Distribution And Interpretation Of The Heat Flow In The Arctic Ocean

Seafloor heat flow is an important way to understand the thermal conditions of the oceanic crust and lithospheric mantle.It is of great significance for the study of heat transfer within the Earth,lithospheric evolution,continental margin formation,plate subduction process and hot spot magmatism.The Arctic Ocean now has high-resolution geophysical maps such as seabed topography,gravity anomalies,and magnetic anomalies for use by polar scientists.So far,there is no map for heat flow.Based on the processing of thermal flow data from previous Arctic scientific expeditions in China,this paper collects the latest T-3 heat flow data from the U.S.Geological Survey in 2019,the heat flow data in the world heat flow database and other data published in papers or reports,and uses a total of 601 heat flow data to produce a heat flow contour map of 50kmx50km in the Arctic Ocean.In this paper,the minimum standard deviation method is designed to deal with the heat flow data of the China's ninth scientific Arctic expedition,which can solve the problem that the geothermal gradient of Ewing-type heat flow meter cannot match the thermal conductivity of the deck accurately.Ewing-type heat flow meters are widely used for heat flow measurements in harsh environments because of their safety and convenience.When using a Ewing-type heat flow meter,the geothermal gradient of seafloor sediments is obtained by in situ measurements while the thermal conductivity of sediment samples is measured in the laboratory.Due to the stake effection,the insertion depth of the sampler in situ is not always consistent with the length of a recovered sample,so it can be difficult to accurately match the measurement positions for thermal conductivity and geothermal gradients,leading to errors up to 3.5 mW·m-2.Based on the principle that heat flow values of the same station at different depths are relatively consistent,a minimum standard deviation method was designed in this study to determine the optimal deviation of Ewing heat flow meter operations.According to an analysis of data collected from 12 stations during China's ninth scientific Arctic expedition,the standard deviation of heat flow values at each depth of the same station decreased from 8.4 mW·m-2 to 3.8 mW·M-2 after the minimum standard deviation method was applied,which is a variation amplitude of about 9%of the average heat flow value.In this paper,theoretical heat flow values are calculated based on the half-space model and crustal age,and combined with the measured data.A 50km×50km heat flow isoline map of the Arctic Ocean was drawn using Kriging meshing method.The rationality of the gridding method was further evaluated through cross-validation,and the reliability of the original data was analyzed based on the distribution of seabed sediments.The analysis of the heat flow data shows that the average value of the heat flow in the Arctic Ocean is 56.1 mW·m-2.There are mainly two areas of high heat flow in the Chukchi Borderland and Lomonosov Ridge,and the average heat flow is 65.6 mW·m-2 and 63.9 mW·m-2,which may be related to higher heat production in the crust.