Terrestrial Heat Flow and Lithospheric Thermal Structure Characteristics in Nanping City of Hainan
The Nanping geothermal field in Hainan is situated within the Wuzhi Mountain fold belt of the South China fold system based on its geotectonic units. Although there is abundant surface heat detected and widespread distribution of Late Mesozoic granite in the area, the geological background of geothe...
Saved in:
| Main Authors: | , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2024-09-01
|
| Series: | Energies |
| Subjects: | |
| Online Access: | https://www.mdpi.com/1996-1073/17/19/4824 |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| _version_ | 1850283601285873664 |
|---|---|
| author | Xiaoxue Yan Xiaolin Wang Guicheng Xue Ruoxi Yuan Feng Yang |
| author_facet | Xiaoxue Yan Xiaolin Wang Guicheng Xue Ruoxi Yuan Feng Yang |
| author_sort | Xiaoxue Yan |
| collection | DOAJ |
| description | The Nanping geothermal field in Hainan is situated within the Wuzhi Mountain fold belt of the South China fold system based on its geotectonic units. Although there is abundant surface heat detected and widespread distribution of Late Mesozoic granite in the area, the geological background of geothermal resources remains unclear. In this article, we collected core samples from boreholes within the Nanping geothermal field to conduct testing and analysis on rock thermal conductivity and heat-production rate. By combining these results with temperature logging data, we discuss a method for diterming the heat flow background of convective geothermal system. Furthermore, the study analyzed the geothermal flux and deep thermal structure of the research area. The results demonstrate that the average radioactive heat production rate of the Baocheng rock mass in the study area is 3.16 μW/m³, primarily attributed to the decay heat of Th and U, while the heat contribution of K is negligible. The thermal conductivity values of the rocks are relatively high, ranging from 2.29 to 3.75 W/(mK), slightly exceeding the average thermal conductivity of the upper crust. The study area represents a typical convective geothermal field influenced by groundwater convection, exhibiting a high geothermal temperature gradient. Using the groundwater-correction method, the geothermal flux in the study area is calculated to be 89–108.27 mW/m², of which the thermal conduction component is 73.17 mW/m² and the convective component is 15.83–35.1 mW/m². Among these components, heat generated from radioactive decay of crustal radioactive elements contributes 35.44 mW/m² to thermal conduction, while deep mantle conduction accounts for a heat flux is 37.73 mW/m², with a ratio of 1:1.07 between them. The difference between crustal and mantle heat fluxes is minimal in this region, indicating an approximation towards a “crust-mantle heat source balance zone”. Furthermore, the thickness of the “hot” lithosphere in the study area ranges from 42 to 46 km, indicating significant characteristics of extension-thinning. |
| format | Article |
| id | doaj-art-a07d2ab80a9f4047b25bfd67e9a24e84 |
| institution | OA Journals |
| issn | 1996-1073 |
| language | English |
| publishDate | 2024-09-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Energies |
| spelling | doaj-art-a07d2ab80a9f4047b25bfd67e9a24e842025-08-20T01:47:45ZengMDPI AGEnergies1996-10732024-09-011719482410.3390/en17194824Terrestrial Heat Flow and Lithospheric Thermal Structure Characteristics in Nanping City of HainanXiaoxue Yan0Xiaolin Wang1Guicheng Xue2Ruoxi Yuan3Feng Yang4Hainan Key Laboratory of Marine Geological Resources and Environment, Haikou 570206, ChinaHainan Key Laboratory of Marine Geological Resources and Environment, Haikou 570206, ChinaHainan Key Laboratory of Marine Geological Resources and Environment, Haikou 570206, ChinaInstitute of Hydrogeology and Environmental Geology, Chinese Academy of Geological Sciences, Shijiazhuang 050061, ChinaHainan Key Laboratory of Marine Geological Resources and Environment, Haikou 570206, ChinaThe Nanping geothermal field in Hainan is situated within the Wuzhi Mountain fold belt of the South China fold system based on its geotectonic units. Although there is abundant surface heat detected and widespread distribution of Late Mesozoic granite in the area, the geological background of geothermal resources remains unclear. In this article, we collected core samples from boreholes within the Nanping geothermal field to conduct testing and analysis on rock thermal conductivity and heat-production rate. By combining these results with temperature logging data, we discuss a method for diterming the heat flow background of convective geothermal system. Furthermore, the study analyzed the geothermal flux and deep thermal structure of the research area. The results demonstrate that the average radioactive heat production rate of the Baocheng rock mass in the study area is 3.16 μW/m³, primarily attributed to the decay heat of Th and U, while the heat contribution of K is negligible. The thermal conductivity values of the rocks are relatively high, ranging from 2.29 to 3.75 W/(mK), slightly exceeding the average thermal conductivity of the upper crust. The study area represents a typical convective geothermal field influenced by groundwater convection, exhibiting a high geothermal temperature gradient. Using the groundwater-correction method, the geothermal flux in the study area is calculated to be 89–108.27 mW/m², of which the thermal conduction component is 73.17 mW/m² and the convective component is 15.83–35.1 mW/m². Among these components, heat generated from radioactive decay of crustal radioactive elements contributes 35.44 mW/m² to thermal conduction, while deep mantle conduction accounts for a heat flux is 37.73 mW/m², with a ratio of 1:1.07 between them. The difference between crustal and mantle heat fluxes is minimal in this region, indicating an approximation towards a “crust-mantle heat source balance zone”. Furthermore, the thickness of the “hot” lithosphere in the study area ranges from 42 to 46 km, indicating significant characteristics of extension-thinning.https://www.mdpi.com/1996-1073/17/19/4824heat flowlithospheric thermal structureconvective geothermal systemthermal conductivity |
| spellingShingle | Xiaoxue Yan Xiaolin Wang Guicheng Xue Ruoxi Yuan Feng Yang Terrestrial Heat Flow and Lithospheric Thermal Structure Characteristics in Nanping City of Hainan Energies heat flow lithospheric thermal structure convective geothermal system thermal conductivity |
| title | Terrestrial Heat Flow and Lithospheric Thermal Structure Characteristics in Nanping City of Hainan |
| title_full | Terrestrial Heat Flow and Lithospheric Thermal Structure Characteristics in Nanping City of Hainan |
| title_fullStr | Terrestrial Heat Flow and Lithospheric Thermal Structure Characteristics in Nanping City of Hainan |
| title_full_unstemmed | Terrestrial Heat Flow and Lithospheric Thermal Structure Characteristics in Nanping City of Hainan |
| title_short | Terrestrial Heat Flow and Lithospheric Thermal Structure Characteristics in Nanping City of Hainan |
| title_sort | terrestrial heat flow and lithospheric thermal structure characteristics in nanping city of hainan |
| topic | heat flow lithospheric thermal structure convective geothermal system thermal conductivity |
| url | https://www.mdpi.com/1996-1073/17/19/4824 |
| work_keys_str_mv | AT xiaoxueyan terrestrialheatflowandlithosphericthermalstructurecharacteristicsinnanpingcityofhainan AT xiaolinwang terrestrialheatflowandlithosphericthermalstructurecharacteristicsinnanpingcityofhainan AT guichengxue terrestrialheatflowandlithosphericthermalstructurecharacteristicsinnanpingcityofhainan AT ruoxiyuan terrestrialheatflowandlithosphericthermalstructurecharacteristicsinnanpingcityofhainan AT fengyang terrestrialheatflowandlithosphericthermalstructurecharacteristicsinnanpingcityofhainan |