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Jurassic volcanism in Skane, southern Sweden, and its relation to coeval regional and global events

Author:
  • Ingemar Bergelin
Publishing year: 2009
Language: English
Pages: 165-175
Publication/Series: GFF
Volume: 131
Issue: 1-2
Document type: Journal article
Publisher: Taylor & Francis

Abstract english

Isolated exposures of basalt in a 1000 km 2 area in the central northern part of Skane have long been known to the local people. A volcanic origin for these rocks was finally resolved by geologists during the early 1800s. Until 1965 the volcanic activity was considered to have occurred during the Cenozoic i.e. not older than 65 Ma. In the 1970s attempts were made to directly date the volcanic activity using the K/A radiometric technique. The obtained dates suggested a much older eruption age namely during the Jurassic-Cretaceous. This paper presents Ar-40/Ar-39 geochronological data from eight volcanic necks revealing evidence for two distinct pulses of volcanic activity in this region of Skane. The first and the main volcanic phase occurred in the Early Jurassic (late Sinemurian to Toarcian) at 191-178 Ma, some 20-30 million years older than previously reported. The second pulse occurred in the late Early Cretaceous (Albian) at 110 Ma. The similar geochemical composition of the basalts from this region despite the long eruption span of approximately 80 million years and the occurrence of repeated tectonic movements in the region favours the following hypothezised mechanism - intermittent release of eutectic melts caused by tectonic decompression of the lithospheric mantle. Similar processes have been proposed for the coeval North Sea volcanism. On a global scale the tectonic movements in the Earth's crust during the Mesozoic are linked to the break-up of the supercontinent Pangea. Apart from generating volcanic events in Skane and the North Sea more voluminous coeval volcanism occurred in the Karoo and Ferrar volcanic provinces in the Southern Hemisphere.

Keywords

  • Geology
  • rift magmatism
  • North Sea
  • Cretaceous
  • Jurassic
  • geochronology
  • Skane
  • alkaline basalt
  • Scanian volcanic province

Other

Published
  • ISSN: 2000-0863
Ingemar Bergelin
E-mail: ingemar [dot] bergelin [at] geol [dot] lu [dot] se

Doctoral student

Lithosphere and Biosphere Science

+46 46 222 95 53

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