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The Keiva ice marginal zone on the Kola Peninsula, NW Russia – a complex marginal deposit of the Fennoscandian ice sheet
Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology. (paleoglaciologi/paleoglaciology)
Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology. (paleoglaciologi/paleoglaciology)
2007 (English)In: Quaternary International, 2007Conference paper (Refereed)
Abstract [en]

One of the key elements in reconstructing the palaeoglaciology of the northeastern sector of the Fennoscandian Ice Sheet is the Keiva ice marginal zone (KIZ) along the southern and eastern coasts of Kola Peninsula, including the Keiva I and II moraines. From detailed geomorphological

mapping of the KIZ, primarily using aerial photographs and satellite images, combined with field work, we observe the following:

(a) The moraines display ice contact features on both the Kola Peninsula- and the White Sea side along its entire length; (b) the Keiva II moraine is sloping along its 220 km length from c. 100 m a.s.l. in the west (Varzuga River) to c. 250 m a.s.l. in the east (Ponoy River); (c) the KIZ was partly overrun and fragmented by erosive White Sea based ice after formation. From these observations we conclude that the KIZ is not a synchronous feature formed along the lateral side of a White Sea based ice lobe. If it was, the moraines should have a reversed slope. Rather, we interpret it to be formed time transgressively at the northeastward

migrating junction between warm-based parts of the Fennoscandian

ice sheet expanding from the southwest into the White Sea depression and across southeastern Kola Peninsula, and a sluggish cold-based ice mass centred over eastern Kola Peninsula. In contrast to earlier reconstructions, we find it unlikely that an ice expansion of this magnitude was a mere readvance during the deglaciation. Instead, we propose that the Keiva ice marginal zone was formed during major expansion of a Fennoscandian Ice Sheet at a time predating the LGM. Our geomorphological interpretation is consistent with new Be-10 cosmogenic isotope data of several boulders embedded in the eastern part of the Keiva II moraine, with apparent exposure ages between 250 and 420 ka. One interpretation of the data is that these boulders were deposited as an integral part of the moraine ridge, hence indicating that the KIZ, or at least sections of it, is of Middle Pleistocene age. Another interpretation is that the KIZ is younger than 250 ka (but older than LGM on the strength of the evidence of post-depositional overriding) and that all boulders sampled have considerable inheritance from previous

exposure periods. The results are also consistent with the geomorphological

observations indicating that the KIZ has a history far more intricate than has previously been acknowledged in most paleoglaciological


Place, publisher, year, edition, pages
URN: urn:nbn:se:su:diva-21166OAI: diva2:187692
Available from: 2007-12-06 Created: 2007-12-06Bibliographically approved

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Hättestrand, ClasStroeven, Arjen
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