Feldspathic rocks on Mars: Compositional constraints from infrared spectroscopy and possible formation mechanisms

Rare feldspar-dominated surfaces on Mars were previously reported based on near-infrared (NIR) spectral data and were interpreted to consist of anorthosite or felsic rocks. Using thermal infrared (TIR) data over the feldspar detections with the largest areal extent in Nili Patera and Noachis Terra, we rule out felsic interpretations. Basaltic or anorthositic compositions are consistent with TIR measurements, but the geologic contexts for these regions do not support a plutonic origin. Laboratory NIR spectral measurements demonstrate that large plagioclase crystals (\u3e~840 μm) can be detected in mixtures with as much as 50 vol % mafics, which is higher than the previously stated requirement of no more than 15% mafics. Thus, anorthositic or felsic interpretations need not be invoked for all NIR-based feldspar detections. Plagioclase-enriched basaltic eruptive products can be formed from Martian basalts through partial crystallization at the base of a thick crust, followed by low-pressure crystallization of the residual liquids

Identification and quantification of diffuse fresh submarine groundwater discharge via airborne thermal infrared remote sensing

Airborne thermal infrared (TIR) overflights were combined with shoreline radionuclide surveys to investigate submarine groundwater discharge (SGD) along the north shore of Long Island, NY between June 2013 and September 2014. Regression equations developed for three distinct geomorphological environments suggest a positive linear relationship between the rate of diffuse SGD and the spatial extent of the observed coastal TIR anomalies; such a relationship provides quantitative evidence of the ability to use TIR remote sensing as a tool to remotely identify and measure SGD. Landsat TIR scenes were unable to resolve any of the 18 TIR anomalies identified during the various airborne overflights. Two locations were studied in greater detail via 222Rn time series and manual seepage meters in order to understand why specific shoreline segments did not exhibit a TIR anomaly. SGD at the first site, located within a large, diffuse TIR anomaly, was composed of a mixture of fresh groundwater and circulated seawater with elevated levels of nitrate. In contrast, SGD at the second site, where no coastal TIR anomaly was observed, was composed of circulated seawater with negligible nitrate. Despite the compositional differences in seepage, both sites were similar in discharge magnitude, with average time series 222Rn derived SGD rates equal to 18 and 8 cm d−1 for the TIR site and non-TIR site, respectively. Results suggest that TIR remote sensing has the ability to identify locations of a mixture between diffuse fresh and circulated seawater SGD. If TIR anomalies can be demonstrated to represent a mixture between fresh and circulated seawater SGD, then the cumulative area of the TIR anomalies may be used to estimate the fresh fraction of SGD relative to the cumulative area of the seepage face, and thus allows for improved SGD derived nutrient flux calculations on a regional scale

Visible, Near-Infrared, and Mid-Infrared Spectral Characterization of Hawaiian Fumarolic Alteration Near Kilauea's December 1974 Flow: Implications for Spectral Discrimination of Alteration Environments on Mars

The December 1974 flow in the SW rift zone at Kilauea Volcano, Hawaii, has been established as a Mars analog due to its physical, chemical, and morphological properties, as well as its interaction with the outgassing plume from the primary Kilauea caldera. We focus on a solfatara site that consists of hydrothermally altered basalt and alteration products deposited in and around a passively degassing volcanic vent situated directly adjacent to the December 1974 flow on its northwest side. Reflectance spectra are acquired in the visible/near-infrared (VNIR) region and emission spectra in the mid-infrared (MIR) range to better understand the spectral properties of hydrothermally altered materials. The VNIR signatures are consistent with silica, Fe-oxides, and sulfates (Ca, Fe). Primarily silica-dominated spectral signatures are observed in the MIR and changes in spectral features between samples appear to be driven by grain size effects in this wavelength range. The nature of the sample coating and the thermal emission signatures exhibit variations that may be correlated with distance from the vent. Chemical analyses indicate that most surfaces are characterized by silica-rich material, Fe-oxides, and sulfates (Ca, Fe). The silica and Fe-oxide-dominated MIR/VNIR spectral signatures exhibited by the hydrothermally altered material in this study are distinct from the sulfate-dominated spectral signatures exhibited by previously studied low-temperature aqueous acid-sulfate weathered basaltic glass. This likely reflects a difference in open vs. closed system weathering, where mobile cations are removed from the altered surfaces in the fumarolic setting. This work provides a unique infrared spectral library that includes martian analog materials that were altered in an active terrestrial solfatara (hydrothermal) setting. Hydrothermal environments are of particular interest as they potentially indicate habitable conditions. Key constraints on the habitability and astrobiological potential of ancient aqueous environments are provided through detection and interpretation of secondary mineral assemblages; thus, spectral detection of fumarolic alteration assemblages observed from this study on Mars would suggest a region that could have hosted a habitable environment

