Tectonics and Structural Geology

Features from the Field: Chevron Folds

Samuele Papeschi June 12, 2020

Chevron folds in the radiolarites from Batain, Oman. Photo © Simon Virgo via Imaggeo

Folds are among the most strikingly beautiful structures we can observe in rocks. There are several ways folds may form in rocks. For instance, folds in sedimentary rocks may develop by liquefaction of soft sediments, but the most common way to produce folds – and also my favorite – is by deformation. When rocks are compressed by tectonic forces, layers (or foliations) bend and warp, p ...[Read More]

Features from the field: crenulation cleavage

Samuele Papeschi April 27, 2020

Crenulation cleavage in schists from the Island of Elba (Italy). Note how the older foliation is folded and a new foliation developed. Photo © Samuele Papeschi

In one of the former episodes of the ‘Features from the field’ series we have talked about foliations, and how they develop when rocks are pushed together by the movement of tectonic plates. It is quite uncommon, however, that tectonic forces are active in the same direction for an unlimited period of time. The rule, rather than the exception, is that the orientation of tectonic forces ...[Read More]

Features from the field: Foliation

Samuele Papeschi August 30, 2019

Jurassic slate in La Grave (Hautes-Alpes, France). These rocks easily split along foliation surfaces that dip towards the left of the image. Don’t believe me? Try to hammer them! Photo © Samuele Papeschi

Have you ever walked on a mountain trail, passing past outcrops of rocks and noticed that many rocks appear to be split along a well-defined orientation? If you have, you might have seen one of the most important structures in metamorphic rocks – called foliation. The term ‘foliation’ derives from the Latin folium, meaning ‘leaf’. A rock with a foliation looks like a pile of R ...[Read More]

Minds over Methods: Virtual Microscopy for Geosciences

Liene Spruženiece July 23, 2019

Information that can be extracted from a thin-section scan using the Virtual Microscope. All micrographs represent the same area within the thin section. From the upper left side: plain polarized light, crossed polarizers rotated by 0°, crossed polarizers rotated by 45°; from the lower left side: colour intensity map, colour saturation map, phase map. Credit: Liene Spruženiece

The next “Minds over Methods” blogpost is a group effort of Liene Spruženiece (left) – postdoctoral researcher at RWTH Aachen and her colleagues Joyce Schmatz, Simon Virgo and Janos L. Urai. The Virtual Microscope is a collaborative project between RWTH Aachen University and Fraunhofer Institute for Applied Information Technology (Schmatz et al., 2010; Virgo et al., 2016). In the ...[Read More]

Meeting Plate Tectonics – Jean-Philippe Avouac

David Fernández-Blanco June 11, 2019

Credit: Grotzinger, J. and Jordan, T. (2014). Understanding Earth. [Plate boundaries by Peter Bird, UCLA]

These blogposts present interviews with outstanding scientists that bloomed and shape the theory that revolutionised Earth Sciences — Plate Tectonics. Get to know them, learn from their experience, discover the pieces of advice they share and find out where the newest challenges lie! Meeting Jean-Philippe Avouac Prof. Jean-Philippe Avouac initially studied mathematics and physics during his underg ...[Read More]

Features from the field: Boudinage

Samuele Papeschi May 19, 2019

Boudins of amphibolite layers (metamorphosed basalts) that were stretched within quartz schists (Norway). Photo credits © Haakon Fossen.

The Features from the Field series is back! In our previous posts, we have shown how rocks can deform during ductile deformation, producing folds. Folds very commonly develop in rocks when rock layers are shortened by tectonic forces in a specific direction. On the other hand, when layers are extended, we develop boudins. Boudins – the term comes from the French word for ‘sausage’ – are frag ...[Read More]

Meeting Plate Tectonics – Dietmar Müller

David Fernández-Blanco April 2, 2019

Credit: Grotzinger, J. and Jordan, T. (2014). Understanding Earth. [Plate boundaries by Peter Bird, UCLA]

These blogposts present interviews with outstanding scientists that bloomed and shape the theory that revolutionised Earth Sciences — Plate Tectonics. Get to know them, learn from their experience, discover the pieces of advice they share and find out where the newest challenges lie! Meeting Dietmar Müller Dietmar Müller is Professor of Geophysics at the University in Sydney and leads the EarthByt ...[Read More]

Meeting Plate Tectonics – Cesar Ranero

David Fernández-Blanco March 19, 2019

Credit: Grotzinger, J. and Jordan, T. (2014). Understanding Earth. [Plate boundaries by Peter Bird, UCLA]

These blogposts present interviews with outstanding scientists that bloomed and shape the theory that revolutionised Earth Sciences — Plate Tectonics. Get to know them, learn from their experience, discover the pieces of advice they share and find out where the newest challenges lie! Meeting Cesar Ranero Prof. Cesar Ranero is an Earth Science researcher, currently Head of Barcelona Center for Subs ...[Read More]

Features from the field: Folding

Mehmet Köküm June 19, 2017

Folding is one of the most common geologic phenomena in the world. I should start with defining the term ‘deformation’ in order to understand the folding process better. In geology, deformation is an alteration of the size or shape of rocks. Deformation is caused by stress, the scientific term for force applied to a certain area. Stresses on rocks can stem from various sources, such as ...[Read More]

Features from the field: Slickenside Lineations

Mehmet Köküm August 22, 2016

Slickenside lineations developed within the Eocene limestone in the East Anatolian Fault Zone

In this Tectonics and Structural Geology blog we will use different categories for our blog-posts. The first category we present to you is all about field geology: “Features from the field”. One of our bloggers, Mehmet Köküm, spends a lot of time in the field for his PhD and will share some of the features used in structural geology with us. This edition of ‘Features of the Field’ will be all abou ...[Read More]