High resolution surface analysis of basaltic grains to support transport mode estimation for Martian sediments

Surface micro-morphological features of Mars relevant basaltic grains were surveyed and found some features already known based on quart grains, but also some new ones were identified which might hep to separate fluvial and aeolian transport modes

Mars-Relevant Field Experiences in Morocco: The Importance of Spatial Scales and Subsurface Exploration

During field work at the Ibn Battuta Mars analogue sites, two research questions were analyzed: (1) How do we identify sampling sites using remote and local imaging and (2) what kind of information can be gained from shallow subsurface exploration? While remote images help in targeting field activities in general, the connection between observations at different spatial scales for different rocky desert terrain types is not well established; in this, focused comparison of remote in situ images of well-selected analogues would help a great deal. Dried up lake beds as discerned in remotely acquired data may not show signatures of past water activity, while shallow subsurface exploration could reveal the lacustrine period. Acquisition of several satellite images of the same terrain under different geometries would help to support the planning of such in situ work. The selection of appropriate sampling sites in fluvial settings could be improved by analyzing long, meter-high, open-air outcrops that formed during most recent fluvial episodes. Such settings are abundant on Earth and could be present on Mars but may be just below the resolution of available data. By using 20–30-cm-deep excavations, shallow subsurface exploration could reveal the last period of geological history that would have been unattainable by surface observation alone. Aggregates embedded in the original strata or from heavily pulverized samples could not be identified; only weakly fragmented samples viewed right after acquisition showed aggregates, and thus, the close-up imager (CLUPI) on the ExoMover might provide information on cementation-related aggregation on the observing plate before crushing. The mechanical separation of different size grains (mainly clays and attached minerals) would also support the identification of individual components. To maximize context information during subsurface exploration, rover imaging should be accomplished before crushing; however, currently planned imaging may not be ideal for this

Characterization and first results of the planetary borehole-wall imager – methods to develop for in-situ exploration

Prototypes of borehole-wall imager instruments were developed and tested at a desert riverbed in Morocco and at a lake’s salty flat in the Atacama desert, to support the drilling activity of ExoMars rover. The onsite recorded borehole images contain information on the context that are lost during the sample acquisition. Benefits of the borehole-wall imaging is the easier maximal energy estimation of a fluvial flow, the detailed information on sedimentation and layering, especially the former existence of liquid water and its temporal changes, including paleo-flow direction estimation from grain imbrication direction. Benefits of laboratory analysis of the acquired samples are the better identification of mineral types, determination of the level of maturity of granular sediment, and identification of the smallest, wet weathered grains. Based on the lessons learned during the comparison of field and laboratory results, we demonstrate that recording the borehole-wall with optical instrument during/after drilling on Mars supports the paleo-environment reconstruction with such data that would otherwise be lost during the sample acquisition. Because of the lack of plate tectonism and the low geothermal gradient on Mars, even Ga old sediments provide observable features that are especially important for targeting Mars sample return and later crewed Mars missions

Wind-snow interactions at the Ojos del Salado region as a potential Mars analogue site in the Altiplano - Atacama desert region

The general characteristics and interactions happening at a unique, potential new Mars analogue site, located in the Altiplano and Atacama Desert region: the Ojos del Salado inactive volcano. The interaction between rare snowing events and strong winds transported large masses of porous volcanic grains there could produce decimeter - meter thick buried snow masses fast, shielded against sublimation for extended periods (years). Subsurface temperature logging suggests that water ice melting is rare and surface modification is dominated by desiccation of the cryosphere and wind activity – just like on Mars. The site contains decameter scale megaripples, which are unusual for Earth and also support the understanding of resemble features on Mars. The shallow subsurface analysis with Mars relevance is supported here by drilled cores of evaporitic sediments

Analysis of surface morphology of basaltic grains as environmental indicators for Mars

Analysing the microtextures of grains from different sediments helps to determine their transport medium. This method is well developed in the case of quartz grains, because quartz is usually dominant in sediments on Earth. In this study, basaltic sands from aeolian and fluvial environments from Iceland and from the Azores Islands were analysed, since basaltic rocks have been found on Mars, and paleo-environment reconstruction is an important goal of future missions. Fixed grains were imaged and analysed by a high-resolution electron microscope. Several different surface identification marks were found corresponding to known examples from quartz micromorphologies: conchoidal fractures, steps, and percussion marks, which are connected to fluvial environments; while precipitation features and bulbous edges were identified and connected to the aeolian transport. In these generally very diverse samples some new micromorphologies, which have not previously been found on quartz grains, were also identified. The identification of such features which are not present on quartz is expected, as the sample has a different composition than quartz. These newly identified features were named as: fan-shaped percussion marks; isometric shaped grains with a rough surface (fluvial); “large voids” with abraded surface and cracked surface (aeolian). Based on our results, a further improved version of the method evaluating grain surface micro-morphology could be useful not only for quartz grains, but in the case of the basaltic grains too. Such information could help to identify the settling environments of grains on Mars, we therefore also discuss the spatial resolution and observational conditions required to do so by in-situ Mars missions there. We conclude that a one order of magnitude increase in the spatial resolution (down to about 1 μm) would greatly support the identification of grain surface features and interpretation of transport methods. This level of resolution is not far beyond that which is currently available

Miről árulkodnak a szállított ásványszemcsék mikromorfológiai bélyegei?

