TY - JOUR
T1 - Temperature reconstructions for SW and N Iceland waters over the last 10 cal ka based on δ18O records from planktic and benthic Foraminifera
AU - Smith, L. Micaela
AU - Andrews, John T.
AU - Castañeda, Isla S.
AU - Kristjánsdóttir, Gréta B.
AU - Jennings, Anne E.
AU - Sveinbjörnsdóttir, Árny E.
N1 - Funding Information: This paper is dedicated to our friend and colleague Professor David Q. Bowen who has worked with many of us at the University of Colorado for several decades! Additionally, we would like to thank the scientists and crew of the B997 cruise who helped with core collection. Nancy Weiner is thanked for help with foraminifera samples and identification, and Sarah Principato for assistance with sampling cores 329, 331, and 332. This work has been supported by grants from the National Science Foundation (ATM-9531397, OPP 972510, OCE98-0900, OPP-0004233, ATM-0317832). Additional support was provided by several Beverly Sears Dean's small grants from the University of Colorado awarded to both Smith and Castañeda. Particular thanks are due to Dr. Helmut Erlenkeuser for the processing of most of the samples reported in this paper. We greatly appreciate his attention to detail and his scientific input into our investigations. The manuscript benefited from comments by D. Kroon and an anonymous reviewer. Data from this paper will be placed in NOAA Paleoclimate database.
PY - 2005/8
Y1 - 2005/8
N2 - We have obtained δ18Ocarb data from planktic (N. pachyderma (s.)) and benthic foraminifera (C. lobatulus, M. barleeanus) from eight cores between 40 and 500 m water depth along the SW (core B997-347) and N Iceland margins (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 δ18O carb 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 δ18O water values for present-day waters off Iceland; and (2) the present-day relationships between δ18Ocarb (or calcite) values of foraminifera and water column temperature and salinity data. We estimate the average error in the temperature estimate to be ∼±0.3°C based on a Monto Carlo simulation of the various error terms. We argue that around Iceland the variations in δ18O carb of both benthic and planktic species over the last 10 cal ka are principally controlled by temperature variations while salinity changes prove less important. Spatial and temporal changes are examined for both bottom water and 50 m water temperature reconstructions based on six and four cores, respectively. Reconstructed temperatures for sites around SW-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 and seafloor temperatures began to cool in N Iceland and to become less stratified in SW Iceland. Over the last 5000 yrs, sea surface temperature variations have been ≤1°C for 50% of the observations with a maximum range of ∼2.5°C. A profound decrease in temperature of ∼1.5°C 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 Iceland cores around 5 cal ka.
AB - We have obtained δ18Ocarb data from planktic (N. pachyderma (s.)) and benthic foraminifera (C. lobatulus, M. barleeanus) from eight cores between 40 and 500 m water depth along the SW (core B997-347) and N Iceland margins (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 δ18O carb 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 δ18O water values for present-day waters off Iceland; and (2) the present-day relationships between δ18Ocarb (or calcite) values of foraminifera and water column temperature and salinity data. We estimate the average error in the temperature estimate to be ∼±0.3°C based on a Monto Carlo simulation of the various error terms. We argue that around Iceland the variations in δ18O carb of both benthic and planktic species over the last 10 cal ka are principally controlled by temperature variations while salinity changes prove less important. Spatial and temporal changes are examined for both bottom water and 50 m water temperature reconstructions based on six and four cores, respectively. Reconstructed temperatures for sites around SW-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 and seafloor temperatures began to cool in N Iceland and to become less stratified in SW Iceland. Over the last 5000 yrs, sea surface temperature variations have been ≤1°C for 50% of the observations with a maximum range of ∼2.5°C. A profound decrease in temperature of ∼1.5°C 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 Iceland cores around 5 cal ka.
UR - https://www.scopus.com/pages/publications/23044481527
U2 - 10.1016/j.quascirev.2004.07.025
DO - 10.1016/j.quascirev.2004.07.025
M3 - Article
SN - 0277-3791
VL - 24
SP - 1723
EP - 1740
JO - Quaternary Science Reviews
JF - Quaternary Science Reviews
IS - 14-15
ER -