What causes a fold to plunge? What are more common, plunging folds or non-plunging? Does plunging occur while a fold is being formed, or afterwards?

-- Henry Richards (herruptah@hotmail.com), May 03, 2001

Answers

I'm not quite sure if this is right, but:

Plunging folds are created when the fold is being formed. I think they become "plunging" folds by stress and/or erosion making their angle tilted with respect to the horizontal axis. From what I understand, most folds are plunging even if their angle is very small.

-- Joel Bouchard (jboucha1@oswego.edu), May 04, 2001.

thank you very much such a this contribution, respect to mechanism plunging of folds and ý agree with your oppinions about this topic. ý think that it s very important subject for determination of the regional tectonic evalution worked area. because its possible to make mistakes on considering about evolition of the regional tectonics, ýf it is interpreted wronly occuring of the mechanism of plunging folds. as answered in your pages, plunging event can become during folding of the succession layers or afterwards folding why the horizantal fold axis can buckle because of changing of regional deformation directions. for example the fold, E-W axis, is occured N-S compressional tectonic regime, and than If in this regione tectonic transport direction direction is N-W, folding can refolding and axis becomes plunging to E or W. and for this region in this situation we can talk about two deformation phases (D1 and D2). however we can mention only one deformation phase effected this region, when plunging accompanies to folding. there are several methods, observation of fields, microtectonics solitions, to solve this generation timing of the folding-plunging ordering.

Except all of these, plunging of folds can be regional subsidance or with effecting stress distribution in the different part of the fold, the area which contents massive blocks and sedimenter units. the existence of the massive blocks in folding area cause the same time plunging and folding. in the first mechanism plunging can occur simultaneous with folding or afterwards. ý think that its very useful arguing this subject and writing the known therotical materials, literatures and field applications in this page.

best regards.

-- isak yýlmaz (iyilmaz@istanbul.edu.tr), February 06, 2003.