Highly variable Pliocene sea surface conditions in the Norwegian Sea

Bachem, Paul; Risebrobakken, Bjørg; Schepper, Stijn De; McClymont, Erin L.

doi:10.5194/cp-13-1153-2017

Cited by 25 publications

(56 citation statements)

References 93 publications

(173 reference statements)

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“…A decline in the relative abundance of F. filifera is observed between 3.284 and 3.281 Ma (Figure ). This is interpreted to reflect the warming of surface waters as recorded in a rise in SSTs of ~5°C to highest values (~15–16°C) within the studied interval between 3.285 and 3.283 Ma, tracing the obliquity cycle (Figure ) (Bachem et al, ). The ABF also increases between 3.287 and 3.284 Ma, suggesting enhanced marine productivity (Figure ) (de Vernal & Mudie, ; Schreck et al, ).…”

Section: Discussionmentioning

confidence: 81%

“…Abundances of F. filifera reach up to 17% during the first half of MIS M2. At the same time, SSTs in Hole 642B are low for the Pliocene and comparable to the Holocene average, with values around 12–13°C (Figure ) (Bachem et al, ), suggesting that F. filifera is a common element of the Piacenzian dinocyst assemblage under conditions similar to today. A proto‐AF was present between Sites 642 and 907 as indicated by a gradient of ~6–10°C (Figure ).…”

Section: Discussionmentioning

confidence: 88%

“…According to their stratigraphic records, these species have previously been classified as cold‐water tolerant species as they are common elements of Pliocene high‐latitude sites in the Northern Hemisphere (Head, , ). However, the high latitudes were markedly warmer than today during the Pliocene (Bachem et al, ; De Schepper et al, ; Herbert et al, ), suggesting that these species could live in relatively mild SSTs. During the Pliocene/Pleistocene, percentages of F. filifera above 5% are associated with Mg/Ca‐based ( Globigerina bulloides ) spring‐summer SSTs of >11°C and abundances of H. tectata > 30% with spring‐summer SSTs between 10 and 16°C (Mg/Ca, G. bulloides ) in the eastern North Atlantic (De Schepper et al, ; Hennissen et al, ).…”

Section: Discussionmentioning

confidence: 99%

“…This is indicative of the establishment of diverse, cool temperate mixed forests, and warmer‐than‐present climatic conditions in northern Norway (Panitz et al, ). With the warming being most pronounced in the SST record from Hole 642B and vegetation changes in northern Norway (Bachem et al, ; Panitz et al, ), it is likely a response to increased obliquity forcing, which strengthened the seasonal contrast and led to warm summers (e.g., Haug et al, ).…”

Section: Discussionmentioning

confidence: 99%

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Mid‐Piacenzian Variability of Nordic Seas Surface Circulation Linked to Terrestrial Climatic Change in Norway

et al. 2017

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During the mid‐Piacenzian, Nordic Seas sea surface temperatures (SSTs) were higher than today. While SSTs provide crucial climatic information, on their own they do not allow a reconstruction of potential underlying changes in water masses and currents. A new dinoflagellate cyst record for Ocean Drilling Program (ODP) Site 642 is presented to evaluate changes in northward heat transport via the Norwegian Atlantic Current (NwAC) between 3.320 and 3.137 Ma. The record is compared with vegetation and SST reconstructions from Site 642 and SSTs from Iceland Sea ODP Site 907 to identify links between SSTs, ocean currents, and vegetation changes. The dinocyst record shows that strong Atlantic water influence via the NwAC corresponds to higher‐than‐present SSTs and cool temperate vegetation during Marine Isotope Stage (MIS) transition M2–M1 and KM5. Reduced Atlantic water inflow relative to the warm stages coincides with near‐modern SSTs and boreal vegetation during MIS M2, KM6, and KM4–KM2. During most of the studied interval, a strong SST gradient between Sites 642 and 907 indicates the presence of a proto‐Arctic Front (AF). An absent gradient during the first half of MIS KM6, due to reduced Atlantic water influence at Site 642 and warm, presumably Atlantic water reaching Site 907, is indicative of a weakened NwAC and East Greenland Current. We conclude that repeated changes in Atlantic water influence directly affect terrestrial climate and that an active NwAC is needed for an AF to develop. Obliquity forcing may have played a role, but the correlation is not consistent.

