C8420 - TECTONOPHYSICS

Learning outcomes

At the end of the course, the student has advanced knowledge of the evidence and models of geodynamic phenomena in the Earth's lithosphere. In particular, the student is able to interpret the rheological behavior of the Earth's interior and constrain large-scale processes (compensation of topographic loads, post-glacial 'rebound', subduction zones) also taking into account surface data.

Course contents

Rheological stratification of the Earth. Thermal lithosphere. Effects of the time scale and stress intensity on rock deformation. Microphysical processes underlying the inelastic behavior of rocks. Mobility of lattice defects. Fick's laws of diffusion. Mechanisms underlying linear and nonlinear rheologies. Dominant rheology in the sublithospheric mantle: constraints from data and models. Viscoelastic solids: analogical models. Elasto-plastic rheology. Geotherm in the oceanic lithosphere. Elastic part of the lithosphere.

Theory of cylindrical flexure of thin elastic plates. Laccolith mountain. Lithospheric flexure produced by horizontal and vertical loads, applications to deformation near a island chain and subduction zones. Universal flexure profile. Plastic hinge in elastic-plastic transition.

Gravitational field equations. Reference field, gravity and ellipsoid. Measurements of gravity at the Earth surface: variations and corrections. Free-air and Bouguer anomalies. Isostasy: conditions and models. Gravitational effects associated with continental lithospheric flexure: compensation ratio. Isostatic seafloor depth.

High-viscosity fluid models. Prandtl number. Lithosphere and asthenosphere. Stress diffusion from a tectonic margin. Estimation of mantle viscosity by studying postglacial deformation. Subduction angle. Fluids and creep in the crust. Fold formation. Estimation of the strength of a tectonic margin. Brittle-ductile transition. Seismic and aseismic creep. Quasi-static problems in viscoelastic Maxwell continuum media: relaxation function and correspondence with elastic solutions.

Readings/Bibliography

-D.L. Turcotte, G. Schubert. Geodynamics. Second or Third Edition, Cambridge University Press.

Teaching methods

Lessons in the lecture-hall using slides.

 

Assessment methods

The learning assessment consists of an oral examination in presence of the teacher and another expert person. The examination tends to evaluate the fulfilment of the Course learning outcomes:

-Knowledge about the rheology of the Earth interior.

-Knowledge of main evidences that allow constraining geodynamic processes and the rheology of the Earth interior.

-Knowledge of modelling of geodynamic processes and related inferences about Earth Interior features.

The final mark of the course of Tectonophysics is determined as the arithmetical average of the marks obtained by answering three questions about the main Course subjects.

18 - 23 Preparation on a rather limited to limited number of the topics covered, which emerges only with the support of the instructor;

24 - 27 Preparation on most of the topics covered and fair to good command of the basic tools;

28 - 30L Comprehensive preparation on the topics covered, good to excellent command of the basic tools, and good to excellent ability to argue and make connections in complex problems.

Teaching tools

Slides are available online on the Virtuale platform.

Students with DSA or temporary or permanent disabilities: it is recommended to contact the responsible University office in good time (https://site.unibo.it/studenti-con-disabilita-e-dsa/it): it will be their responsibility to propose any adaptations to the students concerned, which must however be submitted, 15 days in advance, to the approval of the teacher, who will evaluate the opportunity also in relation to the educational objectives of the course.

Office hours

See the website of Maria Elina Belardinelli