ORCID Profile
0000-0002-0146-9324
Current Organisations
Lund University
,
Københavns Universitet Niels Bohr Instituttet
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Publisher: American Geophysical Union (AGU)
Date: 10-2023
DOI: 10.1029/2022JE007444
Abstract: In situ geologic context mapping (GXM) based on rover and helicopter observations provides documentation of a nearly continuous record of geology and exposed surface structure over a 120 m‐wide corridor along the traverse of the Mars 2020 /Perseverance rover. The results record the geologic context of Mars 2020 c aign sites and s le sites including the local extent of bedrock outcrops, stratigraphy, attitude, and structure from imaging and rover‐based remote sensing, and outcrop lithology based on in situ proximity science. Mapping identifies a sequence of igneous lithologies including: (1) early mafic, possibly intrusive, rocks (2) pervasively fractured and deeply altered massive bedrock of undetermined protolith (3) buried and exhumed lava flows with pahoehoe and aa textures (4) several varieties of regolith and (5) small impact craters.
Publisher: American Geophysical Union (AGU)
Date: 07-2023
DOI: 10.1029/2022JE007446
Abstract: We present a combined geomorphologic, multispectral, and geochemical analysis of crater floor rocks in Jezero crater based on data obtained by the Mast Camera Zoom and SuperCam instruments onboard the NASA Mars 2020 Perseverance rover. The combined data from this analysis together with the results of a comparative study with geologic sites on Earth allows us to interpret the origins of rocks exposed along the Artuby ridge, a ∼900 m long scarp of lower Máaz formation rocks. The ridge exposes rocks belonging to two morphologically distinct members, Artuby and Rochette, both of which have basaltic composition and are spectrally indistinguishable in our analysis. Artuby rocks consist of morphologically distinct units that alternate over the ridge, bulbous, hummocky, layers with varying thicknesses that in places appear to have flowed over underlying strata, and sub‐planar thinner laterally continuous layers with variable friability. The Rochette member has a massive appearance with pronounced pitting and sub‐horizontal partings. Our findings are most consistent with a primary igneous emplacement as lava flows, through multiple eruptions, and we propose that the thin layers result either from preferential weathering, interbedded ash/tephra layers, ʻaʻā clinker layers, or aeolian deposition. Our analyses provide essential geologic context for the Máaz formation s les that will be returned to Earth and highlight the ersity and complexity of geologic processes on Mars not visible from orbit.
Publisher: American Geophysical Union (AGU)
Date: 08-2023
DOI: 10.1029/2022JE007612
Abstract: The first s les collected by the Perseverance rover on the Mars 2020 mission were from the Maaz formation, a lava plain that covers most of the floor of Jezero crater. Laboratory analysis of these s les back on Earth would provide important constraints on the petrologic history, aqueous processes, and timing of key events in Jezero crater. However, interpreting these s les requires a detailed understanding of the emplacement and modification history of the Maaz formation. Here we synthesize rover and orbital remote sensing data to link outcrop‐scale interpretations to the broader history of the crater, including Mastcam‐Z mosaics and multispectral images, SuperCam chemistry and reflectance point spectra, Radar Imager for Mars' subsurface eXperiment ground penetrating radar, and orbital hyperspectral reflectance and high‐resolution images. We show that the Maaz formation is composed of a series of distinct members corresponding to basaltic to basaltic‐andesite lava flows. The members exhibit variable spectral signatures dominated by high‐Ca pyroxene, Fe‐bearing feldspar, and hematite, which can be tied directly to igneous grains and altered matrix in abrasion patches. Spectral variations correlate with morphological variations, from recessive layers that produce a regolith lag in lower Maaz, to weathered polygonally fractured paleosurfaces and crater‐retaining massive blocky hummocks in upper Maaz. The Maaz members were likely separated by one or more extended periods of time, and were subjected to variable erosion, burial, exhumation, weathering, and tectonic modification. The two unique s les from the Maaz formation are representative of this ersity, and together will provide an important geochronological framework for the history of Jezero crater.
Publisher: American Geophysical Union (AGU)
Date: 06-2023
DOI: 10.1029/2022JE007613
Abstract: The Mars 2020 Perseverance rover landed in Jezero crater on 18 February 2021. After a 100‐sol period of commissioning and the Ingenuity Helicopter technology demonstration, Perseverance began its first science c aign to explore the enigmatic Jezero crater floor, whose igneous or sedimentary origins have been much debated in the scientific community. This paper describes the c aign plan developed to explore the crater floor's Máaz and Séítah formations and summarizes the results of the c aign between sols 100–379. By the end of the c aign, Perseverance had traversed more than 5 km, created seven abrasion patches, and sealed nine s les and a witness tube. Analysis of remote and proximity science observations show that the Máaz and Séítah formations are igneous in origin and composed of five and two geologic members, respectively. The Séítah formation represents the olivine‐rich cumulate formed from differentiation of a slowly cooling melt or magma body, and the Máaz formation likely represents a separate series of lava flows emplaced after Séítah. The Máaz and Séítah rocks also preserve evidence of multiple episodes of aqueous alteration in secondary minerals like carbonate, Fe/Mg phyllosilicates, sulfates, and perchlorate, and surficial coatings. Post‐emplacement processes tilted the rocks near the Máaz‐Séítah contact and substantial erosion modified the crater floor rocks to their present‐day expressions. Results from this crater floor c aign, including those obtained upon return of the collected s les, will help to build the geologic history of events that occurred in Jezero crater and provide time constraints on the formation of the Jezero delta.
