Tolstoj quadrangle [SEP] located on astronomical body
Tolstoj quadrangle
The Tolstoj quadrangle in the equatorial region of Mercury runs from 144 to 216° longitude and -25 to 25° latitude. It was provisionally called "Tir", but renamed after Leo Tolstoy by the International Astronomical Union in 1976. Also called Phaethontias.
It contains the southern part of Caloris Planitia, which is the largest and best preserved basin seen by "Mariner 10". This basin, about 1550 km in diameter, is surrounded by a discontinuous annulus of ejecta deposits of the Caloris Group that
mapped within the quadrangle are, however, dominantly northwest (315°) and northeast (35°–40°). A minor, almost north-south trend is also observed. This situation is reminiscent of the so-called lunar grid on the Moon, which is generally ascribed to planetwide internal causes.
Geologic history.
The interpretable geologic history within the Tolstoj quadrangle begins with the period of formation of the intercrater plains, which persisted until shortly after impact of the asteroid that created the Tolstoj Basin. After this