The Mars 2020 Perseverance rover landing site is located within Jezero crater, a ∼ 50 km diameter impact crater interpreted to be a Noachian-aged lake basin inside the western edge of the Isidis impact structure. Jezero hosts remnants of a fluvial delta, inlet and outlet valleys, and infill deposits containing diverse carbonate, mafic, and hydrated minerals. Prior to the launch of the Mars 2020 mission, members of the Science Team collaborated to produce a photogeologic map of the Perseverance landing site in Jezero crater. Mapping was performed at a 1:5000 digital map scale using a 25 cm/pixel High Resolution Imaging Science Experiment (HiRISE) orthoimage mosaic base map and a 1 m/pixel HiRISE stereo digital terrain model. Mapped bedrock and surficial units were distinguished by differences in relative brightness, tone, topography, surface texture, and apparent roughness. Mapped bedrock units are generally consistent with those identified in previously published mapping efforts, but this study's map includes the distribution of surficial deposits and sub-units of the Jezero delta at a higher level of detail than previous studies. This study considers four possible unit correlations to explain the relative age relationships of major units within the map area. Unit correlations include previously published interpretations as well as those that consider more complex interfingering relationships and alternative relative age relationships. The photogeologic map presented here is the foundation for scientific hypothesis development and strategic planning for Perseverance's exploration of Jezero crater.
On the Vøring Margin offshore mid‐Norway, Paleogene continental breakup was characterized by the extrusion of large volumes of flood basalts erupted in different depositional environments. The transition from subaerial to submarine emplacement environment is marked by the formation of the Vøring Escarpment which records the early encroachment of flood basalt into the basin and the buildup of a lava delta system. The increased availability of new and reprocessed high‐quality seismic data allows a more detailed characterization of the along‐strike and across‐strike continuity and variability of the different volcanic seismic facies units. Detailed seismic interpretation shows that the ~350 km long NE‐SW trending Vøring Escarpment is a prominent feature along the Vøring Margin with a height ranging between 200 and 1600 m. Structurally, the Vøring Escarpment is segmented along strike into five segments (E1–E5) with different controlling factors leading to variation in accommodation space. Relative sea level change and magma supply are the major controlling factors for segments E2 and E4 which are characterized by a well‐developed lava delta system and significant escarpment height. Tectonic movements along the Jan Mayen Fracture Zone resulted in second‐order segmentation of the E1 segment into pseudoescarpments with a very thin lava delta system and limited escarpment height. Segments E3 and E5, situated along the flanks of Cretaceous/Paleocene highs, are controlled by the structural highs, which were possibly reactivated during breakup time. Our mapping results provide crucial information about the paleogeography and yield important information regarding the paleo–water depth and depocenter locations prior to and during the breakup of the Vøring Margin.
The Radar Imager for Mars Subsurface Experiment instrument has conducted the first rover-mounted ground-penetrating radar survey of the Martian subsurface. A continuous radar image acquired over the Perseverance rover’s initial ~3-kilometer traverse reveals electromagnetic properties and bedrock stratigraphy of the Jezero crater floor to depths of ~15 meters below the surface. The radar image reveals the presence of ubiquitous strongly reflecting layered sequences that dip downward at angles of up to 15 degrees from horizontal in directions normal to the curvilinear boundary of and away from the exposed section of the Séitah formation. The observed slopes, thicknesses, and internal morphology of the inclined stratigraphic sections can be interpreted either as magmatic layering formed in a differentiated igneous body or as sedimentary layering commonly formed in aqueous environments on Earth. The discovery of buried structures on the Jezero crater floor is potentially compatible with a history of igneous activity and a history of multiple aqueous episodes.
The Radar Imager for Mars’ Subsurface Experiment (RIMFAX) is a Ground Penetrating Radar on the Mars 2020 mission’s Perseverance rover, which is planned to land near a deltaic landform in Jezero crater. RIMFAX will add a new dimension to rover investigations of Mars by providing the capability to image the shallow subsurface beneath the rover. The principal goals of the RIMFAX investigation are to image subsurface structure, and to provide information regarding subsurface composition. Data provided by RIMFAX will aid Perseverance’s mission to explore the ancient habitability of its field area and to select a set of promising geologic samples for analysis, caching, and eventual return to Earth. RIMFAX is a Frequency Modulated Continuous Wave (FMCW) radar, which transmits a signal swept through a range of frequencies, rather than a single wide-band pulse. The operating frequency range of 150–1200 MHz covers the typical frequencies of GPR used in geology. In general, the full bandwidth (with effective center frequency of 675 MHz) will be used for shallow imaging down to several meters, and a reduced bandwidth of the lower frequencies (center frequency 375 MHz) will be used for imaging deeper structures. The majority of data will be collected at regular distance intervals whenever the rover is driving, in each of the deep, shallow, and surface modes. Stationary measurements with extended integration times will improve depth range and SNR at select locations. The RIMFAX instrument consists of an electronic unit housed inside the rover body and an antenna mounted externally at the rear of the rover. Several instrument prototypes have been field tested in different geological settings, including glaciers, permafrost sediments, bioherme mound structures in limestone, and sedimentary features in sand dunes. Numerical modelling has provided a first assessment of RIMFAX’s imaging potential using parameters simulated for the Jezero crater landing site.
We present results of a multidisciplinary study of the northern segment of the Vøring volcanic rifted margin, offshore mid‐Norway. This segment represents a transitional margin domain that is less investigated compared to the adjacent segments of the margin. In order to understand the geological evolution of the study area, we performed an integrated interpretation of an extensive geological and geophysical data set. This data set includes recently acquired and reprocessed 2‐D reflection seismic, published refraction data and potential field data, as well as new borehole data. Two‐dimensional potential field modeling was performed to better assess the crustal architecture and evolution of the northern Vøring Margin. We then consider how crustal‐scale structures and processes affected the basin formation. The outer and distal northern Vøring Margin represents a series of deep Cretaceous (Træna Basin and Någrind Syncline) and Cretaceous‐Paleocene (Hel Graben) sag subbasins underlain by a significantly thinned continental crust. These subbasins developed in between structural highs (Utgard, Nyk, and Grimm Highs), which are underlain by a thicker crust and interpreted as a series of rigid continental blocks (“buffers”). In addition to the regional Late Jurassic‐Early Cretaceous rifting events, we found structural evidence of local Neocomian and mid‐Cretaceous extensional reactivation affecting the northern segment of the Vøring Basin. During the mid‐Late Cretaceous‐Paleocene, the extensional axis within the Vøring Basin province migrated sequentially northwestward to the present‐day continent‐ocean “boundary”. We also show fundamental differences between the volcanic rifted mid‐Norwegian Margin and nonvolcanic (Iberian‐type) margins and how preexisting structures events can shape the evolution and architecture of the margin.
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