Transtensional folding

Research output: Contribution to journalArticle

60 Scopus citations

Abstract

Strain modeling shows that folds can form in transtension, particularly in simple shear-dominated transtension. Folds that develop in transtension do not rotate toward the shear zone boundary, as they do in transpression; instead they rotate toward the divergence vector, a useful feature for determining past relative plate motions. Transtension folds can only accumulate a fixed amount of horizontal shortening and tightness that are prescribed by the angle of oblique divergence, regardless of finite strain. Hinge-parallel stretching of transtensional folds always exceeds hinge-perpendicular shortening, causing constrictional fabrics and hinge-parallel boudinage to develop.These theoretical results are applied to structures that developed during oblique continental rifting in the upper crust (seismic/brittle) and the ductile crust. Examples include (1) oblique opening of the Gulf of California, where folds and normal faults developed simultaneously in syn-divergence basins; (2) incipient continental break-up in the Eastern California-Walker Lane shear zone, where earthquake focal mechanisms reflect bulk constrictional strain; and (3) exhumation of the ultrahigh-pressure terrain in SW Norway in which transtensional folds and large magnitude stretching developed in the footwall of detachment shear zones, consistent with constrictional strain. More generally, folds may be misinterpreted as indicating convergence when they can form readily in oblique divergence.

Original languageEnglish (US)
Pages (from-to)89-102
Number of pages14
JournalJournal of Structural Geology
Volume56
DOIs
StatePublished - Oct 15 2013

Keywords

  • Constrictional strain
  • Folding
  • Oblique divergence
  • Shear zones
  • Transtension

Fingerprint Dive into the research topics of 'Transtensional folding'. Together they form a unique fingerprint.

  • Cite this