Massive lava flows that erupted 132 million years ago and now span parts of Brazil and Namibia, proving these continents were once joined. The flows are so precisely dated that geologists use them as a time standard for correlating rocks across the Southern Hemisphere.
Eurico Zimbres, CC BY-SA 2.5
A continental wound
Around 135 million years ago, the supercontinent of Gondwana began to split apart. This was not a quiet separation. Deep beneath the crust, the Tristan da Cunha mantle plume initiated a colossal volcanic event. For approximately one to two million years, immense fissures tore open across what is now southern Brazil and Namibia, unleashing one of the largest known volcanic outpourings in Earth's history. This event created the Paraná-Etendeka Large Igneous Province.
The sheer scale of the eruption is difficult to comprehend. It produced a total volume of magma estimated to be over 1.5 million cubic kilometers, covering an area of at least 1.5 million square kilometers. The lava flows were predominantly tholeiitic basalt, a low-viscosity magma that spread rapidly across vast distances. In the Paraná Basin, these stacked lava flows, known as the Serra Geral Formation, reached thicknesses of up to 1,700 meters. The eruption was not exclusively effusive; some phases were violently explosive, generating enormous columns of ash and pyroclastic sheets hundreds of meters thick.
A precise marker in deep time
The Paraná-Etendeka event is an precise benchmark in the geological record. The main pulse of volcanic activity was geologically brief, lasting for about a million years around 133 million years ago. High-precision dating methods, particularly Argon-40/Argon-39 and Uranium-Lead dating on minerals like zircon and baddeleyite, have pinpointed the timing of these eruptions with remarkable accuracy.
This precision allows geologists to use the basalt layers as a chronostratigraphic marker. When scientists find volcanic ash or lava flows with the unique geochemical signature and age of the Paraná-Etendeka event in rock layers thousands of kilometers apart, they know those layers were deposited at the same time. The event also occurred during a period of frequent magnetic field reversals, which were imprinted into the cooling basalt. This pattern of magnetic stripes provides another layer of detail for correlating rocks across the now-separated continents. While many large igneous provinces are associated with major mass extinctions, the direct environmental impact of the Paraná-Etendeka traps is still debated, though it coincides with a period of oceanic anoxia known as the Weissert Event.
💡Fun Facts
The total volume of lava erupted could have covered the entire continental United States in a layer several hundred meters thick.
Iguaçu Falls, one of the world's largest waterfall systems, cascades over the hard, erosion-resistant basalt layers of the Paraná traps.
The term "traps" comes from the Swedish word for stairs ("trappa"), describing the step-like landscape created by the erosion of successive lava flows.
The Namibian portion, called the Etendeka traps, is a mirror image of the geology found in Brazil, now separated by the South Atlantic Ocean.
The basalt flows are a regional geological feature, but are best viewed in national parks. Iguaçu National Park in Brazil is open daily, typically from 9:00 AM to 6:00 PM; check official park websites for current hours.
Admission
Varies by park. Admission is required for Iguaçu National Park.
Accessibility
Paved trails and viewing platforms in major parks like Iguaçu are generally accessible. The broader region is characterized by steep canyons and rugged terrain.
