| This paper studies the distribution, geological conditions, water chemicalcharacteristics, and the formation mechanism of hot spings in western Sichuan Basinby collecting geothermal exploration and oil drilling data.(1) Thermal storage structure in the study area is divided into two categories:Layered reservoir and Layered and Ribbon compound reservoir. Layered heatreservoir aquifers are in the formation of T2l-T1j、P1m-P1q、Zbdn, while Layered andRibbon compound reservoir aquifers are in the formation of J3l、J3p-K1t. In thewestern regions, thermal water occurs mainly in the formation of J3l、J3p-K1t、T2l-T1j,besides, themal water occurs mainly in the formation of T2l-T1j、P1m-P1q、Zbdn in thesouthwest areas.(2) In the western regions, the hydrochemical types mainly include type Cl-Na、type Cl SO4-Na、type SO4Cl-Na Ca and type SO4-Na and type HCO3-Na. The degreeof mineralization is0.98~15.37g/L. While in the southwest areas the hydrochemicaltypes mainly include type Cl-Na、 type SO4Cl-Ca Na and the The degree ofmineralization is0.43～17.16g/L.With the help of Na-K-Mg Triangular diagram, thecalculation shows that the west and southwest area’s hot water hasn’t reachedequilibrium state. With the application of PHREEQC software, the saturation indexof various kinds of minerals in hot water is calculated. We can analysis thegeochemistry process of the hot water of constant and trace chemical componentswith the correlation between binding components.(3) According to geological conditions and the characteristics of the buried, thehot spring genetic models.can be divided into2types:.Edge fold low temperaturegeothermal convection type and central depression basin low temperature geothermalconvection type. The former are mainly distributed in the basin mountain belt, themargin of the basin edge fold zone. The distribution features of these hot springobviously controlled by tectonic conditions. The latter are located in the inner area ofrelatively far away from the basin edge, mainly distributed in the chengdu plain, upperCenozoic sedimentary. Two types are divided into four subtypes: 1）The low temperature springs in clastic rock of the central depression basin aremainly in Chengdu plain region, general occurrence of low temperature hot water, thistype of hot spring is controlled by fracture obviously.The recharge of this water is partform fault in infiltration and part from bedding migration. The water migrate alongthe cracks and debris to the deep, and gradually heat in the process of migration. Atlast, the water excretie in the form of a deep hole.2）The low temperature springs in clastic rock of the basin-mountain belt zonemainly accept mountainous atmospheric precipitation infiltration recharge.Groundwater migrate to the basin through the layer or tectonic fissures, and mixedwith the upwelling of the deep underground hot water in piedmont fault zone, finallyform confined aquifer.3）The low temperature springs in carbonate rock of the edge subsidence zonemainly accept carbonate rock area atmospheric precipitation infiltration recharge.Groundwater along the fissures, dissolve gap, the ancient karst passage transport tothe deep stratas. These water in the full absorption of heat, after water-rock reactionwith surrounding rock, under the pressure of the heat supply reservoir, form karstconfined water in low temperature.4）The low temperature springs in carbonate rock of the Semi-closed structureaccept atmospheric precipitation infiltration and the surface water recharge. The wateralong the fracture gap and karst channel transport to deep earth. Under thebackground of high geothermal heating,the water is above90℃, leached withsurrounding rock, ion exchange, and so on. Meanwhile the water has mixedsedimentary water features. Hot groundwater in the basin inside is conceaedexcretioned.(4) Through the analysis of the Sichuan basin, the influence factors of theformation and distribution of hot springs include geologic structure,sedimentary facies,geothermal field. The favorable for hot water resources of the western areas aremainly in Anxian, Dujiangyan, WenJiang, and of southwest areas are in Emei, Jianwei,Yibin, Leshan, etc. |
PDF Full Text Request