Characterization of Origin and Evolution of Formation Water in Buried Hill of Jizhong Depression, China, Using Multivariate Statistical Analysis of Geochemical Data

Abstract

Groundwater samples from buried hill of Jizhong Depression were evaluated using two statistical analyses: hierarchical cluster analysis (HCA) and principal component analysis (PCA). The samples were classified into four clusters, C1-C4, in HCA and the hydrochemical types of C1-C4 are HCO 3 -Na, Cl⋅HCO 3 -Na, Cl-Na, and Cl-Na⋅Ca. From C1 to C2, C3, and C4, the water-rock interaction becomes increasingly intensive, and rNa/rCl gets lower while total dissolved solids and r(Cl-Na)/rMg get higher. Three components of PCA explain 86.87% of the variance. Component1 (PC1), characterized by highly positive loadings in Na + and Cl − , is related to evaporation concentration. Component2 (PC2) is defined by highly positive loading in HCO 3 − and is related to influence of atmospheric water. With high positive loadings in Ca 2+ and high negative loadings in Na + and SO 4 2− , component3 (PC3) suggests plagioclase albitization. The combination of HCA and PCA within the hydrogeological contexts allowed the division of study area into five dynamic areas. From recharge area to discharge area, the influence of atmospheric water gets weaker and water-rock interactions such as evaporation concentration and plagioclase albitization become intensive. Therefore groundwater in buried hill showed paths of hydrochemical evolution, from C1, to C2, C3, and C4. Buried hill reservoir in Jizhong Depression is mainly distributed in hydrodynamic blocking and discharge area; therefore the two regions can be the favorable areas for petroleum migration.

The Temperature Evaluation of the Buried Hill Geothermal Reservoirs in the Jizhong Depression, Bohai Bay Basin, China

“…According to the measured water pressure of the buried hill by drilling, it is converted into the distribution of the current water head, and the distribution diagram of it is drawn (Figure 3). In this region, the groundwater head of the buried hill gradually decreases from the basin periphery to the basin center, forming the movement trend of groundwater from the depression periphery to the center, that is, the characteristics of typical "centripetal flow" [38][39][40].…”

Enrichment Mechanism of Lithium in Geothermal Waters from a Bedrock Reservoir in Xiong’an New Area, China

“…Thus far, the geothermal waters in China Xiong'an New Area have been extensively studied, including hydrogeological and geochemical characteristics, genesis, and geothermal resources [9][10][11][12][13][14][15][16]. However, research on the enrichment mechanism of lithium in the geothermal waters in the study area is very rare, and only the lithium concentrations in the geothermal waters have been reported [17,18].…”