An Analysis On Genetic Model And Development Prospects Of Jiyu Hot Spring In Maoxian County, Sichuan Province

There are as much as305hot springs with a water temperature greater than orequal to25℃in Sichuan Province. These springs approximately have a totalexothermic volume of5.53×1015J/a, ranking fourth in this country. Such well-knownhot springs as Niangchunchi, Emeishan and Luofushan have been successfully andsuccessively developed. With Jiyu hot spring in Maoxian County as the object of theresearch, this paper explores Jiyu hot spring’s genetic mechanism and tries to compareit with that of exposed springs in the edge of Longmen Mountain, so as to expound thegenetic model of geothermal water in Longmen Mountain fault zone. Meanwhile, acomprehensive analysis of Jiyu hot spring’s further development will be presented incombination with the current exploitation situation of Jiyu hot spring.Located in Shigu township’s Jiyu village, Maoxian county, Jiyu hot spring is rightin Jiyu gully, namely on the right bank of Minjiang river. As a hot spring exposed in thedolomite layers of Maowen fault’s upper Sinian Dengying Formation (Zbdn), this hotspring has an elevation of1640m, a water temperature of34.0℃and an approximateflow rate of1.0L/s. On the basis of extensive previous researches, this paper,combining geological methods with hydrogeological investigations, makes apreliminary study on Jiyu hot spring’s exposed features, water chemistry characteristics,water-rock interaction extent and formation mechanism of hot water from theperspective of geological structure, hydrogeological conditions and hydro geochemicalcharacteristics. Integrated geophysical methods are adopted to delineate geothermalanomalies in Jiyu gully, and on such basis the genetic model and developmentprospects of Jiyu hot spring are analyzed. Conclusions are as follows:(1) Analysis on water chemistry characteristics of Jiyu hot spring shows that in hotspring water Ca2+is dominant in cation and SO42－in anion and Ca2+and SO42－havean absolute advantage in content when compared with other components. The waterchemical type of Jiyu hot spring is SO4-Ca·Mg whereas the water chemistry type of#1effluent spot watery,cold spring water and creek water is SO4·HCO3-Ca·Mg, probablyresulting from the fact that#1effluent spot is mixed with cold water from near source. Na-K-Mg equilibrium diagram is used to judge the water-rock interaction levels ofJiyu hot spring. Hot spring water in Jiyu belongs to “immature water”, namely thewater-rock interaction is under no equilibrium state. Therefore, it’s much more accurateto utilize quartz temperature scale to estimate the geothermal reservoir temperaturescale. By calculation, the geothermal reservoir temperature of1#and2#in Jiyu hotspring is respectively100℃, and the circulation depth of hot water ranges from3000m.(2) Jiyu hot spring is uplift deep-circulating hot water in geothermal types. Itsgenetic model can be summarized as follows: under the background of slightly highergeothermal energy, rainfalls or snowmelt in high mountains seep into the ground alongfracture zones and deep fissures and also migrate and circulate under the ground alongfault zones and fissure structures. In the course of migration and circulation, rainfallsand snowmelt constantly absorb heat from surrounding rocks to form hot water andwater temperature can reach as much as100℃in the depth for3000m. During theprocess of geothermal reservoir, hot water migrates to the junction point of Maowenfault belt and Jiyu gully fault area, excretes in places with favorable topography andgeological structure, then crops out ground, thus forming Jiyu hot spring.(3) The mouth of Jiyu gully is under a large regional tectonic setting which takesMoutuo-Shilipu anticlinorium as basic skeleton and reflects huge impact of Maowenfault belt. It also has a small tectonic setting for geothermal water exploration. Thus, thedevelopment plan in this area can be shifted from Jiyu hot spring to the mouth of Jiyugully, and it’s necessary to make a further and deeper study on cap distribution,geothermal reservoir and structure features in this area.(4) The compared analysis on genetic model between Niangchunchi hot spring inLongmen Mountain and Jiyu hot spring draws the conclusion that the two hot springsshare such common features as same geothermal type—they’re both upliftdeep-circulating hot water; There exists no magmatic rock—a special heat resource—in both spring’s shallow parts; Under the background of normally high geothermalenergy, their supply sources both enter into deep circulation along fracture belt orfissure system, form hot water, then crap out the ground in suitable structure parts.