Transgressions of the Baltic Sea and the pecularities of the formation of transgressive coastal deposits
During the history of the Baltic Sea there have been several transgressive and regressive phases. Due to the uneven tectonic uplift of the Fennoscandian Shield and adjacent areas the duration and culmination of transgressions in different Baltic Sea areas were not synchronous and the effect of trans...
| Published in: | Quaternaire |
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| Format: | Article in Journal/Newspaper |
| Language: | French |
| Published: |
PERSEE
1991
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| Subjects: | |
| Online Access: | http://www.persee.fr/doc/quate_1142-2904_1991_num_2_3_1961 https://doi.org/10.3406/quate.1991.1961 |
| Summary: | During the history of the Baltic Sea there have been several transgressive and regressive phases. Due to the uneven tectonic uplift of the Fennoscandian Shield and adjacent areas the duration and culmination of transgressions in different Baltic Sea areas were not synchronous and the effect of transgressions on the sedimentation was different. Owing to the moderate uplift of the Earth's crust the shoreline in the Middle Baltic (Estonia northern Latvia Central Sweden) was rather stable during the transgressions. Therefore the transgressive coastal formations are characterized by a greater thickness of deposits and a greater variety and clarity of coastal relief-forms than the regressive ones. In the course of invasion of the sea the migration of sediments up the shore slope caused more intensive mechanical and mineralogical differentiation in their composition which in its turn brought about an accumulation of heavy minerals in a number of places. Au cours de l'histoire de la Mer Baltique il y a eu plusieurs phases transgressives et régressives. A cause du soulèvement tectonique inégal du bouclier Fennoscandinave et des régions voisines la durée et le maximun des transgressions dans les différents secteurs de la Mer Baltique ne sont pas synchrones et les effets des transgressions sur la sédimentation sont différents. A cause du soulèvement modeste de la croûte la ligne de rivageloc: en moyenne Baltique (Estonie nord Latvia Centre Suède) était plutôt stable durant les transgressions. Par conséquent les formations littorales transgressives sont caractérisées par une épaisseur plus grande de dépôts et une plus grande variété et netteté des constructions littorales que les formations régressives. Au cours de la progression de la mer la migration des sédiments sur la pente côtière provoque dans leur composition une différenciation mécanique et minéralogique plus importante qui amène en de nombreux points une accumulation de minéraux lourds. |
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