Thufur formation in northern Iceland and its relation to holocene climate change

Research areas:

• Environnement, Paléo-Environnement et Bio-Indicateurs (2011 - 2016)

Year:

1998

Authors:

• B Van Vliet-Lanoe
• Olivier Bourgeois
• O Dauteuil

Journal:

PERMAFROST AND PERIGLACIAL PROCESSES

Volume:

9

Number:

4

Pages:

347-365

Month:

OCT-DEC

ISSN:

1045-6740

BibTex:

@article{WOS:000078164600005, author = "B Van Vliet-Lanoe and Olivier Bourgeois and O Dauteuil", abstract = "This gaper compares thufur formation in the northern volcanic zone of Iceland with that of other periglacial hummock forms. The aim of this work is to further the understanding of the extent of thufur in Iceland, in terms of cryogenic mechanisms related to specific edaphic conditions. Thufur may be considered to be hummocks, of a mainly minerogenic nature and specifically developed in volcanic loesses on drained basaltic rocks or openwork glacial or fluvioglacial substratum. They are thus connected to the oceanic cold climate as well as to the occurrence of volcanic loesses with specific physical properties resting on permeable substratum. Their development does not rely on either permafrost or a water table. Rather, they result from deep seasonal freezing, with exaggerated frost heave limited by snow accumulation along with the development of injection patterns along dilation cracks. Thufur may be considered as a subtype of hummock, or of raised-centre non-sorted polygons related to seasonal frost and snowdrift. In Iceland, the high geothermal gradient may, through exaggerated frost heave, enhance hummocky microrelief locally. Thufur expansion is related to the post-Hypsithermal (Atlantic) climate degradation of the Holocene linked to orbital forcing. Thanks to tephro-stratigraphy, it is possible to define several main episodes of thufur growth: around 4500 (BP); after 2600 (BP); prior to colonization (1104 AD); as well as two phases during the Little Ice Age. These growth phases are coherent with the pedoclimatic record on both sides of the North Atlantic. (C) 1998 John Wiley {\&}amp; Sons, Ltd.", doi = "10.1002/(SICI)1099-1530(199810/12)9:4{\&}lt;347::AID-PPP299{\&}gt;3.0.CO;2-4", extra = "PICL", issn = "1045-6740", journal = "PERMAFROST AND PERIGLACIAL PROCESSES", month = "OCT-DEC", number = "4", pages = "347-365", title = "{T}hufur formation in northern {I}celand and its relation to holocene climate change", volume = "9", year = "1998", }

Abstract:

This gaper compares thufur formation in the northern volcanic zone of
Iceland with that of other periglacial hummock forms. The aim of this
work is to further the understanding of the extent of thufur in Iceland,
in terms of cryogenic mechanisms related to specific edaphic conditions.
Thufur may be considered to be hummocks, of a mainly minerogenic nature
and specifically developed in volcanic loesses on drained basaltic rocks
or openwork glacial or fluvioglacial substratum. They are thus connected
to the oceanic cold climate as well as to the occurrence of volcanic
loesses with specific physical properties resting on permeable
substratum. Their development does not rely on either permafrost or a
water table. Rather, they result from deep seasonal freezing, with
exaggerated frost heave limited by snow accumulation along with the
development of injection patterns along dilation cracks. Thufur may be
considered as a subtype of hummock, or of raised-centre non-sorted
polygons related to seasonal frost and snowdrift. In Iceland, the high
geothermal gradient may, through exaggerated frost heave, enhance
hummocky microrelief locally. Thufur expansion is related to the
post-Hypsithermal (Atlantic) climate degradation of the Holocene linked
to orbital forcing. Thanks to tephro-stratigraphy, it is possible to
define several main episodes of thufur growth: around 4500 (BP); after
2600 (BP); prior to colonization (1104 AD); as well as two phases during
the Little Ice Age. These growth phases are coherent with the
pedoclimatic record on both sides of the North Atlantic. (C) 1998 John
Wiley & Sons, Ltd.