Paleomagnetism, geochemistry and dating of the North-eastern Paraná Magmatic Province: tectonic implications

Ernesto, Márcia; Raposo, María Irene Bartolomeu; Marques, Leila Soares; Renne, Paul R.; Diogo, Liliana Alcazar; Min, Ângelo De

doi:10.1016/s0264-3707(99)00013-7

Cited by 138 publications

(97 citation statements)

References 11 publications

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“…These authors used a graphic test and concluded that at 95% confidence levels a Fisher distribution hypothesis cannot be rejected. The scatter determined for these VGPs is slightly Ernesto et al, 1990), Northern PMP, Brazil (NB; Ernesto et al, 1990), Northeastern PMP, Brazil (NEB; Ernesto et al, 1999), Misiones (M; this study), Central PMP, Brazil (CB2; Alva-Valdivia et al, 2003), PMP, Paraguay (P; Ernesto et al, 1996).…”

Section: Vgp Distributionmentioning

confidence: 63%

“…The inverted direction to the mean normal polarity direction is centered in the group of lower inclination reverse directions, suggesting that the high inclination directions may represent a period of pronounced secular variation or transitional field directions. (Ernesto et al, 1990), (b) Southern PMP, Brazil (Ernesto et al, 1990), (c) Northeastern PMP, Brazil (Ernesto et al, 1999), (d) Central PMP, Brazil (Alva-Valdivia et al, 2003, (e) Northern PMP, Brazil (Ernesto et al, 1990), (f) PMP, Paraguay (Ernesto et al, 1996). …”

Section: Paleomagnetic Resultsmentioning

confidence: 99%

“…Other radiometric aging analyses suggested that the age of the main effusion in Brazil extends from 140 to 120 Ma (Cordani et al, 1980;Mantovani et al, 1985;Piccirillo et al, 1987), with the main eruptive phase taking place in the Early Cretaceous between 135 and 130 Ma (Rocha-Campos et al, 1988;Ernesto and Pacca, 1988). More recently, 40 Ar/ 39 Ar radiometric and paleomagnetic data revealed that only a few million years were required for the emplacement of the major part of the igneous rocks in the Paraná Basin (Renne et al, 1992a(Renne et al, , 1992b(Renne et al, , 1996a(Renne et al, , 1996b(Renne et al, , 1997Ernesto et al, 1999). Turner et al (1994) suggested that the Paraná-Etendeka continental flood basalts erupted over 10 million years ago, between 137 and 127 Ma.…”

Section: Geological Settingmentioning

confidence: 99%

“…In Fig. 13(a)-(e) the VGPs corresponding to the north (Ernesto et al, 1990), northeast (Ernesto et al, 1999), central (Ernesto et al, 1990;Alva-Valdivia et al, 2003) and south areas of the PMP (Ernesto et al, 1990) are plotted in the Southern Hemisphere. The distribution of VGPs obtained from basalts and alkaline rocks of Paraguay (Ernesto et al, 1996), although very scattered, also show a distinct elongation (Fig.…”

Section: Vgp Distributionmentioning

confidence: 99%

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Paleomagnetism, rock-magnetism and geochemical aspects of early Cretaceous basalts of the Paraná Magmatic Province, Misiones, Argentina

2006

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The basalts of the Posadas Formation were extruded during the huge continental volcanism that affected the Paraná Basin in the Lower Cretaceous. We have carried out a paleomagnetic and rock-magnetic study on samples collected along a basalt outcrop section in Misiones, Argentina and determined that rocks classified as tholeiitic basalts and andesi-basalts are characterized by a low to intermediate content of Ti. Paleomagnetic and rockmagnetic studies suggest that the main magnetic mineral is low-Ti titanomagnetite of superparamagnetic (SP) to single-domain (SD) sizes, and very low amounts of multi-domain (MD) particles. The stable magnetic remanence enabled us to define characteristic remanent magnetizations (ChRMs) with a maximum angular deviation (MAD) <5• in most cases; and in all the cases, a MAD <10• . The sequence has registered at least two polarity reversions, starting from a normal polarity at the base. The calculated virtual geomagnetic poles (VGPs) present an elongated distribution similar to other distributions of VGPs published for the Paraná Magmatic Province. The elongated distribution of the VGPs could be a real feature of the geomagnetic field at a time of frequent changes of polarity.

