^1,2Andrew B. Foerder,¹Peter A.J. Englert,^3,4Janice L. Bishop,⁵Christian Koeberl,⁶Zachary F.M. Burton,^3,4Shital Patel,⁵Everett K. Gibson
American Mineralogist 109, 682-700 Link to Article [https://doi.org/10.2138/am-2022-8779]
¹Hawai’i Institute of Geophysics and Planetology, University of Hawai’i at Mānoa, Honolulu, Hawai’i 96822-2336, U.S.A.
²Department of Earth, Environmental, and Planetary Sciences, University of Tennessee, Knoxville, Knoxville, TN, 37996-1526, U.S.A.
³SETI Institute, Mountain View, California 94043-5139, U.S.A.
⁴NASA Ames Research Center, Moffet Field, California 94035-1000, U.S.A.
⁵Department of Lithospheric Research, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria
⁶Department of Geological Sciences, Stanford University, Stanford, California, 94305, U.S.A.
⁷NASA Johnson Space Center, Houston, Texas 77058-3607, U.S.A.
Copyright: The Mineralogical Society of America

The McMurdo Dry Valleys of Antarctica provide a testbed for alteration processes on Mars due to the cold, arid, and windy conditions. Analysis of three sediment cores collected from Don Juan Basin, Wright Valley, Antarctica, reveals that surface sediment formation is primarily dominated by physical alteration. Chemical alteration occurs sporadically in this region and is frequently indicated by the accumulation of sulfates and Cl-bearing salts. We investigated the effects of physical and chemical alteration in Don Juan Basin by considering major and trace element abundances in the sediments based on depth and location. Our results indicate inversely related chemical- and physical-alteration gradients with proximity to Don Juan Pond where the current center of the pond represents a more chemically altering environment and the perimeter a more physically altering one. Comparing calculated sulfate abundances for Don Juan Basin cores to rock and soil samples taken by the rover Curiosity at Gale crater, we observed that the core from within Don Juan Pond best matches Curiosity soil sulfate abundances.

A new Chemical Index of Alteration equation that adjusts for salt dilution was also applied to the Antarctic cores and Curiosity rocks and soils. Our analysis indicates a significantly higher degree of chemical alteration than originally reported for most Antarctic and martian samples. Our investigation provides evidence for aqueous-based chemical alteration under cold, hyper-arid conditions in Don Juan Basin, Antarctica. Our work also demonstrates the analogous nature of terrestrial microenvironments to similar, local-scale sample sites on Mars, thereby supporting past or present chemical alteration on Mars.

^1,2Oriel A. Humes,³Audrey C. Martin,¹Cristina A. Thomas,¹Joshua P. Emery
The Planetary Science Journal 5, 5 108 Open Access Link to Article [DOI 10.3847/PSJ/ad3a69]
¹Northern Arizona University, Flagstaff, AZ 86011, USA; oriel.humes@tu-braunschweig.de
²Technische Universität Braunschweig, Braunschweig, NI 38106, Germany
³University of Central Florida, Orlando, FL 32816, USA

We currently do not have a copyright agreement with this publisher and cannot display the abstract here

¹P.J.Gasda et al.(>10)
Journal of Geophysical Research (Planets)(in Press) Open Access Link to Article [https://doi.org/10.1029/2023JE007923]
¹Los Alamos National Laboratory, Los Alamos, NM, USA
Published by arrangement with John Wiley & Sons

Manganese has been observed on Mars by the NASA Curiosity rover in a variety of contexts and is an important indicator of redox processes in hydrologic systems on Earth. Within the Murray formation, an ancient primarily fine-grained lacustrine sedimentary deposit in Gale crater, Mars, have observed up to 45× enrichment in manganese and up to 1.5× enrichment in iron within coarser grained bedrock targets compared to the mean Murray sediment composition. This enrichment in manganese coincides with the transition between two stratigraphic units within the Murray: Sutton Island, interpreted as a lake margin environment, and Blunts Point, interpreted as a lake environment. On Earth, lacustrine environments are common locations of manganese precipitation due to highly oxidizing conditions in the lakes. Here, we explore three mechanisms for ferromanganese oxide precipitation at this location: authigenic precipitation from lake water along a lake shore, authigenic precipitation from reduced groundwater discharging through porous sands along a lake shore, and early diagenetic precipitation from groundwater through porous sands. All three scenarios require highly oxidizing conditions and we discuss oxidants that may be responsible for the oxidation and precipitation of manganese oxides. This work has important implications for the habitability of Mars to microbes that could have used Mn redox reactions, owing to its multiple redox states, as an energy source for metabolism.

