1. Miocene to early Pliocene “biogenic bloom”
Top down and bottom up: Testing the fidelity of two paleoproductivity proxies in the context of the late
Miocene to early Pliocene “biogenic bloom”
Katharina Billups, College of Marine and Earth Studies, University of Delaware
Primary productivity within the surface oceans plays a significant role in the carbon cycle and transfer of carbon from the atmospheric to sedimentary reservoirs. However, modern measurements show that the transfer of organic matter from the surface to the deep ocean is complex. Here we construct
two paleoproductivity proxy records reflecting “opposite” aspects of primary productivity; organic matter production at the sea surface (nannofossil Sr/Ca)
and its consumption on the sea floor (benthic foraminiferal accumulation rates.
One aspect of our study focuses on
a mid-Pliocene section of Ocean
Drilling Program Site 926
(Ceara Rise, western tropical Atlantic)
at which species assemblages have
been published. Our data reveal that coarse
fraction (8-20 mm) nannofossil Sr/Ca (A)
varies positively with insolation (B), relative
changes in carbonate content (C)
Discoaster (D) and Florisphaera (E)
abundances, and benthic foraminiferal
accumulation rates (F).
These results confirm a first order
link between surface ocean
organic matter production and
consumption on the seafloor.