Journal
PALEOCEANOGRAPHY AND PALEOCLIMATOLOGY
Volume 35, Issue 10, Pages -Publisher
AMER GEOPHYSICAL UNION
DOI: 10.1029/2020PA003932
Keywords
-
Funding
- Dutch Ministry of Education, Culture and Science (Ministerie van Onderwijs, Cultuur en Wetenschap)
- Ammodo Foundation
- Royal Society University Research Fellowship
- Bolin Centre for Climate Research, Stockholm
- Danish Council for Independent Research/Natural Sciences (DFF/FNU) [11-107497]
- European Research Council [802835 OceaNice, 771497 SPANC]
- ECORD
Ask authors/readers for more resources
Several studies indicate that North Atlantic Deep Water (NADW) formation might have initiated during the globally warm Eocene (56-34 Ma). However, constraints on Eocene surface ocean conditions in source regions presently conducive to deep water formation are sparse. Here we test whether ocean conditions of the middle Eocene Labrador Sea might have allowed for deep water formation by applying (organic) geochemical and palynological techniques, on sediments from Ocean Drilling Program (ODP) Site 647. We reconstruct a long-term sea surface temperature (SST) drop from similar to 30 degrees C to similar to 27 degrees C between 41.5 to 38.5 Ma, based on TEX86. Superimposed on this trend, we record similar to 2 degrees C warming in SST associated with the Middle Eocene Climatic Optimum (MECO; similar to 40 Ma), which is the northernmost MECO record as yet, and another, likely regional, warming phase at similar to 41.1 Ma, associated with low-latitude planktic foraminifera and dinoflagellate cyst incursions. Dinoflagellate cyst assemblages together with planktonic foraminiferal stable oxygen isotope ratios overall indicate low surface water salinities and strong stratification. Benthic foraminifer stable carbon and oxygen isotope ratios differ from global deep ocean values by 1-2 parts per thousand and 2-4 parts per thousand, respectively, indicating geographic basin isolation. Our multiproxy reconstructions depict a consistent picture of relatively warm and fresh but also highly variable surface ocean conditions in the middle Eocene Labrador Sea. These conditions were unlikely conducive to deep water formation. This implies either NADW did not yet form during the middle Eocene or it formed in a different source region and subsequently bypassed the southern Labrador Sea.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available