OH/H 2 0 Enhancements associated with Some Silicic Volcanism as detected by M 3

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1 OH/H 2 0 Enhancements associated with Some Silicic Volcanism as detected by M 3 Noah Petro LEAG Annual Meeting 2014 October 23, 2014 H/T Carlé Pieters, Rachel Klima, Brad Jolliff, Lillian Ostrach, Tim Glotch, Josh Bandfield

2 It all starts with Roger Clark Clark et al. (2011) Wet vs. Dry Moon workshop

3 Bullialdus Crater (Klima et al., 2013) Clark et al. (2011) Wet vs. Dry Moon workshop

4 OH/H 2 O with M 3 Polar water detection (Pieters et al., 2009; Clark et al., 2012) Bullialdis Central Peak (80 ppm +/- 40 ppm) [Klima et al., 2013]

5 Compton-Belkovich Lunar Prospector Thorium Thorium enhancement measured by LP Silicic volcanic complex, ~20 x 30 km Morphological evidence for small domes and collapse features Offset of Th due to a pyroclastic eruption? (Jolliff et al., 2011; Wilson et al.,2014?) Alpha Dome

6 M 3 Perspective: Data taken while Chandrayaan-1 at 200 km M3G T nm ~3µm Band Strength Ratio A ratio of two bands (2616µm and 2816 µm, B74/B79) highlights ~3 µm feature.

7 3µm Absorption at CB Where it is M3G T ~3µm Band Strength Ratio LROC NAC ROI Mosaic -CompBelkLoB 500m

8 3µm Absorption at CB Where it isn t M3G T ~3µm Band Strength Ratio Alpha Dome Blocky Dome LROC NAC ROI Mosaic -CompBelkLoB 500m

9 What is at and around 3µm? Pieters et al Model near-infrared reflectance spectra of H 2 O and OH applicable for lunar comparisons. A model of a thin layer of H 2 O water (red) and ice (blue) on a 10% reflective surface equivalent to ~1000-ppm abundance is distinct from anorthite (green) and a lunar glass analog (black). The shaded area extends beyond the spectral range of M 3.

10 Detection of OH/H 2 O at C-B Stronger 3µm absorption associated with C-B relative to surroundings Strongest absorptions are associated with craters, some seemingly fresh craters, but not all fresh craters Blocky areas have weakest absorptions in region ~3µm Band Depth Ratio LROC NAC ROI Mosaic -CompBelkLoB 500m

11 What is the origin of the 3µm feature at Compton-Belkovich? Data artifact, the result of thermal correction in the M 3 L2 data Not an artifact: Is there a property of the regolith at C-B relative to its surroundings? Is it due to composition and preferential trapping of OH/H 2 O? Endogenic?

12 OH/H 2 O in Direct Association with C-B Compton-Belkovich is enhanced in OH/H 2 O relative to its surroundings C-B is indistinct from its surroundings in temperature, rock abundance, and upper regolith thickness (Diviner) 750 nm ~3µm Band Ratio C-B does have a distinct radar signature, is rock-free, consistent with large pyroclastic deposits OH concentration is conservatively ~ ppm above than the surroundings LAMP also sees something in the FUV associated with C-B (Hendrix et al., 2013)

13 Dufay Albdeo Anomaly Bright diffuse region north of main Thorium enhancement (Dewar) Appears to be thin deposit with some small craters excavating through

14 Mandel'shtam F 30 km

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18 Diviner CF Map Dufay Albdeo Anomaly Bright diffuse region north of main Thorium enhancement Appears to be thin deposit with some small craters excavating through ~3µm Band Ratio

19 Dufay Albdeo Anomaly Bright diffuse region north of main Thorium enhancement Appears to be thin deposit with some small craters excavating through ~3µm Band Ratio m3g t090105

20 Hansteen Alpha Identified in Earth-based spectra as a red spot Glotch et al. (2010) showed that it is silicic Lawrence et al. (2005) modeled a Th abundance of ~25 ppm M3G T Lat: Lon: -50.2

21 M 3 View of Hansteen Alpha A ratio of two bands (2616µm and 2816 µm, B74/B79) M3G T190900_V01_RFL

22 What is at and around 3µm? Pieters et al Model near-infrared reflectance spectra of H 2 O and OH applicable for lunar comparisons. A model of a thin layer of H 2 O water (red) and ice (blue) on a 10% reflective surface equivalent to ~1000-ppm abundance is distinct from anorthite (green) and a lunar glass analog (black). The shaded area extends beyond the spectral range of M 3.

23 Is This Feature a Result of the Level 2 Processing?

24 Is This Feature a Result of the No Level 2 Processing? Feature is there in Level 1B data, pre thermal removal (I/F or Apparent Reflectance) Appears in multiple Optical Periods

25 What s going on? I m misinterpreting something (as is Klima et al.) We re seeing OH/H 2 O in direct association with silicic volcanic (possibly pyroclastics) at two similar features (C-B and Hansteeen Alpha) and the deposit (pyroclastic?) near Dufay Not all silicic volcanoes (Lassell Massif, Marian Domes) or Th hotspots (SPA) have such features Perhaps a slight enhancement at the Gruithuisen Domes C-B Dufay Hansteen Alpha

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