| 鲁西北平原地热热源机制的气体同位素约束 |
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| 关键词:mechanism of heat sources gas isotope dissolved gas components northwest Shandong Plain |
| 基金项目:国家自然科学基金项目(编号: U1906209; 42072331) |
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| 摘要: |
| Gas Isotope Constraints on the Geothermal Heat Source Mechanism in Northwest Shandong Plain |
| Gas composition, abundance, and isotopic compositions of geothermal systems can not only help identify the source of geothermal fluids but also trace the formation mechanism of heat sources. The geothermal resources in northwest Shandong Plain have been exploited and utilized on a large scale since 1998, but the formation mechanism of their heat sources is unclear. In this study, the characteristics of dissolved gas components and isotopes were used to explore the heat source generation conditions in northern Shandong Plain. The results of dissolved gas composition showed that the geothermal gas is mainly composed of N2, which results from atmospheric precipitation infiltration. It circulates deeply in a relatively closed geological environment, mixing with a certain amount of gas from the deep crust or mantle. The crust-mantle heat source distribution ratio in the study area was calculated to be 0.90–1.57 based on the 3He/4He ratio. The crust heat flow accounts for a high proportion, and the heat source is mainly radioactive heat generated by crust rocks. Among them, the sandstone geothermal reservoir is less affected by tectonic activities, and mantle heat flow accounts for approximately 45%. The karst geothermal reservoir is obviously controlled by structures: the mantle heat flow located near the deep fault or the contact zone between Jinan intrusive rock mass and limestone accounts for a relatively large proportion, up to 48.77%–52.75%, indicating that convective heat flow accumulation occurs from the upper mantle along the deep fault or the contact zone between rock mass and limestone, in addition to heat generation from normal terrestrial heat flow conduction. The mantle heat flow in the stable block between the Qiguang deep fault and the Jinan intrusive rock mass is relatively small, accounting for only 38.87%–40.97%, indicating that the deep heat flow in the relatively stable tectonic area is less. |
| CUI Yang,KANG Feng-xin,ZHONG Zhen-nan,YANG Xun-chang,SUI Hai-bo,ZHAO Qiang.2023.Gas Isotope Constraints on the Geothermal Heat Source Mechanism in Northwest Shandong Plain[J].Acta Geoscientica Sinica,44(1):93-106. |
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