Hi Maarten,
A few years ago I read the paper by JE Treagus (1999) "A structural
reinterpretation of the Tummel Belt etc." (Geological Magazine) and
noticed a number of similarities between his model of crustal-scale
strain partitioning and a model published around the same time by
Aerden & Malavieille (1999). Our paper was inspired by another large
fold nappe in the Montagne Noire (Variscan belt). We suggested that
fold nappes move/deform by a combination of subvertical extrusion in
steeply dipping "root zones" where they flow out from by
gravitational spreading. Gravitational spreading requires a driving
force producing uplift: "diapirism" according to the late Hans
Ramberg (and his great centrifuge models) but alternatively, crustal
shortening is caused by crustal shortening in the footwall of the
nappe pile mechanically decoupled from the overlying spreading
hangingwall. This mechanism was modelled more than 50 years ago by
Bucher (1956) using layers of wax and wooden blocks. More recently
also by Merle (1989) who applied it to the Alps. I have always
wondered what the main problems are for these models as they are not
usually invoked in studies of fold nappes. In any case, I look
forward to see what you find out in the Tay nappe.
Cheers,
Domingo
On 02/03/2009, at 17:46, Krabbendam, Maarten wrote:
> Thanks for all the anwers thus far. I'm writing something up on the
> tay Nappe in the grampian Orogeny in Scotland. Its strike length
> is at least 200 km (Stonehaven to Butte) and possibly longer into
> Northern ireland.
>
> What I want to know if the following sentence would be remotely
> appropriate:
>
> "The Tay Nappe, in terms of strike length, is 1) by far the
> largest / 2) the largest / 3) amongst the largest fold nappes in
> the world"
>
> So far, 2) or 3) appear to be correct...
>
> Maarten
>
>
> -----Original Message-----
> From: Tectonics & structural geology discussion list [mailto:GEO-
> [log in to unmask]] On Behalf Of Yvette Kuiper
> Sent: 02 March 2009 13:54
> To: [log in to unmask]
> Subject: Re: The largest fold nappe?
>
> Dear Maarten,
>
> I don't know if these are the biggest (maybe the ones in Norway are
> bigger?), but in the Foxe Fold Belt of Melville Peninsula there
> seem to
> be fold nappes >70-80 km. See the references below. They are
> refolded by
> another generation of folds that becomes tight towards the WSW, so
> it's
> hard to tell how far the nappes continue. Towards the ENE there is
> a lot
> of water before the Foxe Fold Belt continues on Baffin Island.
>
> Just out of curiosity, why are you asking that question?
>
> Cheers, Yvette
>
> Henderson, J.R., 1981. Structural analysis of sheath folds with
> horizontal X-axes, northeast Canada. Journal of Structural Geology 3,
> 203-210.
>
> Henderson, J.R., 1983. Structure and metamorphism of the Aphebian
> Penrhyn Group and its Archean basement complex in the Lyon Inlet area,
> Melville Peninsula, District of Franklin. Geological Survey of Canada,
> Bulletin 324, 50 pp.
>
>
>
> Krabbendam, Maarten wrote:
>> Dear all,
>>
>>
>> I am curious what the largest fold nappes in the world are.
>> The dimension I'm especially interested in is the strike length.
>>
>> Which is the 'longest' fold nappe?
>>
>> Cheers,
>>
>>
>> Maarten Krabbendam
>> British Geological Survey
>> Murchison House
>> West Mains Road
>> Edinburgh EH9 3LA
>> Tel: 0131 6500256
>> Email: [log in to unmask]
>>
>>
>>
>>
>>
>>
>
>
> --
> Yvette D. Kuiper
> Assistant Professor
> Department of Geology and Geophysics
> Boston College
> Devlin Hall 213
> 140 Commonwealth Avenue
> Chestnut Hill, MA
> 02467 USA
>
> Tel. 617-552-3647
> Fax. 617-552-2462
> http://www2.bc.edu/~kuipery/
>
> --
> This message (and any attachments) is for the recipient only. NERC
> is subject to the Freedom of Information Act 2000 and the contents
> of this email and any reply you make may be disclosed by NERC unless
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Domingo Aerden
Profesor Titular
Departamento de Geodinámica
Facultad de Ciencias
C/ Fuentenueva s/n
18002 GRANADA, Spain
Tel. +34 958242825
Fax: +34 958248527
E-mail: [log in to unmask]
Web: http://www.ugr.es/~aerden
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