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Fältarbete på Färskesjön 2013

Anne Birgitte Nielsen

Universitetslektor

Fältarbete på Färskesjön 2013

Relative sea level changes and glacio-isostatic modelling in the Beagle Channel, Tierra del Fuego, Chile : glacial and tectonic implications

Författare

  • Svante Björck
  • Kurt Lambeck
  • Per Möller
  • Nicolas Waldmann
  • Ole Bennike
  • Hui Jiang
  • Dongling Li
  • Per Sandgren
  • Anne Birgitte Nielsen
  • Charles Porter

Summary, in Swedish

The Beagle Channel crosses the southernmost tip of South America (Tierra del Fuego), connecting the South Atlantic with the Southeastern Pacific. Raised beaches occur up to 10 m above mean sea level (m a.m.s.l.), especially along the northern (Argentinian) shore, and have been dated using marine shells. The southern (Chilean) shore is well-known for its abundance of shell middens at different levels above the present shore, particularly along the island of Isla Navarino, but the relative sea level history in this glacially impacted landscape has not previously been investigated. In this study we present postglacial relative sea level changes on Isla Navarino, based on sediment cores from six lagoons, bogs or lakes, and stratigraphic investigations of three open sections, of which one is of MIS 5e age. In addition, one core from a lagoon in the south-western Beagle Channel has been analysed and a system of terraces was mapped in the north-western Beagle Channel. The analyses of the core sites have resulted in two tentative relative sea level curves, displaying a rapid sea level rise at 8500-6500 cal yr BP, amounting to ~10 and 14 m in eastern and western Isla Navarino, respectively, and reaching levels of ~8 and >10 m, respectively, followed by a slow relative sea level fall. Our sea level observations have been compared with a range of modelling results of glacial-isostatic adjustments (GIA) for estimating timing of deglaciation and ice sheet thicknesses. Based mainly on the GIA modelling of the altitude of the MIS 5e beach sediments, situated at 13 m, we can conclude that no other uplift than GIA is needed to explain their altitude. Regarding the modelling of postglacial sea levels we can conclude that no model has been found that satisfies all of the observational evidence, but that deglaciation most likely preceded Northern Hemisphere main deglaciation by at least 3 kyr, which agrees with the deglaciation age of Isla Navarino (>16 000 cal yr BP). In addition, our model runs imply that the Patagonian and Tierra del Fuego ice sheet thicknesses were in the order of ~1500 m.

Avdelning/ar

  • Kvartärgeologi
  • BECC: Biodiversity and Ecosystem services in a Changing Climate
  • MERGE: ModElling the Regional and Global Earth system

Publiceringsår

2021-01

Språk

Engelska

Publikation/Tidskrift/Serie

Quaternary Science Reviews

Volym

251

Dokumenttyp

Artikel i tidskrift

Förlag

Elsevier

Ämne

  • Geology

Status

Published

ISBN/ISSN/Övrigt

  • ISSN: 0277-3791