| 渭河盆地岩石圈热结构模拟及其对地热系统热源机理的启示 |
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| 关键词:deep temperature field lithospheric thermal structure heat source mechanism geothermal system Weihe Basin |
| 基金项目:国家自然科学基金项目(编号: 41877210; 41502236);中国石化深部地质与资源重点实验室开放基金(编号: 22-ZC0613-0241);油气资源与勘探技术教育部重点实验室青年创新团队项目(编号: PI2018-04) |
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| Simulation of Lithospheric Thermal Structure and Its Implications for Heat Source Mechanism of Geothermal System in Weihe Basin |
| The deep temperature field and lithospheric thermal structure characteristics are important for understanding the deep heat source mechanism of geothermal system. In this paper, on the base of a systematic analysis of the present terrestrial heat flow characteristics in Weihe basin and its adjacent areas, a numerical simulation study was carried out on the deep temperature field and lithospheric thermal structure of Weibei Uplift, Weihe Basin and North Qinling Tectonic Zone using a two-dimensional finite element method. The stratified structure of the crust was revealed by the wide angle reflection/refraction seismic bathymetry section along Xunyi–Xixia. Afterwards, the deep heat source mechanism of the geothermal system was analyzed. The results showed that the present terrestrial heat flow along the Xunyi–Xixia profile ranged from 57.6 to 75.7 mW/m2 with an average of (70.4±4.7) mW/m2, while the mantle heat flow ranged from 29.5 to 38.6 mW/m2, with an average of 34.1 mW/m2. Furthermore, the temperature on the Moho surface ranged from approximately 600 to 740 °C, while the thickness of the thermal lithosphere was approximately 95~110 km. From the Weibei Uplift, Weihe Basin to the Qinling orogenic belt, the present terrestrial heat flow, temperature on Moho surface and mantle heat flow values showed a low→high→low variation trend, while the corresponding thermal lithosphere thickness showed a thick→thin→thick variation trend. The crustal thickness of the Weihe basin thined significantly, and temperature on the Moho surface was significantly higher than that of Weibei Uplift and Qinling orogenic belt, which suggested significant crustal activity in Weihe Basin. However, from Weibei Uplift, Wehe basin to the Qinling orogenic belt, the thickness of thermal lithosphere did not vary much and the crust/mantle heat flow ratio within the Weihe Basin was close to 1.0, indicating that deep activity was not very strong. It was consistent with the passive rift on the deep temperature field and lithospheric thermal structure. On the far-field effect of the collision between the Indian plate and the Eurasian plate, the crust in Weihe area was extended and thinned, and the upper mantle was uplifted under the action of gravity equilibrium. The material with high temperature derived from mantle upwelled along the deep fault and heated the upper crust. Together with the crustal radioactive heat source, it provided heat source for the geothermal system. |
| LU Jia-fei,RAO Song,HUANG Shun-de,SHI Yi-zuo,HU Sheng-biao.2023.Simulation of Lithospheric Thermal Structure and Its Implications for Heat Source Mechanism of Geothermal System in Weihe Basin[J].Acta Geoscientica Sinica,44(1):33-44. |
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