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SEDIMENTARY PETROGRAPHY

Academic year and teacher
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Versione italiana
Academic year
2021/2022
Teacher
EMILIO SACCANI
Credits
6
Didactic period
Primo Semestre
SSD
GEO/07

Training objectives

The purpose of this course is to treat both the theoretical and applied aspects of sedimentary rocks. In particular, terrigenous sedimentary rocks will be discussed in detail. In fact, they represent the vast majority of the rocks cropping out in nature, as well as of the rocks used in different productive and economic activities. This course aims to: (1) provide tools necessary for the macroscopic and microscopic recognition of the main types of sedimentary rocks; (2) provide skills necessary for the study and interpretation of textural and compositional characteristics of sedimentary rocks, also in relation to the recognition of depositional environments; (3) provide skills necessary to the geologist for his/her professional activity, also in relation to the economic and industrial applications of the sedimentary rocks. This course is addressed to the students of all the different curricula of the Degree in Earth Sciences.

Prerequisites


Principles of dynamics of the earth's crust and plate tectonics;
Chemistry of major rock-forming elements;
Rock-forming minerals;
Basic petrology of the main magmatic and metamorphic rocks;
Optical mineralogy and familiarity with the use of polarized microscope

Course programme

The course can be roughly divided into several parts, which are, however, closely interconnected with each other.

Part I. General concepts (ca 2 hours):
Origin of sedimentary rocks, their components and "basic classification" of sedimentary rocks, Genesis of siliciclastic sediments and the main processes of alteration of the source rocks.

Part II. Physical characteristics of the sediments and sedimentary rocks (ca 23 hours):
Grain size, concept of size of an a irregular clast; Grain-size classification of siliciclastic sediments; Main methods of grain size analysis (direct measurements, sieves, sedimentation equipment; Data processing of grain size analysis (graphical and statistical parameters), grain-size distribution in relation to origin, transport and deposition; Interpretation of depositional environments;
Shape and roundness of clastic particles;
Fabric and Packing;
Porosity and Permeability

Part III. Terrigenous sedimentary rocks (ca 19 hours):
Gravels, conglomerates and breccias (textural and compositional characteristics, classification);
Sands and sandstones, compositional parameters; concept of "maturity" of sands and sandstones; Main classifications (Folk, Pettijohn, etc.); The problem of the matrix; Composition and plate tectonics (according Dickinson and Valloni & Mezzadri); the Hybrid Arenites (Zuffa); Heavy Minerals (definition, methods of study, importance, applications)
Muds and Mudstones. Classification; Analytical methods; Textural and compositional features; Distribution of muds and mudstones

Part IV. Diagenesis (ca 4 hours). Definition; Concepts of compaction and cementation; Dissolution of cement; Matrix formation; Deformation and Fracture of grains; Modal compositional variation of sandstone during diagenesis; Determining the diagenetic degree.

Note: hours estimated fort each part are merely indicative. In order to achieve the best results as possible, the actual time devoted to different arguments will depend un the general knowledge and curriculum of the students.

Didactic methods

Theoretical lectures on the course contents. Labs on the microscopic identification of the main types of terrigenous sedimentary rocks, their textures and mineralogical components. Exercises on the interpretation of grain-size analysis. Critical analysis (also in terms of cost, and reliability of the analysis) on the main methods of textural and compositional analysis of sediments and sedimentary rocks.

Learning assessment procedures

Oral exam. Questions will be aimed to test: (1) the ability of the student in using the acquired knowledge and skills for solving problems related to sedimentary rocks; (2) the student's ability to use the right, organized and methodical approach in the interpretation of textural and compositional characteristics of sedimentary rocks; (3) the ability of the student to fix the different topics of the course for the correct recognition and interpretation of sedimentary rocks. The exam might also include the description, the recognition of textural and compositional characteristics, classification of rock samples, as well as the recognition of their sedimentary environment.

Reference texts

E. Saccani (2014) Petrografia delle Rocce Sedimentarie Terrigene. Tipografia Zanzibar, Ancona, 224 p. (Duplicated lecture notes printed and given by the teacher himself)

S. Boggs (2009) Petrology of Sedimentary Rocks, Second Edition. Cambridge University Press, Cambridge, 600p.