Astronomically calibrating early Edicaran evolution
Zhang, T., Ma, C., Li, Y. et al.
Astronomically calibrating early Ediacaran evolution
Nature Communications 16, 3049 (2025)
https://doi.org/10.1038/s41467-025-57201-1
I’m not sure I understood this paper. I believe that the authors filtered sedimentology data in the form of various isotope data to get better dating of some events that show up in that sedimentology data. I do not understand the isotope ratio material, or the sedimentology.
As I understood it, there are glacial deposits in several parts of the world that indicate the end of the Marinoan glaciation, one of the possible snowball earth episodes. These deposits are situated between other layers, so they’re qualitatively dated (below means “before”) to the other layers. Volcanic depositions and igneous rock can be radioisotopically dated, but between the dateable layers, there’s quite a bit of uncertainty.
Filtering aspects of sediment isotope ratios with astronomical assumptions allows chronological dating of the qualitatively dated layers.
The paper isn’t terribly clear about what astronomical data and assumptions they use to do this filtering. We know the Earth’s rotational axis precesses, and we know the Earth’s orbit is a little elliptical. These physical facts about the Earth add up to Milankovitch Cycles. I think the authors uses these kinds of physical facts to date isotope ratio changes.
On the other hand, we also know that the entire Solar system has stability issues of various types. I don’t see that addressed in this paper at all. The sediments in question are better than half a billion years old. I found another paper that claims the Earth’s axis tilt has evolved over time, and during the period considered by this paper, various geological data says the tilt was far larger than today. How can a statistical filter of sedimentology data be any kind of accurate with all that uncertainty?
I also think this paper’s title is a little click-baity. There’s nothing in it about early Edicaran evolution other than some putative dates.