The document describes two types of endogenous (internally driven) landform-building processes: igneous and tectonic processes. Igneous processes create landforms such as volcanoes through volcanic eruptions and igneous intrusions. Tectonic processes like folding, faulting, and lateral faulting form landforms including mountains, rift valleys, escarpments, and are responsible for earthquakes through ongoing tectonic activity.
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Volcanism plutonism
1. A. Endogenous Processes
Endogenous Processes are large-scale landform
building and transforming processes
– they create relief.
1. Igneous Processes
a. Volcanism: Volcanic eruptions Volcanoes
b. Plutonism: Igneous intrusions
2. Tectonic Processes (Also called Diastrophism)
a. Folding: anticlines, synclines, mountains
b. Faulting: rift valleys, graben, escarpments
c. Lateral Faulting: strike-slip faults
Earthquakes evidence of present-day tectonic activity
6. Igneous Rocks (two types)
Extrusive
Lava and Pyroclastic Debris
Extruded at surface or at very
shallow levels and cooled quickly
Intrusive
Magma crystallized slowly within
the crust.
No exposure to the cool
atmosphere.
Plutonic – intrusive igneous rock
cooled slowly at great depth
within crust or mantle.
Basalt is
Extrusive
Granite is
Intrusive
What is the key textural difference between these two rocks?
7. Why Study Igneous Rocks?
All rocks on Earth have evolved from the first igneous
rocks through Igneous Evolution
Provide information about the composition of the
mantle
Absolute age can be obtained through Radiometric
Dating
Features are characteristic of a specific tectonic
environment
Host important mineral deposits (metal ores)
Numerous other critical economic uses
Millions of people are endangered by volcanoes
8. Decompression melting
Convection brings hot rock
to shallower depths
Rifting lowers pressure
Lower pressure causes a
lower melting point
Igneous rock is formed
through a process of
crystallization and magma
differentiation
Why does a lower pressure lower the melting point?
9. Partial Melting
Partial Melting
Silica-rich compounds melt before
other compounds.
Magma Differentiation
Four types:
Magma mixing
Crystal settling
Wall-rock assimilation
Magma migration
10. Bowen’s Reaction Series
• Describes the order and process of magma crystallization
Bowen’s Reaction
Series Animation
11. How Are Igneous Rocks Named?
Texture
Texture depends on crystal size
A. Phaneritic:
Slow cooling (or in the presence of water), larger
crystals, Coarse texture, Intrusive or Plutonic
B. Aphanitic:
Rapid cooling , smaller crystals, Finer texture,
Extrusive or Volcanic
C. Other textures are Glassy, Pyroclastic, Vesicular, and
Porphyritic
Composition
Minerals at the TOP of Bowen’s
Dark in color
Mafic to Ultramafic
12. How Are Igneous Rocks Named?
Composition
Minerals at the TOP of Bowen’s
Dark in color
Mafic to Ultramafic
Iron and Magnesium are dark.
Minerals at the BOTTOM of Bowen’s
Light in color
Felsic
Sodium plagioclase, potassium plagioclase,
and quartz are light
Intermediate composition between these
13. How is Texture Estimated?
• Texture is estimated
using visual grain size
• (depends on
crystallization history)
What has to happen for a porphyritic texture to form in an
igneous rock?
14. How is Composition Estimated?
Composition is estimated using visual color
Can be misleading
15. Classification System for Igneous
Rocks
The classification system for igneous rocks is
based on the following:
Intrusive and extrusive igneous rocks with the
same chemical composition contain the same
minerals
Silica content decreases as iron and magnesium
content increases
Potassium and sodium content decreases as silica
content decreases
16. Seven Common Types of Igneous
Rock
1) Granite
intrusive
2) Rhyolite
extrusive
Felsic Composition
17. Seven Common Types of Igneous
Rock
3) Diorite
intrusive
4) Andesite
extrusive
Intermediate
Composition
18. Seven Common Types of Igneous
Rock
Mafic Composition
5) Gabbro
intrusive
6) Basalt
extrusive
19. Seven Common Types of Igneous
Rock
Ultramafic Composition
7)
Peridotite
intrusive
20. Igneous Evolution
All rocks on Earth have evolved from the first igneous rocks
All Igneous Rocks Result from Magma Differentiation
22. Tectonic Processes
Igneous rock evolves as a product of tectonic processes and is a
major component of Earth’s crust
What is the mechanism that leads to partial melting above a subductio
23. Identify the magma source for each type of volcano. How is the
magma source responsible for the rock composition?
24. Basalt Formation (Spreading
Centers)
High heat flow creates Hydrothermal (hot water) Vents
(black smokers)
Oceanic crust consists of layers of igneous rock
Gabbro crystallizes at the base
Sheeted dikes of basalt extend above the gabbro
Pillow basalt, glassy fragments and metallic sulfide deposits
(at black smokers) form at the sea floor
25. Basalt Formation (Hot Spots)
Intraplate sites of active Plutonism
and Volcanism
Large Igneous Provinces of Flood
Basalts form above mantle hot spots
Plumes of anomalously hot mantle
rock underly active hot spots.
Mantle plumes, which are solid rock,
not magma, rise slowly through the
mantle (but faster than the rate of
mantle convection) due to their
positive buoyancy with respect to
the surrounding rock.
Basalt is also present at many
subduction-related volcanoes, but
typically only in minor amounts.
28. Subduction Zones and Spreading
Centre
Subduction zones and spreading centers are areas in which
magma is formed as a result of partial melting, plutonism, and
volcanism.
What igneous environment is not represented in this image?
