230Th-excess inventory and distribution in a southern Mendeleev Ridge core (Arctic Ocean): linkage with late Quaternary sedimentological and paleogeographical changes

Mapping Intimacies ◽

10.5194/egusphere-egu2020-824 ◽

2020 ◽

Author(s):

Tengfei Song ◽

Claude Hillaire-Marcel ◽

Yanguang Liu

Keyword(s):

Grain Size ◽

Sea Ice ◽

Arctic Ocean ◽

Late Quaternary ◽

Critical Time ◽

Clay Mineralogy ◽

Sedimentation Rates ◽

Central Arctic Ocean ◽

Sea Levels ◽

Ice Production

In addition to 14C-data, sedimentary excesses in 230Th &#160;(230Thxs) in central Arctic Ocean cored sequences yielded critical time constrains and sedimentation rates estimates, at least, at sites characterized by very low sedimentation rates (<< 1cm/ka). Closer to the Russian margin, where higher accumulation rates are recorded based on 14C-ages, the setting of a reliable stratigraphy based on 230Thxs reveals more challenging, as illustrated here, based on the analysis of &#160;a gravity core raised from the southern Mendeleev Ridge (core ARC7-E25; -179.4&#176;E, 79.0&#176;N; 1200 m water depth; 320 cm long). Subsamples were collected at a 4 to 8 cm interval. Measurements included: AMS 14C in foraminifera, grain size, bulk Xray mineralogy, clay mineralogy, geochemistry (Corg, Cinorg,13Corg, 238U, 234U, 230Th, 226Ra, 210Pb). Data indicate that some sediment were lost at core top. Nevertheless, 14C and 230Thxs &#160;data allow estimating a mean sedimentation rate of about 6 to 7 mm/ka during the last two climatic cycles. A comparison of the 230Thxs inventory and distribution pattern with those from other cores allows identifying important parameters involved in the cycling of the water column-produced 230Th in this basin and its sporadic sedimentary accumulation, in particular linkages with sea-ice production over shelves, thus sea-levels, sea-ice rafting routes, grain-size and mineralogy, potential winnowing of fine fractions, role of brines and relative duration of intervals with reduced or nil sedimentation preceding 230Thxs-accumulation intervals.

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Central Arctic Ocean paleoceanography from ~ 50 ka to present, on the basis of ostracode faunal assemblages from SWERUS 2014 expedition

10.5194/cp-2017-22 ◽

2017 ◽

Author(s):

Laura Gemery ◽

Thomas M. Cronin ◽

Robert K. Poirier ◽

Christof Pearce ◽

Natalia Barrientos ◽

...

Keyword(s):

Sea Ice ◽

Arctic Ocean ◽

Large Scale ◽

Late Quaternary ◽

Atlantic Water ◽

Environmental Indicators ◽

The Arctic ◽

Lomonosov Ridge ◽

Central Arctic Ocean ◽

Ice Conditions

Abstract. Late Quaternary paleoceanographic changes in the central Arctic Ocean were reconstructed from a multicore and gravity core from the Lomonosov Ridge (Arctic Ocean) collected during the 2014 SWERUS-C3 Expedition. Ostracode assemblages dated by accelerator mass spectrometry (AMS) indicate changing sea-ice conditions and warm Atlantic Water (AW) inflow to the Arctic Ocean from ~ 50 ka to present. Key taxa used as environmental indicators include Acetabulastoma arcticum (perennial sea ice), Polycope spp. (productivity and sea ice), Krithe hunti (partially sea-ice free conditions, deep water inflow), and Rabilimis mirabilis (high nutrient, AW inflow). Results indicate seasonally sea-ice free conditions during Marine Isotope Stage (MIS) 3 (~ 57–29 ka), rapid deglacial changes in water mass conditions (15–11 ka), seasonally sea-ice free conditions during the early Holocene (~ 10–7 ka) and perennial sea ice during the late Holocene. Comparisons with faunal records from other cores from the Mendeleev and Lomonosov Ridges suggest generally similar patterns, although sea-ice cover during the last glacial maximum may have been less extensive at the southern Lomonosov Ridge at our core site (~ 85.15° N, 152° E) than farther north and towards Greenland. The new data also provide evidence for abrupt, large-scale shifts in ostracode species depth and geographical distributions during rapid climatic transitions.

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Central Arctic Ocean paleoceanography from ∼  50 ka to present, on the basis of ostracode faunal assemblages from the SWERUS 2014 expedition

Climate of the Past ◽

10.5194/cp-13-1473-2017 ◽

2017 ◽

Vol 13 (11) ◽

pp. 1473-1489 ◽

Cited By ~ 3

Author(s):

Laura Gemery ◽

Thomas M. Cronin ◽

Robert K. Poirier ◽

Christof Pearce ◽

Natalia Barrientos ◽

...

