Some unusual rocks at Colorado's Pikes Peak show a missing connection to Snowball Earth's history

About 700 million years ago, the Earth cooled a lot that scientists imagine that vast layers of ice enveloped your entire planet like an enormous snowball. This global deep freeze, often called snowball earthendured for Tens of thousands and thousands of years.

Yet miraculously adolescence not only sustained, but thrived. As the ice melted and the bottom thawed, Complex multicellular life emergedwhich eventually led to the life forms we all know today.

The Snowball Earth Hypothesis is basically based on evidence from sedimentary rocks exposed in areas were once along the coasts and shallow seas as well Climate modeling. Physical evidence that ice sheets covered the inside of continents in warm equatorial regions had previously eluded scientists.

In latest research Published within the Proceedings of the National Academy of Sciences, our team of geologists describe the missing link present in an unusual siliceous sandstone trapped within the granite that forms Pikes Peak in Colorado.

Solve a snowball earth puzzle on a mountain

Pikes Peak, originally called Tavá Kaa-vi Founded by the Ute people, these remarkable rocks are given their ancestral name, Tava. They are consisting of solidified sand injectiteswhich formed in a fashion just like a medical injection when sand-rich fluid was forced into underlying rock.

One possible explanation for the formation of those enigmatic sandstones is the big pressure of an overlying snowball-earth ice sheet, which pushes sediment mixed with meltwater into the weakened rock below.

One obstacle to testing this concept, nonetheless, was the dearth of an age statement for the rocks that will indicate when the suitable geological conditions existed for sand injection.

We found a approach to solve this mystery using iron veins found along the Tava injectites near Pikes Peak and elsewhere in Colorado.

Iron minerals contain very small amounts of naturally occurring radioactive elements, including uranium, which evolve slowly decays into the element lead at a known rate. Current advances in Laser-based radiometric dating allowed us to measure the ratio of uranium to guide isotopes within the iron oxide mineral hematite and thus learn how way back each crystal formed.

The iron veins appear to have formed each before and after the sand was injected into the Colorado bedrock: we found hematite and quartz veins cutting through each Tava dikes and intersected by Tava dikes. This allowed us to find out an age range for the sand injectites, which will need to have formed 690 to 660 million years ago.

So what happened?

The time-frame implies that these sandstones were formed in the course of the Cryogenic period, 720 to 635 million years ago. The name is derived from “cold birth” in ancient Greek and is synonymous with climate change and the disruption of life on our planet – including Snowball Earth.

While the causes of the intense cold on the time are controversial, there are prevailing theories Changes within the activity of tectonic platesThis includes the discharge of particles into the atmosphere that reflect sunlight away from the Earth. Finally, a Accumulation of carbon dioxide from volcanic outgassing could have warmed the planet again.

The tava found on Pikes Peak is assumed to have formed near the equator in the guts of a volcano ancient continent called Laurentiawhich step by step moved over time and over long tectonic cycles to its present northern position in North America.

The origin of the Tava rocks is controversial for over 125 yearsbut latest technology allowed us to conclusively link it to the cryogenic Snowball Earth period for the primary time.

The scenario we imagine for sand injection looks something like this:

An enormous ice sheet with areas of geothermal heating at its base produced meltwater that mixed with quartz-rich sediment below. The weight of the ice sheet created enormous pressures that pushed this sandy fluid into bedrock that had already been weakened over thousands and thousands of years. Similar to today's fracking for natural gas or oil, the pressure cracked the rock and pushed the sandy meltwater in, eventually creating the injectites we see today.

Clues to a different geological mystery

Not only do the brand new findings further support the worldwide Snowball Earth hypothesis, however the presence of Tava injectites in weak, fractured rocks once overlain by ice sheets also provides clues to other geological phenomena.

Time gaps within the rock record attributable to erosion are known as discrepancies can now be seen throughout the United States, most famously on the Grand Canyon, where in places over a billion years of time are missing. Unconformities occur when a sustained period of abrasion prevents the formation of newer rock layers, leaving an unconformable contact.

Our results reveal that a big unconformity will need to have formed near Pikes Peak prior to the cryogenic Snowball Earth. This contradicts hypotheses that attribute the formation of the Great Unconformity to this large-scale erosion through snowball earth ice sheets themselves.

We hope that the secrets of those elusive cryogenic rocks in Colorado will result in the invention of additional terrestrial records of Snowball Earth. Such findings might help develop a clearer picture of our planet during climate extremes and the processes that led to the habitable planet we survive today.