The Earth's crust beneath Turkey is 'dripping' downward, and scientists have uncovered the reason why.
The ground beneath our feet can sink so slowly that it goes unnoticed, yet modern scientific instruments can detect these subtle changes. Satellite data has revealed a fascinating geological phenomenon in the Konya Basin of Turkey's Central Anatolian Plateau. It shows that the Earth's crust is 'dripping' downward, a process that has intrigued scientists for years.
But how can a region that is generally rising also have a sinking center, like a dent in a flat table? A team of earth scientists at the University of Toronto, led by Julia Andersen, set out to find the answer.
Andersen and her team analyzed satellite measurements and various Earth data to understand the crust and upper mantle beneath the Central Anatolian Plateau. They focused on the Konya Basin due to its distinct pattern, as it continues to deepen while the surrounding plateau rises over geological time.
Satellites and seismic waves provide valuable insights. Satellites can track minor ground changes over vast areas, while seismic waves from earthquakes reveal unusual zones inside the planet, as waves speed up or slow down in different materials.
By combining these views, scientists can connect surface motion with what lies deep beneath, potentially tens of miles down. Andersen explained, 'Looking at the satellite data, we observed a circular feature at the Konya Basin where the crust is subsiding, prompting us to examine other geophysical data.'
This led to the discovery of a seismic anomaly in the upper mantle and a thickened crust, indicating high-density material and a likely mantle lithospheric drip.
Understanding Plate Tectonics
Plate tectonics explains how Earth's outer shell breaks into moving pieces. These plates rest on hotter, softer rock below, and heat from within the planet keeps materials in slow circulation.
This movement is responsible for mountain ranges, ocean basins, and many earthquakes and volcanoes. Central Turkey is in a complex zone where large plates press, slide, and rearrange.
However, plate motions alone don't fully explain why a basin would sink within a rising region. Scientists must delve deeper than surface maps to understand the full story.
The Study's Findings
The study, published in Nature Communications, introduces the concept of multi-stage lithospheric dripping. In simple terms, parts of the lower lithosphere can become unusually dense, causing gravity to pull heavy material downward until it detaches and sinks into the mantle.
This sinking alters the balance of forces in the rock column, causing the surface to sag above the descending material, forming a basin. Later, if the dense part detaches and drops further, the surface can rebound and rise, no longer carrying the extra weight.
Previous studies indicate that the Central Anatolian Plateau has risen by approximately 0.6 miles over the last 10 million years, driven by this process.
Russell Pysklywec, a co-author of the study, explains, 'As the lithosphere thickened and dripped below the region, it formed a basin that later sprang up when the weight below broke off and sank into the deeper mantle.'
Simulating Earth's Dripping Crust
To validate their theory, the researchers created lab models that mimic the slow-motion processes of deep Earth. They built layers of materials that behave like the Earth's deep layers, using a plexiglass tank with a silicone polymer fluid for the lower mantle, a mix of fluid and clay for the solid mantle, and a ceramic and silica sphere layer for the crust.
While these materials don't perfectly replicate Earth's crust, they provide valuable insights into the formation and growth of instabilities.
When a dense part sags and detaches in the model, it helps explain how a real lithosphere might do the same over millions of years.
Andersen concluded, 'The findings show that these major tectonic events are interconnected, with one lithospheric drip potentially triggering further activity deep within the planet.'
Earth's Dripping Crust and Exoplanets
The team also compared their findings to the Arizaro Basin in the Andes of South America, suggesting that this process isn't limited to a single country or plateau. Mountain plateaus often involve thick crust, deep heat, and complex stresses, creating conditions for dense lower layers to form and sink.
This research also aids scientists in understanding other worlds. Mars and Venus don't follow Earth's plate tectonics, but their interiors still move heat and shuffle materials. If dense rock can peel off and sink without a plate boundary, it offers planetary scientists new ways to explain surface features on worlds with different tectonic rules.
The full study was published in the journal Nature Communications.
