Some features of deformation structures in an esker on the southern margin of the Fennoscandian shield

• Published in: Bulletin of the Geological Society of Finland
• Main Authors: A. Poleshchuk, D. Zykov, S. Shvarev
• Format: Article in Journal/Newspaper
• Language: English
• Published: Geological Society of Finland 2018
• Subjects: eskers; Fennoscandian Shield; liquefaction; neotectonics; palaeoearthquakes; deformation structures; dislocations; intrusion; Geology; QE1-996.5; Fennoscandian; Ice Sheet
• Online Access: https://doi.org/10.17741/bgsf/90.2.011; https://doaj.org/article/0be0d866ee034a16a83a99ee219da551

As a result of melting of the last ice sheet in the southeastern edge of the Fennoscandian shield, ridge structures called eskers were formed. One of these eskers is the subject of our study. We have identified both typical non-deformed sedimentary layers and specific intrusive mixture of sand and silt in the esker. The sand and silt were deformed with formation of recumbent and overturned folds, which indicate that they have experienced displacement in a ductile (wet) state. The formation of similar dislocations (diapir folds or glacial intrusion structures) can occur as a result of either dead ice melting or liquefaction during earthquakes.