The glaciotectonic evolution of Ven, Sweden: insights from a comprehensive structural, sedimentological, and geomorphological analysis

Sammanfattning

This study presents the results from the first detailed structural analysis of glaciotectonic structures of the northern cliff exposures on Ven alongside the first coherent interpretation of the glaciotectonic evolution of the island. Additionally, the study presents the findings of the first geomorphological mapping of surface features on Ven. The primary objective of this study was to fill gaps in our knowledge regarding the influence of successive advancements of the SIS in the area and address previous claims regarding the surface geomorphology of the island. This was accomplished using a standard sedimentological and geomorphological approach along with detailed structural investigations of glaciotectonic structures. Fifteen distinct lithofacies where identified throughout the northern cliff exposure, which can be summarized as three subglacial till beds connected to the two last glacial advances of the SIS during the late Weichselian, separated by discontinuous layers of deformed outwash and glaciolacustrine deposits. Overall, the interpreted sedimentary succession is interpreted to represent the upper sedimentary succession of the Alnarp Valley fill, one of Scania's most valuable groundwater resources. Measurements of deformational structures alongside the sedimentological revealed a substantial glaciotectonic influence from the last two glacial advances on island`s stratigraphic succession. The findings show that our preexisting knowledge pertaining to the glaciotectonic evolution of the island only show a simplistic overview. This study presents two conceptual models to explain the evolution of the glaciotectonic structures and the sedimentological findings seen in the northern cliff exposures. Furthermore, previous claims of Ven being a prime example of a cupola hill complex could not be entirely dismissed but are shown to be an unlikely interpretation based on the evidence from the geomorphological analysis of the island. Additionally, 10 subtle long-stretched ridges are located throughout the islands otherwise flat surface. The origin of these ridges could not be determined but are postulated to be derived from agricultural activities. This study concludes that additional analysis of the Alnarp valley fill, employing alternative investigative techniques like seismic and ground-penetrating radar, is necessary. Glaciotectonic structures within these sediments are likely overlooked due to the predominant use of sedimentary coring. Furthermore, continued exploration of Ven is recommended to gain a comprehensive understanding of the island's glaciotectonic evolution.