TY  - GEN
N2  - During the evolution of southern Brazil from rift to ?passive? margin, the offshore Campos (CB), Santos (SB), and Pelotas (PB) basins developed highly differing architectures regardless of their associated syn-rift origin. Based on 2D seismic reflection profiles and wells, the three basins have been investigated in terms of 2D seismo-stratigraphy and numerical basin analysis. Within the Barremian-Holocene basin infill (130-0 Ma), twelve to fourteen regional seismic horizons have been mapped and calibrated with bio-/chronostratigraphic ages from the available wells. They define seismo-stratigraphic depositional sequences, which have been classified in terms of accommodation/sedimentation and bounding stratigraphic surfaces. Qualitative interpretations of the evolution of accommodation space and the controlling factors (eustasy, subsidence, sediment supply) have been subsequently quantified by applying inverse-basin modeling. This procedure allowed the restoration of the basin geometry and paleowater depths during each of the chronostratigraphic layers. Furthermore, a comprehensive analysis of the genetic components of total subsidence ? thermo-tectonic, flexural, and compaction-induced subsidence ? provided the temporal interactions and individual contribution of each subsidence component to basin formation. The obtained subsidence data and sediment supply history, combined with seismo-stratigraphy, represent the input information for forward stratigraphic modeling. This method aims to simulate the stratigraphic evolution in terms of a wide range of modeling variables that simulate interdependent tectonic and sedimentary processes. Sensitivity analysis of modeling parameters revealed the most important controls on the basin development, and provided the best-fit values to construct plausible tectono-stratigraphic models to the present-day basin configuration. This integrated approach allows us to assess the inherent model uncertainties from the sequence-stratigraphic interpretation, and evaluate the reliability of various possible geological scenarios. The results show that six subsidence/uplift trends (ST1-ST6), each of 7 to 51 m.y. duration, controlled the Barremian to Holocene basin development. These trends and their distribution along the shelf-to-basin transition are directly linked to the syn-rift-to-drift geodynamic evolution of the southeastern Brazilian margin. Syn-rift extension triggered high thermo-tectonic subsidence (trend ST1) and controlled the creation of accommodation space in all three basins during the Barremian. However, the results show a distinctive crustal evolution of the single basins; Barremian syn-rift continental extension across the Pelotas Basin involved extensive magmatism and a thick volcanic crust affected by post-rift thermal contraction since Early Aptian times (trend ST2). As continental break-up propagated northward from the PB to the CB, the mechanisms of lithospheric deformation and subsidence patterns changed between the basins. In the SB and CB, minor magmatism and brittle deformation during the Early-Middle Barremian evolved to depth-dependent continental stretching during the incipient syn-rift phase in the Late Barremian (trend ST2). The thinned continental crust featured laterally constant subsidence rates, generating wide sag-salt depocenters across the Santos-Campos margin segment. During the Albian post-rift and Cenomanian-Holocene drift evolution (ST3-ST6) changes in the sediment supply and the flexural loading were due to onshore tectono-magmatic events. These key factors were responsible for the differences in architecture and hydrocarbon prospectivity between the three basins analyzed. Based on the process/response relationship established during modeling, the most important stratigraphic-structural processes on the shelf-to-basin sedimentary systems include: (i) tectonic uplift of the source areas triggering increased sediment supply with progradation and deep-water turbidite flows; (ii) flexurally-induced rebound of the shelf realm facilitates sediment bypass and catastrophic shelf-slope failure; (iii) formation of salt basins and salt remobilization, enhancing the instability of the shelf-edge and modifying the flexural loading distribution; (iv) bottom-currents redistributing the deep-marine sediment infill.  This study on the Brazilian continental margin shows that: (i) changes in subsidence and sediment supply on the continental margin varied over 3rd to 2nd order time intervals, and were not subordinate to eustatic sea-level changes; (ii) flexural and compaction-induced subsidence represent the most important controls on accommodation space during the mature drift stage; (iii) structural and plate-tectonic reconfigurations cannot be directly inferred from qualitative sequence stratigraphic frameworks of continental margins; (iv) depositional systems are controlled by a wide range of interconnected tectonic and sedimentary parameters that go beyond qualitative observations from sequence stratigraphy.  Quantitative modeling of the evolution of continental margins must consider a wide range of variables. Crustal deformation and the geomorphological evolution of the continental margin, as well as local-scale sea-level fluctuations are as important as accommodation space and lithologies. This approach provides more accurate interpretation of the ancient tectono-sedimentary systems, which represent key contributions to a better understanding of the complex geodynamic and tectono-stratigraphic evolution of continental margin sedimentary basins.
UR  - https://archiv.ub.uni-heidelberg.de/volltextserver/12323/
A1  - Contreras, Jorham
KW  - Seismo-stratigraphy 
KW  -  numerical basin modeling 
KW  -  Brazilian continental margin
ID  - heidok12323
Y1  - 2011///
N1  - Teile in: Marine and Petroleum Geology, Volume 27, Issue 9, DOI: 10.1016/j.marpetgeo.2010.06.007
TI  - Seismo-stratigraphy and numerical basin modeling of the southern Brazilian continental margin
AV  - public
ER  -