Keyword(s):

Sea Ice ◽

Arctic Ocean ◽

Large Scale ◽

Water Mass ◽

Late Quaternary ◽

High Surface ◽

Environmental Indicators ◽

The Arctic ◽

Lomonosov Ridge ◽

Central Arctic Ocean

Abstract. Late Quaternary paleoceanographic changes at the Lomonosov Ridge, central Arctic Ocean, were reconstructed from a multicore and gravity core recovered during the 2014 SWERUS-C3 Expedition. Ostracode assemblages dated by accelerator mass spectrometry (AMS) indicate changing sea-ice conditions and warm Atlantic Water (AW) inflow to the Arctic Ocean from ∼  50 ka to present. Key taxa used as environmental indicators include Acetabulastoma arcticum (perennial sea ice), Polycope spp. (variable sea-ice margins, high surface productivity), Krithe hunti (Arctic Ocean deep water), and Rabilimis mirabilis (water mass change/AW inflow). Results indicate periodic seasonally sea-ice-free conditions during Marine Isotope Stage (MIS) 3 ( ∼  57–29 ka), rapid deglacial changes in water mass conditions (15–11 ka), seasonally sea-ice-free conditions during the early Holocene ( ∼  10–7 ka) and perennial sea ice during the late Holocene. Comparisons with faunal records from other cores from the Mendeleev and Lomonosov ridges suggest generally similar patterns, although sea-ice cover during the Last Glacial Maximum may have been less extensive at the new Lomonosov Ridge core site ( ∼  85.15° N, 152° E) than farther north and towards Greenland. The new data provide evidence for abrupt, large-scale shifts in ostracode species depth and geographical distributions during rapid climatic transitions.

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Late Quaternary sedimentary processes in the central Arctic Ocean inferred from geophysical mapping

Geomorphology ◽

10.1016/j.geomorph.2020.107309 ◽

2020 ◽

Vol 369 ◽

pp. 107309

Author(s):

Lara F. Pérez ◽

Martin Jakobsson ◽

Thomas Funck ◽

Katrine J. Andresen ◽

Tove Nielsen ◽

...

Keyword(s):

Arctic Ocean ◽

Late Quaternary ◽

Sedimentary Processes ◽

Central Arctic Ocean ◽

Geophysical Mapping

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A New Chronology of Late Quaternary Sequences From the Central Arctic Ocean Based on “Extinction Ages” of Their Excesses in231Pa and230Th

Geochemistry Geophysics Geosystems ◽

10.1002/2017gc007050 ◽

2017 ◽

Vol 18 (12) ◽

pp. 4573-4585 ◽

Cited By ~ 10

Author(s):

C. Hillaire-Marcel ◽

B. Ghaleb ◽

A. de Vernal ◽

J. Maccali ◽

K. Cuny ◽

...

Keyword(s):

Arctic Ocean ◽

Late Quaternary ◽

Central Arctic Ocean ◽

Quaternary Sequences

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Incorporation of satellite-derived thin-ice data into a global OGCM simulation

Climate Dynamics ◽

10.1007/s00382-019-04979-8 ◽

2019 ◽

Vol 53 (11) ◽

pp. 7113-7130

Author(s):

Takahiro Toyoda ◽

Katsushi Iwamoto ◽

L. Shogo Urakawa ◽

Hiroyuki Tsujino ◽

Hideyuki Nakano ◽

...

Keyword(s):

Sea Ice ◽

Arctic Ocean ◽

Model Simulation ◽

Mixed Layer Depth ◽

The Arctic ◽

Sea Ice Thickness ◽

Ice Volume ◽

The Arctic Ocean ◽

Polar Ocean ◽

Ice Production

Abstract The presence of thin sea ice is indicative of active freezing conditions in the polar ocean. We propose a simple yet effective method to incorporate information of thin-ice category into coupled ocean–sea-ice model simulations. In our approach, the thin-ice distribution restricts thick-ice extent and constrains atmosphere–ocean heat exchange through the sea ice. Our model simulation with the incorporation of satellite-derived thin-ice data for the Arctic Ocean showed much improved representation of sea-ice and upper-ocean fields, including sea-ice thickness in the Canadian Archipelago and the region north of Greenland, mixed-layer depth over the Central Arctic, and surface-layer salinity over the open ocean. Enhanced sea-ice production by the thin-ice data constraint increased the total sea-ice volume of the Arctic Ocean by $$5 \times 10^{3}$$ 5 × 10 3 –$$10 \times 10^{3}$$ 10 × 10 3 km3. Subsequent sea-ice melting was also enhanced, leading to the greater amplitude of the seasonal cycle by approximately $$2 \times 10^{3}$$ 2 × 10 3 km3 (15% of the baseline value from the experiment without the thin-ice data incorporation). Overall, our results demonstrate that the incorporation of satellite-derived information on thin sea ice has great potential for the improvement of coupled ocean–sea-ice simulations.

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