uu.seUppsala University Publications
Change search
ReferencesLink to record
Permanent link

Direct link
Indentation of a continent with a built-in thickness change: experiment and nature
Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
Show others and affiliations
2000 (English)In: Tectonophysics, ISSN 0040-1951, E-ISSN 1879-3266, Vol. 320, no 3-4, 243-270 p.Article in journal (Refereed) Published
Abstract [en]

Orogens oblique to the direction of plate convergence are currently attributed to obliquity between the margins of one or both of the sutured continents to their direction convergence. We use a single analogue experiment and natural examples to illustrate a potential additional factor: variations in strength of the indented continent at a high angle to the convergence direction. The wavelengths of structures in laterally shortened lithosphere depend on the strength of the most competent layers. Lateral variations in crustal thickness must therefore lead to structures oblique to any applied lateral compression.

An analogue experiment was performed to explore this phenomenon. A two-layer ‘indented continent’ was modelled by a brittle upper crust of sand above a lower crust of high-viscosity polymer floating on a single layer of low-viscosity syrup representing the mantle. The well-known strike-slip structures allowing lateral escape to distant weak boundaries were hindered by lateral boundaries in front of the indenter. This allowed us to focus on the effects of a thickness change built into the ‘indented continent’ along a zone parallel to the direction in which a vertical rigid wall advancing at a steady rate represented the indenter. Vertical escape led to an ‘orogenic belt’ oblique to the advancing wall; this obliquity influences subsequent lateral escape. Model scaling and interpretations are based on Extended Thin Sheet Approximation (ETSA) and standard theories of faulting.

Four sectors of the Alpine–Himalayan orogen (Iran, Tunisia, the Eastern Alps and the Himalaya) are oblique to the continental convergence direction, and we point to thickness changes at high angles to the suture that may account for this geometry. As crustal thicknesses north of oblique sectors of the Himalayas are not yet known, we speculate on them.

We infer from the main difference between our experiment and all our examples chosen from nature that vertical orogenic escape was oblique to our model suture but can be parallel to natural sutures.

Place, publisher, year, edition, pages
2000. Vol. 320, no 3-4, 243-270 p.
Keyword [en]
analogue modelling, Extended Thin Sheet Approximation (ETSA), indentation tectonics, lateral escape, oblique orogens, transversal crustal thickness variation, eastern Alps, geodynamic applications, lateral extrusion, Iranian plate
National Category
Earth and Related Environmental Sciences
URN: urn:nbn:se:uu:diva-37758DOI: 10.1016/S0040-1951(00)00043-3OAI: oai:DiVA.org:uu-37758DiVA: diva2:65657
Available from: 2007-04-12 Created: 2007-04-12 Last updated: 2013-04-29Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full text

Search in DiVA

By author/editor
Talbot, Christopher J.Koyi, Hemin
By organisation
Solid Earth Geology
In the same journal
Earth and Related Environmental Sciences

Search outside of DiVA

GoogleGoogle Scholar

Altmetric score

Total: 158 hits
ReferencesLink to record
Permanent link

Direct link