Sulfur and chlorine in nakhlite clinopyroxenes: Source region concentrations and magmatic evolution

The volatile concentrations of the martian mantle and martian magmas remain important questions due to their role in petrogenesis and planetary habitability. The sulfur and chlorine concentrations, and their spatial distribution, in clinopyroxenes from nakhlites MIL 03346, Nakhla, and NWA 998 were measured to provide insight into these volatiles in the parental melts and source regions of nakhlites, and to constrain the evolution of the nakhlite melts. Sulfur and chlorine in four clinopyroxene crystals from MIL 03346, four from Nakhla, and five from NWA 998 were measured in crystal cores and rims by synchrotron X-ray fluorescence using beamline I18 at the Diamond Light Source. Portions of two crystals from MIL 03346 and one from Nakhla were mapped for S and Cl; a few reconnaissance analyses of Cl and F in MIL 03346 and Nakhla were made by ion microprobe. Clinopyroxene cores in Nakhla and NWA 998 contain ~ 10 ppm S, ~ 10 ppm Cl and ~ 74 ppm F (only Nakhla analyzed), whereas the cores of MIL 03346 contain ~ 10 ppm S, ~ 5 ppm Cl and ~ 53 ppm F. Using the volatile concentrations in the cores combined with previously determined partition coefficients we calculate that these clinopyroxenes crystallized from evolved basaltic melts containing ~ 500 ppm S, ~ 500 to 1900 ppm Cl, and 160 to 420 ppm F. These evolved melts can be used to calculate primitive melts in equilibrium with martian peridotite and the concentrations of S, Cl and F in the mantle source region of the nakhlite melts. Depending upon the extent of melting (5 to 30 %) necessary to produce the primary melts associated with nakhlites, our calculations indicate that the nakhlite source region has a S concentration between 20 (5 % melting) to 120 ppm (30 % melting), Cl between 16 to 97 ppm, and F between 14 to 48 ppm. These concentrations in the nakhlite magma source region are similar to previous estimates for the martian mantle; our calculated source region concentrations of F and Cl agree best with previous estimates if the martian mantle undergoes 10 to 20% melting to produce primary magmas that evolve to be parental to nakhlites. However, our maximum estimated sulfur concentration of the source (calculated for 30 % melting) is near previous minimum estimates for the martian mantle, suggesting the possibility that the nakhlite source region is depleted in sulfur relative to much of Mars’ mantle. Mapping the spatial distribution of volatiles in three clinopyroxene crystals demonstrates that S and Cl concentrations of the evolving melts changed significantly from the core to the rim, particularly those in MIL 03346. Increasing S and Cl concentrations between the core and rim of MIL 03346 crystals are attributed to incorporation of additional volatiles through assimilation, but the Nakhla crystal shows no such evidence. However, concentrations of Cl and S at some outer crystal rims of one MIL 03346 crystal decrease, most probably due to volatile degassing during the final stages of clinopyroxene growth

The high-resolution map of Oxia Planum, Mars; the landing site of the ExoMars Rosalind Franklin rover mission

This 1:30,000 scale geological map describes Oxia Planum, Mars, the landing site for the ExoMars Rosalind Franklin rover mission. The map represents our current understanding of bedrock units and their relationships prior to Rosalind Franklin’s exploration of this location. The map details 15 bedrock units organised into 6 groups and 7 textural and surficial units. The bedrock units were identified using visible and near-infrared remote sensing datasets. The objectives of this map are (i) to identify where the most astrobiologically relevant rocks are likely to be found, (ii) to show where hypotheses about their geological context (within Oxia Planum and in the wider geological history of Mars) can be tested, (iii) to inform both the long-term (hundreds of metres to ∼1 km) and the short-term (tens of metres) activity planning for rover exploration, and (iv) to allow the samples analysed by the rover to be interpreted within their regional geological context

The high-resolution map of Oxia Planum, Mars; the landing site of the ExoMars Rosalind Franklin rover mission

