Statistical Analysis of Geological and Geophysical Parameters of the Baikal-Mongolia Region

Abstract

The origins and formation mechanisms of neotectonic structures in a part of the Mongolian-Siberian region were identified by geodynamic zoning based on multivariate statistical analysis of numerical data that describe geological-geophysical and geological-geomorphological processes. These processes in the regional lithosphere were described by a set of 11 geological and geophysical parameters, divided into three main groups using the hierarchical method of cluster analysis. The first group includes the seismic moment, the density of active faults, the recent horizontal strain rates, and the magnitude of the deep heat flow. The second group involves the thicknesses of the earth’s crust and exogenously active layer, the recent horizontal crustal velocities, and the amplitudes of vertical neotectonic movements. The third group includes gravity anomalies and the lithospheric thickness. The spatial grouping of the parameters by cluster analysis (K-means method) yields seven clusters, whose spatial position and composition are determined by the geological history, geological structure, geodynamic evolution of the region, and the recent strain rates. Some clusters characterize large rigid lithospheric blocks, while other clusters describe large active fault systems in the studied region. The search for latent factors that make the greatest contribution to the dispersion of the geological and geophysical parameter values was carried out using the principal component method, which allows minimizing the number of factors. Four main factors were identified for areas that differ in the morphology and origin of neotectonic structures: (i) higher horizontal compressive and tensile strains, (ii) dynamic effect of mantle anomalies, manifested in uplifts and doming, (iii) activation of thinned lithosphere within the boundaries of lithospheric plates or large blocks, and (iv) active shear deformation of the earth’s crust. The results of clustering and factor analysis of numerical data describing geological-geophysical and geological-geomorphological processes within the Mongolian-Siberian region are interpreted in the framework of physical mesomechanics.