36Cl Age Study for Deep Geothermal Water of Guanzhong Basin

Abstract

There are abundant geothermal water resources in the deep of Guanzhong Basin, whose origin and renewable ability has been the focus of academic circles .Previous research results of the environmental isotope hydrogeochemistry showed that there was small amount residual sedimentary water formed in the geological time in the deep geothermal water of study area, which was directly related to the sustainable development and utilization of geothermal resources. So this paper uses 36 Cl to study the age of deep groundwater. The results of 36 C l age show that the biggest age of deep groundwater of Guanzhong Basin is 988.69~1123.98ka. Geothermal water with different tectonic units, different closed condition and different genetic types has different 36 Cl age. The study area is located in the central region of the Guanzhong Basin, an area of about 6000 Km 2 , Northern study area is bounded by 10 km north of Weihe fault, south to Qinling piedmont fault, West bounded by the Yabai - Qishan fault and the East bounded is Chang'an - Lintong fault, It's mainly involves X ianli step-fault (Xianyang-liquan step-fault ), Xi'an Sag and Gushi Sag three structural fault block. Geothermal wells in the study area mainly mined thermal reservoirs is Cenozoic Quaternary and Neogene strata, Respectively sanmen Formation of the lower Pleistocene of Quaternary(Qp 1 s),Zhangjiapo Formation of Neocene(N2z),Lantian-Bahe Formation of Neocene(N2l+bh),Gaoling Formation of the Miocene Neocene(N1gl). Among which, Lantian-Bahe Formation is the best of the reservoir condition and is also the main reservoir layer of devolpment and utilization currently, but also the main layer and fundamental purpose of this study.