volcanology

Pinacate Volcanic Field 

Located in far northwest Sonora, Mexico, the Pinacate volcanic field comprises a 1,500 km2 area of Pleistocene lava flows with over 400 cinder cones and 8 maars.

The volcanoes in the Pinacate are monogenetic—meaning they erupt only once and each have a unique magmatic signature. The field today is part of El Pinacate and Gran Desierto de Altar Biosphere Reserve and is also a UNESCO World Heritage Site.

The eastern portion of the field—which is accessible by a vehicle tour route—contains the youngest cones and is mantled by an extensive tephra deposit.  One of the most impressive features on the vehicle route is a large maar caldera, Crater Elegante, formed 32 thousand years ago in an explosive eruption when groundwater interacted with magma. The caldera measures nearly a mile in diameter and is the largest maar in the field.

The cinder cones are accompanied by extensive basaltic lava flows, some of which form spiky stiff peaks. Due to the arid, desert setting of the field, most of the cones have experienced very little erosion and retain a relatively youthful morphology. Extensive dune fields surround the volcanic complex, providing a stark visual contrast to the dark basalt rocks.

Top image from Dan Lynch, all other images by author

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