Seafloor Spreading

Definition

Seafloor spreading is the process by which new oceanic crust forms at mid-ocean ridges and gradually moves away from the ridge, allowing tectonic plates to shift and create geological features. This phenomenon is key in understanding how ocean basins expand, as well as the interactions between tectonic plates that shape Earth's surface.

5 Must Know Facts For Your Next Test

1. Seafloor spreading was first proposed in the 1960s as part of the theory of plate tectonics, revolutionizing our understanding of how continents and ocean floors are formed.
2. The discovery of symmetrical patterns of magnetic stripes on either side of mid-ocean ridges provided strong evidence for seafloor spreading, linking it to Earth's magnetic field reversals.
3. Seafloor spreading contributes to the creation of new ocean floor and can lead to geological phenomena such as earthquakes and volcanic activity along mid-ocean ridges.
4. As new crust forms at mid-ocean ridges, it pushes older crust away from the ridge, which helps explain why oceanic crust is generally younger than continental crust.
5. The rate of seafloor spreading can vary, typically ranging from 1 to 10 centimeters per year, affecting the geological processes and features observed on Earth.

Review Questions

• How does seafloor spreading support the theory of plate tectonics?
  • Seafloor spreading provides a mechanism for plate movement, which is a central idea in the theory of plate tectonics. As new oceanic crust is generated at mid-ocean ridges through volcanic activity, it pushes existing plates apart. This movement not only explains the formation of ocean basins but also connects to phenomena like earthquakes and volcanic eruptions at plate boundaries, reinforcing our understanding of Earth's dynamic nature.
• Evaluate how evidence from paleomagnetism supports the concept of seafloor spreading.
  • Paleomagnetism offers compelling evidence for seafloor spreading through the analysis of magnetic minerals in newly formed oceanic crust. As magma cools at mid-ocean ridges, iron-rich minerals align with Earth’s magnetic field, recording its direction. These magnetic patterns appear symmetrically on either side of mid-ocean ridges, demonstrating that new crust forms continuously and supports the notion that ocean floors are actively expanding outward.
• Synthesize the relationships between seafloor spreading, mid-ocean ridges, and subduction zones in shaping Earth's geology.
  • Seafloor spreading at mid-ocean ridges initiates the formation of new oceanic crust, which then interacts with existing tectonic plates. As new crust pushes older crust away from the ridge, it leads to subduction zones where denser oceanic plates sink beneath lighter continental or oceanic plates. This complex interplay not only drives plate movements but also results in significant geological features such as mountain ranges, deep-sea trenches, and volcanic arcs, illustrating how seafloor spreading influences global geology.

Related terms

Mid-Ocean Ridge: An underwater mountain range formed by plate tectonics, where seafloor spreading occurs and new oceanic crust is created.

Subduction Zone: A region of the Earth's crust where one tectonic plate moves under another, often leading to the recycling of oceanic crust back into the mantle.

Plate Tectonics: The scientific theory explaining the movement of the Earth's lithosphere, which is divided into tectonic plates that float on the semi-fluid asthenosphere beneath.