In the real world everything balances, so John, Hermann, you are correct
that you can't "balance" a single section. However, thinking about how it
might balance and using section techniques on a number of sections and
orientations to help constrain just how much might have gone out of section
is certainly worth some effort.
It's definitely not pointless to have a go quantifying shortening and the
implications of the range of answers you are going to get out of looking at
area and volume conservation assumptions even if you are not going to end up
with a unique answer.
Otherwise you might just as well scribble down any old section or isometric
drawing you like and think looks pretty. That sounds like abstract art and
not geology to me.
alan
Dr Alan Gibbs
Director
Midland Valley Exploration
144 West George Street
Glasgow
G2 2HG
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-----Original Message-----
From: Tectonics & structural geology discussion list
[mailto:[log in to unmask]] On Behalf Of John F. Dewey
Sent: 13 February 2012 19:30
To: [log in to unmask]
Subject: Re: the effect of superposed folding on estimation of crustal
shortening and cross section balancing
>Hermann has it right. Balancing of poly-deformed sections or, indeed,
>any non-plane strain sections is pointless.
Best wishes,
John Dewey
>Koushik,
>
>since there is no true principal section through a fold interference
>systems (except perhaps in case of perfect type III - coaxial fold
>superposition) isn't it pointless to balance such sections?
>
>Hermann
>
>On 2/13/12 4:00 AM, koushik sen wrote:
>>Apologies for multiple posting
>>
>>Hi All,
>>can anyone provide me with references of some papers or books where
>>the effect of superposed folding and/or tight isoclinal folding on
>>cross section balancing and estimation of crustal shortening have been
>>discussed? papers dealing with significance of superposed folding in
>>fold and thrust belts will also be helpful. Thanks in advance.
>>
>>Best Regards
>>Koushik
>>
>>--
>>Dr. Koushik Sen
>>Scientist 'B'
>>Wadia Institute of Himalayan Geology
>>Dehra Dun- 248001
>>India
--
Please note that my email address has changed to: [log in to unmask]
Prof. John F. Dewey FRS, M.R.I.A., FAA, Mem. Acad. Eur., Mem.
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