Glaciomarginal deposition in the Otmuchów Depression, SW Poland, and its palaeogeographical implications

Abstract

Sedymentacja glacimarginalna na obszarze Obniżenia Otmuchowskiego (SW Polska) i wynikające z niej implikacje paleogeograficzne This paper focuses on the problem of depositional environments and the development of glaciomarginal zone in the Otmuchów Depression, SW Poland, during the Odranian (Drenthe) glaciation. The research was conducted at the Wójcice site, which is situated on the southern border of a hill train, the so-called Otmuchów- Nysa Hills, rising on the northern side of the Nysa Kłodzka River valley. The sediments under study were deposited in the distal zone of glaciomarginal fans prograding into a bay of a large lake formed in the dammed valley of the Nysa Kłodzka River. Sedimentation was characterised by frequent oscillations of water level in the lake, which caused fan dissection and lateral migration of depositional subenvironments. These phenomena are recorded by abundant erosion surfaces and vertical succession of alternating lithofacies associations of the deposits, which are typical of different parts of the distal fans. Sedimentological analysis has also enabled palaeogeographical reconstruction of the glaciomarginal zone. It is found that the ice-sheet lobe advanced into the Nysa Kłodzka River valley from the NE.