Ventilation of the Miocene Arctic Ocean : An idealized model study

• Published in: Paleoceanography
• Main Authors: Thompson, Bijoy, Nilsson, Johan, Nycander, Jonas, Jakobsson, Martin, Döös, Kristofer
• Format: Article in Journal/Newspaper
• Language: English
• Published: Institutionen för geologiska vetenskaper 2010
• Subjects: ocean ventilation; Miocene Arctic Ocean; age tracer; 0473 Biogeosciences: Paleoclimatology and paleoceanography; 4255 Oceanography: General: Numerical modeling; 3344 Atmospheric Processes: Paleoclimatology; 4562 Oceanography: Physical: Topographic/bathymetric interactions; Oceanography; Hydrology and Water Resources; Oceanografi; hydrologi och vattenresurser; Arctic; Arctic Ocean; Fram Strait; Lomonosov Ridge
• Online Access: http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-47306; https://doi.org/10.1029/2009PA001883

A model study of an idealized early Miocene Arctic Ocean has been undertaken. The work is motivated by the first drill core retrieved from the Lomonosov Ridge in the central Arctic Ocean, which suggests a transition from anoxic to oxic condition during the early Miocene, a feature presumably related to the opening of the Fram Strait. Here, the ventilation in a semienclosed basin, connected with the ocean through a strait with a sill, is examined using an ocean circulation model that includes a passive age tracer. In particular, we investigate how the ventilation depends on strait geometry, freshwater influx, and surface wind stress. We find that the turnover time, characterizing the bulk ventilation rate, is primarily controlled by the strait width and the wind stress. Generally, the oldest water in the basin is encountered near the sill depth, but wind forcing displaces the oldest water downward. For narrow straits, the turnover time gives an upper bound on the mean age of the basin water. The results have implications when translating local oxygen conditions, recorded in the sediment sequence from the Lomonosov Ridge, to basin-scale circulation patterns. Further, the results indicate that the early Miocene Arctic Ocean became well ventilated when the Fram Strait reached a width of about 100 km.