context (landscape) is necessary as a pre-requisite to understand environments and processes of deposition (e.g., Pondrelli et al., 2008, 2011, 2015, 2019). Unraveling the vertical and lateral stratigraphic relations in order to correlate different coeval deposits, landforms, and structures, and comparing similarities and differences at all scales with different potential analogues on Earth, using the typical multiple working hypothesis approach (Baker, 2014), allows solid interpretations. A solid reconstruction of the geological context must be carried out comparatively also on the potential Earth analogues. On Earth, the depositional environments and processes can be characterized, defining the facies, facies association, lateral transitions, and structure distribution at the outcrop scale, specifically the ones that are suitable for sampling and laboratory analyses, and ultimately understanding the controls on deposition (e.g.., Cavalazzi et al., 2019). This set of information provides fundamental elements to reconstruct the vertical and lateral facies/structures distribution in an analogue planetary setting (e.g., Pondrelli et al., 2008, 2011, 2015, 2019) and drives the sampling site selection but also the choice of more appropriate instrumentation. This approach can provide not only a basic knowledge of the landing site/mission object area but is mandatory for a sample return mission and the selection of the right samples one can take a rock home, but not an outcrop. Thus, context geology is the first requirement to understand where the most significant sampling should be taken. References Baker, V. R. (2014). Terrestrial analogs, planetary geology, and the nature of geological reasoning. Planetary and Space Science, 95, 5–10. Cavalazzi, B., Barbieri, R., Gómez, F., Capaccioni, B., Olsson-Francis, K., Pondrelli, M., et al. (2019). The Dallol Geothermal Area, Northern Afar (Ethiopia)-An Exceptional Planetary Field Analog on Earth. Astrobiology, 19(4), 553–578. Pondrelli, M., Rossi, A., Marinangeli, L., Hauber, E., Gwinner, K., Baliva, A., & Lorenzo, S. (2008). Evolution and depositional environments of the Eberswalde fan delta, Mars. Icarus, 197(2), 429–451. Pondrelli, M., Rossi, A., Platz, T., Ivanov, A., Marinangeli, L., & Baliva, A. (2011). Geological, geomorphological, facies and allostratigraphic maps of the Eberswalde fan delta, Planetary and Space Science, 59(11–12). Pondrelli, M., Rossi, A. P., Deit, L. L., Gasselt, S. van, Fueten, F., Glamoclija, M., et al. (2015). Equatorial layered deposits in Arabia Terra, Mars: Facies and process variability. Geological Society of America Bulletin, 127(7/8). Pondrelli, M., Rossi, A., Deit, L. L., Schmidt, G., Pozzobon, R., Hauber, E., & Salese, F. (2019). Groundwater Control and Process Variability on the Equatorial Layered Deposits of Kotido Crater, Mars. Journal of Geophysical Research: Planets. https://doi.org/10.1029/2018JE005656

Introduction: Chaotic terrains on the icy moon Europa are among the youngest surface features within the satellite’s visible geological history [1]. These regions appear as highly disrupted surfaces formed by irregular groups of isolated plates surrounded by a lumpy matrix material [2]. They are often covered in a reddish-brown material that is interpreted to consist of hydrated sulfates [3] or sulfuric acid hydrate [4]. Current models of chaos formation include a melt-through of the surface provoked by an internal heat source (i.e. a hydrothermal plume) [5], or the mobilization of brines trapped near the surface, in response to partial melting of the outer shell induced by icy diapirs rising through the crust [6]. We investigated two chaotic terrains named Thrace Macula and Thera Macula, both located on the southern hemisphere of Europa. Among the hypotheses proposed to explain their origin are the upwarping of the surface followed by an extrusion of low-viscosity liquids [7, 8], the collapse of large-scale domes [9], or interactions between the ice and shallow subsurface water lenses [10]. Here we provide a geomorphological and stratigraphic analysis of Thrace and Thera Macula, derived from an extensive geological mapping based on the highest-resolution images of the area acquired throughout the Galileo space mission. We also provide preliminary results of a topographic analysis performed on photoclinometric DEMs obtained using Ames Stereo Pipeline [11, 12]. Results: The mapped area includes plains dominated by ridge complexes, bands, linear features (double ridges, troughs), craters (for less than 1%), and chaotic terrains (Fig. 1). Local displacements of band margins and double ridges suggest the occurrence of crustal movements along tectonic faults. Thera Macula is characterized by a distinctive dichotomy between its northern, partly fractured icy plain, and the southern complex of low-albedo chaotic terrains. The margins of the macula, particularly to the north, appear heavily fractured and forming a complex of steep scarps faced towards the macula, with elevations ranging from -30 to -390 m (Fig. 2). The southern lobe is the only one displaying a positive relief up to 360 m in height. The dark, chaotic terrain consists for 85% of matrix material, and for 15% of large plates that show signs of displacement. On average, plates rise up to 320 m from the surrounding matrix, and some can exceed 700 m in height. Apparently, the matrix has replaced a pre-existing terrain which underwent a strong degradation process. Thrace Macula exhibits a larger proportion of matrix material, which makes up to 98% of the macula’s surface, while the remaining 2% is composed of blocks. The latter are represented either by large plates not completely detached from the margins (only identified in the northern sector), or by small sub-kilometer, often tilted blocks found in the center of the macula. In contrast to Thera, the boundaries are not marked by steep scarps, and the matrix looks domed up above the surrounding plain. The macula’s northern and central sectors are separated by a bright, roughly linear stripe that could be an intersecting double ridge postdating the formation of the macula. The high-resolution images of the southern lobe show the presence of a higher-albedo matrix, where any pre-existing structure is no longer recognizable, and a lower-albedo matrix, where the pre-existing features are still preserved and appear mostly unaltered. Discussion: Geological mapping has revealed that around the “non-chaotic” plains are structures intersected by linear features (troughs, double ridges, bands), that appear displaced along two opposite directions. A graphic reconstruction of the original placement of surface units has confirmed that lateral and extensional motion of the icy crust has occurred at some point during Europa’s geological history, generating linear displacements up to 7.50 km in length. Furthermore, the morphology and the orientation of the plates surrounded by the chaotic matrix in Thera Macula indicates they must have undergone shifting, rotation and tilting upon their formation. A reconstruction of the original placement of 17 plates has confirmed that 47% of them have undergone horizontal translation, moving between 0.7 and 9.2 km (Fig. 3). Also, 30% of the plates have rotated by an average of 10.6°, either clockwise or counterclockwise, whereas motion of the plates has prevalently occurred from the inward-facing scarps towards the innermost areas. Finally, we inferred the relative age of the two maculae and the variety of geological features that comprise the surrounding plains by performing a detailed analysis of cross cutting relationships. The resulting stratigraphic column (Fig. 4) can be summarized in a four-stage sequence of events: 1) Formation of plains, including ridge complexes and smooth plains; 2) Formation of bright bands and isolated double ridges; 3) Formation of dark bands and additional linear features; 4) Formation of impact craters and chaos regions, with Thrace Macula possibly having formed earlier than Thera. Acknowledgments: GM acknowledges support from the Italian Space Agency (2018-25-HH.0). References: [1] Prockter L. M. et al. (1999), JGR, 104, 16531-16540. [2] Collins G. and Nimmo F. (2009), in Europa, U. Arizona Press, 259-281. [3] Dalton J. et al. (2005), Icarus, 177, 472-490. [4] Carlson R. W. et al. (2002), Icarus, 157, 456-463. [5] Greenberg R. et al. (1999), Icarus, 141, 263–286. [6] Head J. W. and Pappalardo R. T. (1999), JGR, 104, 1999. [7] Fagents S. A. (2003), JGR, 108, 2003. [8] Miyamoto H. et al. (2005), Icarus, 177, 413-424. [9] Mével L. and Mercier E. (2007), PSS, 55, 915-927. [10] Schmidt B. et al. (2011), Nature, 479, 502–505. [11] Beyer R. et al. (2018), Earth Space Sci, 5. [12] Lesage E. et al. (2021), Icarus, 361, 114373.

