L-S tectonite viewed in the plane of the S fabric
L-S tectonite viewed perpendicular to the plane of the S fabric
Deformed conglomerate showing no strain in one plane (at left) and strong stretching in the other (at right) – an L-tectonite

Tectonites are metamorphic or tectonically deformed rocks whose fabric reflects the history of their deformation, or rocks with fabric that clearly displays coordinated geometric features that indicate continuous solid (ductile) flow during formation. Planar foliation results from a parallel orientation of platey mineral phases such as the phyllosilicates or graphite. Slender prismatic crystals such as amphibole produce a lineation in which these prisms or columnar crystals become aligned.[1] Tectonites are rocks with minerals that have been affected by natural forces of the earth, which allowed their orientations to change. This usually includes recrystallization of minerals, and the foliation formation. Tectonites are studied through structural analysis and allows for the determination of two things:[2]

According to the nature of mineral orientation, there are three main groups of tectonites, L-Tectonites, S-Tectonites, and LS-Tectonites. The different types reflect on the different ways that matter moves.



  1. ^ a b c Best, Myron G., Igneous and Metamorphic Petrology, Wiley-Blackwell, 2nd ed. 2002, p. 448
  2. ^ a b c "Tectonite". The Free Dictionary. Retrieved 2023-07-19.
  3. ^ "TECTONITES, S, LS AND L TYPE". structuralgeology.50webs.com. Archived from the original on 2020-02-18.