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Section: Discussionmentioning

confidence: 81%

Section: Discussionmentioning

confidence: 88%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Mid‐Piacenzian Variability of Nordic Seas Surface Circulation Linked to Terrestrial Climatic Change in Norway

et al. 2017

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“…Previously published Nordic Seas IRD records that cover MIS M2 to mPWP, from ODP Holes 911A, 907A, and 642B (Bachem et al, , ; Fronval & Jansen, ; Jansen et al, ; Knies, Mattingsdal, et al, ) have been compiled and are presented together with new IRD occurrence (presence/absence) data from ODP Holes 911A, 909C, 907A, and 642B. All records from any site are presented using the same chronological framework (see Table ).…”

Section: Methodsmentioning

confidence: 99%

Icebergs in the Nordic Seas Throughout the Late Pliocene

Smith

Hill

Dolan

et al. 2018

Paleoceanog and Paleoclimatol

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The Arctic cryosphere is changing and making a significant contribution to sea level rise. The Late Pliocene had similar CO 2 levels to the present and a warming comparable to model predictions for the end of this century. However, the state of the Arctic cryosphere during the Pliocene remains poorly constrained. For the first time we combine outputs from a climate model with a thermodynamic iceberg model to simulate likely source regions for ice‐rafted debris (IRD) found in the Nordic Seas from Marine Isotope Stage M2 to the mid‐Piacenzian Warm Period and what this implies about the nature of the Arctic cryosphere at this time. We compare the fraction of melt given by the model scenarios with IRD data from four Ocean Drilling Program sites in the Nordic Seas. Sites 911A, 909C, and 907A show a persistent occurrence of IRD that model results suggest is consistent with permanent ice on Svalbard. Our results indicate that icebergs sourced from the east coast of Greenland do not reach the Nordic Seas sites during the warm Late Pliocene but instead travel south into the North Atlantic. In conclusion, we suggest a continuous occurrence of marine‐terminating glaciers on Svalbard and on East Greenland (due to the elevation of the East Greenland Mountains during the Late Pliocene). The study has highlighted the usefulness of coupled climate model‐iceberg trajectory modeling for understanding ice sheet behavior when proximal geological records for Pliocene ice presence or absence are absent or are inconclusive.

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First monodontid cetacean (Odontoceti, Delphinoidea) from the early Pliocene of the north‐western Pacific Ocean

Ichishima

Furusawa

Makino

et al. 2018

Papers in Palaeontology

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Monodontids are among the most enigmatic cetaceans due to their scarcity in the fossil record. Previously, except for fragmentary materials, only three skulls were known from the pre‐Pleistocene; these came from the east coast of the Pacific and both east and west coasts of the Atlantic. Haborodelphis japonicus, a new early Pliocene monodontid cetacean from the north‐west Pacific, significantly expands the palaeobiogeographical extent of the ancestral monodontids. The new taxon differs from all other monodontids in the following character states: the robust postorbital process for the skull size; the short rostrum relative to the whole skull length; the anterior dorsal infraorbital foramina posterior to the level of the antorbital notch; the premaxillary foramen on the level of the antorbital notch; the dorsally gently convex premaxillary sac fossa; the palatines wedged into the maxillae anteriorly on the midline; and the presence of the clearly excavated posteromedial sulcus. Monodontids were almost certainly adapted to warmer waters than their living counterparts Delphinapterus leucas and Monodon monoceros, both of which are confined to the high latitudes of the northern hemisphere. However, closer inspection (based mainly on fossil invertebrates) of the palaeoenvironments from which the monodontid fossils were produced, reveals that they may have preferred cooler conditions than previously thought. Due to the short climatic fluctuation cycles during the Pliocene in the northern hemisphere, and the increase of heterogeneity and regionality of the coastal environments, the dating of layers within a formation is critical for understanding palaeoenvironment in terms of the sea surface temperatures.

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Highly variable Pliocene sea surface conditions in the Norwegian Sea

Abstract: Abstract. The Pliocene was a time of global warmth with small sporadic glaciations, which transitioned towards the larger-scale Pleistocene glacial-interglacial variability. Here, we present high-resolution records of sea surface temperature (SST) and ice-rafted debris (IRD)

Cited by 25 publications

References 93 publications

Mid‐Piacenzian Variability of Nordic Seas Surface Circulation Linked to Terrestrial Climatic Change in Norway

Mid‐Piacenzian Variability of Nordic Seas Surface Circulation Linked to Terrestrial Climatic Change in Norway

Icebergs in the Nordic Seas Throughout the Late Pliocene

First monodontid cetacean (Odontoceti, Delphinoidea) from the early Pliocene of the north‐western Pacific Ocean

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