Судовиков, Н. Г. Материалы по петрологии Западного Беломорья : (гранитизация пород Беломорья) / Н. Г. Судовиков ; Главное геологическое управление. - Ленинград ; Москва : ГОНТИ, Редакция горно-топливной и геолого-развед. литературы, 1939 (Ленинград). - 86, [1] с., [1] л. табл., [1] л. карт. : ил., карты, схемы. - (Труды / Ленинградское геологическое управление ; вып. 19).

which are genetically related with migmatisation and formed during the ac­ cumulation of granitizing matter in fractures. In this favourable conditions are dif­ ferential plasticity of medium with an average degree of granitisation. The closed pegmatite bodies, enclosed in basic rocks which react during granitisation along fractures, present an extremely widespread genetic type in the White-Sea region to which the above-noted conceptions of the writer are applicable. The writer brings forward arguments in favour of these conceptions and makes cert­ ain practical inferences. In the concluding chapter the writer considers the geological sequence and characterizes the process of granitisation. The contents of this chapter is as follows: The g e o l o g i c a l s e q u e n c e for the Precambrian of the White-Sea region begins from the epoch of sedimentation to which corresponds the com­ plex of White-Sea para-gneisses. The conditions of this epoch at the pre­ sent time are not clear, for all the features by which it is possible to repro­ duce the conditions have been altered by the repeated action of metamorphism that followed. Judging by the composition of the best preserved formations the deposition of argillaceous, calcareous and probably arenaceous sediments took place in this epoch on an unknown fundament. Simultaneously with the sedimentation, and may be a little later in the period of folding this series of sediments was intruded and possibly covered by effusive basic rocks. The next folding after sedimentation, chiefly of a north­ easterly direction probably in part preceded and partly took place at the same time with migmatisation and granitisation of sediments. This first epoch of diastrophism embraces folding, metamorphic and granitisation processes. The granite bodies of this epoch probably, did not reach such large dimensions as during the second epoch. The dimensions of areals and the extent of granitisation also were more limited. After the epoch of granitisation begin probably complete consolidation and invasion along fractures of basic rocks represented now by drusites. The metamorphism of these rocks is confined to a young Archaean epoch of granit­ isation, to which the deformation and blocking of their dikelike intrusions are confined. This young Archaean epoch of granitisation is characterized by a great development of extensive areals of migmatisation embracing almost the whole coastal zone. The formation of industrial pegmatites is related to this epoch. The character and direction of movements in this epoch are not clear. The next epoch of erosion and sedimentation is characterized by the ac­ cumulation of thick series of Karelian sediments which, up to the present time, have not been found within the limits of the White-Sea zone. They adjoin it from the west and in zone of contact are separated by postkarelian granites and migmatites. In the Karelian period of sedimentation the White-Sea Archaean fund­ ament presented an entirely consolidated mass, reacting to movements by fracturing with the formation of dikes of basic rocks. In the following epoch of intensive post-karelian movements the Archaean fundament was granitised, forming extensive areals of granites and migmatites found bordering on the zone of karelides. Far from mapped zones of karelides certain regions were also caught by granitisation (Varbar Luda, Pongom Island & others). At the present time due to great difficulties of studying the stratigraphy it is not clear on what scale the granitisation took in the Archaean areas. Some, probably, con­ siderable Archean areas of the White-Sea region formed the fundament for the folded structures of the karelides and during post-karelian granitisation could have been drawn into corresponding (NE — SW) movements. It is probable that the regions with a general north-west strike if detailly studied may prove to have been reformed in post-karelian epoch of granitisation. After this, noting the great signiiicance of achievements of geologists study­ ing ultrametamorphism, the writer gives a characteristic of the process of 86