Friday, 12 September 2008

Image of the week #2

This is from my PhD thesis. Although at first sight it probably looks like a cross-section through a fold/thrust belt, the scale is somewhat different. It's actually a scan of a large thin section. The folds and thrusts are a small-scale slump in finely interbedded sandstone and mudstone of the Albert Formation of New Brunswick, Canada. The base of the slump cuts down through the underlying stratigraphy from left to right. Having measured up a large number of folds in similar slump beds, I found that the palaeoslope was roughly perpenicular to the local faults. So these slumps may have formed during fault-induced slope instability.


Silver Fox said...

There is some minor left tilting of basal beds on right-dipping normal faults. A great thin section!

Paul Wilson said...

Cheers for the comment. It is a pretty neat thin section. The tragedy is that I don't have any of my sections any more. Technically, they all belong to the university where I did my PhD, so they're probably sitting, unused, in a drawer somewhere.