The Origin of Ocean Basins

Flashcards about the origin of ocean basins, plate tectonics, and related concepts, based on lecture notes.

Plate Tectonics

The theory that Earth's lithosphere is divided into plates that move and interact, building major features of Earth’s crust.

Continental Drift

The hypothesis that the continents were once joined together in a supercontinent called Pangea and have since drifted apart.

Pangea

A past super continent , from 200 to 300 MYBP, that broke apart and the continents drifted to their present locations.

Sea-Floor Spreading

The process where the sea floor moves apart at the oceanic ridges and new oceanic crust is added to the edges.

Magnetic Anomalies

Measurements of Earth's magnetic field that alternate strong (positive) and weak (negative) in response to the influence of the sea floor rocks, forming parallel bands arranged symmetrically about the axis of the oceanic ridge.

Paleomagnetism

The permanent magnetic field imparted to a rock as basaltic rocks crystallize and some minerals align themselves with Earth's magnetic field at that time.

Subduction Zone

An area where one part of the sea floor plunges below another and down into the asthenosphere, leading to the destruction of sea floor.

Wadati/Benioff Zone

Area of increasingly deeper seismic activity that runs parallel to a subduction trench and slopes down into the mantle parallel to the down-going plate.

Divergent Boundary

A plate boundary where plates move apart, creating new ocean floor, often characterized by a mid-ocean ridge and shallow earthquakes.

Convergent Boundary

A plate boundary where plates move toward each other, oceanic crust is destroyed and features ocean trench, volcanic arc and deep earthquakes.

Transform Boundary

A plate boundary where segments of plates slide past each other, permitting mid-ocean ridge to move apart at different rates, causing shallow but strong earthquakes.

San Andreas Fault

A continental transform fault system that connects the sea-floor spreading ridge of the Gulf of California with the Juan de Fuca spreading ridge off Oregon and Washington.

Wilson Cycle

Sequence of events leading to the formation, expansion, contracting and eventual elimination of ocean basins.