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Mechanical Model - Structural Geology - Lecture Slides, Slides of Geology

In these lecture slides, following are the main points that have been discussed : Mechanical Model, Internal Architecture, Representation, Structures, Reconstruction, Motions, Rocks, Regional Deformation, Mountain Belts, Submicroscopic

Typology: Slides

2012/2013

Uploaded on 07/22/2013

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Structural Geology
The branch of geology that deals with:
Form, arrangement and internal architecture of
rocks
Description, representation, and analysis of
structures from the small to moderate scale
Reconstruction of the motions of rocks
Structural geology provides information about the
conditions during regional deformation using
structures
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Structural Geology

The branch of geology that deals with:

Form, arrangement and internal architecture of rocks

Description, representation, and analysis of structures from the small to moderate scale

Reconstruction of the motions of rocks

Structural geology provides information about the

conditions during regional deformation using

structures Docsity.com

Main Principles and Concepts

Original Horizontality (Steno)

Uniformitarianism (James Hutton)

Definitions

Tectonics : Study of the origin and geologic

evolution (history of motion and deformation) of

large areas (regional to global) of the Earth’s

lithosphere (e.g., origin of continents; building of

mountain belts; formation of ocean floor)

Structural Geology : Study of deformation in

rocks at scales ranging from submicroscopic to

regional (micro-, meso-, and macro-scale)

Structural Geologist

A geologist who:

Studies deformation of rock and Earth’s crust

Identifies and interprets geological structures and their tectonic implications

Next steps

Explanation of the structures

Kinematics of formation of the

structures – motions that occurred in

producing them

When integrated over a large area,

the motions will help to infer the past

tectonic motions

Use of Models

We use geometric, mechanical, and kinematic models to understand deformation on all scales (micro, meso, macro)

Geometric model: 3D interpretation of the distribution and orientation of features within the earth crust

Kinematic model: Specific history of motion that could have carried the system from an undeformed to its deformed state (or from one configuration to another)

Plate tectonic model is a kinematic model

Analyses

Descriptive :

Recognize, describe structures by measuring their locations, geometries and orientations Break a structure into structural elements - physical & geometric

Kinematic:

Interprets deformational movements that formed the structures

  • Translation, Rotation, Distortion, Dilation

Dynamic :

Interprets forces and stresses from interpreted deformational movements of structures

We Study:

Changes in the original orientation, location, shape and volume of a rock body ( Deformation : changes in shape, position, and/or orientation of a body)

Physical and chemical forces that deform rocks

Geologic structures that form to accommodate changes

Stress - Force applied over an area

Strain - Observable deformation in the rock

Brittle deformation – e.g., fault: the result of rapidly applied high stress which "break the rock"

Ductile deformation – e.g., fold: the result of slowly applied, constant, low stress which "bend the rock"

Structure

A geometric feature in a rock whose shape,

form, and distribution can be described

Microstructure

The small-scale arrangement of geometric

and mineralogical elements within a rock

Texture

Preferred orientation of crystallographic

axes in the sample

Microfabric

Comprises the microstructure and the

texture of a material

Fundamental Structures

Contacts

Primary Structures

Secondary structures

Fractures (Joints, Shear Fractures)

Vein - Precipitated minerals from fluid flowing

through fractures

Fault

Fold