Unit STRATIGRAPHY

Course

Earth science and environment

Study-unit Code

A004725

Curriculum

In all curricula

Teacher

Amalia Spina

Teachers

Amalia Spina

Hours

52 ore - Amalia Spina

CFU

Course Regulation

Coorte 2024

Offered

2026/27

Learning activities

Affine/integrativa

Area

Attività formative affini o integrative

Sector

GEO/02

Type of study-unit

Opzionale (Optional)

Type of learning activities

Attività formativa monodisciplinare

Language of instruction

English

Contents

Definition and Purposes of Stratigraphic Geology

Stratigraphic geology focuses on the study of rock successions and the stratigraphic record. It delves into the history of geology.
Basic Principles of Stratigraphic Geology

Fundamental principles of stratigraphy include Steno's principles and their exceptions. Concepts such as "right-side up" and "upside down," "top" and "bottom" in geology are essential. Understanding what constitutes a "layer" and the "bedding" of a layer, along with the polarity of strata, is crucial. There is also a significant relationship between the bedding of strata and the morphology of slopes.
Rock Successions and Stratigraphic Classification

The basic stratigraphic units include lithostratigraphic, biostratigraphic, and chronostratigraphic units. The Stratigraphy Codes and the International Commission on Stratigraphy are pivotal. The concept of a "stratotype" is defined, as well as "stratigraphic boundary" and "boundary stratotype." Vertical and horizontal transitions and the temporal significance of boundaries are important. The concept of "Stratigraphic Correlation" is also discussed, along with complete, condensed, and reduced successions, and the concept of sedimentation rate.
The Concept of Time in Stratigraphy

Continuous and discontinuous successions, types of unconformities, stratigraphic gaps, and temporal hiatuses are defined. The concepts of "transgression" and "regression" and variations in sea level are explained.
Definition of Facies

Horizontal and vertical variations in facies, units with conformable boundaries, and their relationship with sea level changes are discussed. Walter's principle and major depositional geometries are outlined.
Relative and Absolute Dating Methods

The section covers unstable isotopes, radioactive decay, and radiometric dating. The concept of "half-life" is introduced. Relative dating methods, such as Smith's principle, "index fossils," and the concept of "homotaxy," are explained. The age of the Earth and the initial subdivisions of Geological Time are covered, including the Geological Time Scale. Paleomagnetism and Magnetostratigraphic Units, as well as the concept of "GSSP" (Global Boundary Stratotype Section and Point), are described.
Elements of Biostratigraphy

This includes the concept of an index fossil, biozones, and biostratigraphic methods. The use of biozonation schemes and their application is explained. Major groups of organisms useful in biostratigraphy during the Phanerozoic (such as Trilobites, Graptolites, Conodonts, Chitinozoa, Foraminifera, Calcareous Nannoplankton, Dinoflagellates, Spores, and Pollen) are discussed

Reference texts

P. Doyle, M. Bennett, A. Baxter: The key to Earth History – an introduction to Stratigraphy, Ed. Wiley.
G. Nichols: Sedimentology & Stratigraphy, Ed. Blackwell Science.
Dispense e appunti inseriti nella piattaforma Unistudium.
Websites:
http://www.ucmp.berkeley.edu/exhibit/geology.html
http://www.msnucleus.org/membership/html/jh/earth/stratigraphy/index.html
http://www.stratigraphy.org

Educational objectives

The course aims to equip students with the fundamental principles of stratigraphy to describe, organize, and classify rock successions and correlate them in time and space.
By the end of the course, the student should be able to:
a) Acquire the fundamental principles of Stratigraphic Geology, understanding the mechanisms to define the original setting in which a rock body was formed.
b) Describe and classify rock successions based on basic stratigraphic units.
c) Understand the significance and apply the methods of stratigraphic correlation.
d) Know the main methods for dating a rock succession and the principles on which they are based.
e) Reconstruct the geological history of an area, including the relationship with relative sea level changes, and define the relative chronology for sedimentary events and tectonic phases.
f) Reconstruct stratigraphic columns from schematic geological profiles (even at different scales) and perform stratigraphic correlations.
g) Create an "age-depth" diagram, understanding the meaning of "sedimentation rate," "sedimentary gap," and "temporal hiatus."
h) Recognize stratigraphic units on geological maps.

