Preliminary results of Tolstoj quadrangle (H08) geological mapping

Tolstoj quadrangle is located in the equatorial area of Mercury, between 22.5°N and 22.5°S of latitude and 144° and 216°E of latitude. In this work we present the preliminary results of a geological map (1:3M scale). The main basemap used for the mapping is the MDIS (Mercury Dual Imaging System) 166 m/pixel BDR (map-projected Basemap reduced Data Record) monochrome mosaic compiled using NAC (Narrow Angle Camera) and WAC (Wide Angle Camera) 750 nm-images. Moreover, to distinguish spectral characteristics and topography of the surface, MDIS global color mosaics (Denevi et al., 2016) and the MDIS global DEM (Becker et al., 2009), have been taken into account. Then, the quadrangle has been mapped using ArcGIS at an average scale of 1:400k for a final out-put of 1:3M. So far, most of the geological contacts and lineaments of Tolstoj quadrangle have been mapped. The preliminary geological map shows the Caloris basin-related features dominating the Tolstoj quadrangle. The southern half of the basin is located in the upper left corner of quadrangle and interior and exterior smooth plains of the Caloris basin are the most extended volcanic deposits emplaced in the area. Also structural framework is mainly linked with the basin with radial and concentric grabens located in its floor and wrinkle ridges widespread both on the interior and exterior Caloris smooth plains. Further, thrusts have been detected on the quadrangle. They are located outside the Caloris basin but they are absent within its floor. Besides smooth plains, products of effusive volcanism, features related to explosive volcanism are also frequently detected. Interestingly, several volcanic vents have been identified in the inner Caloris smooth plains, aligned with the rim of Caloris basin. They were surrounded by extended pyroclastic deposits appearing in bright yellow in MDIS enhanced global color mosaics. However, vents are not clustered only inside Caloris basin, but other crater floors are affected by this type of features. Finally, few hollow fields have been detected, mainly located within crater floors.

Once the mapping activity is accomplished, the geological map will be integrated into the global 1:3M geological map of Mercury (Galluzzi et al., 2021), which is being prepared in support to ESA/JAXA (European Space Agency, Japan Aerospace Agency) BepiColombo mission.

 

Acknowledgements:  We gratefully acknowledge funding from the Italian Space Agency (ASI) under ASI-INAF agreement 2017-47-H.0

 

References:

Becker K. J., et al. AGU, Fall Meeting, ab-stract#P21A-1189, 2009

Denevi et al.:LPS XLVII. Abstract#1264, 2016

Galluzzi V. et al.:. Planetary Geologic Mappers 2021, LPI #2610, 2021