THE LATE PLEISTOCENE-HOLOCENE RECORD OF SEA LEVEL IN NORTHEASTERN BRAZIL AND ITS

1. 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

2. Late Quaternary Relative Sea Level Eustatic fluctuations ice sheets Late Cretaceous

3. Late Pleistocene-Holocene relative sea level=>climatic fluctuations Last Interglacial Holocene Transgression Younger Dryas Last Glacial Maximum Sea level (m) Age (kyrs B.P.)

4. MAIN PROBLEMS: 1. Sea level curves have been established with basis on data from a few localities 2. Chronological data are still insufficient to identify and correlate events with regional significance 3. There are many disagreements among available interpretations

5. 7

6. How passive this passive margin is ? • Is there evidence of paleoseismic activity in the sedimentary record of this region ?

7. RELATIVE SEA LEVEL EUSTASY CLIMATE What about TECTONICS ???

8. Barreiras Formation (Early/Middle Miocene)

9. BARREIRAS FORMATION- TILTING Bedding

10. BARREIRAS FORMATION- FAULTS

11. BARREIRAS FORMATION- FAULTS

12. BARREIRAS FORMATION- FAULTS

13. BARREIRAS FORMATION- FOLDS Barreiras Formation experienced extension and compression after deposition.

14. Post-Barreiras Sediments Barreiras Fm. Post-Barreiras Sediments Post-Barreiras Sediments Barreiras Fm. Barreiras Fm.

15. PB1- Late Pleistocene (OSL) Post-Barreiras Sediments PB2 PB1 PB2- Holocene (OSL)

16. POST-BARREIRAS SED. (PB1) Sand dike 2m Convolute beds Massive bedding

17. POST-BARREIRAS SEDIMENTS- PB1 FAULTED, MASSIVE AND CONVOLUTE BEDDING Post-Barreiras Sediments Barreiras Fm.

18. POST-BARREIRAS SED. (PB1) 2m

20. 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 relative Sea level changes in NE Brazil than other factors as eustasy and climate .

21. 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 relative Sea level changes in NE Brazil than other factors as eustasy and climate .

22. 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 .

23. 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 .

24. 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.