5 Geology-Related Things You Should Know About This Week

After a quiet week fighting illnesses, this week I bring you 5 things you should know about to understand some of the mechanisms proposed in causing the PETM. 

1. Kaolinite: Dull as Dishwater but Causing a Stir

Kaolinite is the clay mineral Al₂Si₂O₅(OH)₄ and looks like this:

Kaolinite

It’s not a particularly impressive mineral - it doesn’t dazzle your eyes with its dull earthy lustre and it won’t keep you entertained as much as other minerals like the beautifully named Cummingtonite. If your curiosity takes your fancy there, find out more about it here. 

It is extensively used when pure as a cheap, general-purpose filler and coating material for paper, in ceramics, and also in chemicals and paints. Yet again - nothing too special. It is formed from extensive continental weathering, particularly in hot, humid environments around the tropics, like in tropical rainforest areas. 

What is does do though is provide a convenient measure of paleoenvironments in the past. The Carbon Isotope Excursion (CIE) coincides with higher proportion of Kaolinite in soils across the world from New Zealand, the Southern Ocean and all around the ancient Tethys. This intriguing point is the Kaolinite rich sediments here occur very close to sediments with the minimum isotope value during the PETM, suggesting that deposition occurred within 1 000 - 10 000 years.

Within these sediments, scientist have detected and measured various magnetic readings from magnetic minerals such as magnetite, goethite and hematite. There is evidence that the minerals in the rocks are highly magnetised. 

Magnetite

Goethite

Hematite

Similar observations were made over the K/T boundary at the end of the Cretaceous where there is strong evidence for a meteorite impact which is all too well known for a likely cause for the demise of the dinosaurs. There is a hot debate amongst scientists that a similar event may have occurred at the end of the Paleocene. There is a hot debate amongst scientists that a similar event may have occurred at the end of the Paleocene. So did a meteorite trigger the PETM?

Until next time ...