Hacker News Reader

Comment by athl | Hacker News Reader

In the study linked in the article, this is written: "depositional age is known through litho- and chemostratigraphic correlation with the 892 ± 13-Ma (Re–Os black shale) Boot Inlet Formation (Shaler Supergroup (Sg)), together with other geochronological constraints"

View on HN

May you please ELI5 -- I am super fascinated by this, but I cannot decipher how to to understand this sentence.

The age of the rocks it was found in.

OK, sure, makes sense. But how do they know how old the rocks are? If not by carbon dating that is...

https://www.nature.com/scitable/knowledge/library/dating-roc...

This page has a table of different dating methods that work on minerals and the time ranges to which they are accurate.

The "Re-Os" bit indicates that it was Rhenium-Osmium dating of black shale (a sedimentary rock commonly found on paleo-coastlines) in the formation.

One of the major differences between the paleontologists and archaeologists is their opinion of shale and other mudstones. Paleontologists love the stuff, archaeologists hate it.

Geologists and paleontologist usually use multiple methods to estimate age. Carbon works well for young deposits. Uranium dating can be used for much older materials. As AlotOfReading mentioned Rhenium-Osmium. Sometimes they can use Oxygen ratios in inclusions in Zircon crystals. There are other more specialized measures. Using multiple methods can help calibrate each other.

Thanks everyone, very interesting and probably worth further reading!

Reply on news.ycombinator.com