Tectonic History and the Pacific Plate

Overview

• Focus on understanding Earth's tectonic history.
• Study of tectonic plates, continents, and ocean movements throughout Earth's history.
• Current focus on the Pacific Ocean and the island of Hawaii.

Hawaii and Hot Spots

• Hawaii as a Hot Spot:
  • Hawaii is a hot spot, leaving a track of volcanoes from Hawaii to Kamchatka.
  • The bend in the volcano track is a significant topic of study.

The Bend in the Pacific Plate

• Controversy and Exploration:
  • Bend in the volcano track is controversial; understanding why the Pacific plate changed direction is crucial.
  • Age of the bend: Approximately 50 million years, determined from rock dates from seamounts.

Recent Findings

• Collision Hypothesis:
  • Discovery: A large piece of Kamchatka and northern Japan collided with a margin at 50 million years ago.
  • This collision is theorized to be the cause of the directional change of the Pacific plate.

Seismic Boat Maps

• Developed by Grace Shepard.
• Used to study the North Pacific mantle, showing subducted lithosphere.
  • Indicates an active subduction zone between 80 and 50 million years ago.
  • Kamchatka and northern Japan's location on the subduction zone during this period.

Conclusion

• Collision of landmasses at around 50 million years ago led to the change in direction of the Pacific plate.
• Provides new insights into the tectonic history of the Earth.
• The study of the Pacific Ocean and the tectonic movements is ongoing and exciting.