Uncommon Descent Serving The Intelligent Design Community

Early fossils may just be “chemical gardens”

Figure 1.
McMahon’s chemical garden (from his paper, cited below)

Correct identification, honed on Earth, could help avoid false Eureka! moments during fossil hunts on Mars:

Astrobiologist Sean McMahon created tiny formations in the lab that closely mimic the shape and chemical composition of iron-rich structures commonly found in Mars-like rocks on Earth, where some examples are thought to be around four billion years old.

Dr McMahon created the complex structures by mixing iron-rich particles with alkaline liquids containing the chemicals silicate or carbonate.

This process — known as chemical gardening — is thought to occur naturally where these chemicals abound. It can occur in hydrothermal vents on the seabed and when deep groundwater circulates through pores and fractures in rocks.

His findings suggest that structure alone is not sufficient to confirm whether or not microscopic life-like formations are fossils. More research will be needed to say exactly how they were formed…

Dr Sean McMahon said: “Chemical reactions like these have been studied for hundreds of years but they had not previously been shown to mimic these tiny iron-rich structures inside rocks. These results call for a re-examination of many ancient real-world examples to see if they are more likely to be fossils or non-biological mineral deposits.” – Sean McMahon. Earth’s earliest and deepest purported fossils may be iron-mineralized chemical gardens. Proceedings of the Royal Society B: Biological Sciences, 2019; 286 (1916): 20192410 DOI: 10.1098/rspb.2019.2410

Paper. (open access)

Follow UD News at Twitter!

They don’t mention ‘stromatolites’ specifically. But I would think what they’ve demonstrated here would apply to the stromatolites as well. Anyone have any thoughts?
Either way, those stromatolites are bad for "evolution". If biological, they didn't change at all in 3.5 billion years. So no "evolution". Again. Nonlin.org
What do you mean by “examples alive today”? Would you have a good reference to this?
This is just a brief video, but it should give you an example. https://youtu.be/d3-M9TxWtJg Ed George
Ed George: What do you mean by "examples alive today"? Would you have a good reference to this? Thanks. PaV
It is my understanding that the “fossil” stromatolites are not what we typically think of when we talk about fossilized animals. What we see are layered sedimentary deposits that form specific shapes. We associate them with ancient life because we see modern biological processes facilitating the formation of similar sedimentary deposits. This being said, I think it is reasonable to assume that there could be other explanations for some of the ancient ones. Ed George
PaV- They would need to show that the micro-fossils can be produced en masse and in large quantities. ET
PaV, I guess some fossil stromatolites may simply be the result of chemical and physical action, but there are enough examples alive today to suggest that most of these fossils were the result of life. Ed George
They don't mention 'stromatolites' specifically. But I would think what they've demonstrated here would apply to the stromatolites as well. Anyone have any thoughts? PaV
I think it is fair to say that researchers are sometimes too quick to label something a microfossil. Especially when it predates others. Ed George

Leave a Reply