Annual Report for 2016

Shawn Wright Research Scientist

I. Research

1.) Grant/Cooperative Agreement Number: NNX16AN26G

Program and Title: Topical Workshops, Sessions, and Conferences; Assembling Evidence of Impact at Highly Deformed Impact Craters: A Workshop with Field Trips to the Santa Fe Impact Structure, New Mexico

Wright was funded to organize a workshop concurrent with the Meteoritical Society Annual Meeting in Santa Fe, New Mexico. Three invited speakers have been invited for 20 minute talks on the morning of Sunday, July 23rd, 2017 before a post-lunch field trip looking at shatter cones and breccias of the Santa Fe impact structure. The workshop is designed to educate meteoriticists and lunar/martian geologists on the field geology of old, degraded impact structures and sorting out the regional geologic history amidst the impact event. A second field trip will be held on Wednesday of the MetSoc conference as an optional field trip.

2.) 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

In Year 2, PI Wright went to Lonar Crater, India for fieldwork and sample collection. In 2.5 weeks of fieldwork, Wright noted the locations of suevite breccia, lithic breccia, and categorized the alteration of several dozen lobes of lithic breccia alteration into 12 categories of secondary alteration mineralogy. These categories reflect the pre-impact alteration before the “block” of that pre-impact strata (from depth) was ejected and emplaced into its current position in the Lonar ejecta blanket. A few examples include hematite, zeolite, chlorite, celadonite, calcite, and quartz. In India, Wright also discussed preservation of the crater and ejecta with several local and regional politicians. Retired USGS scientist Dan Milton, at 80 years old, joined Wright in the field for five days. Milton, who authored and co-authored several Lonar papers in the ‘70’s, commended Wright on his knowledge of Lonar ejecta and samples.

An incidental, but noteworthy, discovery was made. Spall off of the continuous ejecta blanket was located by noting the fractured appearance of odd boulders south of the ejecta (Figure 1), and petrography months later confirmed that these boulders are shocked to shock Class 1 (Figure 2) [Kieffer et al., 1976; Wright et al., 2011]. These samples will be carefully archived with details on their location to promote use of these Class 1 spall samples for further research and to suggest protection of the area by the Indian Department of Forest. Wright describes these spall in a GSA abstract [Wright, 2016b]. Wright will work with impact modeler/ physicist Brandon Johnson of Brown University in a 2017 LPSC abstract to 1.) calculate the velocity as the boulder left the spall zone and traveled in a parabolic path to its current location and perhaps 2.) constraints on the shock pressure received by the spall. A second discovery is that of shocked soil (Figure 1 below).

A large GIS/GPS database with basically every VNIR and TIR dataset of Lonar Crater is being merged with Wright’s GPS field data and two different 3-D DEM’s (30-m ASTER and a higher resolution using GPS points from Maloof et al., 2010). This will be used to create a geologic map (an Ejecta Outcrop Map similar to Shoemaker’s at Meteor Crater) of the lobes described above and submitted to both the PDS and USGS map databases.

Thirty more thin sections of shocked and altered basalts were created in Year 2. About twelve are altered basalts shocked to Class 1 pressures as the PI wished to find these in the sample collection while also studying alteration. XRF data and XRD data of 35 samples were collected and their amorphous geochemistries are being examined in a manner similar to the methodology used by the MSL CheMin and APXS teams.

The goals of the grant 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).

30 thin sections / petrography 35 X-Ray Florescence (XRF) geochemical data 35+ X-Ray Diffraction (XRD) patterns for mineralogy 5 with Scanning Electron Microscope (SEM)

Per the goals of the grant, Wright returned to Lonar Crater, India in late December of 2016, and field-mapped precise locations of several types of pre-impact altered basalts. 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 twelve different categories of lobes of unshocked basalt in a lithic breccia layer.

Figure 1. Back-scattered electron (BSE) image of shocked soil (Wright, 2016b). Three inclusions or “clasts” of unshocked soil can be seen from left to right across the center of the left image. The right image shows the first two of three in higher resolution. Note devitrified texture of unshocked soil in contrast to flowing glass throughout the BSE image.

References:

Kieffer et al. (1976) Shocked basalt from Lonar impact crater, India, and experimental analogues, Proceed. 7th Lun. Plan. Sci. Conf., 1391-1412.

Maloof et al., (2010) Geology of Lonar Crater, India, Geol. Soc. Am. Bull., 122, pp. 109–126.

Wright et al. (2011) Thermal emission spectroscopy of shocked basalt from Lonar Crater, India: Implications for Mars orbital, rover, and laboratory data, JGR-Planets, 116, doi:10.1029/2010JE003785.

II. Publications

Peer-reviewed articles:

Farrand, W. H., S. P. Wright, A. D. Rogers, and T. D. Glotch (2016), Basaltic Glass formed from Hydrovolcanism and Impact Processes: Characterization and Clues for Detection of Mode of Origin from VNIR through MWIR Reflectance and Emission Spectroscopy, Icarus, 275, 16-28, doi:10.1016/j.icarus.2016.03.027.

Jaret, S.J., B.L. Phillips, D.T. King, Jr., T.D. Glotch, Z. Rahman, and S.P. Wright (2016) An Unusual Occurrence of Coesite at the Lonar Crater, India, Meteoritics and Planetary Science, MAPS-2561, doi: 10.1111/maps.12745

Abstracts and extended abstracts:

Wright, S.P. (2016a) Shocked Soils and Baked Zones from a Basaltic Target Provide Insight into Mars Sample Return Goals and Detections of Impact Glass, Lunar and Planetary Science Conference, #1001.

Wright, S.P. (2016b) Spall at Lonar Crater, India, Geological Society of America Annual Meeting, abstract 280700.

Wright, S.P. (2016c) Lonar Crater, India: Analog for Mars in the field and in the laboratory, Mars Polar Conference 2016, abstract #6042.

III. Awards and Honors

Wright was acknowledged by Elsevier for being a Recognized Reviewer in 2016 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 in the spring of 2016.

Throughout the summer and fall, Wright mentored an undergraduate student on research through the Planetary Geology and Geophysics Undergraduate Research Program.

Wright was a guest on the Pittsburgh channel 11 PCNC nighttime talk show “Night Talk”, where the host and Wright discussed humans to Mars in 2030.

In India, Wright guest lectured in Mumbai at St. Xavier’s College, met geology students and architects/archeologists in Pune and at Lonar Crater, and discussed Mars science with geology students from the Indian Institute of Technology Bombay geology department while in Mumbai.