Tectonics and Structural Geology

Features from the Field: Shear Zones and Mylonites

Samuele Papeschi, Sandra McLaren and Hannah Davies January 25, 2021

Dextral, ductile shear zones crosscut foliated schist at Cap de Creus (Catalona, Spain). Photo © Jordi Carreras

The San Andreas Fault in California, the Alpine Fault in New Zealand, or the Main Frontal Thrust in the Himalayas are some of the most famous and largest fault zones that accommodate the relative displacement between two adjacent crustal blocks. Such faults, however, represent only the shallower expression of something much bigger: a crustal shear zone. In the first 10 kilometers or so of the crus ...[Read More]

TS Must-Read – Ramsay (1980) Shear zone geometry: a review

The Must-read team January 21, 2021

Ramsay’s 1980 important contribution is a practical and theoretical handbook about shear zones, where the reader can find a detailed classification of shear zones, their description, and mathematical explanation. A definition of the concept of shear zones opens the article, followed by the shear zones classification into three types, namely brittle (e.g., Fig. 1a), brittle-ductile (e.g., Fig ...[Read More]

TS Must-Read – Brace and Kohlstedt (1980) Limits on Lithospheric Stress Imposed by Laboratory Experiments

The Must-read team January 19, 2021

In 1980 Brace and Kohlstedt published a short paper that constrains the strength of continental lithosphere by extrapolating laboratory measurements of rock strength to geological conditions. Their approach follows earlier work by Goetze and Evans (1979) and relies on two key considerations. First, the brittle strength is given by the frictional strength of rocks following Byerlee’s law (Bye ...[Read More]

#OnTheRocks – Because Earth is just beautiful!

Silvia Brizzi January 15, 2021

The El Gordo Megabed from the Tabernas basin in Almeria, Spain. El Gordo which directly translates to the Fat Megabed is a fitting name for this huge sedimentary structure. The photo was taken on the morning after St.Patricks day on a field camp for Irish students. The photographer's previously thought to be incurable hangover was most certainly cured by the site. Credits: Grace Fitzgerald

From the time the first Kodak camera in 1888 went on sale we can say with confidence a geologist somewhere was trying to capture field photographs. We love to capture the beauty of the field and every geologist has a story to tell. The EGU would like to connect these stories globally in our new #OnTheRocks series. #OnTheRocks will produce a compilation of geological photographs on different scales ...[Read More]

TS Must-Read – Mckenzie (1978) On the development of Sedimentary basins

The Must-read team January 8, 2021

Continental extension strongly affects the topography of continents by shaping elongated rift valleys, referred to as rift basins in the geological record. A strong implication of the formation of these basins is a two-step subsidence history: an initial rapid subsidence during extension, and a second, slower subsidence once active extension has ceased. Although this observation was made already l ...[Read More]

TS Must-Read – Sibson (1977) Fault Rocks and Fault Mechanism

The Must-read team December 28, 2020

The paper “Fault Rocks and Fault Mechanisms” by R. H. Sibson (1977), was one of the first studies that established major connections between the rocks that form in faults, and their conditions and mechanics during formation at crustal scale. Concretely, Sibson (1977) established: 1.) links among the textures and lithologies that develop along fault zones (fault rocks), 2.) the rheological and crus ...[Read More]

Maria Vasilyevna Klenova (12 August 1898 – 6 August 1976): The polar scientist who was known as the mother of marine geology.

Anouk Beniest December 21, 2020

An artists illustration of Maria Klenova (credit: Annique van der Boon)

On the 12th of August 1898, Maria Vasilyevna Klenova was born to a working-class family in Irkutsk1. This city started as a military outpost in 1652, but had become a bustling city around the turn of the 20th century with around half a million inhabitants. In the year Maria was born, Irkutsk became connected to Europe by the infamous Trans-Siberian Railway. Maria did not stay in Irkutsk ver ...[Read More]

Beyond Tectonics: Fishing for Continents in the Furious Fifties and Roaring Forties

Derya Gürer and Luca Magri December 18, 2020

Some of the research team of IN2020_V01 in front of the bridge of the R/V Investigator (credit: Paige Maroni)

This edition of “Beyond Tectonics” is brought to you by Dr. Derya Gürer and Luca Magri. Derya is a Lecturer in Earth Sciences at The University of Queensland in Brisbane, and Adjunct Lecturer at the University of Tasmania, and Luca is a PhD student at the University of Tasmania in Hobart, Australia. In early 2020, they participated in a research voyage to one of the most remote places on the plane ...[Read More]

TS Must-Read – Riba (1976) Syntectonic unconformities of the Alto Cardener, Spanish Pyrenees: a genetic interpretation

The Must-read team December 14, 2020

In 1976 Oriol Riba published his paper on “Syntectonic unconformities of the Alto Cardener, Spanish Pyrenees: a genetic interpretation”, and despite appearing as a niche topic at first glance, it was voted as one of the papers in our Must-Read series. A major reason for that is that the paper presents a general model for syntectonic unconformities – an unconformity which illustrates both se ...[Read More]

Mind your Head: Taking care of yourself during the Corona-virus crisis – Part 2

Anne Pluymakers and Hannah Davies December 11, 2020

Credit: Bongkarn Thanyakij. Distributed via Pexels

It has been many months since the first lockdown, in some countries about a year, in other countries perhaps eight months. A continuing learning curve, with many ups and downs. Now the end is slowly appearing on the horizon, with promises of vaccines, and several countries making definite plans on when and how to vaccinate. Still – it will take at least 6 months, quite possibly more, until it is o ...[Read More]