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Variations of North Atlantic inflow to the central Arctic Ocean over the last 14 million years inferred from hafnium and neodymium isotopes

Variations of North Atlantic inflow to the central Arctic Ocean over the last 14 million years inferred from hafnium and neodymium isotopes
Variations of North Atlantic inflow to the central Arctic Ocean over the last 14 million years inferred from hafnium and neodymium isotopes
The warm and saline North Atlantic inflow to the Arctic Ocean is a major component of high northern latitude circulation and the main mechanism of deep water renewal in the Arctic Ocean. Knowledge of its past variability is critical for understanding the high latitude feedback mechanisms of the climate system. Here we present the first combined seawater Hf and Nd isotope compositions of past Arctic Intermediate Water extracted from the authigenic Fe–Mn oxyhydroxide fraction of two sediment cores recovered near the North Pole, to reconstruct changes in contributions from glacial brines of the Eurasian shelf and past inflow of Atlantic waters. The Hf and Nd isotopic compositions obtained from leachates of the authigenic fraction show closely coupled and environmentally controlled variations over the past 14 million years. An observed offset of these data from seawater ?Hf and ?Nd compositions from other ocean basins (seawater array) is interpreted as the result of continuously prevailing glacial weathering conditions on the high latitude Eurasian continent. In the late Quaternary, large amplitude Hf and Nd isotopic variations of Arctic Intermediate Water (AIW) was characterized by more radiogenic isotope signatures generally prevailing under glacial conditions and less radiogenic values during interglacial periods. On the basis of the close coupling between Nd and Hf isotopes, we suggest that the evolution of Hf isotope compositions of central Arctic AIW has primarily been controlled by changes in ocean circulation and provenance of weathering inputs, rather than changes in weathering regime.
0012-821X
82-92
Chen, Tian-Yu
930d4472-4b3e-4264-bc96-7fbc75f3a188
Frank, Martin
09ec65ac-f62d-41da-86b2-81908973b8a1
Haley, Brian A.
d6375324-0988-4da9-bc69-391a48d4a91c
Gutjahr, Marcus
5babbbc4-2a1a-48df-a2e3-d87b2483ea9c
Spielhagen, Robert F.
ace7ee6e-66a2-44c4-80d9-33e916f860d6
Chen, Tian-Yu
930d4472-4b3e-4264-bc96-7fbc75f3a188
Frank, Martin
09ec65ac-f62d-41da-86b2-81908973b8a1
Haley, Brian A.
d6375324-0988-4da9-bc69-391a48d4a91c
Gutjahr, Marcus
5babbbc4-2a1a-48df-a2e3-d87b2483ea9c
Spielhagen, Robert F.
ace7ee6e-66a2-44c4-80d9-33e916f860d6

Chen, Tian-Yu, Frank, Martin, Haley, Brian A., Gutjahr, Marcus and Spielhagen, Robert F. (2012) Variations of North Atlantic inflow to the central Arctic Ocean over the last 14 million years inferred from hafnium and neodymium isotopes. Earth and Planetary Science Letters, 353-354, 82-92. (doi:10.1016/j.epsl.2012.08.012).

Record type: Article

Abstract

The warm and saline North Atlantic inflow to the Arctic Ocean is a major component of high northern latitude circulation and the main mechanism of deep water renewal in the Arctic Ocean. Knowledge of its past variability is critical for understanding the high latitude feedback mechanisms of the climate system. Here we present the first combined seawater Hf and Nd isotope compositions of past Arctic Intermediate Water extracted from the authigenic Fe–Mn oxyhydroxide fraction of two sediment cores recovered near the North Pole, to reconstruct changes in contributions from glacial brines of the Eurasian shelf and past inflow of Atlantic waters. The Hf and Nd isotopic compositions obtained from leachates of the authigenic fraction show closely coupled and environmentally controlled variations over the past 14 million years. An observed offset of these data from seawater ?Hf and ?Nd compositions from other ocean basins (seawater array) is interpreted as the result of continuously prevailing glacial weathering conditions on the high latitude Eurasian continent. In the late Quaternary, large amplitude Hf and Nd isotopic variations of Arctic Intermediate Water (AIW) was characterized by more radiogenic isotope signatures generally prevailing under glacial conditions and less radiogenic values during interglacial periods. On the basis of the close coupling between Nd and Hf isotopes, we suggest that the evolution of Hf isotope compositions of central Arctic AIW has primarily been controlled by changes in ocean circulation and provenance of weathering inputs, rather than changes in weathering regime.

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Published date: 1 November 2012
Organisations: Paleooceanography & Palaeoclimate

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Local EPrints ID: 343228
URI: https://eprints.soton.ac.uk/id/eprint/343228
ISSN: 0012-821X
PURE UUID: cdafcde8-9378-4936-bbea-cc4e610ae428

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Date deposited: 27 Sep 2012 08:40
Last modified: 18 Jul 2017 05:23

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