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| Paraná-Etendeka | |
|---|---|
| Name | Paraná-Etendeka |
| Type | Large Igneous Province |
| Location | South America, Africa |
| Period | Early Cretaceous |
| Main lithology | Flood basalts, rhyolites, pyroclastics |
| Named for | Paraná Basin; Etendeka Plateau |
Paraná-Etendeka is a vast Early Cretaceous large igneous province straddling southeastern South America and southwestern Africa, formed during the breakup of Gondwana and linked to the initial opening of the South Atlantic Ocean under mantle upwelling. The province records flood-basalt volcanism, silicic volcanism, and associated intrusive suites that are temporally and genetically related to mantle plume activity inferred from correlations with the Tristan da Cunha hotspot and seafloor spreading anomalies. Studies of Paraná-Etendeka integrate data from geological mapping, geochronology, geochemistry, paleomagnetism, and basin analysis conducted by teams associated with institutions such as the United States Geological Survey, University of Oxford, Universidade de São Paulo, GeoForschungsZentrum Potsdam, and South African Council for Geoscience.
The province occupies parts of the Paraná Basin, the Uruguay Shield, the Rio Grande Rise conjugate margin, and the Kalahari Craton margin, and its emplacement coincides with rift initiation between the South American Plate and the African Plate. Tectonic reconstructions using data from the Indian Ocean conjugate margin and magnetic anomaly records tied to the mid-Cretaceous magnetic quiet zone link Paraná-Etendeka to the Tristan da Cunha Rise and to plate motions reconstructed with models by groups at Scripps Institution of Oceanography and the British Geological Survey. Structural control on eruption and intrusion is evident along major faults such as the Frontal Fault System and sedimentary depocenters including the Pelotas Basin and Campos Basin.
Paraná-Etendeka volcanism produced extensive flood basalts, compound pahoehoe and aa lava flows, and voluminous silicic ignimbrites associated with explosive eruptions comparable to those described in studies of the Deccan Traps, Siberian Traps, and Karoo-Ferrar provinces. Petrogenetic models invoke high-degree partial melting of a subcontinental lithospheric mantle modified by an upwelling mantle plume analogous to interpretations for the Iceland plume and Hawaii plume, with geochemical affinities documented by research teams at California Institute of Technology and ETH Zurich. Magmatic features include feeder dikes, sills, layered gabbros, and silicic domes mapped by the Servicio Geológico Brasileiro and the Geological Survey of Namibia.
Stratigraphic architecture comprises stacked basalt sequences (e.g., Serra Geral Formation equivalents), intercalated rhyolitic units, and intrusive complexes overlain or interfingered with sedimentary sequences of the Paraná Basin and Etendeka Plateau. Lithologies include tholeiitic basalts, mugearitic to trachytic differentiates, welded tuffs, and coarse volcaniclastic successions studied in cores and outcrops by teams from the Instituto de Geociências (USP) and the Namibian Geological Survey. Correlations utilize biostratigraphic markers from contemporaneous Aptian marine units and lithostratigraphic frameworks developed in collaboration with the International Commission on Stratigraphy.
High-precision radiometric ages from U-Pb zircon analyses, 40Ar/39Ar dating of feldspars and groundmass, and complementary paleomagnetic polarity stratigraphy constrain the main phase of Paraná-Etendeka volcanism to the Early Cretaceous (approximately 132–128 million years ago), contemporaneous with the emplacement age of the Tristan da Cunha – Gough Island volcanic track. Chronostratigraphic work has been published by researchers affiliated with Lamont–Doherty Earth Observatory, Max Planck Institute for Chemistry, and national geological surveys, integrating isotope-systematics with global polarity timescales from the Geological Society of America.
The eruption pulse of Paraná-Etendeka coincided with greenhouse conditions recorded in marine sections and terrestrial floras across the South Atlantic margins, with inferred volcanic gas release affecting atmospheric chemistry and contributing to perturbations recorded in ^13C excursions and anoxia events recognized in cores curated by the British Antarctic Survey and the National Oceanic and Atmospheric Administration. Modeling from groups at Princeton University and IPCC-referenced frameworks suggests transient climate warming, ocean stratification, and potential links to short-term biotic stress evident in the fossil record from the Neuquén Basin and offshore drill cores from the Walvis Ridge region.
Biotic responses include turnover in plant assemblages preserved in continental deposits of the Paraná Basin and marine microplankton shifts documented in micropaleontological studies from the South Atlantic Ocean expedition cores. Correlations with faunal changes in the Aptian faunal provinces, including vertebrate and invertebrate assemblages described by paleontologists at the Natural History Museum, London and the Museu de Ciências da Universidade de Coimbra, suggest ecosystem disruptions and regional extinctions likely driven by habitat alteration, ash fallout, and oceanographic changes tied to flood basalt volcanism.
Paraná-Etendeka host rocks influence regional mineralization, including zeolite-bearing volcaniclastics mined near the Serra do Mar and construction aggregate resources exploited in Rio Grande do Sul and Namibia. Intrusive and hydrothermal systems related to province magmatism have been investigated for potential copper, nickel, and platinum-group element concentrations analogous to economic deposits explored in the Bushveld Complex, with exploration undertaken by companies such as Anglo American plc, Vale S.A., and national mining agencies. Geothermal gradients and CO2 sequestration potential in basaltic flows are subjects of applied research by institutions including CSIR and Lawrence Berkeley National Laboratory.
Category:Large igneous provinces Category:Geology of South America Category:Geology of Africa