11_Ocean Floor

Ocean Floor Overview

• Presenter: Dr. Jackie Miranda

• Date: February 24, 2025

Agenda

• 60-Second News Update: Muhammad and Autumn

• Key Topics:

  • Ocean Basins

  • Continental Margins & Ocean Ridges

  • Seafloor Mapping

  • Ocean Sediments

  • Seafloor Lab

News Updates

• Muhammad and Autumn: Updates related to ocean research and events.

Upcoming Events

Tampa Bay Youth Ocean Summit

• Date: March 1

• Time: 9 AM – 5 PM

• Themes:

  • Wildlife over Waste

  • Save Florida’s Whales

  • Protect Coral in the Florida Keys National Marine Sanctuary

  • Climate Change and Our Ocean

Denis Phillips Guest Lecture

• Date: March 26

• Time: 7 PM – 8:45 PM

• Location: Tarpon Springs Campus, Chris Sprowls Workforce Innovation Hub

• Focus: Community service, social media, and weather

Quiz Questions Review

• Quiz Question 1: Type of stream in the image?

  • Options: A. Braided stream, B. Low sinuosity stream, C. Steep terrain stream, D. Meandering stream

• Quiz Question 2: What is the top horizon of soil called?

  • Answer options: A. True, B. False

Importance of Oceans

• Climate: Contributes to global climate patterns

• Resources: Energy extraction and transportation of goods

• Recreational Use: Provides areas for recreation

Oceans Statistics

• Earth's Surface: 71% is covered by oceans and marginal seas

• Ocean Coverage:

  • Northern Hemisphere: 61% ocean

  • Southern Hemisphere: 80% ocean

Ocean Basins

• Major Ocean Basins:

  • Pacific Ocean: Largest, deepest (average depth: 4,282 m)

  • Atlantic Ocean: Second largest, less depth (average depth: 3,926 m)

  • Arctic Ocean: Shallowest (average depth: 1,205 m)

  • Indian Ocean: Similar depth to Atlantic (average depth: 3,741 m)

  • Southern Ocean: Equivalent depth to Atlantic and Indian (average depth: 3,270 m)

Deep Ocean Exploration

• Exploration Status: Only 5% of the world’s oceans have been explored; 26.1% of the ocean floor mapped as of June 2024.

Continental Margins and Ocean Ridges

• Types of Margins:

  • Active Margins: Associated with tectonic plate boundaries, experience volcanism and earthquakes.

  • Passive Margins: Not associated with plate boundaries, experience little volcanism.

• Continental Shelf: Shallow, flooded edge of the continent, often containing oil and mineral deposits.

• Continental Slope: Steeper area leading from the shelf to deeper regions.

• Continental Rise: Where continental slope becomes gradual and accumulates sediment.

Submarine Canyons and Turbidity Currents

• Submarine Canyons: Deep, steep valleys on continental slopes, often formed by turbidity currents.

• Turbidity Currents: Dense, sediment-laden water flows downslope, depositing turbidite layers characterized by graded bedding.

Active Continental Margins

• Found mainly around the Pacific, featuring deep ocean trenches and significant volcanic activity.

Deep-Ocean Trenches

• Long, narrow, and the deepest parts of oceans located primarily in the Pacific. Associated with volcanic activity and plate tectonics.

Abyssal Plain

• Deep ocean floor covering depths from 4,500 to 6,000 m, characterized by thick sediment accumulations.

Seamounts and Guyots

• Undersea volcanic peaks that can emerge as islands or erode to become flat-topped structures (guyots).

Oceanic Ridge System

• Mid-Ocean Ridge: Longest topographic feature on Earth, characterized by extensive faulting and volcanic structures, spanning approximately 70,000 km.

Hydrothermal Vents

• Critical for supporting unique ecosystems; formed near tectonic plate boundaries with geothermally heated water.

Review Questions

• World's Oceans Coverage: About 71% of Earth.

• Southern Hemisphere Ocean Coverage: True – more ocean coverage than Northern Hemisphere.

Seafloor Mapping Technology

• Tools:

  • Echo sounders for depth measurement.

  • Sidescan sonar and multibeam sonar for detailed mapping.

  • Satellite altimeter for measuring the ocean surface shape from space.

Seafloor Sediments

• Main types of sediments include:

  • Terrigenous: Weathered material from land.

  • Biogenous: Derived from marine organisms.

  • Hydrogenous: Minerals crystallized directly from seawater.

Climate Impact of Sediments

• Provide a record of life and climatic conditions, essential for understanding Earth's climate history.

What Did You Learn Today?

• Reflect on three key takeaways and the most confusing aspects of today’s class.