MECHANICS OF LITHOSPHERIC BLOCKS

Abstract

In order to analyze the history of the continental lithosphere, identify its current movements, and predict earthquakes, the author starts from the view that it consists of relatively small blocks (with areas of 102 to 104 km2) that differ in geological paleontological and paleomagnetic characteristics, as well as in absolute age. These blocks are commonly grouped into megablocks or mesocontinents (these groupings being younger than most of the component blocks) and are separated from each other by boundaries of different ages, but younger than the blocks separated by them. For the most part the boundaries between continental blocks are actually suture zones connecting them. They were generated by collisions between such blocks, and represent remnants of zones of subduction or obduction. Or they may be zones of closure or marginal seas. Instances of formation of multiblock regions of the continental lithosphere are described. It seems that island arcs with plutonic, mostly granitoid roots that form the bulk of their volume are the main structural form of development of new blocks of the continental lithosphere. These blocks are then agglomerated into larger entities by collisions and merger of island arcs, micro- and mesocontinents. Additional aspects of the subject are discussed.