PETROLOG
Y
Module:I:
Introduction to Igneous petrology; its significance, distinguishing features of three types of
rocks; concept of intrusion and extrusion; Magma: Definition, generation and crystallization
and diversification of magma, Tectonic setting and igneous activities; Bowen’s reaction
principle and its petrological significance. Structure, textures and classification of igneous
rocks.
♦Define petrology:
•Petrology means: “STUDY OF ROCKS”
○Petro: Rocks
○Logy: study
The branch of geology that deals with the study of
various aspects of rocks such as origin, association,
occurrence, mineral composition, chemical composition,
texture, structure, physical properties of rocks.
♦Define rocks:
,Rock or stone is a natural substance, a solid aggregate or
more minerals combined together in an orderly manner.
, Rock cycle
The Rock Cycle: A Detailed Explanation
, The rock cycle is a continuous and dynamic process
through which rocks are transformed from one type to
another over time. It involves geological processes such
as weathering, erosion, sedimentation, metamorphism,
and melting. The three major types of rocks—igneous,
sedimentary, and metamorphic—are interconnected
through these processes, forming a cycle.
♦Stages of the Rock Cycle
1. Formation of Igneous Rocks
Igneous rocks form from the cooling and solidification of
molten rock material known as magma (beneath the
surface) or lava (on the surface).
•Intrusive (Plutonic) Igneous Rocks: These form
when magma cools slowly inside the Earth's crust,
resulting in coarse-grained rocks like granite and diorite.
•Extrusive (Volcanic) Igneous Rocks: These form
when lava cools rapidly on the surface, producing fine-
grained rocks like basalt and rhyolite.
2. Weathering, Erosion, and
Sedimentation
Once igneous rocks are exposed to the atmosphere, they
undergo weathering (breaking down into smaller
particles) due to physical, chemical, and biological
processes.
Y
Module:I:
Introduction to Igneous petrology; its significance, distinguishing features of three types of
rocks; concept of intrusion and extrusion; Magma: Definition, generation and crystallization
and diversification of magma, Tectonic setting and igneous activities; Bowen’s reaction
principle and its petrological significance. Structure, textures and classification of igneous
rocks.
♦Define petrology:
•Petrology means: “STUDY OF ROCKS”
○Petro: Rocks
○Logy: study
The branch of geology that deals with the study of
various aspects of rocks such as origin, association,
occurrence, mineral composition, chemical composition,
texture, structure, physical properties of rocks.
♦Define rocks:
,Rock or stone is a natural substance, a solid aggregate or
more minerals combined together in an orderly manner.
, Rock cycle
The Rock Cycle: A Detailed Explanation
, The rock cycle is a continuous and dynamic process
through which rocks are transformed from one type to
another over time. It involves geological processes such
as weathering, erosion, sedimentation, metamorphism,
and melting. The three major types of rocks—igneous,
sedimentary, and metamorphic—are interconnected
through these processes, forming a cycle.
♦Stages of the Rock Cycle
1. Formation of Igneous Rocks
Igneous rocks form from the cooling and solidification of
molten rock material known as magma (beneath the
surface) or lava (on the surface).
•Intrusive (Plutonic) Igneous Rocks: These form
when magma cools slowly inside the Earth's crust,
resulting in coarse-grained rocks like granite and diorite.
•Extrusive (Volcanic) Igneous Rocks: These form
when lava cools rapidly on the surface, producing fine-
grained rocks like basalt and rhyolite.
2. Weathering, Erosion, and
Sedimentation
Once igneous rocks are exposed to the atmosphere, they
undergo weathering (breaking down into smaller
particles) due to physical, chemical, and biological
processes.
