| Limited by the natural conditions of the Arctic,various geological surveys and studies are very low,and its tectonic evolution is one of the most controversial regions on earth.Compared with Eurasian Basin which has a well-constrained tectonic evolution history,the various evolution models of the Amerasia Basin are based on speculation.The crustal thickness is one of the very important parameters to understand the regional evolution process.The data can be used to analyze the regional magmatic process and tectonic process to a certain extent,which is of great significance for understanding the structural evolution of the Amerasia Basin and reconstructing the pattern of the ancient Arctic continent.This paper mainly uses the method of the gravity-derived crustal thickness to calculate the crustal thickness of the Amerasia Basin.,analyzes the differences between the crustal thicknesses between the crustal thicknesses in different regions,and discusses the origin of the basin.This paper systematically collected and collated the latest free-air gravity anomaly(FAA)data,bathymetry data,sediment data,age data,etc.of the Amerasia Basin and using the Parker-Oldenburg method and the improved FA2BOUG method respectively calculate the stone slab correction,terrain correction,and gravity effect correction at the crust-mantle density interface assuming uniform crust thickness in order to obtain the Mantle Bouguer gravity anomaly(MBA)in the study area,and then the same thermal correction was performed to obtain the Residual Mantle Bouguer gravity anomaly(RMBA)).Based on different crustal densities,14 different crustal thickness models were established,and the crustal thickness data obtained from the seismic sections available in the study area were used to constrain the best crustal thickness model in the region.According to the different structural units,this article divides the Amerasia Basin into the Canada Basin,the Podwodnikov and Makarov Basins,the Alpha-Mendeleev Ridge,and the Chukchi Borderland.According to the model results,we can see that:(1)The average crustal thickness of the Canada Basin is 11.37km,which is thin in the north and thin in the west,and thick in the west and east;(2)The average crustal thickness of the Podwodnikov Basin is 13.38km,The overall crustal thickness is thin in the south and thick in the north;(3)The average crustal thickness of the Makarov Basin is 12.32km,and the crustal thickness is gradually increasing from west to east;(4)The change of the crustal thickness of the Alpha-Mendeleev ridge is gentle,with an average crustal thickness value of 21.26km;(5)The crustal thickness of the Chukchi Borderland is closely related to the topography of the internal tectonic unit,and the average crustal thickness value is 25.77km.Combined with relevant data and model results,the following speculations have been obtained:(1)The crustal thickness in the northern part of the Canada Basin is likely to be affected by rifting associated with the High Arctic Large Igneous Province(HALIP);the southern crustal thickness and the slow expansion rate,expansion center,and structure The activity is related to the inversion of the crustal thickness due to factors such as the huge sediments in the Canada Basin.(2)The difference in crustal thickness between the Podvodnikov Basin and the Makarov Basin may be related to the difference in crustal structure.(3)The origin of the Alpha-Mendeleev ridge is closely related to the Arctic Large Igneous Province(HALIP),and may be affected by intraplate volcanic activity and bottom invasion.(4)The crustal thickness of the Chukchi Borderland may be related to the continental crustal extension of the Paleozoic,of which the Northwind Plain may be related to east-west extension,and the Northwind Ridge marginal crustal thickness is related to the collision during the expansion of the Canada basin. |
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