Distribution characteristics and genetic analysis of geothermal water-soluble helium in the Linyi section of the Tanlu fault zone
Objectives:The overwhelming majority of helium reserves are found in oil and gas deposits,with limited research conducted on water-soluble helium in geothermal wells and hot spring wells.As a giant strike-slip fault,the Tancheng—Lujjiang Fault Zone is distributed in multiple geothermal wells and hot springs containing helium.Consequently,it is particularly important to identify the source of helium gas in geothermal water.Methods:In this article,the helium content and distribution characteristics of associated gas in geothermal Wells and hot springs groundwater in Linyi section of Tanlu fault zone are analyzed based on the helium sample analysis results,and the helium source in geothermal water is discussed.Results:The results show that 8 obvious high-value points of helium content were found for the first time in the geothermal water of the Linyi section of the TanLu fault zone.With 15×10-6 as the background value of helium content,the high value points were obviously 11.1 to 1360.0 times higher than the background value,which mainly distributed within and on both sides of the TanLu fault zone;Helium isotopes show that helium gas mainly comes from the crust,a small amount comes from the mantle.The highest helium content in the mantle source is 10.75％.This not only provides evidence for the Tanlu fault zone reaching deep into the mantle,but also provides the source of geothermal water is not directly from the mantle but from deep circulation geothermal heating or radioactive heating.Conclusions:The decay of radioactive elements such as U and Th in the deep crust and basement rock masses in the Tanlu Fault Zone generated a large amount of gas,which was to the surface along with tropical gases.During the migration process,some helium gas was also generated,resulting in the enrichment of helium and geothermal resources.
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