A homokszemcsék mikromorfológiájának vizsgálatával már közel egy évszázada foglalkoznak a kutatók, már akkor felfigyeltek néhány összefüggésre a szemcsék felszínén megfigyelhető formák, valamint a geológiai környezet között. Az általunk bemutatott módszer jelentősége abban rejlik, hogy ideális esetben a bélyegekből és azok együtteseiből valószínűsíteni lehet a szállítási móddal kapcsolatos különböző környezeti tényezőket és időbeli változásukat, sőt akár következtethetünk a forrásterület korábbi éghajlatára is. Folyamatosan fejlődő módszerről van szó, ezért fontos megjegyeznünk, hogy az általa tehető megállapítások még nem tekinthetők olyan biztosnak, mint a nála elterjedtebb, gyakrabban alkalmazott paleokörnyezet-határozásra használt eljárások. Munkánk célja, hogy bemutassuk ezt a törmelékes szedimentológiában alkalmazható, eddig főleg hazánkban kevéssé ismert és elterjedt vizsgálati módszert, amelynek pontosan emiatt nincsen hivatalosan bevezetett és elfogadott magyar nevezéktana. Ebből kifolyólag úttörő munkának számít hazánk tudományos életében, célunk az eredeti angol nevezéktanból kiinduló, magyar nyelvű szakkifejezések bevezetése. A módszerben sok új lehetőség rejlik (pl. statisztikai megközelítés fejlesztése, morfológiai jegyek együttes jelenlétének értelmezése), a téma pedig nemzetközi szinten is egyre népszerűbb. Korunk egyik legnagyobb környezeti kihívása a klímaváltozás. Folyamatainak minél pontosabb megismeréséhez és megértéséhez ismernünk kell ezek múltbéli megfelelőit. Erre már számos módszer létezik (pl. dendrokronológia, jégfuratok izotópösszetételének vizsgálata), ugyanakkor az üledékes szemcsék vizsgálata további értékes, új információt nyújthat a témában

Characterization and first results of the planetary borehole-wall imager — methods to develop for in-situ exploration

Prototypes of borehole-wall imager instruments were developed and tested at a desert riverbed in Morocco and at a lake’s salty flat in the Atacama desert, to support the drilling activity of ExoMars rover. The onsite recorded borehole images contain information on the context that are lost during the sample acquisition. Benefits of the borehole-wall imaging is the easier maximal energy estimation of a fluvial flow, the detailed information on sedimentation and layering, especially the former existence of liquid water and its temporal changes, including paleo-flow direction estimation from grain imbrication direction. Benefits of laboratory analysis of the acquired samples are the better identification of mineral types, determination of the level of maturity of granular sediment, and identification of the smallest, wet weathered grains. Based on the lessons learned during the comparison of field and laboratory results, we demonstrate that recording the borehole-wall with optical instrument during/after drilling on Mars supports the paleo-environment reconstruction with such data that would otherwise be lost during the sample acquisition. Because of the lack of plate tectonism and the low geothermal gradient on Mars, even Ga old sediments provide observable features that are especially important for targeting Mars sample return and later crewed Mars missions

Tracing the Source of Hydrothermal Fluid in Ophiolite-Related Volcanogenic Massive Sulfide Deposits: A Case Study from the Italian Northern Apennines

The Italian Northern Apennines contain several Fe-Cu-Zn-bearing, Cyprus-type volcanogenic massive sulfide (VMS) deposits, which significantly contribute to the Cu resources of Italy. The massive sulfide lenses and related stockwork mineralizations are hosted by several levels (from basalt to serpentinite) of the unmetamorphosed ophiolitic series; therefore, this region offers perfect locations to study the ore-forming hydrothermal system in detail. A combination of fluid inclusion microthermometry, Raman spectroscopy, electron probe analyses (chlorite thermometry) and stable and noble gas isotope geochemistry was used to determine the fluid source of the VMS system at Bargone, Boccassuolo, Campegli, Casali–Monte Loreto, Corchia, Reppia and Vigonzano. This question of the fluid source is the focus of modern VMS research worldwide, as it has a direct influence on the metal content of the deposit. The obtained temperature and compositional data are both in the typical range of VMS systems and basically suggest evolved seawater origin for the mineralizing fluid. Modification of seawater was most commonly due to fluid–rock interaction processes, which happened during long-lasting circulation in the crust. The role of a small amount of magmatic fluid input was traced only at the lower block of Boccassuolo, which may be responsible for its higher ore grade. This fluid origin model is evidenced by O, H and C stable isotopic as well as He, Ne and Ar noble gas isotopic values

Cold, Dry, Windy, and UV Irradiated: Surveying Mars-Relevant Conditions in Ojos del Salado Volcano (Andes Mountains, Chile)

The Special Collection of papers in this issue of Astrobiology provide an overview of the characteristics and potential for future exploration of the Ojos del Salado volcano, located in the Andes Mountains in front of the Atacama Desert in northern Chile. The main benefits of this site compared with others are the combination of strong UV radiation, the presence of permafrost, and geothermal activity within a dry terrain. The interaction between limited snow events and wind results in snow patches buried under a dry soil surface. This leads to ephemeral water streams that only flow duringdaytime hours. On this volcano, which has the highest located subsurface temperature monitoring systems reported to date, seasonal melting of the permafrost is followed by fast percolation events. This is due to the high porosity of these soils. The results are landforms that shaped by the strong winds. At this site, both thermal springs and lakes (the latter arising from melting ice) provide habitats for life; a 6480m high lake heated by volcanic activity shows both warm and cold sediments that contain a number of different microbial species, including psychrophiles. Where the permafrost melts, thawing ponds have formed at 5900m that is dominated by populations of Bacteroidetes and Proteobacteria, while in the pond sediments and the permafrost itself Acidobacteria, Actinobacteria, Bacteroidetes, Patescibacteria, Proteobacteria, and Verrucomicrobia are abundant. In turn, fumaroles show the presence of acidophilic iron-oxidizers and iron-reducing species. In spite of the extreme conditions reported at Ojos del Salado, this site is easily accessible.Comment: Accepted in Astrobiology Special Issue 2020. 04. 1