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Section: Vgp Distributionmentioning

confidence: 63%

Section: Paleomagnetic Resultsmentioning

confidence: 99%

Section: Geological Settingmentioning

confidence: 99%

Section: Vgp Distributionmentioning

confidence: 99%

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Paleomagnetism, rock-magnetism and geochemical aspects of early Cretaceous basalts of the Paraná Magmatic Province, Misiones, Argentina

2006

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“…Ages vary from 129 to 131 for the Ponta Grossa dikes (peak 130.5 Ma) (Renne et al, 1996) and range from 119 Ma to 128 Ma in the Florianopolis dikes (Raposo et al, 1998). Paleomagnetic studies were performed by several authors on Serra Geral volcanics and the dikes of Ponta Grossa and Florianopolis (e.g., Ernesto et al, 1990Ernesto et al, , 1999Raposo and Ernesto, 1995;Raposo et al, 1998;Alva-Valdivia et al, 2003). All of these studies revealed very stable two-polarity characteristic magnetic components carried by titanomagnetite.…”

Section: Geological Setting and Previous Studiesmentioning

confidence: 99%

Paleointensity data from Early Cretaceous Ponta Grossa dikes (Brazil) using a multisample method

et al. 2009

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Definition of the long-term variation of the geomagnetic virtual dipole moment requires more reliable paleointensity results. Here, we applied a multisample protocol to the study of the 130.5 Ma Ponta Grossa basaltic dikes (southern Brazil) that carry a very stable dual-polarity magnetic component. The magnetic stability of the samples was checked using thermomagnetic curves and by monitoring the magnetic susceptibility evolution through the paleointensity experiments. Twelve sites containing the least alterable samples were chosen for the paleointensity measurements. Although these rocks failed stepwise double-heating experiments, they yielded coherent results in the multisample method for all sites but one. The coherent sites show low to moderate field intensities between 5.7±0.2 and 26.4±0.7 μT (average 13.4±1.9 μT). Virtual dipole moments for these sites range from 1.3±0.04 to 6.0 ± 0.2 × 10 22 A m 2 (average 2.9 ± 0.5 × 10 22 A m 2 ). Our results agree with the tendency for low dipole moments during the Early Cretaceous, immediately prior to the Cretaceous Normal Superchron (CNS). The available paleointensity database shows a strong variability of the field between 80 and 160 Ma. There seems to be no firm evidence for a Mesozoic Dipole Low, but a long-term tendency does emerge from the data with the highest dipole moments occurring at the middle of the CNS.

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Density and P‐wave velocity structure beneath the Paraná Magmatic Province: Refertilization of an ancient lithospheric mantle

Chaves

Ussami

Ritsema

2016

Geochem Geophys Geosyst

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We estimate density and P‐wave velocity perturbations in the mantle beneath the southeastern South America plate from geoid anomalies and P‐wave traveltime residuals to constrain the structure of the lithosphere underneath the Paraná Magmatic Province (PMP) and conterminous geological provinces. Our analysis shows a consistent correlation between density and velocity anomalies. The P‐wave speed and density are 1% and 15 kg/m3 lower, respectively, in the upper mantle under the Late Cretaceous to Cenozoic alkaline provinces, except beneath the Goiás Alkaline Province (GAP), where density (+20 kg/m3) and velocity (+0.5%) are relatively high. Underneath the PMP, the density is higher by about 50 kg/m3 in the north and 25 kg/m3 in the south, to a depth of 250 − 300 km. These values correlate with high‐velocity perturbations of +0.5% and +0.3%, respectively. Profiles of density perturbation versus depth in the upper mantle are different for the PMP and the adjacent Archean São Francisco (SFC) and Amazonian (AC) cratons. The Paleoproterozoic PMP basement has a high‐density root. The density is relatively low in the SFC and AC lithospheres. A reduction of density is a typical characteristic of chemically depleted Archean cratons. A more fertile Proterozoic and Phanerozoic subcontinental lithospheric mantle has a higher density, as deduced from density estimates of mantle xenoliths of different ages and composition. In conjunction with Re‐Os isotopic studies of the PMP basalts, chemical and isotopic analyses of peridodite xenoliths from the GAP in the northern PMP, and electromagnetic induction experiments of the PMP lithosphere, our density and P‐wave speed models suggest that the densification of the PMP lithosphere and flood basalt generation are related to mantle refertilization. Metasomatic refertilization resulted from the introduction of asthenospheric components from the mantle wedge above Proterozoic subduction zones, which surrounded the Paraná lithosphere. The high‐density PMP lithosphere is presently gravitationally unstable and prone to delamination.

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Paleomagnetism, geochemistry and dating of the North-eastern Paraná Magmatic Province: tectonic implications

Cited by 138 publications

References 11 publications

Paleomagnetism, rock-magnetism and geochemical aspects of early Cretaceous basalts of the Paraná Magmatic Province, Misiones, Argentina

Paleomagnetism, rock-magnetism and geochemical aspects of early Cretaceous basalts of the Paraná Magmatic Province, Misiones, Argentina

Paleointensity data from Early Cretaceous Ponta Grossa dikes (Brazil) using a multisample method

Density and P‐wave velocity structure beneath the Paraná Magmatic Province: Refertilization of an ancient lithospheric mantle

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