Oceanic versus continental influences over the last 7 kyrs from a mid shelf record in the northern Bay of Biscay (NE Atlantic)

QUATERNARY SCIENCE REVIEWS

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Article

Penaud, A.¹  Ganne, A.¹  Eynaud, F.²  Lambert, C.³  Coste, P. O.¹  Herledan, M.¹  Vidal, M.¹  Goslin, J.⁴  Stephan, P.⁵  Charria, G.⁶  Pailler, Y.⁷  Durand, M.⁸  Zumaque, J.⁹  Mojtahid, M.⁸ 

[1] Univ Brest UBO, CNRS, UMR 6538, LGO, F-29280 Plouzane, France

[2] Univ Bordeaux, CNRS, UMR 5805, EPOC, F-33405 Talence, France

[3] Univ Vannes UBS, UMR 6538, LGO, F-56000 Vannes, France

[4] IFREMER, Ctr Bretagne, Geosci Marines, ZI Pointe Diable, CS 10070, F-29280 Plouzane, France

[5] Univ Brest, CNRS, UMR 6554, LETG, F-29280 Plouzane, France

[6] Univ Brest, CNRS, UMR6523, IFREMER,LOPS, F-29280 Plouzane, France

[7] IUEM, Inrap, UMR 8215 Trajectoires, F-29280 Plouzane, France

[8] Univ Angers, Univ Nantes, CNRS, LPG BIAF UMR CNRS 6712,UFR Sci, 2 Bd Lavoisier, F-49045 Angers, France

[9] Geotop Univ Quebec Montreal, Montreal, PQ, Canada

关键词: Holocene;    Vegetation dynamics;    Stable isotopes;    Atlantic subpolar gyre;    Rapid climate changes;    Precipitation regimes;    Winter horizontal thermohaline front;   

DOI  :  10.1016/j.quascirev.2019.106135

来源: Elsevier

【 摘 要 】

We discuss paleoenvironments of north-western France over the last 7 kyrs in terms of: i) long-term changes (relative sea-level rise and boreal summer insolation), ii) rapid climate changes (millennial scale Bond events and multi-decadal regimes of the North Atlantic Oscillation: NAO) and iii) growing human impacts in watersheds. Our study focuses on the CBT-CS11 core, retrieved in the northern Bay of Biscay, with new high-resolution (70 years) palynological data (dinoflagellate cysts and pollen), combined with sedimentological and oxygen stable isotopic records. This multiproxy approach enabled us to gain a better understanding of the influence of varying Middle to Late Holocene climate regimes on marine, coastal and terrestrial ecosystems as well as on human coastal societies. We especially show that the slowdown of the relative sea -level rise, starting at around 5.9 ka BP, led to the stabilization of tidal flats in estuarine environments. Subsequently, increasing river flows to the ocean resulted in a progressive seasonal stratification of the shelf under increasing winter precipitations and establishment of the modern winter thermohaline front at 33 ka BP. In addition, within the 4-2 ka BP interval, palynological and sedimentological evidence suggests increasing river discharges in north-western France, in a context of a weakened Atlantic subpolar gyre and recurrent negative NAO-like conditions. Finally, we identified a major transition at around 1.2 ka BP (Early Middle-Ages) that appears to be linked to a period of maximal anthropogenic landscape opening and soil erosion, implying stronger primary productivity in coastal surface waters of the studied region. (C) 2019 Elsevier Ltd. All rights reserved.

【 授权许可】

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