Tectonostratigraphic evolution of a salt giant during passive margin development: Santos Basin, offshore Brazil
The stratigraphy of ancient salt giants provides constraints on syndepositional basin tectonics and physiography, and/or variations in climate or sea level. Moreover, subsequent deformation and dissolution of salt directly controls the distribution and architecture of the sedimentary overburden. Hen...
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| Other Authors: | , , |
| Format: | Doctoral or Postdoctoral Thesis |
| Language: | unknown |
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Earth Science & Engineering, Imperial College London
2018
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| Online Access: | http://hdl.handle.net/10044/1/76371 https://doi.org/10.25560/76371 |
| Summary: | The stratigraphy of ancient salt giants provides constraints on syndepositional basin tectonics and physiography, and/or variations in climate or sea level. Moreover, subsequent deformation and dissolution of salt directly controls the distribution and architecture of the sedimentary overburden. Hence, salt directly influence the overall tectono-stratigraphic evolution and hydrocarbon potential of salt-dominated passive margins. This study focuses on the Santos Basin, a salt-dominated basin offshore eastern Brazil. To date, few studies have attempted to characterise the architecture of this stratified salt giant (i.e., Ariri Fm.) deposited during Late Aptian opening of the South Atlantic Ocean. In addition, no studies have characterised the deep-water salt tectonic structural style or salt dissolution and its control on deep-water sedimentation. In this study, 3D seismic reflection and borehole data are integrated to constrain the regional tectono-stratigraphic evolution of the Ariri Fm., from its deposition, to its subsequent deformation and partial dissolution. The integration of 3D seismic and borehole data shows that an up 2.5 km thick Ariri Fm. comprises four key evaporite-dominated intervals of distinct composition recording at least 12 cycles of basin filling and dessication in < ca. 530 ka. Moreover, this study reveals that rifting-inherited basin physiography controlled salt thickness and composition leading to stratigraphic variations across structural domains. Overall, thinner salt and higher anhydrite net thickness occur towards structurally high domains, compared to, structurally lower domains where the salt is thicker and anhydrite net thickness is less. In addition, results of this work suggest that more anhydrite was deposited closer to the entrance of fresh seawater, whereas more bittern salts were deposited in more hydrologically restricted locations. Seismic stratigraphy and seismic attribute analysis illustrate how subsequent gravity-driven downdip salt flow directly controlled the Santos ... |
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