Maksim V. MITIAYEV POLISH POLAR STUDIES Murmansk Marine Biological Institute XXVI Polar Symposium Russian Academy of Sciences 17 Vladimirskaya, 183010 Murmansk RUSSIA

Lublin, June 1999

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LATE CAINOZOIC NEOTECTONIC MOVEMENTS OF EAST MURMAN

PÓŹNOKENOZOICZNE RUCHY NEOTEKTONICZNE WSCHODNIEGO MURMANA

The obtained data allow to consider the history of the region from the last re-gression (18,000 years ago). In this stage, strong neotectonic raising movements including the whole Baltic Shield and particularly the part of the Kola Peninsula could not but caught the adjacent Barents Sea watershed. At that time a thick continental glacier with its glaciation centre in Scandinavia moved in three direc-tions: south, north and east. The analysis of the geomorphological structure of East Murman and the adjacent Barents Sea watershed shows that in the western regions west, of the Voronia River estuary, the glacier was active in the eastern part as far as to the promontory Sviatoy Nos, - "dead." Glacial deposits are widely spread from Kolska Bay to Teriberka Bay. Large areas of esker-kame relief, morai-ne beds and fluvioglacial delta, in the Voronia River valley and Bolshogo Paduna region, are observed. This stage (18,000-12,000 years ago) is characterized by a re-

Fig. 1. Diagram of raising movements in the East Murman region; 1 - the averaged diagram of raising in the region between the Voronia River and the Easter Lica River, 2 - the diagram of raising in the re-

gion of Yarnyshanya Bay, 3 - the diagram of raising at the Zolotaya River estuary

Late Cainozoic Neotectonic Movements of East Murman 185

lative neotectonic calm. At that period or a bit later a basic deformation of relief took place under the influence of continental glacier.

The following postglacial transgressive stage (started by the catastrophic abla-tion of the continental glacier) is characterized by a stirring up of neotectonic mo-vements. At the same time the level of oceans rose by over 100 m. In this period the neotectonic movements have a distinct block character. The rate of raising mo-vement in individual blocks indicates a catastrophic character reaching up to 30 me-tres/a thousand years. The general amplitude of raising in Holocene was 100-140 m. In most regions a slowing down of the raising movement is observed between the Boreal and Subatlantic climatic phases.

Figure 1 shows the profile of raising movements of the river estuary parts from the Voronia River to the Easter Lica River. The course of this curve indicates inten-sive raising movements in the Early and Late Holocene whose amplitude gradually decreases at the end of Early Holocene. In the Middle Holocene the raising move-ment amplitude decreases but at the end of the third part of the Subboreal phase the raising movements are more intensive. In Late Holocene the movement ampli-tude becomes stable and insignificant. Thus in Holocene there takes place a stable but uneven raising of the ground caused by an uneven raising of individual blocks. The general amplitude of river estuary raising parts in Holocene was 80 m which is a little less than the total amplitude of the East Murman raising.

The rate and amplitude of Late Pleistocene-Holocene raising movement refer to the contemporary relief depression forms. The amplitude and rate of raising move-ments of the watershed areas are a little higher, being 100-160 m at an average rate of raising of about 13 m during 1,000 years. During the whole Holocene a stable increase of the land area takes place. The evidence for which are marine settlements in the lake valleys, dried paleobays, Holocene marine terrace comple-xes and natural levee.

Figure 2 shows the neotectonic movement amplitudes from Oligocene to Holo-cene. The general force of the movements is 600 m, gradually decreasing from west to east to 350 m. Isobath + 100 m corresponds to the Late Pleistocene-Holo-cene stage of region development which corresponds to 1/3 of the neotectonic am-plitude of the ground raising. Thus the movement intensification from Oligocene to Holocene takes place and the tectonic regime is stabilized at the end of Holoce-ne. The last activization of upward tectonic movements took place at the begin-ning of the climate Subboreal phase.

REFERENCE

MUSATOV E. E. 1995: Neotektonika Zakhodno-Arkticheskoy Kontinentalnoy okrainy. Dissert na soiska-nye uchenoy stiepieni doktora geologo-mineralogicheskikh nauk. Sankt Petersburg: 360-368.