¹K.Yumoto et al. (>10)
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2024.116122]
¹Department of Earth and Planetary Science, The University of Tokyo, Bunkyo, Tokyo, Japan
Copyright Elsevier

Asteroids (162173) Ryugu and (101955) Bennu observed by Hayabusa2 and Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer (OSIRIS-REx) share many global properties, but high-spatial-resolution spectral observations by the telescopic Optical Navigation Camera (ONC-T) and MapCam detected subtle but significant differences (e.g., opposite space weathering trends), which may reflect differences in their origin and evolution. Comparing these differences on the same absolute scale is necessary for understanding their causes and obtaining implications for C-complex asteroids. However, ONC-T and MapCam have a large imager-to-imager systematic error of up to 15% caused by the difference in radiometric calibration targets. To resolve this problem, we cross calibrated albedo and colour data between the two instruments using the Moon as the common calibration standard. The images of the Moon taken by ONC-T and MapCam were compared with those simulated using photometry models developed from lunar orbiter data. Our results show that the cross-calibrated reflectance of Ryugu and Bennu can be obtained by upscaling the pre-cross-calibrated reflectance of Bennu by 13.3 ± 1.6% at b band, 13.2 ± 1.5% at v band, 13.6 ± 1.7% at w band, and 14.8 ± 1.8% at x band, while those for Ryugu are kept the same. These factors compensate for the imager-to-imager bias caused by differences in targets used for radiometric calibration and solar irradiance models used for data reduction. Need for such large upscaling underscore the importance of using the cross-calibrated data for accurately comparing the Ryugu and Bennu data. The uncertainty in these factors show that the reflectance of Ryugu and Bennu can be compared with <2% accuracy after applying our results. By applying our cross calibration, the geometric albedo of Bennu became consistent with those observed by ground-based telescopes and the OSIRIS-REx Visible and InfraRed Spectrometer (OVIRS). Our result can be simply applied by multiplying a constant to the publicly available data and enables accurate comparison of the optical spectra of Ryugu and Bennu in future studies.

^1,2R. L. Cheng,^1,2J. R. Michalski,^3,4K. A. Campbell
Journal of Geophyiscal Research (Planets)(in Press) Open Access Link to Article [https://doi.org/10.1029/2023JE007999]
¹Department of Earth Sciences, The University of Hong Kong, Hong Kong, China
²Laboratory for Space Research, The University of Hong Kong, Hong Kong, China
³School of Environment, The University of Auckland, Auckland, New Zealand
⁴Te Ao Mārama—Centre for Fundamental Inquiry, Faculty of Science, The University of Auckland, Auckland, New Zealand
Published by arrangement with John Wiley & Sons

Siliceous hot spring deposits, or sinters, deposit from hot spring discharge at Earth’s surface and are sites of exceptional preservation of biosignatures. Their macro- and micro-textures are regarded as important evidence of past microbial activities in hydrothermal environments. However, biology mimics do occur, and bona fide microbial textures could be destroyed by subsequent diagenesis or other post-depositional processes. Thus, it is paramount to narrow the search for prospective Martian silica-rich deposits that may contain biosignatures from both orbital and rover-based perspectives. This study investigates hydrothermal deposits in Chile, which are analogs of high-silica deposits discovered in the Gusev crater on Mars, through remote sensing and laboratory analysis. Results indicate that compositional remote sensing based on multispectral data with a high spatial resolution of <4 m/pixel reflects various concentrations of silica, which assisted in identifying the direction of discharged hydrothermal flows from the vent to the apron. Micro-infrared mapping of sinters from similar hydrothermal fields linked spectral features to specific textures revealed by scanning electron microscope and chemical compositions confirmed by electron microprobe analysis, indicating that sinters with no shift in their emissivity minimum in the thermal infrared range were more likely to preserve cellular structures. An instrument for collecting multispectral data with higher spatial resolution could aid in characterizing the geologic settings of potential hot springs on Mars. Locating emissivity minima in the infrared regions of silica that do not shift to a lower position would suggest the potential for well-preserved microbial structures in Martian sinters, if life ever did exist there.

