Analogue modelling of brittle shear zone propagation across upper crustal morpho-rheological heterogeneities

A. S. Gomes, F. M. Rosas*, J. C. Duarte, W. P. Schellart, J. Almeida, R. Tomás, V. Strak

*Corresponding author for this work

Research output: Contribution to JournalArticleAcademicpeer-review

Abstract

Crustal shearing of pre-tectonic weak bodies (e.g. salt pillows, igneous pockets) associated with basement strike-slip fault systems is common in nature. Yet the structural pattern arising from the interference between a brittle shear zone and such weak rheological heterogeneities is still not fully explained. In the present work, different sand-box analogue modelling experiments were carried out to better understand, not only the shear zone perturbation effect caused by a strictly rheologic (viscous-weak) anomaly, but also the one arising from a combined morphological perturbation (i.e. traverse topographic crest). Obtained results show that the development of different shear zone deformation patterns is in each case essentially determined by the interplay between: (i) ductile wrenching strain accommodation in the (viscous) weak body; and (ii) coincidence vs. mismatch between main brittle-viscous rheological boundaries and (crest-related) topographic steps. Comparison of the experimentally obtained results with complying natural examples is further discussed, and essentially focused on the NE Atlantic tectono-magmatic interference between the Gloria transform fault and the Tore-Madeira submarine ridge.

Original languageEnglish
Pages (from-to)175-197
Number of pages23
JournalJournal of Structural Geology
Volume126
DOIs
Publication statusPublished - 1 Sep 2019

Keywords

  • Analogue modelling
  • Basement strike-slip fault
  • Brittle shear zone
  • Gloria transform fault
  • Pre-tectonic crustal viscous anomaly
  • Shear-zone structural pattern
  • Tore-Madeira rise tectono-magmatic interference

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