Early cretaceous ostracoda of the santos basin, Brazil: biostratigraphic analysis and palaeoenvironmental interpretation of the pre-salt strata
The opening of the proto-South Atlantic Ocean during the Early Cretaceous facilitated the formation of some of the largest non-marine hydrocarbon systems on the planet. One basin in particular, the Brazilian Santos Basin, has been shown to contain vast hydrocarbon reserves, sourced from and stored w...
| Main Author: | |
|---|---|
| Format: | Thesis |
| Language: | unknown |
| Published: |
2017
|
| Subjects: | |
| Online Access: | https://doi.org/10.4225/03/58d1d2569d6bb https://figshare.com/articles/thesis/Early_cretaceous_ostracoda_of_the_santos_basin_Brazil_biostratigraphic_analysis_and_palaeoenvironmental_interpretation_of_the_pre-salt_strata/4774858 |
| Summary: | The opening of the proto-South Atlantic Ocean during the Early Cretaceous facilitated the formation of some of the largest non-marine hydrocarbon systems on the planet. One basin in particular, the Brazilian Santos Basin, has been shown to contain vast hydrocarbon reserves, sourced from and stored within sediments underlying thick layers of evaporites. The evaporites are known as the “Salt”; thus, the underlying sediments constitute the “Pre-Salt”. Fossilised ostracods from two Santos Basin exploration wells, Bem-Te-Vi and Taquari, were studied to determine the nature of any significant Pre-Salt bioevents. Ostracods were relatively rare throughout the Bem-Te-Vi samples, with only 1,086 specimens recovered from a 771m stratigraphic section, though were more common in Taquari, from which 6,969 ostracods were extracted in a 318m interval. Analysis of cutting samples from these wells, drilled 155km apart, led to the observation of numerous stratigraphic and biological events common to both: 1) the base of the Salt (i.e. the top of the Pre-Salt); 2) an interval bereft of ostracods; 3) the first downhole occurrence of the ostracod species Kroemmelbeincypris symmetrica and Kroemmelbeincypris angulata; 4) a second, minor barren interval; 5) an interval preserving abundant specimens of Kroemmelbeincypris spp.; and 6) the first downhole occurrence of Pattersoncypris salitrensis. Taquari did not penetrate much further below the first downhole occurrence of P. salitrensis, meaning that further correlation between the wells was not possible in this study. However, much of the Bem-Te-Vi well below this event was dominated by igneous rocks; thus, few fossils were recovered. The identification of Kroemmelbeincypris (a new genus described herein) and Pattersoncypris in the Santos Basin Pre-Salt allowed an Aptian age to be applied to the majority of the sediments in the wells studied. This was determined through extrapolation (with modification) of biostratigraphic zonation schemes used in other proto-South Atlantic basins to the ... |
|---|