Many tend to view the asteroid that wiped out the dinosaurs as a single, terrible day — a moment of fire and destruction that marked the end of an entire era. Typically, the narrative stops there, with death.
However, something persisted beneath the debris. Within the buried crater lie rocks that formed slowly, over a span of time sufficient to alter what scientists believed was possible. The findings of a new study are published in the journal Communications Earth & Environment.
The impact resulted in a crater approximately 180 kilometers in diameter on the land that is now Mexico’s Yucatan Peninsula, which geologists refer to as the Chicxulub crater. The resulting radioactive fallout darkened the skies and triggered the mass extinction event that continues to be documented in research.
All this heat, trapped by groundwater and seawater seeping through the shattered rock, created a hydrothermal system beneath the crater floor. For centuries, hot fluids circulated through fissures underground, leaving behind distinct mineral deposits as they cooled.
Unraveling these minerals became the task for Annamaria Przyllersgill from the University of Glasgow. Altered clays and crystals within the crater rock indicate the presence of a fluid system that continued to operate long after the impact.
To achieve this record, drilling was required. In 2016, an international team drilled into the crater’s peak ring — a band of rock that forms at the center of a giant impact crater — and extracted rock samples from about 600 meters below the seafloor.
These cores contained heavily altered rocks, baked and chemically reworked by long-gone fluids. Among them was a potassium-rich feldspar, a mineral that crystallized directly from hot water during the system’s operation.
This feldspar proved to be a crucial find. Because it only formed when warm fluids were moving through the rock, the age of each crystal precisely pinpoints the moment when warm water was likely still flowing.
To determine the age of these crystals, the team used argon-argon dating, which works because traces of radioactive potassium in the mineral slowly decay into gaseous argon, which remains trapped within it. The more argon present, the older the crystal.
The ages of the feldspars did not align to a single date. Instead, they revealed a broad scatter of values, spanning a period from the meteorite’s impact 66 million years ago to about 58 million years ago.
Until now, the lifespan of the buried hot water system within the crater had been determined through computer models and indirect evidence, with no one having measured it crystal by crystal. It is this spread of ages that represents the core of the discovery.
Earlier studies had suggested the system operated for roughly two million years. Those figures came from computer models developed in the early 2000s, and even their authors had labeled them as conservative.
The new range of dates extends this period to at least eight million years. Four times longer, and the longest such system ever documented on Earth. Its youngest crystals continued to form long after the surface had cooled and stabilized.
To validate their findings, the team recreated computer models using the actual measurements obtained from studying the extracted rock. The best-fit model indicated that fluid movement had finally ceased around eight million years later. This corresponded precisely with the answer the crystals had already provided.
Duration plays a crucial role when considering the potential for life to exist in a place. Heat and water, percolating through fractured, shielded bedrock, create a kind of haven where thermophilic microbes can settle.
“Anywhere on Earth where you find circulating warm water, you find life,” says Przyllersgill.
On modern Earth, these microbes are concentrated around deep-sea hydrothermal vents and volcanic seeps, thriving on chemicals rather than sunlight – a system long considered in reviews of life’s origins.
The longer heat persists, the more time chemical processes have to slowly forge life and allow early organisms to proliferate. Direct evidence of microbes within impact craters is rare but not unheard of.
Earth has almost entirely erased the evidence of the giant collisions that reshaped the early solar system, reprocessing its old crust back into the planet over time. A clean slate, in essence. A well-preserved crater symbolizes these vanished cataclysms.
Mars is an obvious place for further exploration. It retains countless craters, many formed when water still flowed across its surface. Some of these could harbor hidden systems similar to the one recently discovered in a crater closer to home.
Such subterranean refuges could endure harsh surface conditions. This makes ancient craters attractive targets for missions seeking signs of past life. Przyllersgill highlighted worlds without Earth’s dense atmosphere, where similar impacts have accumulated repeatedly.
This is what the rocks now clearly reveal. The subterranean hot water system formed by the collision that killed the dinosaurs persisted for at least eight million years, four times the previous estimate and longer than any other known impact-generated system.
Direct measurement, rather than speculation based solely on models, allows for a revision of scientists’ predictions about how long a location might remain habitable after a major meteorite impact. This changes how life beyond Earth is searched for and how researchers interpret craters on other worlds.
There are indications that the system extended even further. Samples taken from a borehole miles from the source, already decades old, show even younger ages, suggesting heat was retained for approximately 16 million years. According to the researchers, this is the thread worth following next.
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