Geological Oceanography
Geological oceanography reads the rocks, sediments, and shape of the seafloor to reconstruct how ocean basins form and evolve and how the deep-sea record preserves the history of Earth's climate and oceans.
Definition
Geological oceanography, or marine geology, is the study of the structure, composition, history, and evolution of the ocean floor and basins, including the sediments and rocks that record Earth and ocean history.
Scope
This area covers the tectonics of the ocean floor and seafloor spreading, the nature and accumulation of marine sediments, the morphology and structure of ocean basins from ridges to trenches, and paleoceanography — the use of marine sediment records to reconstruct past ocean and climate conditions.
Sub-topics
Core questions
- How do ocean basins open, evolve, and close through plate tectonics?
- What sediments accumulate on the seafloor, and what controls where they form?
- What does the shape and structure of the seafloor reveal about its origin?
- How do marine sediment records reconstruct past ocean circulation and climate?
Key theories
- Seafloor spreading and plate tectonics
- New ocean crust forms at mid-ocean ridges and spreads outward, recording Earth's magnetic reversals and providing the mechanism that underlies plate tectonics and the opening and closing of ocean basins.
- Sediment archives of Earth history
- Deep-sea sediments accumulate slowly and continuously, preserving microfossils and chemical signals that serve as archives of past climate, ocean chemistry, and circulation.
Clinical relevance
Geological oceanography supports the assessment of marine mineral and energy resources, the evaluation of submarine geohazards such as earthquakes, tsunamis, and slope failures, and the reconstruction of past climate that calibrates models of future change.
History
Marine geology was transformed in the 1950s-1960s when seafloor mapping by Tharp and Heezen revealed the global mid-ocean ridge system, Hess proposed seafloor spreading, and magnetic stripe patterns confirmed it, providing decisive evidence for plate tectonics; scientific ocean drilling then opened the sediment record to systematic study.
Key figures
- Harry Hess
- Marie Tharp
- Bruce Heezen
- Cesare Emiliani
Related topics
Seminal works
- seiboldBerger2017
- kennett1982
Frequently asked questions
- How old is the oldest ocean floor?
- Because ocean crust is continually created at ridges and recycled at subduction zones, the oldest seafloor is only about 180 to 200 million years old, far younger than the most ancient continental rocks.
- How do scientists study the deep seafloor?
- They use acoustic mapping (sonar), seismic profiling, sediment and rock coring, and scientific ocean drilling, increasingly supplemented by submersibles and remotely operated vehicles.