Stratigraphy of the Caloris basin, Mercury

Geology of the Victoria quadrangle (H02), Mercury

“…These craters often have a hummocky and densely cratered floor. This class approximately corresponds to M10/C2 to M10/C1 craters of McCauley et al (1981). Type-areas: 310.3°E, 30.80°N (Figure 3(a)); 289.3°E, 36.4°N (Figure 3(d)).…”

“…Arthur, Agnieray, Horvath, Wood, & Chapman, 1963;Baker & Head, 2013;Cintala, Head, & Mutch, 1976;Leake, 1982;McCauley, Guest, Schaber, Trask, & Greeley, 1981;Pohn & Offield, 1970;Spudis & Guest, 1988;Wood, 1979;Wood & Anderson, 1978;Wood, Head, & Cintala, 1977). The M10 geological mapping project used a crater classification system with five classes of craters (McCauley et al, 1981): M10/C1 are the oldest and most degraded craters, while M10/C5 are the youngest and least degraded craters. The ascending class order from subdued to crisp craters was chosen to reflect a normal stratigraphic order.…”

Volcanism on Mercury: Evidence from the first MESSENGER flyby for extrusive and explosive activity and the volcanic origin of plains

“…1) are volcanic in origin. Other color and crater size-frequency distribution relationships suggest that large areas near the basin rim are unlikely to be Cayley-like ponded ejecta deposits (they are younger than the basin fill), and that at least some of the units interpreted to be related to the emplacement of Caloris basin ejecta (such as the Odin Formation; McCauley et al, 1981;Spudis and Guest, 1988) may instead be volcanically resurfaced or volcanic in origin. Large impact craters show a sequence of embayment of interior floor and exterior ejecta deposits that supports a volcanic origin for filling material.…”

“…The major units interpreted to be the deposits associated with the formation of the~1550-km-diameter Caloris impact basin were defined by McCauley et al (1981) as the Caloris Group and are summarized in Spudis and Guest (1988): mountain material (Caloris Montes Formation), intermontane plains (Nervo Formation), hummocky plains (Odin Formation), and lineated plains (Van Eyck Formation). A major question posed by the Mariner 10 results was an impact versus volcanic origin of smooth plains exterior to the Caloris basin ( Fig.…”

“…Furthermore, crater densities on the broad smooth plains regions proximal to the Caloris rim, and on parts of the Odin Formation, are considerably below those on the interior plains of Caloris . These relationships suggest that these units are unlikely to be Cayley-like ponded ejecta deposits (they are younger than the basin fill), and that at least some of the units interpreted to be related to the emplacement of Caloris basin ejecta (such as the Odin Formation; McCauley et al, 1981;Spudis and Guest, 1988) may instead be volcanically resurfaced or of volcanic origin. Further analysis of MDIS color data and more detailed crater size-frequency distribution studies are needed to: (1) map additional exterior deposits (Figs.…”