Publisher: Wiley
Date: 26-10-2022
Publisher: Wiley
Date: 29-05-2019
DOI: 10.1111/MAPS.13309
Publisher: Elsevier BV
Date: 05-2021
Publisher: American Association for the Advancement of Science (AAAS)
Date: 13-05-2022
Abstract: Nakhlite meteorites are igneous rocks from Mars that were aqueously altered ~630 million years ago. Hydrothermal systems on Earth are known to provide microhabitats knowledge of the extent and duration of these systems is crucial to establish whether they could sustain life elsewhere in the Solar System. Here, we explore the three-dimensional distribution of hydrous phases within the Miller Range 03346 nakhlite meteorite using nondestructive neutron and x-ray tomography to determine whether alteration is interconnected and pervasive. The results reveal discrete clusters of hydrous phases within and surrounding olivine grains, with limited interconnectivity between clusters. This implies that the fluid was localized and originated from the melting of local subsurface ice following an impact event. Consequently, the duration of the hydrous alteration was likely short, meaning that the martian crust s led by the nakhlites could not have provided habitable environments that could harbor any life on Mars during the Amazonian.
Publisher: American Association for the Advancement of Science (AAAS)
Date: 05-11-2021
Abstract: The Perseverance rover landed in Jezero crater, Mars, in February 2021. Earlier orbital images showed that the crater contains an ancient river delta that was deposited by water flowing into a lake billions of years ago. Mangold et al . analyzed rover images taken shortly after landing that show distant cliff faces at the edge of the delta. The exposed stratigraphy and sizes of boulders allowed them to determine the past lake level and water discharge rates. An initially steady flow transitioned into intermittent floods as the planet dried out. This history of the delta’s geology provides context for the rest of the mission and improves our understanding of Mars’ ancient climate. —KTS
Publisher: American Association for the Advancement of Science (AAAS)
Date: 25-11-2022
Abstract: Perseverance's Mastcam-Z instrument provides high-resolution stereo and multispectral images with a unique combination of spatial resolution, spatial coverage, and wavelength coverage along the rover's traverse in Jezero crater, Mars. Images reveal rocks consistent with an igneous (including volcanic and/or volcaniclastic) and/or impactite origin and limited aqueous alteration, including polygonally fractured rocks with weathered coatings massive boulder-forming bedrock consisting of mafic silicates, ferric oxides, and/or iron-bearing alteration minerals and coarsely layered outcrops dominated by olivine. Pyroxene dominates the iron-bearing mineralogy in the fine-grained regolith, while olivine dominates the coarse-grained regolith. Solar and atmospheric imaging observations show significant intra- and intersol variations in dust optical depth and water ice clouds, as well as unique ex les of boundary layer vortex action from both natural (dust devil) and Ingenuity helicopter-induced dust lifting. High-resolution stereo imaging also provides geologic context for rover operations, other instrument observations, and s le selection, characterization, and confirmation.
Publisher: American Geophysical Union (AGU)
Date: 07-2023
DOI: 10.1029/2022JE007440
Abstract: The Máaz formation consists of the first lithologies in Jezero crater analyzed by the Mars 2020 Perseverance rover. This formation, investigated from Sols (Martian days) 1 to 201 and from Sols 343 to 382, overlies the Séítah formation (previously described as an olivine‐rich cumulate) and was initially suggested to represent an igneous crater floor unit based on orbital analyses. Using SuperCam data, we conducted a detailed textural, chemical, and mineralogical analyses of the Máaz formation and the Content member of the Séítah formation. We conclude that the Máaz formation and the Content member are igneous and consist of different lava flows and/or possibly pyroclastic flows with complex textures, including vesicular and non‐vesicular rocks with different grain sizes. The Máaz formation rocks exhibit some of the lowest Mg# (=molar 100 × MgO/MgO + FeO) of all Martian igneous rocks analyzed so far (including meteorites and surface rocks) and show similar basaltic to basaltic‐andesitic compositions. Their mineralogy is dominated by Fe‐rich augite to possibly ferrosilite and plagioclase, and minor phases such as Fe‐Ti oxides and Si‐rich phases. They show a broad ersity of both compositions and textures when compared to Martian meteorites and other surface rocks. The different Máaz and Content lava or pyroclastic flows all originate from the same parental magma and/or the same magmatic system, but are not petrogenetically linked to the Séítah formation. The study of returned Máaz s les in Earth‐based laboratories will help constrain the formation of these rocks, calibrate Martian crater counting, and overall, improve our understanding of magmatism on Mars.
No related grants have been discovered for Sanna Alwmark.