[Tectonos] Conferencia en el CIG- Profesor Stephen Flint (Universidad de Manchester, Reino Unido)

[Daniel Poire]

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   Ciclo de Conferencias Invitadas del CIG ​                     ​ “Permian Deepwater Clastic Systems along the 
 Exhumed Gondwana Margin: Lessons from Outcrop Studies�   Dr. Stephen S. Flint Professor of Stratigraphy, Associate Vice-President - Internationalisation, 
 The University of Manchester (UK)   Lunes 26 de septiembre a las 11 hs Auditorio "Adrián Mario Iñiguez Rodríguez" del CIG Diagonal 113 N° 275 (esq. 64) B1904DPK La Plata, Argentina     Over 15 years of outcrop studies integrated with 20 cored research wells and radiometric dating has constrained the time-stratigraphic  evolution of the Permo-Triassic Karoo Gondwana margin. The stratigraphy is remarkably similar along the margin but with important difference in thicknesses, volumes and partitioning of sand between basin floor and submarine slope. A consistent hierarchy is applied based on depositional sequences (recognised in outcrop and well data) that stack into composite sequences (mappable at seismic scale). The Tanqua Karoo depocentre includes 800 m of silty mudstone overlain by 4 basin floor fans, each up to 50 m thick with dip lengths of 40 km+, showing a progradational stacking pattern. Grain size never exceeds fine sand. The submarine slope section is only 120 m thick, above which are shelf edge clinoforms and a 500 m of mixed influence shelf edge to shelf deltas. Some 80 km along margin the 1200 m thick Laingsburg succession comprises a 300 m+ basin floor fan composite sequence set overlain by an 800 m thick muddy slope succession with slope valleys feeding fan system 80-100 km long and up to 60 km3 in volume. Shelf edge clinoforms mark eastward progradation of a 500 m thick mixed influence delta system. The Prince Albert  area 100 km east is characterized by large mass transport complexes likely derived from a lateral non-depositional section of margin. Overlying shelf deposits are sand-poor. Some 400 km further east, the 1700 m Ecca Pass section includes a 300 m thick basin floor fan complex overlain by a 100 m thick siltstone and slope channel deposits. Grain size is coarse sand. The shelf section is sand poor, suggesting a switch in sand delivery location between deepwater and shelf. The exhumed Karoo margin provides a well exposed example  of lateral variability in basin margin physiography convolved with late icehouse to greenhouse transition glacio-eustatic sea level and long wavelength subsidence to control spatial and temporal variability in deepwater systems architecture and overlying shelf delta style.         

 Centro de Investigaciones Geológicas(UNLP-Conicet)Diagonal 113 Nº 275, esq. 641900 La PlataArgentinaTel +54 221 644 1230 
             

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