Recharge zone

Inverse correlatiOTt of MgO content with CaO content in altered igneous rocks is formd (Fig. 4.3). This is caused by the reaction 

Therefore, MgO content of altered rocks indicates the extent of seawater-rock interaction (degree of alteration). The contents of some elements (Fe, H2O) positively correlate with MgO content, but some (CaO, K2O) negatively do. 

Etufferfar fluids du reaction with bass — igneous rocks anorthite Itk / 

The decrease in Si02 content with increasing MgO content is due to the formation of Mg-chlorite containing smaller Si02 content than original rock. 

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Formation of albite which is characteristic mineral of propylitic alteration occurs by heating of rocks and descending fluids at recharge zone in the hydrothermal system (Giggenbach, 1984 Takeno, 1989). Thus, it is considered that the propylitic alteration takes place at recharge zone in the hydrothermal system, while potassic alteration at discharge zone. 

Phreatic aquifers are often regarded as recharge zones feeding adjacent confined systems. A continuous through-flow is commonly envisaged, controlled by (and deduced from) water level gradients and transmissivities. However, in certain cases a discontinuity is observed between the phreatic and confined parts of a system, reflected in abrupt changes in the chemical... 

Identification of the Nature of the Unsaturated Recharge Zone A Porous Medium or a Karstic System... 

Type of Plant Community that Grew in the Ancient Recharge Zone... 

C shows that calcite, quartz, and clay minerals also exist in the rocks and sediments found at the surface of the contributing and recharge zones. 

Figure 6 shows XRD patterns of the <2 pm fraction (oriented and glycol-solvated) of samples of soils found in the recharge zone. The 17 A, 8.4 A and 5.64 A peaks in the pattern of Edwards soil A show that smectite, not BS I/S, is present in that sample. Furthermore, Edwards soil A does not contain illite, which is present in the Barton Springs suspended sediment. Therefore, Edwards soil A is not the source of the clastic material discharged from Barton Springs. Neither is Edwards soil B, which is also found... 

Figure 6. XRD patterns of the <2 pm fraction (oriented and glycol solvated) of soils from Oie recharge zone. S = smectite, other pe labels as in Figure 5.

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