Evolution of a cratonic basin: insights from the stratal architecture and provenance history of the Parnaíba Basin
L. A. Menzies, A. Carter, David I. M. MacDonald, 2018. "Evolution of a cratonic basin: insights from the stratal architecture and provenance history of the Parnaíba Basin", 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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The processes that govern formation and development of cratonic basins are poorly understood, both individually and as a class. The cratonic Silurian–Jurassic Parnaíba Basin in NE Brazil is less well-studied than North American examples such as Williston, Illinois and Michigan but offers an opportunity to study stratal architecture both in outcrop and the subsurface. Published stratigraphic compilations emphasize basin-wide unconformities separating layer-cake, basin-wide packages; analysis of geological maps indicates this interpretation is over-simplified, with at least 12 local unconformities, concentrated along the SW basin margin. Comparison of basin-margin and intrabasinal well-correlation panels shows that unconformities are more common in marginal areas, so the current exposure margins may have some validity as near-original margins. Palaeocurrents suggest a consistent SW–NE transport direction for the Serra Grande and lower Canindé groups. Supporting heavy mineral analysis from Silurian–Carboniferous strata on the SW and NE basin margins show that assemblages are dominated by ultra-stable zircon, tourmaline and rutile with minor amounts of staurolite, especially in the SW and older units. Tourmaline varietal results are remarkably consistent across the basin. U–Pb age spectra from detrital zircons are dominated by Neoproterozoic grains, with subsidiary Meso-Paleoproterozoic provenance. We infer that the source terrane was a medium-grade regionally metamorphosed mica schist, probably the Araguaia Fold Belt. These results are indicative of a large sediment routing system feeding material across an evolving crustal sag, analogous to observations from North American cratonic basins; this suggests that cratonic basins may not have strongly shaped or controlled the routing system.
Supplementary material: High-resolution geological map of the Parnaíba Basin as a PDF. This shows all of the basement units and small details of the stratigraphic relationships between different basin-fill formations. This map is derived from the ArcGIS files of CPRM (2004). Supplementary material available at https://doi.org/10.6084/m9.figshare.c.4183472
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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.