The Rio Malinfier West section in the central Carnic Alps provides important data on the evolution of the Lochkovian (Lower Devonian) sedimentary basins of the Variscan belt. An exposure of about 100 m documents five lithostratigraphic units (Alticola, Rauchkofel, Nolbling, La Valute and Findenig formations) spanning in age from the latest Silurian to the Early Devonian. The complex structural setting of the section results from a main fault dividing the succession in two separate segments. A precise lithological characterization was carried on at a macro- and micro-scale. Macrofauna includes, among others, abundant cephalopods and crinoids (loboliths). The biostratigraphic assignment to the uppermost Silurian-lowermost Devonian (Lochkovian) was possible basing on a moderately abundant conodont fauna, that provided thirty-two taxa belonging to thirteen genera, among which the new species Zieglerodina schoenlaubi. The Rio Malinfier West section testifies that a differentiation between shallow and deep water parts of the Devonian basin was already present during Lochkovian times, prior to the establishment of the conditions enabling the colonization of the well-known upper Lower-Middle Devonian reef buildings.

Arabia Terra is a region of Mars where signs of past-water occurrence are recorded in several landforms. Broad and local scale geomorphological, compositional and hydrological analyses point towards pervasive fluid circulation through time. In this work we focus on mound fields located in the interior of three casters larger than 40 km (Firsoff, Kotido and unnamed crater 20 km to the east) and showing strong morphological and textural resemblance to terrestrial mud volcanoes and spring-related features. We infer that these landforms likely testify the presence of a pressurized fluid reservoir at depth and past fluid upwelling. We have performed morphometric analyses to characterize the mound morphologies and consequently retrieve an accurate automated mapping of the mounds within the craters for spatial distribution and fractal clustering analysis. The outcome of the fractal clustering yields information about the possible extent of the percolating fracture network at depth below the craters. We have been able to constrain the depth of the pressurized fluid reservoir between ∼2.5 and 3.2 km of depth and hence, we propose that mounds and mounds alignments are most likely associated to the presence of fissure ridges and fluid outflow. Their process of formation is genetically linked to the formation of large intra-crater bulges previously interpreted as large scale spring deposits. The overburden removal caused by the impact crater formation is the inferred triggering mechanism for fluid pressurization and upwelling, that through time led to the formation of the intra-crater bulges and, after compaction and sealing, to the widespread mound fields in their surroundings.

The Middle Devonian Epoch, ~ 393–383 million years ago, is known for a peak in diversity and highest latitudinal distribution of coral and stromatoporoid reefs. About 388 million years ago, during the late Eifelian and earliest Givetian, climax conditions were interrupted by the polyphased Kačák Episode, a short-lived period of marine dys-/anoxia associated with climate warming that lasted less than 500 kyr. Reconstruction of the seawater temperature contributes to a better understanding of the climate conditions marine biota were exposed to during the event interval. To date, conodont apatite-based paleotemperatures across the Eifelian–Givetian boundary interval have been published from Belarus, France, Germany and North America (10–36° S paleolatitude). Here we provide new δ18Oapatite data from the Carnic Alps (Austria, Italy) and the Prague Synform (Czech Republic). For better approximation of the paleotemperature record across the Kačák Episode, a latitude-dependent correction for Middle Devonian seawater δ18O is applied. Because δ18Oapatite data from shallow marine sections are influenced by regional salinity variations, calculated mean sea surface temperatures (SST) are restricted to more open marine settings (22–34° S paleolatitude). Water temperatures reach ~ 34 °C in the Prague Synform and ~ 33 °C in the Carnic Alps and suggest that SSTs of the southern hemisphere low latitudes were ~ 6 °C higher than previously assumed for this time interval.

