The pre-Silurian Riachão basin: a new perspective on the basement of the Parnaíba basin, NE Brazil

Porto, Amanda; Daly, M. C.; Terra, Emanuele F. La; Fontes, Sergio L.

doi:10.1144/sp472.2

Cited by 11 publications

(10 citation statements)

References 24 publications

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“…• The points above describe the significant heterogeneity of the crust beneath the Parnaíba Basin. This theme is further developed by the description of remnants of Ediacaran-Cambrian stratigraphy incorporated within the crystalline basement (Porto et al 2018) • Hollanda et al (2018) and Menzies et al (2018) both tie the sediment fill to the Proterozoic basement terranes surrounding the basin. These areas appear to have provided the sediment input into the basin throughout the life of the basin.…”

Section: Discussionmentioning

confidence: 99%

“…Concentrating on the nature of the upper crust, Porto et al (2018) discuss the basement of the mid-western part of the Parnaíba Basin, south of the regional geophysical profile corridor. From an array of c. 1300 line km of legacy 2D seismic data and nine exploration wells they have mapped the remnants of a north-south trending, pre-Silurian sedimentary basin, surrounded by Proterozoic crystalline basement beneath the Parnaíba Basin.…”

Section: Lithospheric and Crustal Structure Of The Parnaíba Cratonic mentioning

confidence: 99%

“…They also discuss the future direction of exploration in this large and underexplored basin, and the clues left by earlier exploration wells that indicated both oil and gas phases were present. Specifically, the underexplored pre-Silurian section of the remnant Riachão Basin (Porto et al 2018) in the SW and the narrow, volcanic-prone, pull-apart rifts developed along the Transbrasiliano Fault Zone are both seen as areas of interest. In conclusion, it seems likely that new and insightful data will continue to flow from exploration of this underexplored and increasingly important region as Brazil's energy endowment is further assessed and developed.…”

Section: The Parnaíba Basin Petroleum Systemmentioning

confidence: 99%

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Cratonic basin formation: a case study of the Parnaíba Basin of Brazil

Daly

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Julià

et al. 2018

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Cratonic basins comprise a significant component of the Earth's continental crust and surface geology. Their subcircular form and large areas of flat-lying, largely undeformed sedimentary rocks characterize the central regions of many continents, and are also a significant habitat for water, mineral and petroleum resources. These basinal regions have been extensively studied, yet there is little consensus on the driving mechanism of their subsidence or their greater tectonic context. Here we present the results of an integrated basin analysis of the Paleozoic-Early Mesozoic Parnaíba cratonic basin of NE Brazil. The analysis integrates existing geological and geophysical data, and a new deep-crustal geophysical dataset, to determine the deep structure of the basin and the underlying crust and mantle. Several major features have emerged from this which constrain the basins genesis: (1) continental-shallow-marine stratigraphy characterized by an exponentially decreasing tectonic subsidence with a relatively long time constant of the order of 70-90 myr; (2) a complex Proterozoic-Early Paleozoic basement that comprises at least three major crustal blocks defined by seismic facies and conductivity contrasts with no evidence of an extensive rift system beneath the basin; (3) a mid-crustal fabric that appears to define the top of a dense and seismically fast lower crust (V p 6.7-6.8 km s −1 and V s 3.7-3.8 km s −1) and upper mantle (V p 8.2-8.4 km s −1) directly beneath the basin, and which correlates with a sediment-corrected Bouger gravity anomaly high of +40-60 mGal; (4) a Moho that is generally as deep or deeper beneath the basin (40-45 km) than its surrounding region (34-40 km), and which appears stepped at the terrane boundaries; (5) a relatively conductive crust and upper mantle beneath the basin, and relatively resistive crust along the boundaries of the basement blocks; and (6) igneous events immediately before and after formation of the cratonic megasequence and a geochemically enriched mantle beneath the basin that sourced two major episodes of Mesozoic igneous intrusions. These latter events are responsible for the development of an atypical gas-prone petroleum system dependent on local magmatic events for heat generation and trapping configurations. The data describing these features are presented and discussed, and their implications used to draw conclusions about the formation of the Parnaíba Basin specifically and cratonic basins more generally. Cratonic basins are large, isolated, basinal areas developed exclusively on continental lithosphere (Fig. 1). They occupy a little over 10% of today's exposed continental crust and are characterized by large areas of mostly undeformed, flat-lying sedimentary rocks. Several features are universal in the categorization of a cratonic basin, notably: development upon thickened lithosphere (>150 km) (McKenzie & Priestley 2016); a subcircular to equant outline; a pronounced basal unconformity of the cratonic megasequence (Daly et al. 2014); a long-lived stratigraphic me...

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Section: Discussionmentioning

confidence: 99%

Section: Lithospheric and Crustal Structure Of The Parnaíba Cratonic mentioning

confidence: 99%

Section: The Parnaíba Basin Petroleum Systemmentioning

confidence: 99%

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Cratonic basin formation: a case study of the Parnaíba Basin of Brazil

Daly

Fuck

Julià

et al. 2018

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“…The Riachão unit (TS‐1) includes the oldest preserved sediments in the basin. These sediments are believed to be Late Neoproterozoic to Cambrian in age [ Mesner and Wooldridge , ; Porto et al ., ] and are recorded from seismic and well data in the southwestern area of Parnaíba. de Castro et al .…”

Section: Geological Settingmentioning

confidence: 99%

“…However, this view has recently been challenged by Porto et al . [], who, on the basis of industry two‐dimensional seismic data and two wells, interpreted the Riachão as a remnant foreland basin, bounded by thick skinned thrust faults of Cambro‐Ordovician age.…”

Section: Geological Settingmentioning

confidence: 99%

Crustal structure, gravity anomalies, and subsidence history of the Parnaíba cratonic basin, Northeast Brazil

2017

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Cratonic basins cover more than 10% of Earth's continental surface area, yet their origin remains enigmatic. Here we use a 1400 km long, deep (20 s two‐way travel time) seismic reflection profile, five wide‐angle split‐spread receiver gathers, gravity anomaly, and well data to constrain the origin of the Parnaíba Basin, a cratonic basin in Northeast Brazil. In the center of the basin, the depth to pre‐Paleozoic basement is ~3.3 km, a zone of midcrustal reflectivity (MCR) can be traced laterally for ~250 km at depths between 17 and 25 km and Moho depth is ~42 ± 2 km. Gravity and P wave modeling suggests that the MCR represents the upper surface of a high density (2985 kg m−3) and Vp (6.75–7.0 km s−1) lower crustal body, likely of magmatic origin. Backstripping of well data shows a concave up decreasing tectonic subsidence, similar in form to that observed in rift‐type basins. We show, however, that our seismic and gravity data are inconsistent with an extensional origin. Other basin forming mechanisms are therefore required. We show that an intrusive body in the lower crust that has loaded and flexed the surface of the crust, combined with sediment loading, provides a satisfactory fit to the observed gravity anomaly. A buried load model is consistent with seismic data, which suggest that the Moho is as deep or deeper beneath the basin center than its flanks and accounts for at least part of the tectonic subsidence through a viscoelastic stress relaxation that occurs in the lithosphere following load emplacement.

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