Mars’ Eridania Region Shows Evidence of Early Tectonic and Volcanic Activity, Implications for Ancient Life
Scientists have discovered evidence that suggests early Mars was more tectonically and volcanically active than previously believed. The discovery of 63 new examples of various volcanoes in the Eridania region of Mars, located in the planet’s southern hemisphere, indicates that the landscape was shaped by changes occurring within Mars’ crust. This finding challenges the notion that forces from above or below influenced the region’s formation.
The Eridania region was once home to a lake system known as the Eridania paleolake, which was up to a mile deep at its peak. The presence of long-lived volcanic sources near abundant water suggests the possibility of hydrothermal systems that could have nurtured life. This discovery expands the potential areas where signs of ancient life on Mars can be found.
Unlike Earth, modern-day Mars has little to no volcanic or tectonic activity. The fact that around half of Mars’ surface is older than 3.5 billion years suggests that crustal recycling has not occurred extensively on the planet. On Earth, crustal recycling is driven by plate tectonics, where one tectonic plate slips under another, causing surface material to be recycled into the mantle.
To study the Eridania region, scientists analyzed data from spacecraft orbiting Mars, including the Mars Global Surveyor, Mars Odyssey, and the Mars Reconnaissance Orbiter. They identified 63 examples of previously unknown volcanism across four different volcano types: volcanic domes, stratovolcanoes, pyroclastic shield, and caldera complexes.
The Eridania basin in southern Mars is believed to have once held a sea approximately 3.7 billion years ago. Seafloor deposits in the region likely resulted from underwater hydrothermal activity. The team of scientists suspects that there are hundreds of other examples of volcanic activity in the Eridania region alone, remnants of extreme geologic activity on Mars around 3.5 billion years ago. They also believe that similar volcanic activity could be found in other regions of the Martian surface.
The geological activity observed on Mars through these findings is vertical tectonics, where land shifts upwards, causing uplift and subsidence. This type of activity is a precursor to the full plate tectonics seen on Earth today. The changes in the Martian crust that led to these volcanic features are comparable to a step in Earth’s evolutionary pathway towards plate tectonics over 2.5 billion years ago.
The incorporation of water in Earth’s lower crust caused mineral transformations that made the deep crust denser. As a result, the crust sagged downwards into the mantle, pushing water-rich minerals deeper into the crust and forming buoyant magmas. This process caused other regions of the crust to rise upwards, resulting in large basins where the crust sagged and mountain chains where the crust rose. The volcanic rocks in the Eridania region have a more silica-rich composition than rocks from mantle sources, similar to what is seen on Earth.
This newly discovered geology on Mars not only provides an opportunity to study a period in Earth’s past that is inaccessible in our planet’s geological record but also offers insights into how life may have emerged on Earth. The processes behind these features could be analogous to scenarios involving the origins of life around porous hydrothermal vents, where heated, mineral-laden seawater spilled from cracks in the ocean crust.
The scale of activity in the Eridania region is astonishing, with a landscape nearly the size of Europe or Arabia shaped by interconnected tectonic processes. The preservation of this Martian landscape provides an excellent opportunity to investigate planetary landscape evolution in more detail.
The team’s research was published in the journal Nature, shedding new light on the geological history of Mars and its potential implications for the search for ancient life on the Red Planet.