The Pre-Variscan Sequence of the Carnic Alps is exposed across the state border between north-east Italy and Austria. It includes Middle Ordovician to lower Pennsylvanian rocks that, although affected by both Variscan and Alpine orogenesesorogeny, preserve continuous and non-metamorphosed successionssequences. Depositional settings vary from shallow water to open marine environments. Remarkable is the presence of the largest Devonian reefs of Europe, and related deposits from back reef to fore-reef and basin. The field trip is organized as a pre-congress excursion of the 90th congress of the Italian Geological Society (Trieste, September 2021) and includes three days to visit the main localities of the central sector of the Carnic Alps, focusing on various aspects of stratigraphy, palaeontology and tectonics of the sequence.

An extensive distribution of water-altered equatorial layered deposits (ELDs) characterizes the densely cratered terrain of Arabia Terra (AT), Mars. The majority of these deposits reside within craters and are easily identified by laterally continuous layering. The processes that led to their formation have been widely investigated, but remain unresolved. Furthermore, their precise spatial distribution as a whole, as well as their relationship to one another individually, has yet to be fully appreciated. This work examines 1,013 craters and emphasizes 45 that were observed to contain ELDs within the eastern half of AT. We present the statistical relationships between crater characteristics (e.g., location, diameter, depth), as well as evidence supporting a southeast-northwest facies change. The 30-2,000-m range of measured deposit thicknesses, accompanied with individual layer thicknesses, correlate with crater elevation either due to water level differences within craters, or a proximal-distal relationship to the source. Air fall or fluid expulsion appear to stand out among all the prevailing depositional hypotheses, however the volume required to fill these craters in an ash fall scenario is in opposition with the locations of known volcanic provinces and the volume of ash that volcanic eruptions produce. This new evidence of a regional facies change provides a unique opportunity to better understand past climate and sedimentary processes on Mars, as well as the putative groundwater level in ancient AT. Ultimately, our results do not agree well with a unified depositional method for these deposits and the possibility of mixed origins should be taken seriously.

The quantity, quality, and type of available datasets on Mars have improved in the last couple of decades. Context Camera (CTX) (Malin et al., 2007) on board the NASA Mars Reconnaissance Orbiter (MRO) provides a global coverage with an average resolution of 6 meters/pixel while the High Resolution Imaging Science Experiment (HiRISE) on board MRO (McEwen et al., 2007) allows up to 30 cm/pixel analyses at the local scale. These data allow at places also the DTM generation, but extensive topographic reconstructions at an average scale of 50 meters/pixel are possible using the High Resolution Stereo Camera (HRSC) on board of ESA Mars Express (MEX) (Neukum et al., 2004). Moreover compositional constraints can be provided by the spectral data coming from Observatoire pour la Minéralogie, l’Eau, les Glaces, et l’Activité (OMEGA) on board MEX and from Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) on board the NASA Mars Reconnaissance Orbiter (MRO) (Murchie et al., 2007). These relatively recent datasets coupled with the older datasets and Geographical Information Systems (GIS) provide an impressive suite of tools to develop meaningful planetary geological maps. In principle, these new data allow to add to the traditional geomorphological or chronostratigraphic mapping approaches, also a geological map approach somewhat akin to the one well-known on Earth, although, a ‘true’ geological map should be based on the lithological characters of the mapped units; using tone, texture, absence/presence of sedimentary structure, and, if possible, compositional hints to define the units, may represent an adequate ‘planetary perspective’, obviously in addition to the stratigraphic position within the succession. This map approach has the advantages to be relatively objective (and so potentially more useful for geological context analyses) and to represent the stratigraphic complexity within a region. This approach is complementary to the more interpretative (because it includes the processes/environments of formation of the different features) one of the geomorphological maps, which has the obvious advantage to describe the environments/processes active in the region. In the framework of the GMAP (Geologic MApping of Planetary bodies) project, we present here an attempt to merge these two cartographic products taking advantage of GIS-based tools. Moreover, we aim at testing, where possible, the Earth-born symbols designed for the Geological Map of Italy (ISPRA, 2009, 2018) to try to make the ‘language’ of geological maps as uniform as possible. In order to perform these analyses, we selected a series of putative fluvio-lacustrine landforms located in Holden crater, along the south-eastern inner rim (coordinates 26.9°S-33.5°W). The geological map allowed to distinguish several units separated by unconformities. In particular, the Impact unit, equivalent to the one recognized by Tanaka et al. (2014) is nonconformably covered by the materials located inside the crater and along the crater rim. These materials can be distinguished in two groups separated by a disconformity, the first characterized by a relatively large lateral extension of the units and the second by a scattered appearance of the units. Within the first group, a disconformity separates a lower part from the upper part of the succession. The geomorphological map allows to genetically interpret these units, defining: i) a first impact stage, correspondent to the emplacement of Holden crater, ii) a ‘water-related’ phase (correspondent to the lower group of the geological map), and iii) an aeolian phase made of mega-ripples and dunes (correspondent to the upper group of the geological map). The ‘water-related’ phase can be further divided in a fluvio-lacustrine and a glacial phase. We propose the realization of a unique geologic and geomorphologic product that includes a polygon layer with the geological units map described above, a linear layer with the unit contacts (i.e., stratigraphic characterization), and a linear shapefile with tectonic features and geomorphological interpretations. The polygonal units’ layer might be also suitable to subdivide the units in lower-order ranked units, using appropriate fields (i.e., formation/members on Earth). This approach might be best suited for projects developed at the local scale, similar to what is done on Earth, while a chronostratigraphic approach is more fitting and recommended at the regional and global scale. We will identify a possible set of graphical symbols describing the surface features, locating potential limits in current GIS symbology implementation. The GMAP project represents an opportunity to share our experience and to collect current practices in planetary and terrestrial geological and geomorphological mapping, identifying what elements are still lacking and need to be discussed or developed. References ISPRA (2009) - Carta Geologica d’Italia. Guida alla rappresentazione cartografica. Modifiche e integrazioni ai Quaderni 2/1996 e 6/1997. Roma, pp. 166 ISPRA (2018) - Carta Geomorfologica d’Italia. Guida alla rappresentazione cartografica. Modifiche e integrazioni al Quaderno 4/1994. Roma, pp. 95 Malin, M. C., J. F. Bell, B. A. Cantor, M. A. Caplinger, W. M. Calvin, T. R. Clancy, K. S. Edgett, L. Edwards, R. M. Haberle, and P. B. James (2007), Context camera investigation on board the Mars Reconnaissance Orbiter, Journal of Geophysical Research: Planets(1991–2012), 112(E5). McEwen, A. S., E. M. Eliason, J. W. Bergstrom, N. T. Bridges, C. J. Hansen, A. W. Delamere, J. A. Grant, V. C. Gulick, K. E. Herkenhoff, and L. Keszthelyi (2007), Mars reconnaissance orbiter’s high resolution imaging science experiment (HiRISE), Journal of Geophysical Research: Planets (1991–2012), 112(E5). Murchie, S. et al. (2009), Evidence for the origin of layered deposits in Candor Chasma, Mars, from mineral composition and hydrologic modeling, Journal of Geophysical Research: Planets, 114, E00D05, doi:10.1029/2009je003343. Neukum, G, R Jaumann, and H. the and Team (2004), HRSC—The High Resolution Stereo Camera of Mars Express, European Space Agency Special Publication, SP-1240, 17–35. Tanaka, K., J. Skinner, J. Dohm, R. Irwin, E. Kolb, C. Fortezzo, T. Platz, G. Michael, and T. Hare (2014), Geologic map of Mars, USGS Scientific Investigations Map 3292, doi:10.3133/sim3292.

