A Meteorite Hit Scotland More Recently Than Previously Believed

We’ve found that a meteorite impacted northwest Scotland 1 billion years ago—200 million years more recently than earlier estimates. Our findings are published today in the journal Geology.

This impact now coincides with some of the earliest known land based, non-marine microbial fossilsh, providing fresh insights into how meteorite collisions may have influenced our planet’s environment and the development of life.

A rich stash of geological wonders

Geologists highly value the Torridonian rocks of northwest Scotland as some of the best-preserved records of ancient lakes and river systems that existed a billion years ago.

Those bodies of water hosted microbial ecosystems made up of eukaryotes—single-celled organisms with complex internal structures that gave rise to all plants and animals.

However, the Torridonian environments and their microbial communities were severely disrupted when a meteor struck the Earth.

The event’s evidence remains preserved in a geological formation called the Stac Fada Member, which consists of distinctive layers of rock fragments shattered and melted by the impact.

Additionally, and importantly, researchers have found shock-altered minerals that closely resemble those at well-known impact sites like Chicxulub (Mexico) and Sudbury (Canada).

In the case of the Stac Fada, the impact trapped these minerals in high-energy, ground-level flows of shattered rock, which spread across the ancient landscape.

What makes our new date for the Stac Fada impact exciting is that it now coincides with the age of microfossils found in other parts of the Torridonian rocks.

This brings up some intriguing questions. For instance, how did the meteorite impact affect the environmental conditions that early non-marine microbial ecosystems depended on?

Determining the date

Figuring out when a meteorite struck is a challenging task.

We can use minerals to determine the age, but they must be the right type. Specifically, the clocks need to remain largely unaltered by the extreme heat, pressure, and fluids from the impact, yet be strong enough to endure the effects of deep geological time.

Such suitable minerals are very rare, but we found a few in the Stac Fada rocks. One was reidite, a mineral that forms only under extreme pressure. The other was granular zircon, a uranium-containing mineral created by intense impact temperatures.

These minerals essentially act as tiny stopwatches, with their clocks starting to “tick” when they form. While the impact and subsequent heat pulse often damage these clocks, we used mathematical modeling to estimate the most likely time of the impact.

Taken together, these methods consistently indicated an event that occurred 1 billion years ago, rather than 1.2 billion years ago as previously thought. Considering such immense time spans, a 20% difference in age may not seem significant.

However, the new age reveals that the timing of the impact aligns with the appearance of early non-marine eukaryotic fossils. It also coincides with a major mountain-building event, indicating that the Torridonian lifeforms had to adapt to significant, environment-altering events.

Why this matters for you, me, and life overall

The origin of life is an incredibly complex process that probably started with a sequence of pre-biotic chemical reactions. Although much is still unknown, it is fascinating that two ancient meteorite impacts—the 3.5-billion-year-old North Pole impact in Western Australia and the 1-billion-year-old Stac Fada deposit in northwest Scotland—occur near significant milestones in the fossil record.

The North Pole impact occurs within a layer of rocks that contains stromatolites, among the oldest known fossils, which researchers believe indicate the presence of microbial life.

All life depends on energy. Researchers believe volcanic hydrothermal springs linked to the earliest life forms, but impacts present a plausible alternative.While the immediate aftermath of a meteorite strike is harsh and catastrophic, the long-term effects could create conditions conducive to key biological processes.

Meteorite impacts fracture rocks, create lasting hydrothermal systems, and form crater lakes that concentrate essential ingredients for life, including clays, organic molecules, and phosphorus— a vital element for all living organisms.

The Stac Fada impact preserves ancient microbial ecosystems before disruption

In Scotland, the Stac Fada impact occurred within an ancient river and lake setting that hosted microbial ecosystems colonizing the land. What makes the Stac Fada impact deposits particularly intriguing is that, unlike most other impacts on Earth, they preserve the environments where these pioneering organisms thrived just before the impact.

Moreover, the impact deposits were buried later as non-marine microbial habitats reestablished themselves. As a result, the Stac Fada rocks offer a unique opportunity to observe how microbial life recovered after the impact.

Meteorite collisions from extraterrestrial sources may have done more than just scar Earth’s surface—they could have shaped its future, transforming catastrophic events into natural cratered havens for life.

Read the original article on: Sciencealert

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