Neonatal brain tissue classification with morphological adaptation and unified segmentation

Measuring the distribution of brain tissue types (tissue classification) in neonates is necessary for studying typical and atypical brain development, such as that associated with preterm birth, and may provide biomarkers for neurodevelopmental outcomes. Compared with magnetic resonance images of adults, neonatal images present specific challenges that require the development of specialized, population-specific methods. This paper introduces MANTiS (Morphologically Adaptive Neonatal Tissue Segmentation), which extends the unified segmentation approach to tissue classification implemented in Statistical Parametric Mapping (SPM) software to neonates. MANTiS utilizes a combination of unified segmentation, template adaptation via morphological segmentation tools and topological filtering, to segment the neonatal brain into eight tissue classes: cortical gray matter, white matter, deep nuclear gray matter, cerebellum, brainstem, cerebrospinal fluid (CSF), hippocampus and amygdala. We evaluated the performance of MANTiS using two independent datasets. The first dataset, provided by the NeoBrainS12 challenge, consisted of coronal T2-weighted images of preterm infants (born ≤30 weeks’ gestation) acquired at 30 weeks’ corrected gestational age (n= 5), coronal T2-weighted images of preterm infants acquired at 40 weeks’ corrected gestational age (n= 5) and axial T2-weighted images of preterm infants acquired at 40 weeks’ corrected gestational age (n= 5). The second dataset, provided by the Washington University NeuroDevelopmental Research (WUNDeR) group, consisted of T2-weighted images of preterm infants (born <30 weeks’ gestation) acquired shortly after birth (n= 12), preterm infants acquired at term-equivalent age (n= 12), and healthy term-born infants (born ≥38 weeks’ gestation) acquired within the first nine days of life (n= 12). For the NeoBrainS12 dataset, mean Dice scores comparing MANTiS with manual segmentations were all above 0.7, except for the cortical gray matter for coronal images acquired at 30 weeks. This demonstrates that MANTiS’ performance is competitive with existing techniques. For the WUNDeR dataset, mean Dice scores comparing MANTiS with manually edited segmentations demonstrated good agreement, where all scores were above 0.75, except for the hippocampus and amygdala. The results show that MANTiS is able to segment neonatal brain tissues well, even in images that have brain abnormalities common in preterm infants. MANTiS is available for download as an SPM toolbox from http://developmentalimagingmcri.github.io/mantis

Thermal Infrared and Raman Microspectroscopy of Moganite-bearing Rocks

We present the first thermal infrared reflectance spectral characterization of moganite and mixtures of moganite with microcrystalline quartz. We find that for relatively high (\u3e50%) abundances of moganite, the absolute reflectance for samples is significantly reduced. Using microscopic-Raman (~1 μm/pixel) measurements, we estimate the moganite content for various samples. We then compare Raman-derived moganite abundances with microscopic infrared reflectance (25 μm/pixel) spectra to determine the effects of increasing moganite abundance on thermal infrared spectra. We find that moganite is broadly spectrally similar to quartz with major reflectance maxima located between ~1030 and 1280 cm−1 and ~400 and 600 cm−1; but there are characteristic differences in the peak shapes, peak center positions, and especially the relative peak reflectance magnitudes. For regions with high (\u3e50%) moganite content, the relative magntitudes of the reflectance maxima at 1157 and 1095 cm−1(R1095/R1157 band ratio) can be used to estimate the moganite content. This work demonstrates the utility of thermal infrared microspectroscopy in isolating phases that are intimately mixed in a sample, and has applications in planetary science, where constituent phases of quartz-rich sedimentary rocks can be identified using remote or in situ thermal infrared spectroscopy

Surface mineralogy of martian low-albedo regions from MGS-TES data: Implications for crustal evolution and surface alteration