In the Carnic Alps, located across the border between Italy and Austria, several sections span the Silurian/Devonian boundary in different sedimentary settings, from very shallow water to moderately deep shelf. All studied sections yielded conodonts and based on the first and last occurrences of the conodont taxa in the upper part of the Upper Oul. el. detortus Zone and in the lower part of the I. hesperius Zone a detailed conodont biostratigraphic framework was able to be constructed for this interval. Comparison of data from different depositional settings demonstrates that, although the majority of species are documented everywhere in the Carnic basin, a few taxa, mainly represented by coniforms, are limited to shallow water, whereas others, mainly ozarkodinids, occur only in open sea deposits.

Southern highlands of Mars have experienced regional to global scale deformations in the history of its evolution. Deformational structures originated from impact-induced stresses and later viscous relaxation of the impact basin to cooling related global contraction. Here in this study, we investigated an Early Hesperian (Eo-Archean / Paleo-Archean equivalent to the Earth) aged lobate scarp i.e., surface signature of thrust fault, possibly originated because of global contraction. We used ‘offset crater perimeter’ measurement technique using high-resolution data (both image and DTM) to execute most precise estimation of fault plane slope and length–displacement relationship. The derived range of fault plane slope is much narrower (21°–29°) than the previously cited 20° to 35° range. Displacement–length ratio (4.51 × 10−3) is also unique and lower than the previously evaluated values of lobate scarps from other region (mainly from dichotomy boundary) of Mars. The newly derived results from the morphometric analysis are due the differential stress pattern and the distinct basement rock rheology. Our results highlight the need for more high-resolution estimation of lobate scarps from several regions with the methodology employed in this study to better understand the global Martian early tectonic scenario.

Aeolis Dorsa is a topographic depression, ∼800 km east of Gale Crater, located along the Mars’ dichotomy boundary. This area hosts a set of fluvial sedimentary rocks displaying an exceptional record of depositional environments and fluvial channels patterns that suggest the presence of a large amount of surface and/or subsurface water. We interpreted the plain as an ancient waterlogged environment, a sedimentary basin passing into distal depositional environments. Regional mapping of the area revealed the presence of a large-scale fluvial system that points to a long-term and extensive hydrological cycle. A significant wet period with changing environmental conditions in Hesperian/Amazonian occurred in the study area diverging from the present-day climate. Our map (Main Map) contributes to the understanding of past climatic conditions on Mars. Moreover, it provides an interesting perspective for future missions looking for evidence of present-day and/or past extraterrestrial organisms as the life as we know it needs liquid water.

The polyphased Kacak Episode near the Eifelian-Givetian boundary (Middle Devonian), well documented globally, resembles other global biotic extinction events driven by climate change. High-resolution conodont biodiversity patterns from shallow marine, slope and pelagic bathymetric settings within the same basin from the Carnic Alps show that while conodonts experienced diversification during the latest Eifelian ensensis Biozone, assemblages suffered extinction during the early Givetian hemiansatus Biozone. Although a similar general pattern is observed in different bathymetric settings there is a changed taxonomic composition of conodont assemblages across the stage boundary. Based on microfacies analysis this change is contemporaneous with changes in palaeoenvironmental conditions in the earliest Givetian.

