The Earth's crust is constantly moving, and certain regions of the globe offer us unique windows to observe these movements imperceptible to the naked eye. Researchers have just made a major discovery in Turkey that sheds new light on how continents are slowly tearing apart.
The study of ancient lava flows along the Tuz Gölü fault in central Turkey allowed a team from Curtin University to document for the first time the pure extension of this geological structure. These volcanic flows, which solidified before being fractured by earthquakes, served as natural markers to measure displacements over thousands of years. Scientists were able to reconstruct their original position and precisely calculate their displacement over time.
Fictional image of a fault cutting a city in two.
The analysis methods employed combine satellite imaging with helium dating techniques performed at the John de Laeter Centre. The zircon crystals present in the lava flows played the role of natural geological chronometers. By measuring the concentrations of uranium, thorium, and helium trapped in these minerals, researchers determined the precise age of the volcanic eruptions and quantified the displacements that followed.
Professor Axel Schmitt specifies that this fault is pulling apart at a rate of about one millimeter per year (0.04 inches), an unexpected extensional movement that contrasts with the dominant lateral slip in the region. This discovery changes our understanding of plate dynamics in this area where the Eurasian, Arabian, and African plates interact. It helps refine models of continental deformation on a global scale.
Janet Harvey's expertise in remote sensing was crucial for analyzing landscape deformations on this fault where earthquakes are less frequent than on other Turkish structures. These slow but continuous movements accumulate stresses that can generate destructive earthquakes. Understanding their mechanism helps better assess seismic and volcanic risks throughout the Alpine-Himalayan belt.
Mount Hasan volcano, source of the studied lava flows.
Credit: Axel Schmitt
The combination of radiometric dating and spatial observation opens new perspectives for deciphering landscape evolution over geological timescales. This work illustrates how seemingly insignificant processes can durably shape the surface of our planet.
The role of zircon crystals as geological clocks
Zircon crystals constitute exceptional mineral archives for tracing geological history. These minerals form in magma and naturally trap radioactive elements like uranium and thorium during their crystallization. Over time, the radioactive decay of these elements produces helium that accumulates in the zircon's crystal structure.
The amount of trapped helium depends directly on the time elapsed since the rock solidified. By precisely measuring the ratios between uranium, thorium, and helium, geologists can determine when a lava flow cooled. This dating technique, called helium thermochronology, functions as an extremely precise natural chronometer.
In the Turkish study, these crystals allowed dating the eruptions of Mount Hasan volcano and tracking the displacement of lava flows fractured by seismic activity. Each analyzed zircon tells part of the region's geological history, from the volcanic eruption to subsequent tectonic movements. This method offers remarkable temporal resolution for events that occurred thousands of years ago.
The use of zircon as a temporal indicator revolutionizes our ability to reconstruct landscape evolution. These tiny crystals preserve information that surface observations cannot reveal, enabling scientists to quantify slow but continuous geological processes.
The interaction of tectonic plates in central Anatolia
Turkey is located at the confluence of three major tectonic plates: the Eurasian plate to the north, the Arabian plate to the southeast, and the African plate to the southwest. This unique configuration generates stresses that manifest through different types of movements along faults. The region constitutes a natural laboratory for studying the dynamics of colliding plates.
The Tuz Gölü fault occupies a key position in this interactive system. Traditionally, scientists thought this geological structure operated mainly through lateral slip, like the famous North Anatolian Fault. The new study demonstrates that it is actually an extensional fault where rock blocks are gradually pulling apart.
This pulling-apart movement reflects the stretching of the Earth's crust under the effect of regional tectonic forces. The Arabian plate pushes northward against the Eurasian plate, creating zones of compression but also zones of extension where the crust thins and fractures. This process contributes to the formation of basins like that of Lake Tuz.
Understanding these interactions helps scientists model how continents deform under the pressure of tectonic collisions. This knowledge applies to other regions of the world where plates are colliding, such as in the Himalayan chain. It also helps refine seismic risk assessments by identifying the precise mechanisms that generate earthquakes.