Research On The Characteristics And Causes Of Longling Hot Springs In Yunnan

Longling hot spring hydrothermal activity is located in the famous Yunnan Tibet tropical zone,which is ric h in geothermal resources.In order to better understand the distribution and genetic mechanism of Longling hot springs,this paper takes 40 hot springs(groups)in Longling County,Yunnan Province as the research object,studies the spatial distribution,hydrogeochemical characteristics and structural heat control mechanism of hot springs,and establishes the genetic model of Longling hot springs.In order to provide a theoretical basis for the development and utilization of local geothermal resources.the following understandings are obtained through this study:(1)Longling hot spring is dominated by medium temperature-medium high temperature hot springs with temperature ranging from 25 to81?.Only Banglazhang hot spring is high temperature hot spring w ith water temperature up to 98?.The salinity of the water sample is105?927mg/L,which is light mineral water.The hydrochemical types of Longling hot spring are mainly HCO ₃-Na type and HCO₃-Ca/Mg type,and a few are HCO₃·SO₄-Na type.The hydrochemical t ypes of hot springs in different hydrothermal activity areas are different.The hot springs in Banglazhang Huangcaoba hydrothermal activity area and Chaoyang pingda hydrothermal activity area are HCO ₃-Na type,with high temperature,p H and TDS content.The hot springs in Nujiang fault hydrothermal activity area are HCO₃-Ca/Mg type,with relatively low temperature,p H and TDS.The recharge source of geothermal water in the study area is atmospheric precipitation,and the elevation of the recharge are a is estimated to be about1493?2470m;the Si O₂ geothermal temperature s cale method is used to estimate the heat storage temperature of th e study area to be about72.0?202.8?.(2)The distribution of Longling hot springs is strictly controlled by the distribution direction of faults,and the spatial distribution of hot springs is characterized by zonal aggregation and uneven distribution.Hot springs are densely distributed along Nujiang fault and Longling Ruili fault in linear or beaded shape.The hydrothermal acti vities in the area can be divided into Nujiang North trending structural hydrothermal activity zone and Longling Ruili arc-shaped structural hydrothermal activity zone.The latter includes Banglazhang Huangcaoba hydrothermal activity zone and Chaoyang pingda hydrothermal activity zone.Through the interpretation of remote sensing structure,the heat and water conducting structure in the area is clarified.The nearly N S and NE trending faults are the heat conduction faults,which control the overall structur e of the hydrothermal activity area;the nearly EW or NW trending faults are the water conduction faults.The relationship between Characteristics of hot springs and fault structures is discussed by using Kriging spatial interpolation and buffer analysis.It is found that most of the hot springs are exposed in the range of 300?800m on both sides of the fault,and high temperature hot springs are distributed in the composite part of the fault intersection.(3)The formation model of hot springs in the study area can be summarized as follows:the groundwater is recharged by the infiltration of meteoric water in the mountain area,and the groundwater flows to the basins.After deep circulation,the hot springs are heated by the heat flow from the deep,and rise along the fracture of the fault zone or intrusive body and gush out of the surface to form a hot spring,which is a fault deep circulation geothermal system.