Early Mars might have been more active in terms of tectonic and volcanic events than previously believed. Evidence of tectonic movements approximately 4 billion years ago was uncovered through the identification of 63 new instances of diverse volcanoes in a peculiar region of Mars exhibiting unique characteristics distinct from the rest of the planet’s highlands.
A group of planetary scientists revealed that the terrain in the southern hemisphere of Mars, particularly in the Eridania region, seemed to have been molded by internal changes within the planet’s crust rather than external forces. This significant finding could impact the ongoing exploration for ancient life signs on Mars, a mission currently undertaken by NASA’s rovers.
The Eridania region was once home to a lake system named the Eridania paleolake, which reached depths of approximately a mile at its peak, as mentioned by Aster Cowart, a planetary geologist at the Planetary Science Institute. The proximity of long-lasting volcanic sources to abundant water sources might have facilitated hydrothermal systems that could have supported life forms.
Moreover, the discovery expands the search scope for potential evidence of past life forms on Mars.
In contrast to the present-day Earth, Mars lacks significant volcanic or tectonic activities. The age of about half of Mars’ surface, exceeding 3.5 billion years, suggests a limited occurrence of crustal recycling processes on the planet.
On Earth, plate tectonics drive crustal recycling by subduction of one tectonic plate beneath another, leading to the recycling of surface materials into the mantle between the Earth’s crust and its molten core.
The research team scrutinized the morphology and mineral composition of Mars’ Eridania region in the southern hemisphere using data collected from various spacecraft orbiting the Red Planet, including the Mars Global Surveyor, Mars Odyssey, and the Mars Reconnaissance Orbiter.
The Eridania region stands out due to its distinct composition revealed by gamma-ray spectroscopy, lower density and greater thickness compared to the rest of Mars’ crust indicated by gravity data, and intense magnetization of the crust evident from magnetic data.
They identified 63 instances of previously unknown volcanic activity belonging to four different types of volcanoes: volcanic domes, stratovolcanoes, pyroclastic shields, and caldera complexes.
The Eridania basin on southern Mars is believed to have housed a sea around 3.7 billion years ago, with seafloor deposits likely originating from underwater hydrothermal processes. The team speculates that the Eridania region alone may harbor hundreds of other volcanic remnants from the intense geological activities on Mars around 3.5 billion years ago. They also suggest that the volcanic diversity observed in this region might be replicated in other parts of Mars.
The geological activity observed on Mars, characterized by vertical tectonics causing uplift and subsidence, is a precursor to the plate tectonics seen on Earth today.
The alterations in the crust behind these newly discovered volcanic features mirror a crucial step towards the development of plate tectonics on Earth over 2.5 billion years ago. The incorporation of water into the deeper crust levels initiated mineral transformations, increasing the density of the deep crust.
As these mineral transformations progressed, sections of Earth’s crust began to sink into the mantle, a process known as ‘sagduction.’ This movement pushed water-rich minerals formed near the surface deeper into the crust, where they contributed to the formation of buoyant magmas. The buoyancy of these magmas led to the uplifting of other crustal regions.
This geological process resulted in a landscape featuring large basins where the crust subsided, mountain ranges where the crust rose, and volcanic rocks with a silica-rich composition distinct from mantle-derived rocks, akin to the features observed in the Eridania region.
The newfound geology on Mars not only offers insights into a period of Earth’s history inaccessible in its geological record but also provides clues on the emergence of life on our planet.
The processes shaping these Martian features could closely resemble scenarios on Earth where life forms thrive around porous hydrothermal vents, locations where heated mineral-laden seawater emerges from cracks in the oceanic crust.
The vast scale of geological activity in the Eridania region is remarkable, showcasing a landscape comparable in size to Europe or Arabia sculpted by a series of interconnected tectonic processes. This Martian landscape, shaped by ancient processes and preserved over time, presents a unique opportunity to delve deeper into planetary landscape evolution.
The team’s research, published on Monday (Feb. 12) in the journal [Journal Name], sheds light on the intriguing geological history of Mars and its implications for understanding planetary evolution and the potential for life beyond Earth.