This 1:30,000 scale geological map describes Oxia Planum, Mars, the landing site for the ExoMars Rosalind Franklin rover mission. The map represents our current understanding of bedrock units and their relationships prior to Rosalind Franklin’s exploration of this location. The map details 15 bedrock units organised into 6 groups and 7 textural and surficial units. The bedrock units were identified using visible and near-infrared remote sensing datasets. The objectives of this map are (i) to identify where the most astrobiologically relevant rocks are likely to be found, (ii) to show where hypotheses about their geological context (within Oxia Planum and in the wider geological history of Mars) can be tested, (iii) to inform both the long-term (hundreds of metres to ∼1 km) and the short-term (tens of metres) activity planning for rover exploration, and (iv) to allow the samples analysed by the rover to be interpreted within their regional geological context.The ExoMars Rosalind Franklin Mission is a partnership between ESA and NASA. The Rosalind Franklin Rover has eight instruments in its ‘Pasteur’ Payload, with Principal Investigators from seven countries all of whom we would like to thank for there support of this project. We would like to acknowledge the following funding bodies, people and institutions supporting the lead authors of this work. We thank the UK Space Agency (UK SA) for funding P. Fawdon, on grants; ST/W002736/1, ST/L00643X/1 and ST/R001413/1, MRB on grants; ST/T002913/1, ST/V001965/1, ST/R001383/1, ST/R001413/1, P. Grindrod on grants; ST/L006456/1, ST/R002355/1, ST/V002678/1 and J. Davis on grants ST/K502388/1, ST/R002355/1, ST/V002678/1 through the ongoing Aurora space exploration programme. C. Orgel was supported by the ESA Research Fellowship Program. Alessandro Frigeri: was funded by the Italian Space Agency (ASI) grant ASI-INAF number 2017-412-H.0 (ExoMars/Ma_MISS) and D. Loizeau was funded by the H2020-COMPET-2015 programme (grant 687302), C. Quantin-Nataf was supported by the French space agency CNES, I. Torres was supported by an ESA Young Graduate Traineeship, A. Nass was supported by Helmholtz Metadata Projects (#ZT-I-PF-3-008). We thank NASA and the HiRISE camera team for data collection support throughout the ExoMars landing site selection and charectorisation process. The USGS for the HiRISE DTM data and maintaining the ISIS and SOCET SET DEM workflows. The authors wish to thank the CaSSIS spacecraft and instrument engineering teams. CaSSIS is a project of the University of Bern and funded through the Swiss Space Office via ESA's PRODEX programme. The instrument hardware development was also supported by the Italian Space Agency (ASI) (ASI-INAF agreement no. I/2020-17-HH.0), INAF/Astronomical Observatory of Padova, and the Space Research Center (CBK) in Warsaw. Support from SGF (Budapest), the University of Arizona (Lunar and Planetary Lab.) and NASA are also gratefully acknowledged. Operations support from the UK Space Agency under grant ST/R003025/1 is also acknowledged. This research has made use of the USGS Integrated Software for Imagers and Spectrometers (ISIS) Technical support for setup of the Multi-Mission Geographic Information System for concurrent team mapping was provided by F. Calef (III) and T. Soliman at NASA JPL and S. de Witte at ESA-ESTEC.This work was supported by Agencia Estatal de Investigación [grant number ID2019-107442RB-C32, MDM-2017-0737]; Agenzia Spaziale Italiana [grant number 2017-412-H.0]; Bundesministerium für Wirtschaft und Technologie [grant number 50 QX 2002]; Centre National de la Recherche Scientifique; Centre National d’Etudes Spatiales; Euskal Herriko Unibertsitatea [grant number PES21/88]; Istituto Nazionale di Astrofisica [grant number I/ 060/10/0]; Ministerio de Economía y Competitividad [grant number PID2019-104205GB-C21]; Ministry of Science and Higher Education of the Russian Federation [grant number AAAA-A18-118012290370-6]; National Aeronautics and Space Administration [grant number NNX15AH46G]; Norges Forskningsråd [grant number 223272]; European Union's Horizon 2020 (H2020-COMPET-2015) [grant number 687302 (PTAL)]; Sofja Kovalevskaja Award of the Alexander von Humboldt Foundation; MINECO [grant number PID2019-107442RB-C32]; The Open University [grant number Space Strategic Research Area]; European Union's Horizon 2020 research and innovation programme [grant number 776276]; H2020-COMPET-2015 [grant number 687302]; The Research Council of Norway, Centres of Excellence funding scheme [grant number 223272]; Helmholtz Metadata Projects [grant number ZT-I-PF-3-008]; The Research Council of Norway [grant number 223272]; Swiss Space Office via ESA's PRODEX programme; Ines Torres was supported by an ESA Young Graduate Traineeship; Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung [grant number 200021_197293]; Science and Technology Facilities Council [grant number 1967420]; UK Space Agency [grant number ST/K502388/1, ST/R002355/1, ST/V002678/1]. The ExoMars Rosalind Franklin Mission is a partnership between ESA and NASA. The Rosalind Franklin Rover has eight instruments in its ‘Pasteur’ Payload, with Principal Investigators from seven countries all of whom we would like to thank for there support of this project. We would like to acknowledge the following funding bodies, people and institutions supporting the lead authors of this work. We thank the UK Space Agency (UK SA) for funding P. Fawdon, on grants; ST/W002736/1, ST/L00643X/1 and ST/R001413/1, MRB on grants; ST/T002913/1, ST/V001965/1, ST/R001383/1, ST/R001413/1, P. Grindrod on grants; ST/L006456/1, ST/R002355/1, ST/V002678/1 and J. Davis on grants ST/K502388/1, ST/R002355/1, ST/V002678/1 through the ongoing Aurora space exploration programme. C. Orgel was supported by the ESA Research Fellowship Program. Alessandro Frigeri: was funded by the Italian Space Agency (ASI) grant ASI-INAF number 2017-412-H.0 (ExoMars/Ma_MISS) and D. Loizeau was funded by the H2020-COMPET-2015 programme (grant 687302), C. Quantin-Nataf was supported by the French space agency CNES, I. Torres was supported by an ESA Young Graduate Traineeship, A. Nass was supported by Helmholtz Metadata Projects (#ZT-I-PF-3-008). We thank NASA and the HiRISE camera team for data collection support throughout the ExoMars landing site selection and charectorisation process. The USGS for the HiRISE DTM data and maintaining the ISIS and SOCET SET DEM workflows. The authors wish to thank the CaSSIS spacecraft and instrument engineering teams. CaSSIS is a project of the University of Bern and funded through the Swiss Space Office via ESA's PRODEX programme. The instrument hardware development was also supported by the Italian Space Agency (ASI) (ASI-INAF agreement no. I/2020-17-HH.0), INAF/Astronomical Observatory of Padova, and the Space Research Center (CBK) in Warsaw. Support from SGF (Budapest), the University of Arizona (Lunar and Planetary Lab.) and NASA are also gratefully acknowledged. Operations support from the UK Space Agency under grant ST/R003025/1 is also acknowledged. This research has made use of the USGS Integrated Software for Imagers and Spectrometers (ISIS) Technical support for setup of the Multi-Mission Geographic Information System for concurrent team mapping was provided by F. Calef (III) and T. Soliman at NASA JPL and S. de Witte at ESA-ESTEC.Peer reviewe

