PRESENT-DAY AND HOLOCENE HORIZONTAL MOVEMENTS ON THE BAIKAL GEODYNAMIC TEST GROUND

Abstract

In the framework of the Russian-French project, a series of geodesic stations for studying present-day crust deformations by the GPS method was organized on the Baikal geodynamic test ground. Processing of data of 3-year-long observations permitted obtaining a field of vectors of the rates of present-day horizontal movements in the southern and central parts of the Baikal Rift System. The authors have established the absence of dislocations from the internal field of the Siberian Platform and a concordant southeastward shift of bench marks in West Transbaikalia. The major parameters of the vectors do not contradict the dislocations predicted by structure-geological and seismological data. On the basis of direct instrumental measurements made in 1994-97, it has been first established that the opening of the Baikal Rift occurs at an average rate of 4.5±1.5 mm/year toward 100° N. The directions and rates of horizontal block displacements in the south of the Baikal Rift System in the Holocene are in agreement with the GPS data. In the central part of the rift, the expansion of blocks in the Holocene occurred toward 130° N, and between the blocks of East Sayan and the Siberian Platform oblique divergent movements toward 100° N took place.