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Stratigraphic templates for ice core records of the past 1.5 Myr
Ist Teil von
Climate of the past, 2022-07, Vol.18 (7), p.1563-1577
Ort / Verlag
Katlenburg-Lindau: Copernicus GmbH
Erscheinungsjahr
2022
Link zum Volltext
Quelle
Free E-Journal (出版社公開部分のみ)
Beschreibungen/Notizen
The international ice core community has a target to obtain
continuous ice cores stretching back as far as 1.5 Myr. This would
provide vital data (including a CO2 profile) allowing us to assess
ideas about the cause of the Mid-Pleistocene Transition (MPT). The European
Beyond EPICA project and the Australian Million Year Ice Core project each
plan to drill such a core in the region known as Little Dome C. Dating the
cores will be challenging, and one approach will be to match some of the
records obtained with existing marine sediment datasets, informed by
similarities in the existing 800 kyr period. Water isotopes in Antarctica
have been shown to closely mirror deepwater temperature, estimated from
Mg/Ca ratios of benthic foraminifera, in a marine core on the Chatham Rise
near to New Zealand. The dust record in ice cores resembles very closely a
South Atlantic marine record of iron accumulation rate. By assuming these
relationships continue beyond 800 ka, our ice core record could be
synchronised to dated marine sediments. This could be supplemented, and
allow synchronisation at higher resolution, by the identification of rapid
millennial-scale events that are observed both in Antarctic methane records
and in emerging records of planktic oxygen isotopes and alkenone sea surface
temperature (SST) from the Portuguese Margin. Although published data remain
quite sparse, it should also be possible to match 10Be from ice cores
to records of geomagnetic palaeo-intensity and authigenic 10Be/9Be
in marine sediments. However, there are a number of issues that have to be
resolved before the ice core 10Be record can be used. The approach of
matching records to a template will be most successful if the new core is in
stratigraphic order but should also provide constraints on disordered
records if used in combination with absolute radiogenic ages.