Hallo Sanjeet,
Thank you for sharing this very interesting field photo.
Small scale thrusting in this fashion can be the result of uplift with 'locked-in' horizontal stress.
If the horizontal stresses cannot be released during uplift, the only stress orientation that is reduced is the vertical stress.
This is inevitable, because the vertical stress is simply the weight of the overburden. For example, if the uplift is 1000 m, and the mean specific gravity of the sediments is about 2,5 gr/cm3, the effective stress reduces with 150 bar.
I tried the construction with a Mohr circle, but for a basin in rest and a weak rock with a Poissons ration of 0.3 I could not create a thrust by uplift only.
However, in a situation with a relatively weak rock and a compressional state of stress to start off with (not thrusting but e.g. a strike-slip regime) the small scale thrusting that you show could potentially be the result.
The suggestion for this process comes from (I believe) John Ramsey, but I do not have the reference at hand.
I think the example that John Ramsey used came from a Kimmeridge outcrop at the English coast, I am sorry that I cannot be more precise.
Regards, Dirk
Dirk Nieuwland
4e Binnenvestgracht 13
2311NT Leiden
Dear All,
Please give your comments on the structure present in this pic.
With regards.
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Sanjeet Sharma
M.Sc. Applied Geology(2011)
Department of Earth and Planetary Sciences
University of Allahabad
Allahabd-211002, INDIA
Mob. No. : +91-945-283-0062
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