Earthstructureinternal - Copy - Copy.ppt

Earth's crust

1. Geochemistry
Lecture
Geochemistry

2. Structure of the Earth
2
The stratification of
Earth into distinct
layers represents a
pivotal event in its
geologic history. This
process culminated in
the development of a
core, a crust, and
subsequently, the
formation of
continents. During this
differentiation, lighter
elements were
expelled from the
interior, leading to the
creation of the ocean
and atmosphere. The
four segments are of
equal dimensions.

3. Structure of the Earth
3
Crust
The Earth's crust is the outermost solid shell of our planet,
distinguished by its composition, structure, and role in geological
processes.
It can be broadly categorized into two types: continental crust and
oceanic

4. Structure of the Earth
4
Crust: Continental
Crust
1.Continental Crust:
Composition: Primarily composed of granitic rocks rich in silicate
minerals such as quartz and feldspar.
Thickness: Averages about 35-40 kilometers but can exceed 70
kilometers in mountainous regions.
Age: Generally older, with some regions dating back over 4 billion
years, making it significantly more ancient than oceanic crust.
Density: Less dense than oceanic crust, with an average density of
approximately 2.7 grams per cubic centimeter.

5. Structure of the Earth
5
Crust: Oceanic Crust
Oceanic Crust:
Composition: Mainly basaltic rocks, which are richer in magnesium
and iron compared to continental crust.
Thickness: Typically about 7-10 kilometers thick.
Age: Younger, with the oldest sections being less than 200 million
years old, due to the continuous process of seafloor spreading and
subduction.
Density: More dense than continental crust, with an average density
of about 3.0 grams per cubic centimeter.
Formation and Dynamics: The Earth's crust is formed through
complex processes involving tectonic activity, volcanic eruptions, and
sediment deposition. The movement of tectonic plates leads to
interactions at their boundaries, resulting in various geological
phenomena such as earthquakes, mountain building, and the creation
of ocean basins.