Caribbean Geological History and Tectonics

Introduction

• Caribbean famous for tropical beaches and palm trees.
• Interesting geological history dating back 130 million years.
• Caribbean Plate:
  • 16th largest tectonic plate in the world.
  • Size comparable to India.
  • Mostly submerged beneath the sea, with tectonic activity around its margins.

Political Entities

• Margins of the Caribbean Plate host 13 independent countries and 17 dependencies.
  • Dependencies of the US, Netherlands, France, and UK.

Tectonic Boundaries of the Caribbean Plate

• Northern and Southern Boundaries:
  • Bounded by strike-slip faults and subduction zones.
  • North: Bounded by the North American Plate.
  • South: Bounded by the South American Plate.
• Plate Movement:
  • Caribbean Plate moves east relative to North and South American plates.
  • Northern strike-slip faults: Sinistral (left-lateral).
  • Southern strike-slip faults: Dextral (right-lateral).
• Western Boundary:
  • Cocos Plate subducts eastward beneath Central America.
• Eastern Boundary:
  • Atlantic Oceanic Plate subducts westward beneath the Lesser Antilles.

Geological Features

• Strike-slip Faults Diversity:
  • Transpression and transtension phenomena occur.
  • Pull-apart basins:
    • Caiman Trough: Shortest oceanic spreading ridge, active for 40 million years.
    • Falcon and Bonaire Basins.
  • Formation of islands like Aruba, Bonaire, Curacao due to transtension and transpression.

Subduction Zones and Volcanism

• Earthquake hypocenters indicate subduction:
  • Depths range from 0 to 300 km.
  • Wadati-Benioff zone: Earthquake activity zone.
• Recent volcanism:
  • Central America and Lesser Antilles.

Formation Models of Caribbean Plate

• Two Main Models:
  • In-situ Model:
    • Formed as North and South American plates separated post-Pangea breakup in Mesozoic.
  • Pacific Origin Model:
    • Formed over a mantle plume in the Pacific; migrated eastward.

Historical Tectonic Events

• Greater Antilles Arc Formation:
  • Formed over a south-dipping subduction zone in Cretaceous and Paleogene times.
  • Collision with North America ~50 million years ago, forming the northern strike-slip margin.
• Southern Collisions:
  • Accretion of oceanic terrains on South America's northwestern margin since Late Cretaceous.

Conclusion

• 130 million years of tectonic evolution resulted in the current Caribbean Plate configuration.