CE11 - Lecture 7 - Plate Tectonics

Divergent boundary

A plate boundary where tectonic plates move apart, often causing decompression melting and forming new crust.

Convergent boundary

A plate boundary where tectonic plates collide, often causing flux melting and forming features like trenches and volcanoes.

Mantle plume

A stationary column of hot mantle material that rises through the crust, creating volcanic chains as the crust moves over it.

Decompression melting

Melting of hot rock due to reduced pressure, commonly occurring at divergent boundaries.

Flux melting

Melting caused by the addition of water or volatiles, which lowers the melting point of rock, typically at subduction zones.

Heat-induced melting

Melting of mantle material due to increased heat, the least common method of magma formation.

Continental rifting

The stretching and thinning of continental crust, allowing mantle material to rise, often leading to the formation of rift valleys.

Joints

Planar fractures in rock caused by extension forces, often filled with sediments or minerals, important for rock mass usability.

Faults

Fractures in the Earth's crust where movement has occurred, often associated with earthquakes and ground motion.

Normal fault

A dip-slip fault where the hanging wall moves down relative to the footwall, caused by extension forces.

Reverse fault

A dip-slip fault where the hanging wall moves up relative to the footwall, caused by compression forces.

Strike-slip fault

A fault where movement is horizontal along the strike, classified as left-lateral or right-lateral based on the direction of movement.

Philippine Mobile Belt (PMB)

A tectonically active region in the Philippines formed by the collision of the Sunda Plate, Philippine Sea Plate, and Indo-Australian Plate.

Palawan Continental Block (PCB)

A stable terrane in the Philippines rifted from mainland Asia, containing the country's oldest rocks.

Philippine Fault

The longest fault in the Philippines, a left-lateral strike-slip fault traversing the archipelago.

Subduction zone

An area where one tectonic plate is forced beneath another, often causing volcanic activity and earthquakes.

Rock deformation

Changes in rock structure due to tectonic forces, resulting in features like folds, faults, and joints.

Engineering considerations

Factors like fault stability, groundwater drainage, and slope stability that must be evaluated in construction due to geologic structures.