Prerequisites

Acquiring the Main Concepts of Geology

Teaching methods

Lectures and practical exercises

Learning verification modality

Written Exam with open and Multiple-Choice Questions

Extended program

Introduction to the Course
Stratigraphic Geology: Definition and Objectives; the Stratigraphic Record
Steno and the Principles of Stratigraphy
Definition of Layer and Bedding: Understanding the concept of a "layer" and the "bedding" of a layer is fundamental.
Principle of Superposition and Exceptions: This principle states that in any sequence of undisturbed strata, the oldest layer is at the bottom and the youngest is at the top. Exceptions include overturned sequences.
Concepts of "Right-side Up" and "Upside Down," "Top" and "Bottom" in Geology: These terms help in understanding the orientation of rock layers.
Methods for Determining Strata Polarity: Techniques used to identify the original position of rock layers.
Folded and Faulted Successions: Examining the effects of tectonic forces on rock layers.
Relationship Between Bedding and Slope Morphology: How the orientation of rock layers influences the shape of the landscape.

Principle of Lateral Continuity: Layers of sediment initially extend laterally in all directions.

Principle of Original Horizontality: Layers of sediment are originally deposited horizontally. Exceptions occur due to post-depositional processes.

Principles of Inclusion and Intrusion; Principle of Cross-cutting Relationships: These principles help in determining the relative ages of rocks.

Concept of Stratigraphic Classification
International Stratigraphy Codes: Guidelines for the classification and nomenclature of stratigraphic units.
Concept of "Stratotype": A reference section for a particular stratigraphic unit.
Stratigraphic Units
Lithological and Lithostratigraphic Correlation: Comparing rock units based on lithology and stratigraphy.
Definitions of Lithostratigraphic Units
Concept of Sedimentation Rate: The rate at which sediment accumulates.
Condensed and Comprehensive Series: Types of sedimentary sequences based on their completeness.
Continuous and Discontinuous Successions: Types of rock sequences and their formation processes.
Stratigraphic Gap: A break in the sedimentary record.
Stratigraphic Boundaries: Limits that separate different stratigraphic units.
Stratigraphic Boundaries
Vertical and Horizontal Transitions: Changes in rock types or characteristics.
Temporal Significance of Boundaries: Understanding the time implications of stratigraphic boundaries.
Relationships Between Lithostratigraphic Units and Time: How rock layers correlate with geologic time.

Concept of "Facies": The character of a rock expressed by its formation conditions.
Horizontal and Vertical Variations of Facies
Sea Level Variations; Ideal Eustatic Curve: Fluctuations in sea level and their representation on a curve.
Concept of Transgression and Regression: Changes in sea level causing shifts in sediment deposition.
Transgressive and Regressive Series (Sedimentary Cycle)
Walther's Principle: The vertical succession of facies reflects lateral changes in environment.
Unconformities: Definitions and Types: Breaks in the geological record and their classifications.

Methods for Dating Rock Successions
Radiometric Dating
Radioactive Decay and Half-life: Principles of decay and the time it takes for half of the radioactive isotopes to decay.
Major Radiometric Dating Methods
Relative Dating Methods
Biostratigraphic Units: Classifying rocks based on fossil content.
Smith's Principle of Faunal Succession: Using fossils to determine the relative ages of rocks.
Index Fossils: Fossils used for correlating and dating rock layers.
Biostratigraphic Correlation: Matching rock layers based on fossil content.
Types of Biozones and Biohorizons: Different classifications within biostratigraphy.
Concept of Homotaxy: The similarity of fossil content in different locations.

Integration of Radiometric Dating and Biostratigraphy

Geological Time
Age of the Earth and Initial Geological Time Subdivisions
Principle of Actualism and Uniformitarianism
Chronostratigraphic Units: Definitions and Hierarchies: Classifying rocks based on time.
Geological Time Scale: The timeline of Earth's history.
Relationships Between Chronostratigraphic Units and Other Units

Chronostratigraphic Unit Boundaries

Stratotypes and the Concept of GSSP (Global Stratigraphic Section and Point): Reference points for the boundaries of chronostratigraphic units.

Stratigraphic Units with Inconformable Boundaries ("UBSU")

Depositional Geometries: Patterns of sediment deposition
On-lap, Down-lap, Top-lap: Types of contact relationships.
Aggrading, Prograding, and Retrograding Successions, and Their Relationship with the Eustatic Curve: Different types of sediment build-up in relation to sea level changes.

Obiettivi Agenda 2030 per lo sviluppo sostenibile