A Correlation Study on Volcanic Features and their Geological Context on Mercury.

Abstract

The Planet Mercury has been studied by the earlier MESSENGER mission which results show that Mercury’s history is expressed by: (i) volcanism, (ii) global contraction with consequent formation of tectonic-compressive features, and (iii) impact cratering with consequent formation of basins or minor craters [e.g., 1, 2]. However, it is still unclear how the interplay between tectonic induced by impact basins and compressional activity has influenced volcanism. Thus, we investigated the presence and the absence of a correlation between the various volcanic features and their geological context (e.g., inside craters and/or basins, relationship with tectonic structures) to understand which processes could have influenced the volcanic activity of the planet. The study was developed using the ESRI ArcGIS (Geographic Information System) software package. The data and base maps used in the main part of the project come from the MESSANGER mission. To carry out the correlation study on a global scale, a new GIS database was created in which all the volcanic structures identified so far on Mercury, their morphological characteristics and their associations with various other tectonic or volcanic have been specified. Specifically, we included 346 samples comprehensive of (i) volcanic vents and their morphological classification [3, 4], (ii) presumed volcanic cones [5], and (iii) irregular pitted terrains [6, 7]. Once this global database was created, the study was divided into two parts. The first qualitative part was based on the study of the global distribution of the volcanic features considered concerning the basin structures [8] and global compressional tectonic features [9]. This part allowed us to identify patterns and areas of interest for more detailed observations and analyses. A second quantitative part evaluated the presence of a correlation between the different parameters and geological features considered. Our study has highlighted how the majority of these volcanic centers are distributed on the margins of large basins whether they were formed inside or outside craters. The studied volcanic features are also often related to compressive tectonic structures at distances ranging from 10 to 200 km. Explosive volcanic activity on a global scale seems to have been triggered mainly in areas where minor impacts were formed near critically stressed tectonic basin structures (caused by the large impact) reactivated by the global compression. Dike propagation along those areas has likely caused the explosive eruptions in weaker areas often triggered by smaller impacts.