Guangdong Province in Southeast China is noted for its numerous geothermal resources due to tectonic episodes,mainly occurred during the Cretaceous.The surface heat flow and geothermal gradient are the most direct way...Guangdong Province in Southeast China is noted for its numerous geothermal resources due to tectonic episodes,mainly occurred during the Cretaceous.The surface heat flow and geothermal gradient are the most direct ways to understand the temperature of the Earth.However,geothermal resources are poorly utilized in Guangdong Province due to limited numbers of boreholes and surficial hydrothermal fluids.To improve the understanding of underground temperature distribution in Guangdong Province,we have applied power-density spectral analysis to aeromagnetic anomaly data to calculate the depth of the Curie isothermal surface.Upward continuation is applied and tested to the magnetic data.The calculated Curie isotherm is between 18.5 km and 25 km below surface.The fluctuation in the depth range reflects lateral thermal perturbations in the Guangdong crust.In particular,the eastern,northern,western and coastline areas of the province have a relatively shallow Curie isotherm.By comparing the surface heat flow,geothermal gradient,distribution of Mesozoic granite-volcanic rocks,and natural hot springs,we conclude that during Mesozoic,magmatism exerted great influence on the deep thermal state of Guangdong Province.A shallow Curie isotherm surface,as well as numerous natural hot springs and high heat flow,show clear signatures of shallow heat sources.展开更多
Using the aeromagnetic data and the method of 3-D magnetic stratum inversion, the data of aeromagnetic anomalies in the investigated region have been processed; and thereby the quantitative buried depth of the Curie i...Using the aeromagnetic data and the method of 3-D magnetic stratum inversion, the data of aeromagnetic anomalies in the investigated region have been processed; and thereby the quantitative buried depth of the Curie isothermal surface in Sichuan Basin and its western marginal area has been obtained. The reliability of the inversion results has been confirmed by the features of regional tectonics, the distribution of geothermal gradient and the results of deep seismic sounding. By analyzing the deep geothermal field, it is concluded that the followings are the environmental conditions for the development and occurrence of earthquakes in the western marginal area of Sichuan Basin: (1) The collision of the Yangtze block with the Sichuan Qinghai block and Kangdian rhombic block has produced strong stress accumulation; and (2) Plastic creep in the middle lower crust owing to the upwelling of mantle flux has provided an adjusting unit for rock rupture and stress release.展开更多
基金This research was supported by grant from the National Natural Science Foundation of China:Study of radioactive heat in the mantle with Geoneutrino(No.41874100).
文摘Guangdong Province in Southeast China is noted for its numerous geothermal resources due to tectonic episodes,mainly occurred during the Cretaceous.The surface heat flow and geothermal gradient are the most direct ways to understand the temperature of the Earth.However,geothermal resources are poorly utilized in Guangdong Province due to limited numbers of boreholes and surficial hydrothermal fluids.To improve the understanding of underground temperature distribution in Guangdong Province,we have applied power-density spectral analysis to aeromagnetic anomaly data to calculate the depth of the Curie isothermal surface.Upward continuation is applied and tested to the magnetic data.The calculated Curie isotherm is between 18.5 km and 25 km below surface.The fluctuation in the depth range reflects lateral thermal perturbations in the Guangdong crust.In particular,the eastern,northern,western and coastline areas of the province have a relatively shallow Curie isotherm.By comparing the surface heat flow,geothermal gradient,distribution of Mesozoic granite-volcanic rocks,and natural hot springs,we conclude that during Mesozoic,magmatism exerted great influence on the deep thermal state of Guangdong Province.A shallow Curie isotherm surface,as well as numerous natural hot springs and high heat flow,show clear signatures of shallow heat sources.
文摘Using the aeromagnetic data and the method of 3-D magnetic stratum inversion, the data of aeromagnetic anomalies in the investigated region have been processed; and thereby the quantitative buried depth of the Curie isothermal surface in Sichuan Basin and its western marginal area has been obtained. The reliability of the inversion results has been confirmed by the features of regional tectonics, the distribution of geothermal gradient and the results of deep seismic sounding. By analyzing the deep geothermal field, it is concluded that the followings are the environmental conditions for the development and occurrence of earthquakes in the western marginal area of Sichuan Basin: (1) The collision of the Yangtze block with the Sichuan Qinghai block and Kangdian rhombic block has produced strong stress accumulation; and (2) Plastic creep in the middle lower crust owing to the upwelling of mantle flux has provided an adjusting unit for rock rupture and stress release.
