Morphotectonics, Seismicity, and Exogenous Processes of the Kola Peninsula

Abstract

Abstract —The purpose of this study is to determine a morphologically pronounced fault–block structure identified with the neotectonic stage and compare it with sites with manifested exogenous processes, as well as modern and historical paleoseismicity in order to establish faults activated in the postglacial time. Based on the analysis of space images (Landsat-ETM+) and a digital elevation model (GTOPO-30), the territory of the Kola Peninsula and the adjacent part of North Karelia is subjected to morphostructural interpretation with identifying morpholineaments and an elementary block structure. It is shown by the analyzing the directions and extent of elementary, single (simple), and complex (echeloned, parallel conjugated, and imbricated) linear structures and their zones that both linear (fault) and areal (block) structures are characterized by a predominance of a single system of northwestern and northeastern differences with a clear dominance of the former and unimodal distribution of the extent of faults and the area of blocks, depending on their number. This indicates a single (recent) stage in the formation of the morphotectonic appearance of the territory and no discrete hierarchy of the morphostructures. The degree of fragmentation of the territory at different depths is calculated depending on the number and extent of morpholineaments. It is determined that morpholineaments have a high degree of inheritance from Archean–Proterozoic structures (≈50%). Elementary morphotectonic blocks are grouped into composite blocks bounded by linear zones of great extent (100–600 km) having individual physiognomic features determined by fault patterns, which indicates the nature of the neotectonic dynamics and the degree of inheritance or reformation of the structural plan. The localization of manifestations of exogenous processes, epicenters of paleo-, historical, and modern earthquakes is determined on the basis of the analysis of topographic maps scaled at 1:100,000, catalogs of historical and paleoearthquakes, and the consolidated literature (including the data obtained by the authors of this study) on paleoseismic deformations. A geoinformation base is compiled, which is used to simulate the spatial distribution of endo- and exogenous signs of tectonic activity and compare it with the neotectonic fault–block structure. The spatial similarity of endogenous and exogenous activation zones and their confinement to faults, defined as activated in the postglacial time, are revealed. It is revealed that the following elements are most active in the postglacial–Holocene. First, flank elements on the Kola Peninsula along the Barents Sea coast, the Kandalaksha Bay shores, and the Gorlo Strait of the White Sea. Second, the central (nodal) part with the Khibiny and Lovozero massifs. Third, submeridional (transverse) secant structures separating the eastern part of the peninsula from the western part (Khibiny–Kola and Khibiny–Niva). The spatial parameters of the activated zones indicate a range of earthquake magnitudes M ≈ 6.5–7.5 generated by these structures both in the postglacial period and in the Neopleistocene as a whole.