Causes of Plate Motion

Mechanisms of Plate Motion

Scientists generally agree that convection occurring in the mantle is the basic driving force for plate movement.

• Convective flow is the motion of matter resulting from changes in temperature.

Causes of Plate Motion

Mechanisms of Plate Motion

Slab-Pull and Ridge-Push

• Ridge-push menyebabkan kerak samudera tergelincir causes oceanic lithosphere to slide down the sides of the oceanic ridge under the pull of gravity. It may contribute to plate motion.

• Slab-pull mekanisme yg berkontibusi pd pergerakan lempeng: kerak samudera yg dingin dan padat tenggelam dalam lapisan mantel dan “pulls” di sepanjang litosfer.

Yang menyebabkan bergeraknya lempeng:

Mechanisms of Plate Motion

Konveksi mantel

• Penyebaran suhu yang tidak sama dalam tubuh bumi konveksi thermal dalam mantel menimbulkan plate motion.

• Mantle plumes adl massa dg T >>> (mantel) yg bergerak ke permukaan bumi penyebab aktivitas magmatisme

Mantle Convection Models

Convection Currents

The force responsible for plate movement is __________.

Plate Boundaries

• The following two slides show maps of the current major plate boundaries and their relative motions.

• You should be able to describe various landforms created by different plate movements.

Earth’s Major Roles

Plate Tectonics

According to the plate tectonics theory, the uppermost mantle, along with the overlying crust, behaves as a strong, rigid layer. This layer is known as the lithosphere.• A plate is one of numerous rigid sections of the lithosphere that

move as a unit over the material of the asthenosphere.

Types of Plate Boundaries

Plate Tectonics

Divergent boundaries (also called spreading centers) are the place where two plates move apart.

Convergent boundaries form where two plates move together.

Transform fault boundaries are margins where two plates grind past each other without the production or destruction of the lithosphere.

Divergent boundary of two continental plates.

Creates a __________. Example: _____________rift valley East African Rift

Convergent boundary of two oceanic plates.

Creates an ________ and a _____. Example: _____island arc trench Japan

Convergent boundary of an oceanic plate and a continental plate. Forms a _______ mountain range and a ______. Examples: _______ or _______ Mts

volcanic trenchCascades Andes

Convergent boundary of two continental plates. Forms a ______ mountain range. Examples: ___________, Alps, ______________folded Himalayas

Appalachians

Transform-fault boundary where the North American and Pacific plates are moving ____ each other.

Example: ________________ in California

past

San Andreas Fault

Breakup of Pangaea