Annual Report for 2015 Shawn Wright
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Annual Report for 2015 Shawn Wright Research Scientist I. Research NASA Award Number: NNX14AP52G Program and Title: Planetary Geology and Geophysics; Alteration Trends in a Full Range of Shocked Basalt: Comparison to Unshocked Basalts and Ejecta Localities from Field and Remote Mapping Sample/Laboratory Research: The goals of Year 1 are to characterize a range of shocked basalt with laboratory analyses prior to, as the grant title suggests, comparing the alteration products to unshocked basalt. Using the sample data (listed below) acquired, a spreadsheet has been developed that organizes the 1.) primary igneous minerals, 2.) secondary alteration minerals, 3.) clays and Fe-bearing minerals in the first two categories (for future work in Year 3 with remote VNIR data), and 4.) impact glasses (e.g., maskelynite up to complete impact melt) [Wright, 2015; Jaret et al., 2015]. 60 thin sections / petrography 30 X-Ray Florescence (XRF) geochemical data 100+ X-Ray Diffraction (XRD) patterns for mineralogy 5 with Scanning Electron Microscope (SEM) Results of Sample Analyses The thin section have shown that the majority of Wright’s collection of 200 intermediately shocked basalts are Class 2, or maskelynite-bearing like the shergottites. An interesting find were of two shocked (basaltic) soils in the sample collection; these will likely be the topic of a short, GRL-type paper, as literary research has suggested to the PI that these shocked soils have not been found at the other ~180 known impact sites. The XRF data, when compared to XRD mineralogy, show increased iron and different amounts of reduced or oxidized iron in some samples; this is being investigated to compare to mineralogy. XRD patterns have revealed a wealth of secondary alteration minerals and primary igneous minerals. The amorphous character of the impact glasses has been noted. See Figure 1 for a comparison of XRD patterns of impact melt versus a soil in Gale Crater, suggesting that impact glasses could be a part of the Martian soil. Back-scattered electron (BSE) images of altered, shocked basalt have shown “feathery” textures indicative of clays (Figure 2) that are difficult to see with petrography and XRD, as these materials have poor optical properties and sometimes weaker peaks in XRD data than well-crystalline, primary igneous minerals. Figure 1. MSL CheMin data of Rocknest sands from the PDS compared to laboratory XRD data of a highly shocked “Class 5” impact melt from Lonar Crater. Both XRD patterns have a broad hump (region highlighted in gray) indicative of amorphous component. The amorphous component of the Lonar impact melt is shock-melted basaltic glass. Figure 2. BSE image of a Class 2 shocked basalt of an altered protolith showing “feathery” alteration texture. Scale bar measures 1 mm. Fieldwork Per the goals of the grant, Wright returned to Lonar Crater, India in late December of 2015, and located clasts of shocked baked zones and more shocked soils. More Class 3 and probable Class 4 clasts were sampled as well, in addition to suevite matrix and pre-impact soil for comparison. The locations of suevite outcrops were mapped as well as at least seven different categories of lobes of unshocked basalt in a lithic breccia layer. II. Publications Jaret, S.J., Woerner, W.R., Phillips, B.L., Ehm, L., Nekvasil, H., Wright, S.P. and T.D. Glotch (2015) Maskelynite formation via solid-state transformation: Evidence of infrared and X-ray anisotropy, Journal of Geophysical Research: Planets, Vol. 120, issue 3, pp doi: 10.1002/2014JE004764 Wright, S.P. and S.M. Bales (2015) Microbial Diversity Analyses of Terrestrial Shocked Basalt and Shocked Basaltic Soil: Implications for Panspermia and Future Exobiology Measurements, 46th Lunar and Planetary Science Conference, #2758. Wright, S.P. (2015) Lonar Crater, India: An Analog for Mars in the Field and in the Laboratory, 46th Lunar and Planetary Conference, #2912. Wright, S.P. and S.M. Bales (2015) The Potential for Lonar Crater, India to be an Analog for Exobiology Suggested by Early Microbial Diversity Analyses of Shocked Basalt and Shocked Basaltic Soil, Astrobiology Science Conference 2015, #7694. Farrand, W.H., S.P. Wright, and T.D. Glotch (2015) Characterization of altered and minimally altered basaltic glasses using visible-thermal infrared spectroscopy, X-ray diffraction, and Raman spectroscopy, Lunar and Planetary Science Conference, #2409. Jaret, S.J., Glotch, T. D., Phillips, B. L., Wright, S. P., and D.T. King, Jr. (2015) Coesite at the Lonar Crater: The Importance of Pre-Impact Alteration and Shock Heterogeneity, 46th Lunar and Planetary Science Conference, #2086. III. Awards and Honors Wright was acknowledged by Elsevier for being a Recognized Reviewer in 2015 for reviewing several journal manuscripts. IV. Service to the Science Community Panel reviewer for nspires / ROSES programs Journal reviews for Icarus, Meteoritics and Planetary Science, and JGR-Planets V. Public Outreach While teaching a Geology course in Houston, Texas, Wright took the classes on several field trips around campus and to Galveston Bay .