Abstract

When interpreting airphotos, radar images and space (photo and TV) images of the Earth’s surface, there are visible a great many lineaments. The geological content of the lineaments revealed depends on the scale of the photos and the rate of picture generalization (resolution) for the images. On large scale airphotos, most of the lineaments identified correspond to small fissures. With decrease in scale of the airphoto, the small fissures combine to show as fissure zones, separate faults and, as lineaments. Linear (in plan) geological structures are also recognized. Lineaments which correspond to large faults are prevalent on space images.

When analysing the lineament patterns, such parameters are considered as the length of lineaments, their geological characteristics (whether they separate or mark the boundary of different geological structure blocks or mark the presence of plication zones, shear zones, zones of metamorphic change, the linear distribution of intrusions and the presence of slip) and, their character as defined by geophysical data.

The analysis of lineaments in the Kazakhstan, Central Asia and some other regions has allowed us to establish the presence of four series of faults combined into two systems: meridional-latitudinal and NW-NE. The frequency of faults within each of these four series is not identical for different regions. One can see a definite periodicity to the distribution of the largest faults. Interruption of this periodicity in some cases is occasioned by large horizontal movements of the Earth’s crustal blocks. In Kazakhstan and Middle Asia, where all the four series are well expressed, the faults of the sub-meridional series have a periodicity of 70-100 km as well as a distinctive S-shaped form in plan. The periodicity of sub-latitudinal faults is about 220 km and, in plan, they have a gently-sloping wave shape. The periodicity of faults in the NW and NE series is about 70-100 km. In the Kun Lun mountain range, apart from the sub-latitudinal faults which have a periodicity of about 100 km, the NE faults which have a periodicity of from 100 to 150 km are best of all defined.

On the space photos (Kazakhstan, Urals) the ring faults bordering oval blocks are also distinguished. These probably correspond to old (Archean) divisions of the Earth’s crust.

The combined analysis of photo and image interpretation data and geophysical data convince us that the largest faults are developed to great depth in the crust.