Вестник МГТУ. 2019, Т. 22, № 1.

Сорохтин Н. О. и др. Первая находка алмаза на полуостровах Средний и Рыбачий. the described period as a secondary process with no significant shifts along faults. These facts of the Paleozoic structural arrangements in the north-eastern Baltic Shield indicate different timing of the fault systems origination. First, the north-western and north-eastern systems formed; next, the submeridional and sublatitudinal systems occurred. Tensile stress in the eastern Baltic Shield produced a number of rift structures. According to geophysical data, there are two systems of rift formations in the Kola Peninsula, i. e. the White Sea and Barents Sea systems. They mark faults of the north-western strike and an extension fault system that is normally oriented towards the faults. This extension is marked by the water area of the White Sea Throat. The origin and renewal of the described fault systems at about 450-320 Ma should be confined to the intensive alkaline-ultrabasic and kimberlitic magmatism in the Baltic Shield and northern Russian Platform. Massifs of alkaline-ultrabasic intrusions are localized in the central Kola Peninsula and eastern Finland (Fig. 2). Explosion pipes are distributed east of the localized alkaline-ultrabasic intrusions and occupy a small area within the Yermakovsky Graben. An individual explosion pipe has been first discovered near the Ivanovskaya Bay on the Barents Sea shore. Explosion pipes have been also discovered in the Arkhangelsk region, all gathered in the Zimnebrazhnaya area of the kimberlitic and melilitite magmatism. Most of the explosion pipes on the Tersky coast of the Kandalaksha Bay and an individual find on the Murmansk shore of the White Sea have the melilitite composition. In the Arkhangelsk region, there was both the melilitite, and deeper kimberlitic magmatism. Besides intrusions and explosion pipes, the Caledonian and Hercynian magmatism in the Kola Peninsula is characterized by widespread dyke complexes that occur as two separate areas. One of them stretches along the Murmansk coast from northern Norway to the Ivanovskaya Bay in the east (Fig. 2). These dykes are alkaline- ultrabasic mostly. There are also doleritic dykes in the western part of the distribution area mainly. *« \ i I*» |g I* ★ |9 И ю Г'-J 1 Г~ -J 12 Fig. 2. Geological scheme of the eastern Baltic Shield: 1 - hydrosphere; 2 - sedimentary cover of the Russian Platform; 3 - Archaean continental-crustal associations; 4 - Early Proterozoic (Svecofennian) sedimentary-volcanogenic and intrusive complexes; 5 - Caledonian allochthone covers; 6 - alkaline-ultrabasic intrusions; 7 - picrite and melilitite explosion pipes; 8 - kimberlites; 9 - lamproites; 10 - transform-type fractures; 11 - subduction zones and directions of subduction (indicated by arrows) o f the Early Proterozoic oceanic plates (1.9-1.8 Ga ago); 12 - axis of the Paleozoic Kandalaksha-Dvina rift system Рис. 2. Геологическая схема восточной части Балтийского щита: 1 - гидросфера; 2 - осадочный чехол Русской платформы; 3 - континентально-коровые ассоциации архея; 4 - осадочно-вулканогенные и интрузивные комплексы раннепротерозойского (свекофеннского) возраста; 5 - аллохтонные покровы каледонского возраста; 6 - интрузии щелочно-ультраосновного состава; 7 - трубки взрыва пикритового и мелилититового составов; 8 - кимберлиты; 9 - лампроиты; 10 - разрывные нарушения трансформного типа; 11 - зоны субдукции и направления поддвига океанических плит (показаны стрелками) раннепротерозойского возраста (1.9-1.8 млрд лет назад); 12 - ось Кандалакшско-Двинской рифтовой системы палеозойского возраста 38