Temperature reconstructions for SW and N Iceland waters over the last 10cal ka based on delta O-18 records from planktic and benthic Foraminifera

Smith, L. M. and Andrews, J. T. and Castaneda, I. S. and Kristjansdottir, G. B. and Jennings, A. E. and Sveinbjornsdottir, A. E. (2005) Temperature reconstructions for SW and N Iceland waters over the last 10cal ka based on delta O-18 records from planktic and benthic Foraminifera. Quaternary Science Reviews, 24 (14-15). pp. 1723-1740. ISSN 0277-3791 DOI 10.1016/j.quascirev.2004.07.025

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Abstract

We have obtained d18Ocarb data from planktic (N. pachyderma (s.)) andbenthic foraminifera (C. lobatulus, M. barleeanus) from eight cores between 40 and500 m water depth along the SW (core B997–347) andN Icelandmargins (cores B997-321, -324, -327, -328, -329, -330, and-332) that span the last 10 cal ka. Sampling resolution varies between centuries to millennial scales. Over this time range, changes in d18Ocarb in foraminifera are the product of changes in the global ice volume, and the temperature and salinity of the water at the level in which the foraminifera live. In order to evaluate the relative roles of these variables we investigate: (1) the salinity (S%) and d18Owater values for present-day waters off Iceland; and (2) the present-day relationships between d18Ocarb (or calcite) values of foraminifera andwater column temperature and salinity data. We estimate the average error in the temperature estimate to be 70.3 1C basedon a Monto Carlo simulation of the various error terms. We argue that aroundIcelandthe variations in d18Ocarb of both benthic andplanktic species over the last 10 cal ka are principally controlledby temperature variations while salinity changes prove less important. Spatial andtemporal changes are examinedfor both bottom water and50 m water temperature reconstructions basedon six andfour cores, respectively. Reconstructed temperatures for sites aroundSW-N Iceland indicate that surface and seafloor water temperatures were warmest in the early Holocene (10–6 cal ka). Beginning at 6 cal ka, surface andseafloor temperatures began to cool in N Iceland andto become less stratifiedin SW Iceland. Over the last 5000 yrs, sea surface temperature variations have been p1 1C for 50% of the observations with a maximum range of 2.5 1C. A profoundd ecrease in temperature of 1.5 1C is recorded in our fjord site (B997-328) during the Little Ice Age. An abrupt, earlier cold event is well expressed in at least three N Icelandcores around5 cal ka.

Item Type: Article
Additional Information: BP Exploration Alaska;cml
Uncontrolled Keywords: NIL AREP
Subjects: 01 - Climate Change and Earth-Ocean Atmosphere Systems
Divisions: 01 - Climate Change and Earth-Ocean Atmosphere Systems
Journal or Publication Title: Quaternary Science Reviews
Volume: 24
Page Range: pp. 1723-1740
Identification Number: 10.1016/j.quascirev.2004.07.025
Depositing User: Sarah Humbert
Date Deposited: 10 Nov 2010 17:21
Last Modified: 23 Jul 2013 09:59
URI: http://eprints.esc.cam.ac.uk/id/eprint/1831

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