Oblique contractional reactivation of inherited heterogeneities: Cause for arcuate orogens

• Published in: Tectonics (Washington, D.C.) Vol. 36; no. 3; pp. 542 - 558
• Main Authors: Calignano, Elisa, Sokoutis, D., Willingshofer, E., Brun, J.‐P., Gueydan, F., Cloetingh, S.
• Format: Journal Article
• Language: English
• Published: United States Blackwell Publishing Ltd 01-03-2017; American Geophysical Union (AGU); John Wiley and Sons Inc
• Subjects: Analog models; Analogs; Continental Contractional Orogenic Belts and Inversion Tectonics; Continental Tectonics: Compressional; Deformation; Direction; Earth Sciences; Heterogeneity; Lithosphere; Localization; oblique shortening; Orientation; Ouachita orogen; Sciences of the Universe; strong domain; Structures; Studies; Subduction; tectonic inheritance; Tectonics; Tectonophysics; oblique shortening; strong domain; Ouachita orogen; tectonic inheritance; analog models
• ISSN: 0278-7407; 1944-9194
• DOI: 10.1002/2016TC004424

We use lithospheric‐scale analog models to study the reactivation of pre‐existing heterogeneities under oblique shortening and its relation to the origin of arcuate orogens. Reactivation of inherited rheological heterogeneities is an important mechanism for localization of deformation in compressional settings and consequent initiation of contractional structures during orogenesis. However, the presence of an inherited heterogeneity in the lithosphere is in itself not sufficient for its reactivation once the continental lithosphere is shortened. The heterogeneity orientation is important in determining if reactivation occurs and to which extent. This study aims at giving insights on this process by means of analog experiments in which a linear lithospheric heterogeneity trends with various angles to the shortening direction. In particular, the key parameter investigated is the orientation (angle α) of a strong domain (SD) with respect to the shortening direction. Experimental results show that angles α ≥ 75° (high obliquity) allow for reactivation along the entire SD and the development of a linear orogen. For α ≤ 60° (low obliquity) the models are characterized by the development of an arcuate orogen, with the SD remaining partially non‐reactivated. These results provide a new mechanism for the origin of some arcuate orogens, in which orocline formation was not driven by indentation or subduction processes, but by oblique shortening of inherited heterogeneities, as exemplified by the Ouachita orogen of the southern U.S.
Key Points
Analog models investigate oblique shortening of a heterogeneous lithosphere
Obliquity of a strong domain determines degree of strain localization
An arcuate orogen forms for certain obliquity angles of the strong domain