Qualla: Araguainha Crater

Araguainha Crater: Introduction

Thu, 16 Apr 2026 00:00:00 GMT

Photo credit NASA, Public domain. Two hundred and fifty-four million years ago, something the size of a small mountain slammed into a shallow sea in what is now central Brazil. The impact punched a 24-kilometer hole straight through Paleozoic sedimentary rock, vaporized itself on contact, and released enough energy to lift the ground beneath it back up into a granite dome while the walls collapsed outward to make a 40-kilometer ring. That ring is still there. It is still the largest known impact crater in South America. And it may have helped kill 81 percent of marine species on Earth.

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Image: NASA | Public domain

Araguainha Crater: Reading the Ring

Thu, 16 Apr 2026 00:00:00 GMT

Photo credit NASA, Public domain. From the air, or from a satellite's elevation model, the shape is unmistakable - a bullseye pressed into the landscape on the border between Mato Grosso and Goiás states, between the villages of Araguainha and Ponte Branca. At the center sits an uplifted core of basement granite,...

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Image: NASA | Public domain

Araguainha Crater: The Evidence

Thu, 16 Apr 2026 00:00:00 GMT

Photo credit NASA, Public domain. For most of the 20th century, geologists who noticed the dome called it a crypto-volcanic structure. The 1971 reconnaissance by Silveira Filho and Ribeiro described lavas, breccias, and tuffs around the core and suggested ancient volcanism. Two years later, Dietz and French ident...

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Image: NASA | Public domain

Araguainha Crater: Dating the Catastrophe

Thu, 16 Apr 2026 00:00:00 GMT

Photo credit Public domain. Getting a reliable date on an impact crater is genuinely hard. The first radiometric effort, in 1992 by Deutsch and collaborators, used rubidium-strontium methods. Engelhardt and colleagues reported a detailed study of the uplifted core and proposed about 246 million years. Later...

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Image: Public domain

Araguainha Crater: The Oil Shale Hypothesis

Thu, 16 Apr 2026 00:00:00 GMT

Photo credit NASA, Public domain. The energy released by the Araguainha impact, by itself, is not enough to explain a global mass extinction. The crater is big - the biggest in South America - but the Chicxulub crater that ended the dinosaurs was four times larger, and some extinction events appear to have no imp...

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Image: NASA | Public domain

Araguainha Crater: Visiting the Dome

Thu, 16 Apr 2026 00:00:00 GMT

Photo credit NASA, Public domain. The crater is remote by Brazilian standards. Reaching it means driving from either Goiânia or Cuiabá along unpaved state roads. The stretch between Ponte Branca and Araguainha cuts directly across the central uplift - you can stand on granite that was lifted from several kilomete...

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Image: NASA | Public domain