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SUMMARY:Reconstructing deep ocean circulation pathway and strength using s
 ediment dispersion - Alex Piotrowski (Dept of Earth Science)
DTSTART:20180208T173000Z
DTEND:20180208T183000Z
UID:TALK95404@talks.cam.ac.uk
CONTACT:Dr Rachael Rhodes
DESCRIPTION:Ocean circulation is thought to play a key role in the Earth
 ’s climate system because surface ocean currents transport heat from the
  equator to the poles and deep ocean water sequesters carbon dioxide from 
 the atmosphere.   Geochemical proxies measured on the biogenic components 
 of marine sediments have been widely-utilized to reconstruct past ocean ch
 anges.  However\, because these proxies are controlled by biology and chem
 istry in addition to physical circulation it is difficult to use them to q
 uantitatively reconstruct physical oceanographic parameters such as deep w
 ater advection speed.   I will present new data of coupled sediment grains
 ize and source measurements\, from highly resolved grain-size separates ac
 ross the clay and silt fraction\, allowing reconstruction of the dispersio
 n of fine detrital sediment by ocean currents.  We have initially worked i
 n the North Atlantic because it hosts a strong deep current that transport
 s sediment from geological sources with distinct and well-constrained geoc
 hemistry (i.e. Iceland and the Canadian Shield).  Our core-top data shows 
 that grainsize separation in the 0-63 m range allows “unmixing” of 
 North Atlantic marine sediment samples into at least three different sourc
 es\; the finest grain-sizes are derived from Scandinavia and Iceland and h
 ave been transported great distances by deep current flow\, while the coar
 ser fractions are locally derived.   Time slice reconstruction during the 
 last deglaciation place new constraints on glacial-interglacial changes in
  sediment sources\, input\, and ocean circulation pathways.  \n\nQuaternar
 y Discussion Group seminar
LOCATION:Latimer Room (Old Court)\, Clare College\, Trinity Lane
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