A comparative study of the Parnaíba, Michigan and Congo cratonic basins
A. B. Watts, B. Tozer, M. C. Daly, J. Smith, 2018. "A comparative study of the Parnaíba, Michigan and Congo cratonic basins", Cratonic Basin Formation: A Case Study of the Parnaíba Basin of Brazil, M. C. Daly, R. A. Fuck, J. Julià, D.I.M. MacDonald, A. B. Watts
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We used compilations of geological and geophysical data to compare the structure, subsidence history and evolution of the Parnaíba, Michigan and Congo cratonic basins. These basins consist of 3–6 km of Paleozoic to Recent sediments and are located on thick (>150 km) lithosphere, far from plate boundaries. Sediment-corrected Bouguer gravity anomalies show that the basins are associated with a central high of up to 40–60 mGal. The high could reflect crustal thinning, but seismic refraction data suggest that the Moho is either at a similar depth or deeper beneath the basins than beneath their flanks. The seismic reflection profiles show no evidence of extensional structures in the underlying basement. We propose that the central high reflects an extensive igneous intrusion, which, on solidification, loaded the crust and lithosphere, causing a surface flexure into which sediments accumulated. Viscoelastic plate modelling of the backstripped well data shows that a subsurface load can explain the tectonic subsidence of the basins as well as some details of their internal stratigraphy, including offlap. Offlap, a ubiquitous feature of cratonic basins, can therefore be explained by tectonics in the form of flexure and does not require other controlling factors such as long-term sea-level changes.
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Cratonic Basin Formation: A Case Study of the Parnaíba Basin of Brazil
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Cratonic basins are large, distinctive features of the continental crust. They are preferentially developed on thick continental lithosphere, are typically sub-circular in shape and subside over periods of hundreds of millions of years. They are also endowed with significant resources. However, in spite of their location in continental interiors and often well-known geology, the subsidence driving mechanism and tectonic setting of these basins remains controversial.
This volume presents both lithospheric and basin scale datasets acquired specifically to interrogate the tectonic process of cratonic basin formation. Focused on the Silurian to Triassic Parnaíba cratonic basin of Brazil, the papers discuss the results of a multidisciplinary basin analysis project comprising new geophysical, geological and geochemical data. This unique dataset enables the characterization of the lithospheric crust and mantle beneath the Parnaíba Basin, constrains the detailed evolution of the basin itself, and enables comparisons with cratonic basins globally. Several convergent themes emerge providing new and powerful constraints for models of the driving mechanisms of these enigmatic basins.