| 陕西关中盆地地热资源及壳幔温度结构的地球物理分析 |
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| 引用本文： | 张 健,董 淼,王蓓羽,艾依飞,方 桂.陕西关中盆地地热资源及壳幔温度结构的地球物理分析[J].延边大学理工学报,2021,0(1):150-163. |
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| 作者姓名： | 张 健 董 淼 王蓓羽 艾依飞 方 桂 |
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| 作者单位： | (中国科学院大学 中国科学院计算地球动力学重点实验室,北京 100049) |
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| 摘 要： | 陕西关中盆地地下热水资源丰富,是中国典型的隐伏型中、低温地热资源分布区。为研究关中盆地中、低温地热系统形成机理,认识深部热源条件,利用地球物理方法分析了该区壳幔温度结构。结果表明:计算得到的居里面平均深度为25.0 km,莫霍面平均深度为36.6 km,地壳平均地温梯度为22.60 ℃·km-1,咸礼断阶、西安凹陷、固市凹陷地壳地温梯度高于平均值,是地热地质条件较好的构造分区。咸阳、西安之下,上地幔存在向南下倾的高温带,咸阳北侧约175 km深度是一个温度大于1 500 ℃的高温区; 其上,莫霍面、居里面上隆,形成高温基底,加热沉积地层中的地下水。富平、渭南之间,上地幔存在“下沉”低温区,低温区北、南两侧约175 km深度分别对应温度大于1 450 ℃的高温区; 高温区之上,莫霍面、居里面上隆,形成聚热中心,为地表地热资源提供稳定热源条件。总体上,关中盆地新生代潜水受莫霍面、居里面上隆带入的地幔热量传导加热,热物质随莫霍面、居里面向上抬升,是盆地中、低温地热田的深部热源。上地幔流变边界层控制研究区重要的构造活动,此边界层受周缘构造带不同动力作用,在重力均衡调整过程中,导致深大断裂活动,进而引起地壳深、浅部水体沿断裂带热对流,形成带状分布热泉。
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| 关 键 词： | 地热资源 地球物理分析 莫霍面 居里面 地壳温度 地震剪切波 流变边界层 上地幔热结构 关中盆地 |
Geophysical Analysis of Geothermal Resources and Temperature Structure of Crust and Upper Mantle Beneath Guanzhong Basin of Shaanxi,China |
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| ZHANG Jian,DONG Miao,WANG Bei-yu,AI Yi-fei,FANG Gui.Geophysical Analysis of Geothermal Resources and Temperature Structure of Crust and Upper Mantle Beneath Guanzhong Basin of Shaanxi,China[J].Journal of Yanbian University (Natural Science),2021,0(1):150-163. |
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| Authors: | ZHANG Jian DONG Miao WANG Bei-yu AI Yi-fei FANG Gui |
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| Affiliation: | (Key Laboratory of Computational Geodynamics of Chinese Academy of Sciences, University of Chinese Academy of Sciences, Beijing 100049, China) |
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| Abstract: | Guanzhong Basin in Shaanxi is a typical area with concealed medium-low temperature geothermal resources in China, and has abundant underground hot water resources. In order to study the formation mechanism and heat source conditions of the medium-low temperature geothermal system of Guanzhong Basin, the temperature structure of crust and upper mantle was analyzed by the geophysical method. The results show that the average depths of Moho and Curie surfaces in Guanzhong Basin are 36.6 km and 25.0 km respectively, and the crustal average geothermal gradient is 22.60 ℃·km-1. The crustal temperature is higher than the average value in Xianli fault terrace, Xi’an sag and Gushi sag, which are the tectonic area with better geothermal geological conditions. Underground in Xianyang and Xi’an, there is a southward inclined geotropics in the upper mantle, and there is a hidden high-temperature zone above 1 500 ℃ in the depth of 175 km to the northern side of Xianyang. Above the high-temperature zone, Moho and Curie surfaces uplift with high geothermal gradient, forming a high-temperature basement, heating the groundwater in the sedimentary strata. Between Fuping and Weinan, there is a “sinking” low-temperature zone in the upper mantle, and there are high-temperature areas greater than 1 450 ℃ at the depth of about 175 km corresponds to the southern and northern sides of the “sinking” low-temperature zone. Above the high-temperature areas, Moho and Curie surfaces also uplift to form a heat accumulation center, providing stable heat source conditions for surface geothermal resources. Generally, the Cenozoic phreatic water in Guanzhong Basin is heated by mantle heat conduction brought by upper uplift of Curie and Moho surfaces, and the thermal material uplifts with Moho and Curie surfaces, which provides stable deep heat source for the basin’s medium-low temperature geothermal fields. The rheological boundary layer of the upper mantle plays an important role in tectonic activities in the research area. The rheological boundary layer is affected by different dynamic forces of the surrounding tectonic belt,which would lead the activity of deep large faults in process of gravity equilibrium adjustment, and then cause the thermal convection of deep and shallow water bodies in the crust along the fault zone, forming a zonal distribution hot spring. |
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| Keywords: | Key words: geothermal resource geophysical analysis Moho surface Curie surface crustal temperature seismic shear wave rheological boundary layer thermal structure of upper mantle Guanzhong Basin |
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