Sea-Level changes and Global Monsoon System: Clues from marine cores in Brazil

Resumo: Tropical regions are a major source of heat to mid- and high-latitudes. The Atlantic Ocean-
Atmosphere system is unique as it is the only system that currently transports heat across the
equator. Therefore, accomplishing accurate global climate reconstructions, documentation and
implementation of Atlantic climates in large-scale climate models is essential. This, however,
has been hampered for most of the Cenozoic due to the lack of sufficient low-latitude sediment
records. Here we propose to investigate paleoceanographic changes across the Cenozoic driven
by longer and shorter term forcings from the Eocene greenhouse to icehouse conditions in the
Quaternary, through the reconstruction of atmospheric, oceanographic and biological processes.
The Brazilian Margin is a passive and stable continental margin that developed following the
opening of the central Atlantic Ocean in mid-Cretaceous. A peculiar aspect of this margin is that
it remained tectonically “passive” and approximately at the same equatorial latitude since its
formation and, consequently, it has maintained continually a mainly oligotrophic inter-tropical
environment. This project will take advantage of these unique attributes for obtaining highquality
sedimentological, paleoclimatic, and paleoceanographic data for the Cenozoic, proposing
to drill transects across the Brazilian Margin from the uppermost part of the continental slope to
the abyssal plain. The expected stratigraphic continuity along these transects will allow the
detailed study of the relation between pCO2, sea-level and climate changes throughout the
Cenozoic by constraining the fundamental parameters for calculating the climate sensitivity. This
stratigraphic record will define the low-latitude climatic response to the major Cenozoic climatic
events, such as the EECO, MECO, EOT, OMT, MCO and iNHG (see text for details). Sediments
are expected to yield calcareous and organic microfossils, which will allow for studying the
response of tropical ecosystems to these climatic events and also provide independent substrates
for climate and carbon cycle reconstructions. Sediments will contain also fine eolian particles as
well as terrigenous sediments related to increased run-off therefore more precipitations, which
are associated to the South American Monsoon System as part of the Global Monsoon System.
By undertaking a depth transect of sites selected from a wealth of seismic reflection data,
integrated with high-resolution sedimentological records to reconstruct sea-level changes. In
particular, these sites were chosen to establish a landmark for high-resolution Eocene-Recent
tropical climate reconstructions, which will provide the following outcomes: 1) detail the
relationship between tropical climate (temperature), sea-level and atmospheric pCO2; 2)
evolution of the Atlantic Meridional Overturning Circulation driven by longer (tectonic) and
shorter term (solar input) forcings and interplay with the South American Monsoon System.

Data de início: 11/11/2019
Prazo (meses): 48

Participantes:

Papel	Nome
Pesquisador	ALEX CARDOSO BASTOS