Application Of Global Magnetic Anomalies In Super Continent Reconstruction

The assembly, outgrowth, breakup, reconstruction/configuration of supercontinents are of significant in the history of the earth, and the assembly and breakup of supercontinents play a key role in the earth dynamics research. Supercontinents reconstruction mainly consider the consistence of the continent' bounderies, and with limited geologic paleoclimate, paleontology, stratum and tectonic information and high quality paleomagnetism data. Global Earth Magnetic Anomaly Grid dataset,which released in 2009, compiled from compiled from satellite, ship, and airborne magnetic measurements. It has been studying in the earth's deep tectonic structures,rock circle morphological features and geodynamics problems with a great deal of scientific data and evidences. In this thesis, the geomagnetic lithospheric anomalies are applied to the reconstruction of the supercontinent, examining the connections between the plates based on geological constraints and paleomagnetic results. In return, the current supercontinent framework can also help us to indicate the origin of the middle and long scale wavelength of magnetic anomalies.In this thesis, The global Earth Magnetic Anomaly Grid dataset is mapped to the magnetic anomaly map in Gplates software. It can be see that the magnetic anomalies in the ocean are significantly different from that of the continental magnetic anomalies,and the amplitude magnetic anomalies in the continent are generally greater than that of the ocean. This thesis analyzes the magnetic anomalies of the ocean and considers that there are three types of magnetic anomalies in the ocean: strips of oceanic magnetic anomalies, large igneous province beneath the sea-level and some parts of the continent that extend into the sea. In this paper, the characteristics of magnetic anomalies in the continents are analyzed, and the magnetic anomalies can be divided into two types: the orogenic magnetic anomalies and the craton magnetic anomalies.Magnetic anomalies' intensities are relatively strong and wavelengths are longer in Archean cratons, whereas anomalies wavelengths in orogenic belts are shorter. The orogenic belts and craton magnetic anomalies are significantly different, and they can be used to divide tectonic units.This thesis has reconstructed the 1590 Ma Nuna super-continent, the 900 Ma Rodinia super-continent, the 230Ma Pangea supercontinent and Gondwana supercontinent that is the part in Pangea period. Next, the structures of the supercontinent are carried by the corresponding modern geomagnetic information, which is reflected by the magnetic anomalies of the geomagnetic field. It can be seen that the connection in continental cratons' magnetic anomalies reflects the ancient crystalline basement in the supercontinent period are linked together, and magnetic anomalies of connectivity between orogenic belt reflects the same period of orogenic time. This thesis focuses on the magnetic anomaly characteristics of Laurentia, Greenland, Baltica and Siberia,The connection between these cratons during the period of 1590Ma was reconstructed by magnetic anomalies image, which was relatively well connected, indicating that the Nuna core model was reasonable.