- Marine magnetic field information is an important part of environmental information construction of naval battle field, and is one of the main contents of geophysical field and marine geological science research.
- The task of marine magnetic survey is to obtain the distribution and change characteristics of the geomagnetic field in the ocean area by various means, and provide basic data support for the development of marine magnetic field.
In recent years, with the continuous development of the relevant technology of marine magnetic survey, the technology is more and more mature, and the application of marine magnetic survey technology in the civil field is more and more wide. For example, ocean magnetic surveys have found banded magnetic anomalies on the seafloor, providing important evidence for the theory of plate tectonics. Marine magnetic survey technology has a broad space in the development of marine engineering.
What is a marine magnetic?
Marine magnetic survey is one of the methods of marine geophysical survey. The method is based on the principle that the seabed rock strata have different magnetic properties and generate different magnetic fields, and the Earth’s magnetic field is measured at sea. Marine magnetic survey technology is an important means to understand and develop the ocean, and is also one of the main contents of geophysical field and marine geological science research. At the same time, the information of marine magnetic field is also an important part of constructing the environmental information of naval battle field
This technology is mainly used to measure the geomagnetic field or geomagnetic anomaly field. Because the geomagnetic field varies with time and space, marine magnetic survey is a weak magnetic field detection technique. Its mission is to obtain the distribution and variation characteristics of the geomagnetic field in the ocean area by various means, so as to provide basic data support for further interpretation, application and in-depth exploration.
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The characteristics of the marine magnetic anomaly
The magnetic anomalies on the continental shelf and continental slope are continental, which are closely related to the occurrence of magnetic bodies, and form more complex magnetic anomaly images. Through the analysis and interpretation of magnetic anomalies, tectonic zoning can be carried out to determine the range of sedimentary basins and the uplift and depression of the second order, the distribution of large fault zones and the active areas of igneous rocks, and then the distribution of ore deposits can be inferred.
The characteristics of the magnetic anomalies in the ocean basin are quite different from those in the continent, which are represented by a series of high amplitude peak-like magnetic anomalies caused by magnetic seamounts and seamount chains and a series of chain magnetic anomalies. By analyzing the banded magnetic anomalies, the formation and age of the ocean basin can be inferred.
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how is marine magnetic detected?
At the beginning of the 20th century, the early marine magnetic survey mainly used induction magnetometer for magnetic declination measurement. In the 1940s, the fluxgate magnetometer was successfully developed, which greatly improved the magnetic measurement accuracy. Fluxgate magnetometer is a vector magnetometer, which can measure three components, but compared with quantum magnetometer, the measurement accuracy can not meet the needs of high-precision magnetic measurement.
With the development and maturity of quantum magnetic measurement technology, since the 1970s, proton magnetometer and optical pump magnetic force have been widely used in marine magnetic survey. At present, the marine magnetometer is mainly based on proton magnetometer and optical pump magnetometer. Several foreign companies such as Geometrics of the United States, Scintrex of Canada and Bartington of the United Kingdom have developed their marine magnetometer products early, with many kinds and good reliability, and almost occupy the vast majority of the global market.
