What technology is being used to detect Spreading Boundaries?

Answer 1

Oceanic ridges were first discovered during World War II during submarine reconnaissance missions. There is much data that shows that the sea-floor gradually spreads away from these ridges.

1) sea-floor sediments: Based on the current rate of sedimentation scientists can calculate the depth of an oceanic layer of sediments that would accumulate over billions of years if the sea floor remained motionless over time. On the other hand, this depth would be much less if the sea floor has been continually recycled over the course of geologic history. Scientists have used exploratory drilling vessels to sample sediment depths at a variety of locations in the ocean basins. They have found that the sea floor must be a part of a dynamic system because the layer of oceanic sediments is not very deep at all.

2) Paleomagnetism: The earth has a magnetic field that reverses itself in a cyclic fashion over time. The North magnetized pole becomes the south magnetized pole and vise versa. As molten rock crystallizes iron containing minerals in the rock align themselves toward the north pole of earths magnetic field. Scientists sample such rocks and determine their age and magnetic direction. In this way we have documented the time intervals between magnetic field reversals and have developed a magnetic timescale.

at divergent plate boundaries the magma solidifies regularly and every time a rock is formed the rock preserves the earths magnetic field at that time. Oceanographers have used magnetometersto determine that running parallel to spreading centers are strips of normally or reversely magnetized crust. Additionally, the pattern is stripped and symmetrical on either side of the spreading center. This indicates that as lava is solidified it preserves the magnetic field (normal or reversed) and pushes the plate forward to make way for the next layer of new crust. And this occurs until the earths magnetic field reverses again and then a new strip of crust is oppositely magnetized from the previous strip.

3) Geochronology: Scientists can date the age of oceanic crust by drilling past the layer of sediment on the sea floor and to the crust. The marine fossils that they find on the interface of the sediment layer and crust layer indicates the age of that crust. In this way it has been determined that the oceanic crust age increases with distance from spreading centers. This is a strong peace of evidence that the sea floor is spreading.

4) Satellites: very sensitive satellites can detect tiny motions on the surface of the earth. Scientists have used this sort of data to determine the rates that lithospheric plates are moving.