Geological Processes and Plate Tectonics Fundamentals

Oceanic and Continental Crust

Oceanic Crust: Thinner and more dense, it is installed underwater. Continental Crust: Areas that are thicker and lighter, coinciding with emerged land.

Wegener and Continental Drift

Alfred Wegener made a significant step toward the theory of plate tectonics. In his work, he proposed that continents are not static but move slowly. Wegener suggested that Earth's landmasses were once a single continent (Pangea) surrounded by a single ocean (Panthalassa).

Geothermal Gradient

The internal heat of the Earth increases in temperature as depth increases.

The Wilson Cycle

• 1. Formation of an intracontinental rift.
• 2. Formation of a ridge (oceanic expansion).
• 3. Formation of subduction zones and mountain ranges.
• 4. Closure of the basin and formation of a mountain range.

Convergent Boundaries: Lithospheric Destruction

The destruction process takes place in subduction zones. In these areas, the oceanic lithosphere converges, causing fractures between plates. One plate penetrates the asthenosphere, where high temperatures produce the fusion of materials; the resulting magma ascends, causing volcanic activity. The contact plane between the two plates is called the Benioff zone, which typically has an inclination angle of approximately 45 degrees.

Types of Subduction Zones

• Andean-type subduction: The contact area between a plate with continental lithosphere and one with oceanic lithosphere, where the denser oceanic plate subducts under the continent.
• Island arc subduction: The contact area between two oceanic plates where one subducts under the other, generating intense volcanism that creates volcanic islands aligned along the contact area.

Geological Structures and Processes

• Folds: Deformations of strata that form an anticline (older rocks in the center) or a syncline (younger rocks in the center).
• Faults: Fractures in the Earth's crust.
• Magmatism: The fusion of rocks on the seafloor during subduction (volcanism/plutonism).
• Metamorphism: The transformation of rocks due to pressure and temperature.
• Overthrusts: Formations that evolve from faults when compression forces cause one block to scroll over another.