the late pleistocene-holocene record of sea level in northeastern brazil and its relation to...
TRANSCRIPT
THE LATE PLEISTOCENE-HOLOCENE RECORD OF
SEA LEVEL IN NORTHEASTERN BRAZIL AND ITS RELATION TO CLIMATE, EUSTASY AND
TECTONICS
Dilce F. Rossetti1, Francisco H. R. Bezerra2, Ana M. Góes3,
Márcio M. Valeriano1, Clódis O. Andrades-Filho1, Juan C. R. Mittani4, Sonia H. Tatumi4,
Benjamim B. Brito-Neves3
1INPE, 2UFRN, 3USP, 4FATEC
Late Cretaceous
Late Quaternary Relative Sea Level
Eustatic fluctuations ice sheets
Age (kyrs B.P.)
Sea level (m
) Younger Dryas
Last Glacial Maximum
Holocene Transgression Last Interglacial
Late Pleistocene-Holocene relative sea level=>climatic fluctuations
MAIN PROBLEMS:
1. Sea level curves have been established with basis on data from a few localities
2. Chronological data are still insufficientto identify and correlate events with regional significance
3. There are many disagreements among available interpretations
35°0'0"W40°0'0"W
10°0'0"S
Altitude (m)1,000
0
EarthquakeMagnitude
234 - 5
0 100 200 30050km
Atlantic Ocean
Study area
Historical andpaleo-liquefaction sites
BRAZIL
7
• How passive this passive margin is ?
• Is there evidence of paleoseismic activity in the sedimentary record of this region ?
EUSTASY CLIMATE
What about TECTONICS ???
RELATIVE SEA LEVEL
Barreiras Formation(Early/Middle Miocene)
Bedding
BARREIRAS FORMATION- TILTING
BARREIRAS FORMATION- FAULTS
BARREIRAS FORMATION- FAULTS
BARREIRAS FORMATION- FAULTS
BARREIRAS FORMATION- FOLDS
Barreiras Formation experienced extension and compression after deposition.
Post-Barreiras Sediments
Barreiras Fm.
Barreiras Fm.
Post-Barreiras Sediments
Barreiras Fm.
Post-Barreiras Sediments
PB1
PB2
Post-Barreiras Sediments
PB2- Holocene (OSL)
PB1- Late Pleistocene (OSL)
2m
POST-BARREIRAS SED. (PB1)
Sand dike
Convolute bedsMassive bedding
POST-BARREIRAS SEDIMENTS- PB1 FAULTED, MASSIVE AND CONVOLUTE BEDDING
Post-Barreiras Sediments
Barreiras Fm.
2m
POST-BARREIRAS SED. (PB1)
CONCLUSIONS
Late Pleistocene and Holocene sedimentary deposits (i.e., Post-Barreiras Sediments) are geographically widespread along the NE Brazilian coast;
These strata contain the imprint of relative sea level and of their controlling mechanisms, thus they are of great interest in studies aiming to reconstruct the effect of Late Quaternary sea level changes in Brazil;
The Post-Barreiras Sediments contain a variety of soft sediment deformation structures and massive sands attesting large scale slumps, large scale liquefaction and re-sedimentation , which are mostly due to reactivation of tectonic structures. In addition to generate these seismites within the PBS, this event also deformed the underlying Barreiras Formation;
Tectonics might have played a more important control on relativeSea level changes in NE Brazil than other factors as eustasy and climate .
CONCLUSIONS
Late Pleistocene and Holocene sedimentary deposits (i.e., Post-Barreiras Sediments) are geographically widespread along the NE Brazilian coast;
These strata are of great interest in studies aiming to reconstruct the effect of Late Quaternary sea level changes in Brazil;
The Post-Barreiras Sediments contain a variety of soft sediment deformation structures and massive sands attesting large scale slumps, large scale liquefaction and re-sedimentation , which are mostly due to reactivation of tectonic structures. In addition to generate these seismites within the PBS, this event also deformed the underlying Barreiras Formation;
Tectonics might have played a more important control on relativeSea level changes in NE Brazil than other factors as eustasy and climate .
CONCLUSIONS
Late Pleistocene and Holocene sedimentary deposits (i.e., Post-Barreiras Sediments) are geographically widespread along the NE Brazilian coast;
These strata are of great interest in studies aiming to reconstruct the effect of Late Quaternary sea level changes in Brazil;
The Post-Barreiras Sediments contain a variety of soft sediment deformation structures and massive sands attesting large scale slumps, large scale liquefaction and re-sedimentation, which are mostly due to reactivations of tectonic structures;
In addition of generating seismites within the PBS, these events have also deformed the underlying Barreiras Formation;
Tectonics might have played a more important control on relative sea level changes in NE Brazil than other factors as eustasy and climate .
CONCLUSIONS
Late Pleistocene and Holocene sedimentary deposits (i.e., Post-Barreiras Sediments) are geographically widespread along the NE Brazilian coast;
These strata are of great interest in studies aiming to reconstruct the effect of Late Quaternary sea level changes in Brazil;
The Post-Barreiras Sediments contain a variety of soft sediment deformation structures and massive sands attesting large scale slumps, large scale liquefaction and re-sedimentation, which are mostly due to reactivations of tectonic structures;
In addition of generating seismites within the PBS, these events have also deformed the underlying Barreiras Formation;
Tectonics might have played a more important control on relative sea level changes in NE Brazil than other factors as eustasy and climate .
CONCLUSIONS
Late Pleistocene and Holocene sedimentary deposits (i.e., Post-Barreiras Sediments) are geographically widespread along the NE Brazilian coast;
These strata are of great interest in studies aiming to reconstruct the effect of Late Quaternary sea level changes in Brazil;
The Post-Barreiras Sediments contain a variety of soft sediment deformation structures and massive sands attesting large scale slumps, large scale liquefaction and re-sedimentation, which are mostly due to reactivations of tectonic structures;
In addition of generating seismites within the PBS, these events have also deformed the underlying Barreiras Formation;
Tectonics might have had an important control on relative sea level changes in NE Brazil.