Mike Hudec on Salt Tectonics

Listen here or wherever you get your podcasts.

Salt structures tens of kilometers in scale are common occurrences in the Earth’s crust. And because salt is extremely weak compared to most other rocks and minerals, it is the first to deform in the presence of stresses. This can have a dramatic effect on what happens to surrounding rocks, especially in compressive environments.

Hudec is a Research Professor at the Bureau of Economic Geology at the University of Texas at Austin.

Headshot of a man with gray curly hair, wearing a dark purple shirt, smiling against a light gray background.

Podcast Illustrations

Courtesy of Michael Hudec

Map of the world’s salt basins. Each of these have salt diapir structures. In the podcast, Hudec mentions several of the large salt deposits shown, including the formation under the deep-water seafloor off Angola and the Gulf of Mexico.

Map showing areas around the world highlighted in yellow.
A van parked on a salt flat with several people gathered around it, some sitting on chairs and others walking nearby.

Salt glacier flowing down a valley in the Zagros mountains, Iran.

Mountain landscape featuring rugged, rocky terrain with a glacier or snow-capped peaks under a clear blue sky.
People working with shovels on a dry, rocky landscape with camels and some water patches in the background.

Cardona Salt Mountain in Spain is an exposed salt dome. While the mountain is made of salt, which is soluble in water, it does not dissolve as it is shielded by surrounding rock and clay.

3D topographical map of mountain peaks with labeled glaciers and ridges, including Kuh-e-Chachal, Aliabad disapiar, Kuh-e-Gach Anticline, salt glaciers, Gach diapir, Kuh-e-Burkh Anticline, and Siah Tagh diapir.

Onion Creek salt dome, Paradox Basin, Utah. The formation labeled “caprock” is a salt diapir.

An oil drilling tower emitting black smoke into the sky, with people and equipment on the ground nearby.

Salt being deposited by evaporation in the Great Salt Lake, Bolivia.

Traditional salt mining techniques are still practiced in the Danakil Depression, Ethiopia.

People walking towards a dark tunnel at the base of a large, rugged mountain with light-colored, steep rock faces and a partly cloudy sky.
Colorful layered mountains with labels indicating Caprock, Vertical limestone bed, and Permian Cutler Group in a desert landscape.
Black and white photo of a mountain landscape with a large, snow-capped mountain and rugged cliffs.
Interior of a cave or rock chamber decorated as a church or chapel with chandeliers, religious statues, and altar.

Chapel of St. Kinga, carved out of salt in the Wieliczka salt mine, near Krakow, Poland. The mine dates back to the 13th century and is a UNESCO World Heritage Site. The chapel was carved from 1896-1964.

Block diagram showing the wide range of shapes that salt diapirs can assume.

Multiple salt glaciers flowing into a valley in the Zagros mountains of Iran.

Exposed salt dome in the Ravar Basin, Iran.

A human skull with long, blond hair attached, set against a green background.

Head of Salt Man 1, recovered from Douzlakh salt at the Chehrabad salt mine, Iran. This miner died in the mine around 2,400 years ago, and his body was preserved in salt until its discovery in 1993.

In 1901, the Spindletop oil gusher launched the modern age of petroleum. The oil came from caprock units above the top of a salt dome.

Diagram of an iceberg showing various parts including salt-wall canopy, salt wall, salt anticlime, salt roller, thin salt, fallen diapir, salt overthrust, salt glacier on surface, salt pillow, salt welt, salt mass, salt stock, bulb, stem, salt stock canopy, detached salt stock with teardrop diaphragm, and multiple layers of salt sheets and salt-ducts, with a scale on the left indicating distance in kilometers and inches.