Young asteroid mixing revealed in ordinary chondrites: The case of NWA 5764, a polymict LL breccia with L clasts

International audiencePolymict chondritic brecciasrocks composed of fragments originating from different chondritic parent bodiesare of particular interest because they give insights into the mixing of asteroids in the main asteroid belt (occurrence, encounter velocity, transfer time). We describe Northwest Africa (NWA) 5764, a brecciated LL6 chondrite that contains a >16cm(3) L4 clast. The L clast was incorporated in the breccia through a nondestructive, low-velocity impact. Identical cosmic-ray exposure ages of the L clast and the LL host (36.6 +/- 5.8Myr), suggest a short transfer time of the L meteoroid to the LL parent body of 0.1 +/- 8.1Myr, if that meteoroid was no larger than a few meters. NWA 5764 (together with St. Mesmin, Dimmitt, and Glanerbrug) shows that effective mixing is possible between ordinary chondrite parent bodies. In NWA 5764 this mixing occurred after the peak of thermal metamorphism on the LL parent body, i.e., at least several tens of Myr after the formation of the solar system. The U,Th-He ages of the L clast and LL host, identical at about 2.9Ga, might date the final assembly of the breccia, indicating relatively young mixing in the main asteroid belt as previously evidenced in St. Mesmin

The high-resolution map of Oxia Planum, Mars; the landing site of the ExoMars Rosalind Franklin rover mission

International audienceThis 1:30,000 scale geological map describes Oxia Planum, Mars, the landing site for theExoMars Rosalind Franklin rover mission. The map represents our current understanding ofbedrock units and their relationships prior to Rosalind Franklin’s exploration of this location.The map details 15 bedrock units organised into 6 groups and 7 textural and surficial units.The bedrock units were identified using visible and near-infrared remote sensing datasets.The objectives of this map are (i) to identify where the most astrobiologically relevant rocksare likely to be found, (ii) to show where hypotheses about their geological context (withinOxia Planum and in the wider geological history of Mars) can be tested, (iii) to inform boththe long-term (hundreds of metres to ∼1 km) and the short-term (tens of metres) activityplanning for rover exploration, and (iv) to allow the samples analysed by the rover to beinterpreted within their regional geological context