Ocean Floor Magnetic Anomalies

First the hypothesis that the anomalies are produced in the upper 500 metres of oceanic crust has had to be abandoned.

Ocean floor magnetic anomalies. Marine magnetic anomalies typically represent 1 percent of the total geomagnetic field strength. Mapping of variation over an area is valuable in detecting structures obscured by overlying material. A symmetrical pattern of positive and negative magnetic lines emanates from the mid ocean ridge. Then calculate the time duration between the start or end of the first anomaly and the second anomaly delta t and the distance delta x between these two points on the profile.

A marine magnetic anomaly is a variation in strength of earth s magnetic field caused by magnetism in rocks of the ocean floor. The magnetic variation in successive bands of ocean floor parallel with mid ocean ridges is important evidence supporting the theory of. New rock is formed by magma at the mid ocean ridges and the ocean floor spreads out from this point. The oceanic crust displays a pattern of magnetic lines parallel to the ocean ridges frozen in the basalt.

In geophysics a magnetic anomaly is a local variation in the earth s magnetic field resulting from variations in the chemistry or magnetism of the rocks. These two things were the magnetic striping on the ocean floor and the age of seafloor rocks. The initial highly simplistic seafloor spreading model for the origin of ocean magnetic anomalies has been disproven by ocean drilling hall and robinson 1979. Magnetic striping of the sea floor after mid ocean ridges and trenches were discovered more evidence was discovered that helped to support the theory that the continents had moved around.

Once the anomalies are matched the spreading rate is calculated by noting the start and end time of an anomaly at each end of the profile. With a substantial thickness of the ocean crust having magnetic properties aligned in the direction of the earth s field when the crust cooled they will make a measureable change in the intensity of the field. They can be stronger positive or weaker negative than the average total read more. Xavier le pichon james r.