The first geological map of the Hokusai quadrangle (H05) of Mercury

Jack Wright1, D. A. Rothery1, M. R. Balme1, S. J. Conway2

1School of Physical Sciences, The Open University, Milton Keynes, MK7 6AA, UK [email protected] 2CNRS UMR 6112, Laboratoire de Planétologie et Géodynamique, Université de Nantes, France @wrightplanet

H01 - Borealis [2] Geological mapping update complete H05 - Hokusai H04 - Raditladi H03 - Shakespeare H02 - Victoria MESSENGER data are being used to construct Jack Wright Paolo Mancinelli Laura Guzzetta Valentina Galluzzi [this work] [3] [4] [5] geological maps of Mercury (Fig. 1; refs 1–10). in progress H10 - Derain H09 - Eminescu H08 - Tolstoj H07 - Beethoven H06 - Kuiper These will provide science context and targets for Chris Malliband El Yazidi/Tognon Laura Guzzetta Laura Guzzetta Lorenza Giacomini [6] Beethoven [9] the ESA/JAXA BepiColombo mission [11,12], Rembrandt A. Lewang starting soon A. Semenzato [8] which launched in October 2018. Here we present H14 - Debussy [7] H13 - Neruda H12 - Michelangelo H11 - Discovery David Pegg Felix PruBe Valentina Galluzzi an update on this mapping effort (Fig. 2) and our [10] Anja Lentz unassigned geological map of H05 (below), which has been H15 - Bach submitted for publication in Journal of Maps (final Fig. 1. Mercury quadrangles and current Fig. 2. MESSENGER-era maps and mappers [1]. publication scale will be 1:3,000,000). status of MESSENGER-era maps [1].

Geological units Crater materials Geological units Present Smooth plains Geological map of the Hokusai quadrangle c 5 Kuiperian sp Sparsely cratered plains. Probably volcanic where areally extensive. Small patches perched within crater terraces/ejecta are probably impact melt. Intermediate plains 1:4,000,000 scale 1 Ga c4 Mansurian ip Patches of smooth material confined by high-standing rough material. Probably intercrater plains partially inundated by volcanic smooth plains. 0125 250 500 750 1,000 Intercrater plains 0° 90°E icp Heavily cratered plains with a rough, hummocky texture. km 2 Ga Probably volcanic plains that have been heavily reworked by impact cratering. 10°E cfs cfh Crater materials 80°E 20°E c3 c crater 60°N Calorian 5 70°E 3 Ga c5 Pristine craters with sharp rims and internal peaks. 30°E Textured ejecta blankets. Albedo rays present. 40°E 50°E 60°E 60°N sp ip? c4 crater c4 Well-preserved craters with sharp rims and internal peaks. c2 icp 4 Ga Tolstojan Textured ejecta blankets. Albedo rays absent. c 1 Pre-Tolstojan c3 crater Hokusai c3 Degraded craters with somewhat muted rims and internal peaks. Correlation of map units based on superposition Ejecta blankets present but not strongly textured. relationships in H05 and model ages from crater

c2 crater size-frequency distributions [13–17]. c2 Degraded craters. Rims mostly complete, but subdued. Rustaveli 50°N Peaks and distal ejecta rare. B O R E A L I S c1 crater c1 Extremely degraded craters indicated in topography. 50°N Map projection Rims highly incomplete or absent. Ejecta around largest examples only. Projection: Lambert Conformal Conic Degraded catenae dc Central meridian: 45°E Rims of smooth-floored crater chains (intermediate plains). Standard parallel 1: 30°N Smooth crater floor Standard parallel 2: 58°N cfs Smooth material confined to craters. Sousa Sphere radius: 2440 km Probably impact melt (c5), volcanic (c1/c2), or either/both (c3/c4). Hummocky crater floor P L A N I T I A Rough or cratered material confined within craters. 40°N cfh Probably original crater floor texture in c5/c4 craters. Probably degraded wall/floor material in c1–c3 craters. 40°N

Surface features Crater rays Hollows Catenae Secondary impact crater chains Faculae 30°N Putative pyroclastic deposits Copland 30°N We have worked with Galluzzi et al. to merge the H02 and H05 maps Nathair

Facula Unity Rupes 0° 90°E Hodgkins Rachmaninoff

Contacts 10°E Certain—confident location 80°E Approximate—uncertain location Faults + + Thrust—confident identification 20°E + + Thrust—uncertain identification Structures 70°E Crater rims Graben Found within volcanic crater fills 30°E Rim crest of crater (diam.≥ 20 km) 60°E Ridge 40°E 50°E Rim crest of crater (5 < diam. < 20 km) Found within volcanic crater fills Next steps Wrinkle ridge Rim crest of subdued or buried crater Contractional landform common within smooth plains - Work with Mancinelli et al. to merge the H04 and H05 maps Irregular pit Wrinkle ridge ring Putative volcanic vent Contractional landform located above buried impact crater - Update mapwork for V2 (final) BDR basemaps

References: [1] Galluzzi V. et al. (2019) Geophys. Res. Abs., 21, EGU2019-18802-1. [2] Ostrach L. R. et al. (2018) LPS XLIX, #1747. [3] Mancinelli P. et al. (2016) J. Maps, 12, 190–202. [4] Guzzetta L. et al. (2017) J. Maps, 12, 227–238. [5] Galluzzi V. et al. (2016) J. Maps, 12, 227–238. [6] Malliband C. C. et al. (2019) LPS L, #1807. [7] Semenzato A. et al. (2018) EPSC, 12, EPSC2018-344. [8] Acknowledgements: JW completed this work as part of his UK Science and Lewang A. et al. (2018), LPS XLIX, #1846. [9] Giacomini L. et al. (2018) EPSC, 12, EPSC2018-721-1. [10] Pegg D. L. et al. (2019) LPS L, #1271. [11] Benkhoff J. et al. (2010) Planet. Space Sci., 58, Technology Facilities Council funded PhD (grant ST/N50421X/1). JW's travel 2–20. [12] Rothery D. A. et al. (2010) Planet. Space Sci., 58, 21–39. [13] Marchi S. et al. (2013) Nature, 499, 59–61. [14] Whitten J. L. et al. (2014) Icarus, 241, 97–113. [15] Ostrach L. R. et al. (2015) and publication costs are supported by Planmap, an EU Horizon 2020 project Icarus, 250, 602–622. [16] Byrne P. K. et al. (2016) Geophys. Res. Lett., 43, 7408–7416. [17] Banks M. E. et al. (2017) J. Geophys. Res. Planets, 122, 1010–1020. (grant 776276). JW is grateful to Valentina Galluzzi for providing Figs 1 and 2. DAR and MRB are also supported by Planmap. SJC is supported by CNES.