Asset Details
Do you wish to reserve the book?
Glacial episodes of a freshwater Arctic Ocean covered by a thick ice shelf
Hey, we have placed the reservation for you!
By the way, why not check out events that you can attend while you pick your title.
Oops! Something went wrong.
Looks like we were not able to place the reservation. Kindly try again later.
Are you sure you want to remove the book from the shelf?
Glacial episodes of a freshwater Arctic Ocean covered by a thick ice shelf
Do you wish to request the book?
Glacial episodes of a freshwater Arctic Ocean covered by a thick ice shelf
Please be aware that the book you have requested cannot be checked out. If you would like to checkout this book, you can reserve another copy
We have requested the book for you!
Your request is successful and it will be processed during the Library working hours. Please check the status of your request in My Requests.
Oops! Something went wrong.
Looks like we were not able to place your request. Kindly try again later.
Journal Article
Glacial episodes of a freshwater Arctic Ocean covered by a thick ice shelf
2021
Overview
Following early hypotheses about the possible existence of Arctic ice shelves in the past
1
–
3
, the observation of specific erosional features as deep as 1,000 metres below the current sea level confirmed the presence of a thick layer of ice on the Lomonosov Ridge in the central Arctic Ocean and elsewhere
4
–
6
. Recent modelling studies have addressed how an ice shelf may have built up in glacial periods, covering most of the Arctic Ocean
7
,
8
. So far, however, there is no irrefutable marine-sediment characterization of such an extensive ice shelf in the Arctic, raising doubt about the impact of glacial conditions on the Arctic Ocean. Here we provide evidence for at least two episodes during which the Arctic Ocean and the adjacent Nordic seas were not only covered by an extensive ice shelf, but also filled entirely with fresh water, causing a widespread absence of thorium-230 in marine sediments. We propose that these Arctic freshwater intervals occurred 70,000–62,000 years before present and approximately 150,000–131,000 years before present, corresponding to portions of marine isotope stages 4 and 6. Alternative interpretations of the first occurrence of the calcareous nannofossil
Emiliania huxleyi
in Arctic sedimentary records would suggest younger ages for the older interval. Our approach explains the unexpected minima in Arctic thorium-230 records
9
that have led to divergent interpretations of sedimentation rates
10
,
11
and hampered their use for dating purposes. About nine million cubic kilometres of fresh water is required to explain our isotopic interpretation, a calculation that we support with estimates of hydrological fluxes and altered boundary conditions. A freshwater mass of this size—stored in oceans, rather than land—suggests that a revision of sea-level reconstructions based on freshwater-sensitive stable oxygen isotopes may be required, and that large masses of fresh water could be delivered to the north Atlantic Ocean on very short timescales.
Unexpected intervals of low
230
Th concentration in marine sediment cores are explained by considering that during at least two such periods, the Arctic Ocean and Nordic seas were composed entirely of fresh water and covered by a thick ice shelf.
Publisher
Nature Publishing Group UK,Nature Publishing Group
Subject
