Lecture 1 …a jolly beginning… GLY 326 Structural Geology Lecture 1 …a jolly beginning… Dr. Marcus Bursik Autumn, 2016

(mib@buffalo.edu; office: Hoch 413) Credits: 4.00 Dr. Bursik (mib@buffalo.edu; office: Hoch 413) Credits: 4.00 When: Tuesdays & Thursdays 11:00am-12:20pm! Where: Cooke 434 Labs (TA: Andrew Harp): Cooke 15 on T, 2:00 – 4:30pm OR F 10:00am – 12:30pm

Da bookie… Haakon Fossen, Structural Geology We will also do readings of scientific papers, web pages, etc.

The lab book… get it new!

OBJECTIVES OF THE COURSE Introduction to the description, classification and interpretation of geological structures in terms of the tectonic settings, plus the practical techniques for structural analysis

What is Structural Geology? Structural geology is the study of deformed rocks… to do so we perform very tricky geometry (and math) to study the rock bodies in 3-D. Then we measure translation, rotation, strain, stress etc… In fact, the discipline is strongly related with some engineering disciplines like rock mechanics…. With a big difference…

In structural geology we deal with the end of the process (the deformed rock) and we try to infer the process by which the deformation occurred, while in engineering it is more important to predict what is going to happen… given a process like an earthquake…

This is more like solving a puzzle

This is more like solving a puzzle

Key point: what we study is the strain (i. e Key point: what we study is the strain (i.e. the end products of the deformation after rotations and translations). We only indirectly behold directly the stress, i.e. the forces responsible for the deformation

Do not mix the terms or you will burn at the stake!!! Strain: the deformation (the product). Stress: the forces (not seen) Kramer and Sprenger (1487) The Malleus Maleficarum

Shortening (contraction) We can classify then: Stress Strain Compression Shortening (contraction) Tension Lengthening (extension) Mind you: The stress is generally no longer present… what is left is the deformation!

“Levels” of structural study: Geometry: basically how big or extensive something is or how it is aligned in space (orientation)…. Kinematics: The description of movement: the beginning, the end, and intermediate states (time). Mechanics: The study of the forces that are responsible for the strain (how the deformation is produced).

Plate tectonics Postulates: Silicate earth is divided into lithosphere (brittle) and asthenosphere (ductile). Asthenosphere convects. Lithosphere divided in plates.

Plate tectonics After Basaltic Volcanism Study Project (1981). Lunar and Planetary Institute.

Divergent:Where lithospheric plates are moving away from one another at their boundary, new lithosphere must be created. This is accomplished by mid-ocean ridges and continental rifts.

Convergent: Where lithospheric plates are moving towards one another at their boundary, lithospheric area must be consumed. This is accomplished by subduction or thickening and delamination.

Transform Plate Boundaries Where the motion of two plates is parallel to their boundary, lithosphere is neither created nor deformed, but strain is concentrated and seismicity is common.