The Dallol volcano and its associated hydrothermal field are located in a remote area of the northern Danakil Depression in Ethiopia, a region only recently appraised after decades of inaccessibility due to severe political instability and the absence of infrastructure. The region is notable for hosting environments at the very edge of natural physical-chemical extremities. It is surrounded by a wide, hyperarid salt plain and is one of the hottest (average annual temperature Dallol : 36-38°C) and most acidic natural systems (pH Dallol ≈0) on Earth. Spectacular geomorphologies and mineral deposits produced by supersaturated hydrothermal waters and brines are the result of complex interactions between active and inactive hydrothermal alteration of the bedrock, sulfuric hot springs and pools, fumaroles and geysers, and recrystallization processes driven by hydrothermal waters, degassing, and rapid evaporation. The study of planetary field analog environments plays a crucial role in characterizing the physical and chemical boundaries within which life can exist on Earth and other planets. It is essential for the definition and assessment of the conditions of habitability on other planets, including the possibility for biosignature preservation and in situ testing of technologies for life detection. The Dallol area represents an excellent Mars analog environment given that the active volcanic environment, the associated diffuse hydrothermalism and hydrothermal alteration, and the vast acidic sulfate deposits are reminiscent of past hydrothermal activity on Mars. The work presented in this paper is an overview of the Dallol volcanic area and its hydrothermal field that integrates previous literature with observations and results obtained from field surveys and monitoring coupled with sample characterization. In so doing, we highlight its exceptional potential as a planetary field analog as well as a site for future astrobiological and exploration programs, This is a contribution to the Europlanet 2020 Research Infrastructure programme funded under the European Commission's Horizon 2020 programme (No. 654208

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An ultra-miniaturised (mass 1.5 kg; volume ~22 × 6 × 12 cm3) instrument which combines X-ray diffraction and fluorescence has been developed for the mineralogical and chemical characterization of Martian soils/rocks and was included in the ExoMars-Pasteur payload. The simultaneous in situ acquisition of elemental and mineralogical information would significantly improve any robotic missions and may unravel doubtful points regarding the mantle composition, crustal evolution and resource potential. The instrument employs a fixed reflection geometry to fulfil the diffraction principle which can be applied to unprepared sample as well. The instrument basically consists of a radioisotope as source of X-rays and a CCD-based detection system. This is the first successful diffraction experiment using a radioisotope since the early tests in the 60s. For terrestrial application the radioisotope can be easily replaced with a cathodic tube. The reduced dimension as well as the possibility to perform non-destructive analysis makes it suitable for terrestrial applications, particularly in the archaeometry field. We are envisaging an X-ray tomographer to map the mineralogical and elemental composition of an artefact (i.e., painting, pottery) directly on the object without sample preparation. Nowadays, X-ray radiography or computer tomography are becoming standard techniques widely used and accepted by art historians, archaeologists, curators and conservators as these methods enable information about the manufacturing process and the condition of an object without touching the artefact or even taking original sample material.

The documentation of a palaeodoline and the recovery of a loose block with shrinkage cracks in the Rio Sglirs area (central Carnic Alps) suggest subaerial exposure during the late Tournaisian. Both structures have been dated to the anchoralis conodont zone. This episode occurred well before the globally documented sequence boundary at the Tournaisian-Visean boundary. These data, combined with other evidence from different areas in the Carnic Alps suggest that the evolution of the Carnic Basin was influenced by high frequency sealevel fluctuations during the late Tournaisian.

Gale Crater is filled by sedimentary deposits including a mound of layered deposits, Aeolis Mons. Using orbital data, we mapped the crater infillings and measured their geometry to determine their origin. The sediment of Aeolis Mons is interpreted to be primarily air fall material such as dust, volcanic ash, fine-grained impact products, and possibly snow deposited by settling from the atmosphere, as well as wind-blown sands cemented in the crater center. Unconformity surfaces between the geological units are evidence for depositional hiatuses. Crater floor material deposited around Aeolis Mons and on the crater wall is interpreted to be alluvial and colluvial deposits. Morphologic evidence suggests that a shallow lake existed after the formation of the lowermost part of Aeolis Mons (the Small yardangs unit and the mass-wasting deposits). A suite of several features including patterned ground and possible rock glaciers are suggestive of periglacial processes with a permafrost environment after the first hundreds of thousands of years following its formation, dated to ~3.61 Ga, in the Late Noachian/Early Hesperian. Episodic melting of snow in the crater could have caused the formation of sulfates and clays in Aeolis Mons, the formation of rock glaciers and the incision of deep canyons and valleys along its flanks as well as on the crater wall and rim, and the formation of a lake in the deepest portions of Gale.

The conodont stratigraphy of the lower Lochkovian part of the famous Cellon section is presented. The association includes twenty-two taxa belonging to nine genera, and allows discriminating the two biozones of the lower Lochkovian (Icr. hesperius and Icr. postwoschmidti zones). Three taxa (Zieglerodina formosa, Z. mashkovae and Z. prosoplatys) are reported for the first time from the Carnic Alps, and other two species of Zieglerodina, probably new, are described in open nomenclature.

We report the detection of mound-like landforms interpreted as mud volcanoes within Firsoff crater, in the Arabia Terra region of Mars. The mounds stratigraphically overlie layered deposits within the crater, which consist of high albedo well-bedded deposits disrupted in meter-sized polygons. Hundreds of mounds are observed on the crater floor, as isolated or composite subcircular cones 100–500 m in diameter and tens of meters high. More than one third of the mounds (35%) have subcircular depressions 5–39 m in diameter at their apices that we interpret as vents. The mounds consist of meter-sized boulders of high albedo, embedded in an apparently finer-grained unit; we interpret these deposits as mud volcanic breccia, containing boulders of reworked light-toned layered deposits carried upward from deeper portions of the succession. The mounds are mainly located near the rim-bordering faults and in places aligned with fractures, suggesting subsurface pathways for fluid migration. The mounds are interpreted as fossil mud volcanoes, recording the upward migration of overpressured fluids through the crater infill from deeper crustal sources, localized by impact-related faults. The geological conditions and processes that might have controlled sedimentary expulsion on Mars are discussed. Mud volcanism has most of its controls in the subsurface. As a consequence, subsurface fluid flow processes could be expected in other craters within Arabia Terra and are less likely in higher, adjacent highland terrains.

