Abstract

On the basis of studying more than 250,000 measurements of lineaments on the surface of the Earth, Mars, Mercury and the Moon, and of generalizing the material on fracturing obtained in the USSR, the USA, Great Britain, the Federal Republic of Germany, the Hungarian People’s Republic and the Czechoslovak Socialist Republic, three classes of lineaments can be distinguished, viz., global (or planetary), regional (radial-concentric) and local - G, R and L. Characteristic for the G and R classes is the systematic pattern of directions, whereas for the L class, on the contrary, the non-systematic pattern is characteristic.

The global system of G faults is the deepest, probably most ancient and most developed system of lineaments. The minor and major planetary fracturing, associated with the rotational field of the planet, obeys the law of the four series of systematic directions which form two genetic systems of dia- and ortho-structures.

There are also other systematic directions: NNW and ENE, WNW and NNE, yet they are less distinctly marked and are of less representative character. Sometimes directions actually associated with the R - or L - classes of fractures are erroneously taken for additional 5th and 6th series of planetary fracturing. Depending on regional geological and tectonic conditions, the planetary fracturing itself may change, acquiring azimuthal dispersion or being reduced to 3 or 2 series of systematic directions. In order to reveal all the 4 series of the planetary system G it is necessary to use photographs or topographic maps of a scale not larger than 1:500,000 (i.e. the size of an area under study should be not less than 250 × 330 km).

The mechanism of formation of planetary fracturing is associated with changes in the volume, shape and rotational regime of the planet determined by the law of preservation of its torque.

Regional radial-concentric systems of lineaments R can be easily identified by their characteristic pattern. The grid G-system of the Moon is very ancient. The R-systems associated with the genesis of lunar maria are, on the contrary, younger formations. The R-systems on Mars and on the Earth are less developed than on the Moon and Mercury.

The antiquity of the G-system of Martian lineaments does not preclude rejuvenation along its components as may be seen, for example, in the case of the diagonal alignment of relatively young volcanoes and canyons in the region of Tharsis and Lacus Noctis on Mars.

The third, nonsystematic class of lineaments L is genetically associated with local tectonic activity which has no planetary or regional extension. Fractures of that class form the youngest and the largest population of lineaments which are also of less depth than those of the G- and R-systems.