Contributions to the geological mapping of Mors, Denmark - A study based on a large-scale TEM survey

F. Jørgensen, Peter B.E. Sandersen, Esben Auken, Holger Lykke-Andersen, Kurt Sørensen

Publikation: Bidrag til tidsskriftArtikelForskningpeer review

37 Citationer (Scopus)

Abstrakt

Recent improvements of the transient electromagnetic (TEM) method provide unprecedented capabilities of imaging geological features in the uppermost few hundred metres of the subsurface. This is documented with an example from the island of Mors, Northern Jutland, Denmark, where 2655 TEM soundings have been acquired as a part of Viborg County's hydrogeological investigation programme. Horizontal aspects of the interpreted TEM soundings are presented in thematic maps revealing variations of resistivities in specified depth intervals and depths to the resistivity basement, i.e. the deepest recorded low-resistive layer. Vertical aspects are displayed in cross-sections. The dense coverage of TEM soundings, combined with borehole logs, allows the precise delineation of major geological features. These comprise the Mors salt diapir, intricate systems of buried Quaternary valleys and several glaciotectonic complexes, all contributing to a complicated geological framework for the island. The layers above the salt diapir, which have been subject to severe erosion, are distinctly imaged in the thematic maps, even though they are frequently dissected by buried valleys. At least four generations of buried valleys can be identified on the basis of their preferred orientations; these were mainly formed during early glaciations. Large parts of the island were glaciotectonically deformed during the Late Weichselian subsequent to valley formation, and it is suggested that the presence of deep valleys may have affected the process of glaciotectonic deformation.

OriginalsprogEngelsk
Sider (fra-til)53-75
Antal sider23
TidsskriftBulletin of the Geological Society of Denmark
Vol/bind52
Udgave nummer1
StatusUdgivet - nov. 2005
Udgivet eksterntJa

Programområde

  • Programområde 2: Vandressourcer

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