Possible periglacial and relict glacial landforms in the ancient mountain range of the Thaumasia Highlands, Mars, are described. The landforms include large-scale mantling, lineated crater and valley-fill materials, debris aprons, protalus lobes and ramparts. The most pristine icerelated landforms appear to be small-scale protalus lobes and ramparts with no visible distinct impact craters at both medium (High Resolution Stereo Camera (HRSC)) and high (Mars Orbiter Camera (MOC) narrow angle (NA), Context Camera (CTX)) spatial resolution. These small landforms are possibly active at present and post-date more extensive features such as crater fills, possibly formed during high obliquity climatic periods. In contrast to the rock glacier-like landforms with distribution preferentially occurring on southfacing slopes, possibly controlled by enhanced exposure to the Sun, older, less pristine lineated fill materials show a less systematic distribution of flow directions, suggesting a more generalized periglacial and possibly glacial environment in the Thaumasia Highlands.

International audience; Ares Vallis is one of the greatest outflow channels of Mars. Using high-resolution images of recent missions to Mars (MGS, 2001 Odyssey, and Mars Express), we investigated Ares Vallis and its valley arms, taking advantage of 3-dimensional analysis performed using the high-resolution stereo capability of the Mars Express High Resolution Stereo Camera (HRSC). In our view, Ares Vallis is characterized by catastrophic flood landscapes partially superimposed by ice-related morphologies. Catastrophic flood landforms include erosional terraces, grooved terrains, streamlined uplands, giant bars, pendant bars, and cataract-like features. Ice-related morphologies include probable kame features, thermokarstic depressions, and patterned grounds. Our investigations outline that throughout the Hesperian age, Ares Vallis and its valley arms had been sculpted by several, time-scattered, catastrophic floods, originating from Iani, Hydaspis and Aram Chaos. Geomorphological evidence suggests that catastrophic floods were ice-covered, and that climatic conditions of Mars at this time were similar to those of the present day. At the end of each catastrophic flood, ice masses grounded, forming a thick stagnant dead-ice body. Each catastrophic flood was followed by a relatively brief period of warmer-wetter climatic conditions, originated as a consequence of catastrophic flooding. During such periods thermokarstic depressions originated, liquid water formed meandering channels, and ice-contact deposits were emplaced by ice-walled streams. Finally, the climate turned into cold-dry conditions similar to the present-day ones, and ice masses sublimated.

The Eberswalde crater and its contributing basins have been analyzed in detail in order to reconstruct the geological evolution of the water-related landforms with particular focus on the Eberswalde delta-like feature. Based on a complex strata organization characterized by a topset–foreset–bottomset geometry, typical of delta progradation on Earth, we interpret the Eberswalde feature to be a fan delta associated with a lacustrine system. Depositional sub-environments have been recognized and mapped and the sedimentary processes discussed. A sequence stratigraphy approach has been used to evaluate the system, which we interpret to result from three depositional sequences. These sequences suggest relative water level fluctuations and a longer trend over time towards decreasing water content inside the basin.

Light-toned layered deposits are widespread on Mars in different geographical and geological settings and many different processes have been suggested to explain their formation, including lacustrine, sub-ice volcanism, weathering of basalts, pyroclastic, impact base surge and dust airfall. Interplay between airfall and aeolian processes with groundwater fluctuations leading to episodes of evaporite precipitation, interaction between lacustrine deposition and hydrothermal vents or large mud volcanoes, groundwater upwelling leading to spring deposits precipitation and/or mud volcanoes deposition have been also proposed. In order to contribute to this discussion, we present the recently published results on the Equatorial Layered Deposits (ELDs) of Arabia Terra in Firsoff crater and on the adjacent plateau. We produced a detailed geological map that included a survey of the relative stratigraphic relations and crater count dating. We reconstructed the geometry of the layered deposits and inferred some compositional constraints. We analyzed the sedimentary structures and textures observable at the available scale both inside and outside the craters. ELDs drape and onlap the plateau materials of Late Noachian age while they are unconformably covered by Early and Middle Amazonian units. ELDs show the presence of polyhydrated sulfates. Layer morphologies, albedo, structure, composition and stratigraphic setting enable us to include the ELDs in Firsoff crater and the surrounding plateau in the wider frame of the sulfate-bearing layered deposits seen elsewhere on Mars at the Noachian-Hesperian transition. ELDs found in craters and in the plateau can be distinguished from each other on the basis of basin-scale morphologies (kilometers-thick crater bulges vs 100s meter-thick sheet drape deposits) and local-scale morphologies (rounded shape, sub-circular depressions, raised rims, bowl-shaped appearance and serrated layer vs flat-topped bodies or dune fields with cross stratification). These morphologic differences suggest that genetic processes might at least partly be different, too. In the crater ELDs consist of mounds made of breccia sometimes displaying an apical pit laterally grading into a light-toned layered unit disrupted in a meter-scale polygonal pattern. These units are frequently associated with fissure ridges suggestive of subsurface sources. We interpret the ELDs inside the craters as spring deposits, originated by fluid upwelling through the pathways likely provided by the fractures related to the crater formations, and debouching at the surface through the fissure ridges and the mounds leading to evaporite precipitation. On the plateau, ELDs consist of rare mounds, flat-lying deposits and cross-bedded dune-fields. We interpret these mounds as possible smaller spring deposits, the flat-lying deposits as playa deposits, and the cross-bedded dune-fields as aeolian deposits. Groundwater fluctuations appear to be the major factor controlling ELDs deposition, leading to different depositional environments depending on the physiography of the basin.

