Preliminary geologic terrain map of Mercury

Abstract

A geologic terrain map of Mercury has been constructed by use of the photogeologic methods employed for the moon and Mars. The oldest and most widespread unit, intercrater plains, forms nearly level to rolling surfaces on which are superposed numerous secondary impact craters. This unit may represent a very old surface that predates the last heavy bombardment of the inner planets. The effects of this bombardment are recorded in a second widespread unit, heavily cratered terrain, consisting of closely spaced craters and basins from 30 km to several hundred kilometers in diameter. Units formed by excavation of the 1300‐km‐diameter Caloris basin are widespread on one hemisphere of the planet. The development of the Caloris basin was followed relatively quickly by emplacement of widespread plains materials, most of which are probably volcanic. Younger craters, including some with rays, followed emplacement of the plains; they are much less abundant than the preplains craters. The geologic history of Mercury is remarkably similar to that of the moon.

Geology of the Victoria quadrangle (H02), Mercury

“…In their first geologic map of Mercury derived from Mariner 10 (M10) imagery, Trask and Guest (1975) introduced the concept of 'terrain units' asserting that '[ … ] on Mercury, surface morphology reflects the age, composition, lithology, and mode of formation of the underlying rock unit ' (p. 2461). Terrain units of Mercury were revisited during geologic mapping of Mercury at 1:5,000,000 scale, based on M10 images (De Hon, Scott, & Underwood, 1981;Grolier & Boyce, 1984;Guest & Greeley, 1983;King & Scott, 1990;McGill & King, 1983;Schaber & McCauley, 1980;Spudis & Prosser, 1984;Strom, Malin, & Leake, 1990;Trask & Dzurisin, 1984;merged maps, Frigeri, Federico, Pauselli, & Coradini, 2009) and termed 'geologic provinces' by Spudis and Guest (1988), who adopted this term to denote regional scale areas 'characterized by a similar inferred origin or a distinctive history ' (McCauley & Wilhelms, 1971, p. 363).…”

Some aspects of core formation in Mercury

“…(2) Large areas on Mercury's surface are covered with smooth plains, which from stratigraphic relationships and similarities to lunar maria are thought to be largely volcanic in origin (Murray et al, 1974a, b;Trask and Guest, 1975;Strom et al, 1975). The inferred melting necessary Lo produce widespread igneous activity and the close similarity of the surfaces of Mercury and the moon suggest that Mercury has an iron-rich core and a silicate crust and mantle (Murray et al, 1974x, b, 1975.…”

“…The inference from photogeology that Mercury's near surface regions are moon-like (Murray et al, 1974a, b), however, would require efficient differentiation of the shallow portion of Mercury prior to events recorded in the present morphology of the surface. Trask and Guest (1975). Murray et al (1975) of Mercury ' s history, an early source of heat is necessary.…”

“…Because of the detection of an apparently intrinsic magnetic field in the planet Mercury (Ness et al, 1974;1975a;b) and in light of several deductions about Mercury's history made after study of Mariner lU photographs of the planet's surface (Murray et al, 1974a(Murray et al, , b, 1975Trask and Guest, 1975;Strom et al, 1975), several questions dealing with the nature and history of any large metallic core in Mercury need to be asked. Does Mercury have a core?…”

Radar altimetry of Mercury: A Preliminary analysis

“…The Mariner 10 photographic images, which covered 45% of the planet at 0.1-4 km resolution, revealed a heavily cratered, lunar-like surface [Murray et al, 1974;Trask and Guest, 1975]. The images suggested tectonics dominated by compressive forces as manifested in the unique Mercurian scarp system.…”