Geology of the Bach quadrangle (H15), Mercury

Mercury's Bach quadrangle (H15) is the area poleward of 65°S. We mapped this geologically using remote sensing-based observations of surface morphology revealed on MESSENGER data products. This map contributes to a series of quadrangle maps providing geological context forthe ESA-JAXA BepiColombo mission to Mercury. We performed digitisation at ∼1:400,000 scale and final publication scale is 1:3,000,000. There are four morphologically distinct plains units: intercrater, intermediate, smooth, and very smooth. Impact craters cover much of H15's surface. Following convention, we mapped crater materials for all craters ≥20 km, classifying them on the basis of morphological evidence for degradation. We produced two map versions, using a three-class and a five-class crater degradation scheme. We include two geological aspects that have not featured in previous maps of the series, by mapping occurrences of lobate ejecta at craters ≥20 km and depicting the distribution of the south polar permanently shadowed regions.