Theory of Sea Floor Spreading
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When new oceanic crust is created by volcanic activity along mid-ocean ridges, it slowly drifts away from the ridge, and a process known as seafloor spreading takes place.
sprawling sea floor
Harry Hess proposed that the seafloor moves as it spreads from a central axis, carrying the continents with it.
This theory states that convection currents originate in the mantle as a result of the extreme heat produced by radioactive materials in the mantle, which is located between 100 and 2900 km below the surface of the earth.
Oceanic ridges form on the seafloor where the rising limbs of these currents meet, while trenches form where the failing limbs meet.
causes the ocean floor to replenish with new material while displacing older materials from the ridge.
Molten material erupting from the mantle spreads out and pushes older rocks to the sides of the breach, creating new ocean floor along these cracks in the ocean crust.
The process of sea-floor spreading adds fresh ocean bottom continuously.
These diverging plate boundaries are responsible for the world's longest mountain range, the Mid-Ocean Ridge.
Evidence of seafloor spreading :
Evidence of seafloor spreading from the mid-ocean ridge;
Evidence from magnetic stripes
Evidence from drilling samples;
Evidence from subduction,
Shreds of evidence from Deep Ocean Trench;
Evidence of Molten material: Rocks with pillow-like shapes indicate that molten material has repeatedly erupted from fissures along the mid-ocean ridge and swiftly cooled.
Evidence Derived from Melted Materials
Evidence from Magnetic Stripes: The magnetizing stripes etched into the rocks that comprise the ocean floor serve as a record of the reversals in Earth's magnetic field.
The seafloor's alternating magnetic striping pattern
Proof from Samples Drilled The youngest rocks are located in the heart of the ridge, while older rocks are found further out from it, according to core samples taken from the ocean floor.
Evidence from Drilling Samples Subduction is the process that allows a portion of the ocean bottom to return to the mantle after sinking beneath a deep ocean trench.
Subduction:
Subduction zones are the location of the Deep Ocean Trench:
Where the marine crust bends downward, deep underwater canyons are created.
Subduction:
Dispersion of Volcanoes and Earthquakes along Mid-Ocean Ridges
The seafloor normally has a temperature gradient of 9.4° C/300 m, but it gets greater near the ridges, suggesting an upwelling of magmatic material from the mantle.
The Atlantic and other oceans' core regions have dots that are nearly parallel to the coasts. This suggests that the seabed has gotten wider over time.
Whereas the earthquakes along the Alpine-Himalayan belt and the Pacific rim are deep-seated, the earthquake foci in the regions of mid-oceanic ridges are typically shallow.
Mid Ocean Ridge
Many of the unresolved issues were resolved by seafloor spreading.
The issue of older rocks being found as one moves away from the center of the ridges and younger age crust being found at the mid-oceanic ridges was resolved.
It also clarified the reason for the comparatively thin sediments at the cores of the oceanic ridges.
The spreading of the sea floor supported Alfred Wegener's idea of continental drift and aided in the development of plate tectonics.
