the late pleistocene-holocene record of sea level in northeastern brazil and its relation to...

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.