Mars Global Surveyor Thermal Emission Spectrometer (MGS-TES) data are used to derive the modal mineralogy of spectrally distinct Martian low-albedo regions and to identify spatial trends in mineralogic assemblages. Results from this work are consistent with the major results of previous spectroscopic studies: (1) Plagioclase and clinopyroxene are the dominant minerals of most southern highlands regions, (2) the northern plains exhibit the lowest pyroxene abundance within Martian low-albedo regions, and (3) the highest concentrations of high-silica phase(s) are found in the northern plains, Solis Planum and a few southern high-latitude regions. Low-albedo regions may be classified into four units on the basis of relative abundances of plagioclase, pyroxene, and high-silica phase(s). Unit distributions between ±45° latitude exhibit moderate correlation with distinct provinces (e.g., Syrtis Major, Aonium Sinus) defined by large-scale morphology, elevation, and to some extent, surface age, suggesting that the spectral and compositional differences between these units are more strongly controlled by original bedrock mineralogy than by surface-atmosphere interactions and alteration. Syrtis Major exhibits a difference in mineralogy from the surrounding highlands suggesting a differing degree of fractional crystallization, assimilation, or source region composition. Areas with thick crust near the Tharsis Plateau exhibit lower abundances of olivine and greater plagioclase/pyroxene ratios than surrounding highland terrains, suggesting that magmas in this region may have undergone increased olivine fractionation. Regions where surface alteration is more likely to be the primary control on observed spectral signatures are the high-latitude areas (\u3e45°), where globally, surfaces dominated by high-silica phase(s) are most commonly found

Closing Gap in Digital Divide of the Vulnerable Women in the Community via Assistive Technology: The Chromebook

Aims to address the gap in digital division by providing low-income individuals with essential computer skills. These individuals are currently facing health challenges due to economic constraints, limited access to healthcare services, and overall lack of familiarity in digital literacy. At Wellspring Women’s Center, nearly 200 individuals are affected by this issue. The Chromebook could be delivered in a flexible model such as in-person workshops, online tutorials, and 1:1 mentoring. This approach ensures accessibility and empowerment of the participants to develop essential digital literacy skills to promote independence in their own health management. The Chromebook can open gates to enhancing digital health literacy and access to health care. Additionally, to achieve overall quality of life and well-being of the underserved communities while fostering a sense of self-sufficiency, digital empowerment, and inclusivity

Thank You to Our 2020 Peer Reviewers

International audiencePeer reviewing is the selfless act of evaluating and providing feedback on scientific papers submitted in journals like JGR: Planets. Every review is written with the objective of clarifying the article and often contains suggestions for additional analyses or topics of discussion. Reviewers often spend hours examining the rigor of the methods, the validity of the results, and the significance of the conclusions in the submitted manuscripts. The extra effort of our pool of reviewers in a year when we all needed to adjust our daily routines in response to a pandemic has not gone unnoticed. In 2020, JGR: Planets benefited from 1,168 reviews provided by 705 unique reviewers. We are particularly grateful to the scientists who remained involved in the review process. We also understand that many of us had to reduce our reviewing commitment this year. Hopefully, the coming year will see a return to normalcy in your lives. To our reviewers, past, present, and future, the entire editorial board of JGR: Planets wishes to express here our most heartfelt gratitude. Thank you

Quantitative Compositional Analysis of Sedimentary Materials Using Thermal Emission Spectroscopy: 1. Application to Sedimentary Rocks

Thermal emission spectroscopy is used to determine the mineralogy of sandstone and mudstone rocks as part of an investigation of linear spectral mixing between sedimentary constituent phases. With widespread occurrences of sedimentary rocks on the surface of Mars, critical examination of the accuracy associated with quantitative models of mineral abundances derived from thermal emission spectra of sedimentary materials is necessary. Although thermal emission spectroscopy has been previously proven to be a viable technique to obtain quantitative mineralogy from igneous and metamorphic materials, sedimentary rocks, with natural variation of composition, compaction, and grain size, have yet to be examined. In this work, we present an analysis of the thermal emission spectral (~270–1650 cm−1) characteristics of a suite of 13 sandstones and 14 mudstones. X-ray diffraction and traditional point counting procedures were all evaluated in comparison with thermal emission spectroscopy. Results from this work are consistent with previous thermal emission spectroscopy studies and indicate that bulk rock mineral abundances can be estimated within 11.2% for detrital grains (i.e., quartz and feldspars) and 14.8% for all other mineral phases present in both sandstones and mudstones, in comparison to common in situ techniques used for determining bulk rock composition. Clay-sized to fine silt-sized grained phase identification is less accurate, with differences from the known ranging from ~5 to 24% on average. Nevertheless, linear least squares modeling of thermal emission spectra is an advantageous technique for determining abundances of detrital grains and sedimentary matrix and for providing a rapid classification of clastic rocks