The Geochemical Character Of Geothermal Liquid In Tianjin Area

Tianjin is located in Northeast of the North China Plain,120km from Beijing.East of Bohai, north of Yanshan, across an area of11919km2. Geomorphologicalfeatures from Jixian northern mountains, piedmont, elevation stepped down to thesouthern plains region formed from north to south, from west to east in the form. Thehighest elevation of the Jixian Kowloon peak of1085.5m, the lowest Tanggu DistrictDagu-2m; altitude of less than5m in the area accounts for about80%of the city.Tianjin is in the North China Plain partition of the Shandong and Henan and Hebeistratigraphic region of the North China stratigraphic superregion. From Archean toCenozoic Quaternary, besides lack of Neoproterozoic Nanhuan System, Sinian system,the Paleozoic Ordovician, Silurian, Devonian, Lower Carboniferous, Mesozoic, andthe three Permian, upper Jurassic, upper Cretaceous and Paleogene Paleocene, otherstrata basically complete.In tectonic, Tianjin area is a part of first-order tectonic units: the North Chinaparaplatform. With the regional deep fault of Ninghe-Baodi fault as the boundary,dividing the Tianjin tectonic unit for two second grade tectonic units: Yanshan foldbelt (North) and the North China fault depression (South). To the north of exposedbedrock shallow,lithology in the Neoproterozoic the Great Wall system, Jixian systemand Qingbaikou system mainly in the northwest side of the Jixian piedmont fault withgranite intrusion; southern NNE fracture development, among which the Cangdongfault and Tianjin fault after the large scale faults in the Ninghe-Baodi fault. Therealso was a NNE alternately in Huabei fault depression substructural units of uplift anddepression, the bedrock strata were covered with Cenozoic strata in different ages, thesedimentary thickness by Cangxian uplift to the both side of the depressions areagradually thickening.From1936the French at first geothermal wells drilled so far, the city has morethan470geothermal wells eyes, the deepest drilled4041m and the highest outlettemperature of102℃.t top-down exploitation of the Neogene and MinghuazhenGuantao and Paleogene Dongying group, Paleozoic Ordovician and Cambrian,Middle Proterozoic Jixian System Wumishan six geothermal reservoir. Through thestudy of these original data are found, from north to south, the change regulation ofhydrochemistry of each geothermal reservoir and groundwater flow direction isconsistent, but in the east-west direction, lithology, structure, fracture is the dominantfactor affecting hydrochemistry characteristics of geothermal fluid: Tianjin fault onthe west side of geothermal fluid mineralization degree is higher. Up to3~5g/L; theCangdong fault on the east side of the mineralization degree is low, around1.7g/L,between the chemical characteristics of geothermal fluid somewhere during highbulge parts of the two, has the obvious things to the horizontal zonation. In this paper,through the analysis of water quality and isotopic data, in-depth study of the lithology,structure, especially the Tianjin fault and the Cangdong fault influence on geothermalfluid hydrochemistry distribution, which will help Tianjin to better development andutilization of geothermal resources.