¹Carolyn A. Crow,¹Cynthia Tong,²Timmons M. Erickson,³Desmond E. Moser,¹Aaron S. Bell,⁴Nigel M. Kelly,⁵Tabb C. Prissel
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.14162]
¹Department of Geological Sciences, University of Colorado Boulder, Boulder, Colorado, USA
²NASA JSC\Jacobs Technology, Houston, Texas, USA
³Western University, London, Ontario, Canada
⁴Bruker Corporation, Billerica, Massachusetts, USA
⁵NASA JSC, Houston, Texas, USA
Published by arrangement with John Wiley & Sons

Investigations of trapped melt inclusions in minerals can yield insights into the compositions and conditions of parent magmas. These insights are particularly important for detrital grains like many of the lunar zircons found in samples returned by the Apollo missions. However, unlike their terrestrial counterparts, lunar zircons have potentially been exposed to billions of years of impact bombardment. Samples from terrestrial impact structures and impact shock experiments have revealed that deformation during an impact event produces melt and glass blebs that can mimic igneous melt inclusions in both morphology and composition. We have undertaken a geochemical and textural investigation of zircons from Apollo impact melt breccia 14311 to assess their formation mechanisms. The association of trapped melts with shock microtwins and monomineralic melt compositions suggests some inclusions formed as a result of the high pressures and temperatures of impact shock. All other inclusions in this study are associated with curviplanar features, planar features, crystal plastic deformation, or embayments (large regions in contact with adjacent melts or minerals) suggesting that they are not igneous melt inclusions. While these textures can be produced in tectonic environments, impacts are a likely formation mechanism since impacts are the main driver of tectonics on the Moon. The results of this study demonstrate that a combination of textural and compositional analyses can be employed distinguish between igneous melt inclusions and melt blebs in zircons from impact environments.

¹Ko Hashizume et al. (>10)
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.14175]
¹Faculty of Science, Ibaraki University, Mito, Japan
Published by arrangement with John Wiley & Sons

The nitrogen isotope compositions of two samples returned from the asteroid Ryugu were determined using a stepwise combustion method, along with Ivuna (CI) and Y-980115, a CI-like Antarctic meteorite, as references. The two Ryugu samples A0105-07 and C0106-07 showed bulk δ15N values of +1.7 ± 0.5‰ and +0.2 ± 0.6‰, respectively, significantly lower than Ivuna with +36.4 ± 0.4‰, but close to Y-980115 with +4.0 ± 0.3‰. The Ryugu samples are further characterized by C/N and 36Ar/N ratios up to 3.4× and 4.9× the value of Ivuna, respectively. Among all Ryugu samples and CI chondrites, a positive correlation was observed between nitrogen concentrations and δ15N values, with samples with lower nitrogen concentrations exhibiting lower δ15N. This trend is explained by a two-component mixing model. One component is present at a constant abundance among all CI-related samples, with a δ15N value around 0‰ or lower. The other varies in abundance between different samples, and exhibits a δ15N value of +56 ± 4‰. The first 15N-poor endmember is seemingly tightly incorporated into a carbonaceous host phase, whereas the 15N-rich endmember can be mobilized and decoupled from carbon, potentially because it is in the form of ammonia. Asteroid materials with volatile compositions that are similar to those reported here for the Ryugu samples are attractive candidates for the volatile sources among Earth’s building blocks.

^1,2Maree McGregor,^1,2John G. Spray,²Christopher R. M. McFarlane
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.14172]
¹Planetary and Space Science Centre, University of New Brunswick, Fredericton, New Brunswick, Canada
²Department of Earth Sciences, University of New Brunswick, Fredericton, New Brunswick, Canada
Published by arrangement with John Wiley & Sons

In situ LA-ICP-MS/MS U-Pb and Rb-Sr geochronology combined with geochemical analysis and electron microscopy have been performed on ejecta components sampled from the Mid-to-Late Triassic Mercia Mudstone Group at Churchwood Quarry, SW England. The layer comprises altered impact spherules, melt-rich and fragment-rich accreted grain clusters (AGCs), along with shocked mineral phases. Late Triassic ages are obtained: a U-Pb age of 219 ± 72 Ma from variably shock-metamorphosed apatite and a Rb-Sr age of 213 ± 31 Ma from melt-rich AGCs. A post-depositional U-Pb age of 200 ± 7.5 Ma obtained from the carbonate host matrix correlates with an early Jurassic dolomitization event associated with regional marine transgression. Several links to the Manicouagan impact structure, Canada, are identified that complement previous provenance studies: (1) rare earth element compositions of impact spherules and melt-rich AGCs match those of the Manicouagan impact melt sheet; (2) the preservation of Archean and Paleo- to Neoproterozoic target rock U-Pb ages in zircon and apatite match those recorded within Manicouagan basement lithologies; and (3) impact spherules and melt-rich AGCs record initial 87Sr/86Sr compositions that overlap with those of the Manicouagan impact melt sheet and the target rocks involved in their generation.