The development and behavior of million year- scaled depositional sequences recorded within Palaeozoic carbonate platform has remained poorly examined. There- fore, the understanding of palaeoenvironmental changes that occur in geological past is still limited. We herein undertake a multi-disciplinary approach (sedimentology, conodont biostratigraphy, magnetic susceptibility (MS), and geochemistry) of a long-term succession in the Carnic Alps, which offers new insights into the peculiar evolution of one of the best example of Palaeozoic carbonate platform in Europe. The Freikofel section, located in the central part of the Carnic Alps, represents an outstanding succession in a fore-reef setting, extending from the Latest Givetian (in- det.falsiovalis conodont zones) to the Early Famennian (Lower crepida conodont zone). Sedimentological analysis allowed to propose a sedimentary model dominated by distal slope and fore-reef-slope deposits. The most distal setting is characterized by an autochthonous pelagic sedi- mentation showing local occurrence of thin-bedded turbi- ditic deposits. In the fore-reef slope, in a more proximal setting, there is an accumulation of various autochthonous and allochthonous fine- to coarse-grained sediments origi- nated from the interplay of gravity-flow currents derived from the shallow-water and deepwater area. The temporal evolution of microfacies in the Freikofel section evolves in two main steps corresponding to the Freikofel (Unit 1) and the Pal (Unit 2) limestones. Distal slope to fore-reef lithologies and associate changes are from base to top of the section: (U1) thick bedded litho- and bioclastic breccia beds with local fining upward sequence and fine-grained mud- stone intercalations corresponding, in the fore-reef setting, to the dismantlement of the Eifelian-Frasnian carbonate platform during the Early to Late Frasnian time (falsiovalis to rhenana superzones) with one of the causes being the Late Givetian major rift pulse; (U2) occurrence of thin- bedded red nodular and cephalopod-bearing limestones with local lithoclastic grainstone intercalations corre- sponding to a significant deepening of the area and the progressive withdrawal of sedimentary influxes toward the basin, in relation with Late Frasnian sea-level rise. MS and geochemical analyses were also performed along the Fre- ikofel section and demonstrate the inherent parallel link existing between variation in MS values and proxy for terrestrial input. Interpretation of MS in terms of palaeo- environmental processes reflects that even though distality remains the major parameter influencing MS values, car- bonate production and water agitation also play an impor- tant role.

The Carnic Alps represent the best exposed Paleozoic succession within the Alpine domain being fossiliferous, mostly non-metamorphic and largely complete. This study focuses on the area around Mt. Pizzul, because the bedrocks record well the basin dynamics and most of the units are conodont bearing. Our aims were to contribute to the procedure of formalization of the lithostratigraphic units and to understand the depositional and deformation history of the study area. The area has been mapped, tectonic overprint constrained and the successions described, measured and dated. As a second-order aim, we discuss these data to infer the relations with other parts of the Carnic basin and to recognize the global controls on sedimentation. The depositional evolution can be sketched as follows: pre-Hirnantian ramp-type margin; Hirnantian glacioeustatic-related deposits and unconformity; pelagic deposition in a ramp-type margin (Přidoli–Eifelian); slope formation and differentiation in buildup, foreslope and pelagic environments (Eifelian–Frasnian); transgression and reef drowning (Frasnian–Visean); probable subaerial exposures likely during in uppermost Famennian and Visean times; and turbidite deposition (Visean). Global controls or deposits suggesting a global control are documented, including the Boda Event, the Hirnantian glaciation, the Middle Devonian reef growth, the Kacak Event, and the high-frequency sea-level fluctuations around the Devonian–Carboniferous boundary. The drowning of the buildups here and elsewhere in the Carnic Alps started during the Frasnian, unlike observed globally. This suggests that local tectonics lead to progressive deepening up to the transition to turbidite deposition.

The equatorial layered deposits of Arabia Terra are investigated to understand their genesis and the controls on their evolution. We interpret the deposits found within the craters as having been formed by spring deposition based on the large-scale geometry, the presence of morphologies consistent with fluid expulsion, the composition, and the sedimentary structures. Outside of the craters, we found evidence of dune forms and cross-stratification suggestive of aeolian activity, possibly associated with playa deposition. Groundwater fluctuations are suggested as the control on deposition.

This area of Lunae Planum (centred around 4°S and 298°E) has been studied by various authors, who have described the presence of exhumed channels (sinuous lineations), Light Layered Deposits (LLD), and detected hydrated sulphates associated with LLDs. We performed sedimentological, geomorphological, and stratigraphic analyses of the LLDs and produced geological maps of the area. The geological maps can serve as a guide for scientific or landing site analyses, and they represent a tool for making lateral correlations and for detecting different units in the vertical dimension. Our aim is to contribute to the debate about processes associated with the presence of water, the factors controlling these processes, and the residence time of liquid water on the surface of Mars. The significant element that emerges from this work is the complex evolutionary history of the study area and, to our knowledge, the area represents a unique example on Mars of clear evidence of tectonic influence on sedimentation.

Sedimentary deposits within Eberswalde Crater are generally interpreted as having formed in a fluviolacustrine depositional environment. The Eberswalde fan delta consists of five lobes (four deltaic), the relative stratigraphy of which can be unravelled through simple cross-cutting relationships, allowing inferences to be made of the approximate water level from the transition between delta plain and delta front. Switching between different lobes is inferred to have been controlled by allogenic control. We distinguish three water-level fluctuations, possibly associated with system tracts, on which a higher order regressive trend is superimposed. The three lower-order cycles may partly reflect control by transient and/or localized processes, but the cyclic behaviour suggests the presence of climatic control.

We present a large-scale spring hypothesis for the formation of various enigmatic light-toned deposits (LTDs) on Mars. Layered to massive LTDs occur extensively in Valles Marineris, chaotic terrains, and several large craters, in particular, those located in Arabia Terra. Most of these deposits are not easily explained with either a single process or multiple ones, either in combination or occurring sequentially. Spring deposits can have a very wide range of internal facies and exhibit complex architectural variations. We propose the concept of large-scale spring deposits for explaining LTDs on Mars. Stable volcano-tectonic settings, such as the ones typical on Mars, are compatible with a large-scale, long-term, multistage formation of spring deposits. The large-scale spring deposit model can explain the formation of LTDs with a common process, although active in different times and locations, compatible with coeval local or regional processes and deposits, such as volcaniclastic ones. LTDs, if formed as spring deposits derived from subsurface fluids, could potentially offer favorable conditions both to life and to the fossilization of past life forms.

