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Karl Ljung

Karl Ljung

Universitetsadjunkt

Karl Ljung

Possible Late Pleistocene volcanic activity on Nightingale Island, South Atlantic Ocean, based on geoelectrical resistivity measurements, sediment corings and (14)C dating

Författare

  • Anders Anker Bjork
  • Svante Björck
  • Anders Cronholm
  • James Haile
  • Karl Ljung
  • Charles Porter

Summary, in English

Tristan da Cunha is a volcanic island group situated in the central South Atlantic. The oldest of these islands, Nightingale Island, has an age of about 18Ma. In the interior of the island, there are several wetlands situated in topographic depressions. The ages of these basins have been unknown, and their genesis has been debated. Aiming towards the reconstruction of the geomorphological history of these basins, we conducted geoelectrical resistivity measurements to map the subsurface topography, extracted peat and sediment cores and dated the onset of sedimentation applying the radiocarbon method. The irregular shapes of the basins and the lack of clear erosional features indicate that they are not eruption craters and were not formed by erosion. Instead, we regard them as morphological depressions formed between ridges of trachytic lava flows and domes at a late stage of the formation of the volcanic edifice. The onset of sedimentation within these basins appears to have occurred between 24 and 37 ka with the highest situated wetland yielding the highest ages. These ages are very young compared to the timing of the main phase of the formation of the island, implying volcanic activity on the island during the Late Pleistocene.

Avdelning/ar

  • Kvartärgeologi
  • Berggrundsgeologi
  • MERGE: ModElling the Regional and Global Earth system

Publiceringsår

2011

Språk

Engelska

Sidor

141-147

Publikation/Tidskrift/Serie

GFF

Volym

133

Issue

3-4

Dokumenttyp

Artikel i tidskrift

Förlag

Taylor & Francis

Ämne

  • Geology

Nyckelord

  • South Atlantic
  • Nightingale Island
  • peat bogs
  • subsurface topography
  • (14)C dating
  • young volcanism

Status

Published

ISBN/ISSN/Övrigt

  • ISSN: 2000-0863