¹Lingxi Zhang,^1,2Xiaohui Fu,^1,2Zongcheng Ling,¹Erbin Shi,¹Haijun Cao
Journal Geophysical Research (Planets)(in Press) Link to Article [https://doi.org/10.1029/2023JE008157]
¹Shandong Provincial Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment, Institute of Space Sciences, Shandong University, Weihai, China
²CAS Center for Excellence in Comparative Planetology, Chinese Academy of Sciences, Hefei, China
Published by arrangement with John Wiley & Sons

Akaganeite and jarosite were detected in two mudstone drill samples from Vera Rubin ridge (VRR), Gale crater by Chemistry & Mineralogy X-Ray Diffraction (CheMin). The co-occurrence of these two minerals is quite rare in both terrestrial and Martian aqueous environments. In order to confine the chemical conditions of paragenetic akaganeite and jarosite, and provide insight into late-stage diagenetic alterations at VRR, we synthesized akaganeite and jarosite with varying SO42− concentrations and initial pH levels. Synthetic samples were characterized using Field Emission Scanning Electron Microscopy, X-ray powder diffraction and Raman spectroscopy. Our study reveals that akaganeite and jarosite exist in equilibrium in the solution with 0.011–0.028 M SO42− with respect to 0.6 M Cl− and an initial pH of 1.3–2.2. In combination with the CheMin detection results, the chemistry and pH values of the fluids at VRR can be further constrained. Considering the absence of goethite and the relative higher portion of akaganeite than jarosite in the drill samples, the pH values should be 1.4–2 and the S/Cl molar ratio should be within the range of 0.018–0.042. Based on our laboratory results, we hypothesize that the presence of akaganeite and jarosite at VRR represents an individual episode of acidic groundwater activity. During the late-stage diagenetic process at VRR, upwelled acidic groundwater dissolved the local chlorides to form the Cl−-dominated fluids. Subsequent evaporation further concentrated the acid saline fluids and therefore resulted in an extremely acidic environment (1.4 ≤ pH＜2 with S/Cl molar ratio of 0.018–0.042), which produced akaganeite and jarosite.

^1,2Ery C. Hughes,²Katherine de Kleer,²John Eiler,³Francis Nimmo,⁴Kathleen Mandt,⁵Amy E. Hofmann
Journal of Geophysical Research (Planets)(in Press) Open Access Link to Article [https://doi.org/10.1029/2023JE008086]
¹Te Pū Ao, GNS Science, National Isotope Centre and Avalon, Lower Hutt, Aotearoa New Zealand
²Division of Geological and Planetary Science, Caltech, Pasadena, CA, USA
³Earth & Planetary Sciences Department, University of California Santa Cruz, Santa Cruz, CA, USA
⁴NASA Goddard Space Flight Center, Greenbelt, MD, USA
⁵Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
Published by arrangement with John Wiley & Sons

Stable isotope fractionation of sulfur offers a window into Io’s tidal heating history, which is difficult to constrain because Io’s dynamic atmosphere and high resurfacing rates leave it with a young surface. We constructed a numerical model to describe the fluxes in Io’s sulfur cycle using literature constraints on rates and isotopic fractionations of relevant processes. Combining our numerical model with measurements of the 34S/32S ratio in Io’s atmosphere, we constrain the rates for the processes that move sulfur between reservoirs and model the evolution of sulfur isotopes over time. Gravitational stratification of SO2 in the upper atmosphere, leading to a decrease in 34S/32S with increasing altitude, is the main cause of sulfur isotopic fractionation associated with loss to space. Efficient recycling of the atmospheric escape residue into the interior is required to explain the 34S/32S enrichment magnitude measured in the modern atmosphere. We hypothesize this recycling occurs by SO2 surface frost burial and SO2 reaction with crustal rocks, which founder into the mantle and/or mix with mantle-derived magmas as they ascend. Therefore, we predict that magmatic SO2 plumes vented from the mantle to the atmosphere will have lower 34S/32S than the ambient atmosphere, yet are still significantly enriched compared to solar-system average sulfur. Observations of atmospheric variations in 34S/32S with time and/or location could reveal the average mantle melting rate and hence whether the current tidal heating rate is anomalous compared to Io’s long-term average. Our modeling suggests that tides have heated Io for >1.6 Gyr if Io today is representative of past Io.