Thermal evolution of the Palaeozoic–Triassic sequences of the Carnic Alps has been characterised by b cell dimension and Kübler Index (illite “crystallinity”) of K-white micas (KI), Árkai Index (AI) of chlorites, clay mineral assemblages and conodont Colour Alteration Index (CAI). Data indicate at least two metamorphic events, Variscan and Alpine. In the older event high anchizonal conditions predominated although epizonal conditions were reached over wide areas. It was characterised by low-intermediate pressure facies. The thermal peak, was due mainly to an extensional regime during the Bashkirian. A younger thermal overprint generated by Alpine orogeny was of lower grade, reaching high diagenetic–anchizonal conditions characterised by high pressure facies. Inverted metamorphic patterns are associated with middle to late Miocene thrusting. Hydrothermal alteration in the northern part of the region can be linked with emplacement of Oligocene plutons and high heat flow along the Periadratic lineament.

We studied north Tyrrhena Terra, an approximately 39,000 km2 area, located in the transition region straddling the Amenthes and Mare Tyrrhenum Mars Chart quadrangles 14 and 22, respectively. The study area comprises ancient terrains with infilled craters, ridges and valleys. Interpretation of orbiter data of ancient terrains is inherently difficult, but valuable information can be obtained using multiple datasets and analyzing various geological features. Using data from the High Resolution Stereo Camera on board Mars Express, complemented by Mars Global Surveyor MOLA DEM and MOC Narrow Angle datasets, we observed and interpreted surface morphologies at a scale suitable for geologic investigation. Morphometric examination of a 31 km diameter large impact crater indicated that tectonism and volcanism were responsible for its morphologic modification. Small impact crater depth/diameter relationships indicated that smooth surfaces of valleys are composed of highly consolidated material. Surface cracks and lobate fronts further suggested that the rocks are volcanic. Examination of tectonic features revealed that in the study area: a dominant NW-SE fabric is related to a ridge/bench-scarp-valley repetition consistent with synthetic and antithetic normal faulting; a NNW-SSE lineament represents the surface expression of normal faulting post-dating all other tectonic features. A weak NE-SW fabric is observable as small sublinear depressions, and at the contact between units internal to one large crater. One 20 km diameter crater in the study area was interpreted to be a caldera, infilled by thick volcanic rock layers. Identification of wrinkle ridges further indicated that thick layered lava flows infilled the main depressions of the study area. The available evidence suggests that the study area underwent multiple episodes of extension and volcanism. © 2007 Elsevier Inc. All rights reserved.

The ~150 km wide Holden crater lies in an area characterized by high density of valley networks implying conditions conducive to forming of water-related environments. We undertook geological mapping and a stratigraphic survey in order to probe the evolution of water-related landforms and their paleoenvironmental implications. Our investigations lead us to propose that the Holden area was subjected to a ``wet'' lacustrine phase of Hesperian age and an ``icy'' phase during the Amazonian. Deltaic, coastal, and lacustrine environments occurred during the ``wet'' phase, some displaying a cyclic depositional pattern presumably related to autogenic processes. Water was delivered to the basin by the Uzboi Vallis and by surface runoff channels from a series of drainage basins along the crater walls. Fan delta geometries and coastal onlap enabled estimation of major water levels. Two levels of major stand of the water have been recognized, possibly reflecting allogenic controls. Geologic units related to this ``wet'' lacustrine phase were subsequently eroded by glacial abrasion and plucking and were disconformably overlain by glacial deposits of Amazonian age, defining an ``icy'' phase. These features are consistent with a warm-based glacier entering the Holden crater through the wide Uzboi Vallis to form a proglacial lake in the central part of the crater. Changes in sedimentary units reflect changes of depositional environments probably connected with climatic variation.

Geological mapping is a key tool for understanding the evolution of any planetary surface. The availability of ever growing data sets (e.g., multispectral and hyperspectral imaging and subsurface radar sounding) requires increasing effort in analyzing, integrating, and exploiting them for mapping purposes. To discuss these issues, about 80 planetary geoscientists gathered in Italy at a workshop co-organized by the Italian Space Agency (ASI), the International Research School of Planetary Sciences (IRSPS), and the U.S. Geological Survey (USGS). The workshop focused on both data and concepts and covered a range of scientific and technical topics.

Geological, facies, geomorphological and allostratigraphic map of the Eberswalde fan delta area are presented. The Eberswalde fan delta is proposed as a sort of prototype area to map sedimentary deposits, because of its excellent data coverage and its variability in depositional as well as erosional morphologies and sedimentary facies. We present a report to distinguish different cartographic products implying an increasing level of interpretation. The geological map – in association with the facies map – represents the most objective mapping product. Formations are distinguished on the basis of objectively observable parameters: texture, color, sedimentary structures and geographic distribution. Stratigraphic relations are evaluated using Steno’s principles. Formations can be interpreted in terms of depositional environment, but an eventual change of the genetic interpretation would not lead to a change in the geological map. The geomorphological map is based on the data represented in the geological map plus the association of the morphological elements, in order to infer the depositional sub-environments. As a consequence, it is an interpretative map focused on the genetic reconstruction. The allostratigraphic map is based on the morphofacies analysis – expressed by the geomorphological map – and by the recognition of surfaces which reflect allogenic controls, such as water level fluctuations: unconformities, erosional truncations and flooding surfaces. As a consequence, this is an even more interpretative map than the geomorphological one, since it focuses on the control on the sedimentary systems. Geological maps represent the most suitable cartographic product for a systematic mapping, which can serve as a prerequisite for scientific or landing site analyses. Geomorphological and allostratographic maps are suitable tools to broaden scientific analysis or to provide scientific background to landing site selection.