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Accueil du site → Master → Etats Unis → 2016 → Using geochemistry and gravity data to pinpoint sources of salinity in the Rio Grande and fault networks of the Mesilla Basin

University of Texas at El Paso (2016)

Using geochemistry and gravity data to pinpoint sources of salinity in the Rio Grande and fault networks of the Mesilla Basin

Hiebing, Matthew Steven

Titre : Using geochemistry and gravity data to pinpoint sources of salinity in the Rio Grande and fault networks of the Mesilla Basin

Auteur : Hiebing, Matthew Steven

Université de soutenance : University of Texas at El Paso

Grade : Master of Science (MS) 2016

Présentation
Fresh water resources are scarce in the American Southwest, especially in the semi-arid to arid regions of El Paso, TEXAS. The Rio Grande and Mesilla Basin are both major suppliers of freshwater for the city of El Paso and its cropland along the river. Maintaining a steady source of freshwater is critical in sustaining the growing demands of irrigation and population in the area. Modeling the flow system of the Mesilla basin and its relation to the Rio Grande has provided information on the potential salt influxes from the fault networks of the Mesilla Basin. Most of the salinity observed in the groundwater is due to the dissolution of evaporites in the middle and lower Santa Fe units. In addition, we observed a thermal upwelling component that is supplying the Mesilla basin with some of its higher Chloride/Bromide ratios. Surface water runoff has also contributed to the overall salinity by introducing water characterized by higher Calcium/Sodium ratios coming from the Ordovician limestone rocks exposed at the Franklin Mountains’ surface. Furthermore, this study has identified potential areas of salinity introduction into the shallow Mesilla Basin and eventually, the Rio Grande through artificial pumping and irrigation. The addition of two new gravity surveys has updated the UTEP Database and has established a more confident interpretation of fault locations within the Mesilla Basin. In total, five fault locations were mapped. Three of them were updated locations from previous studies and two of them were new interpretations. Horizontal Gradient Magnitude mapping (HGM) has confirmed the structural complexity of the basin which coincides with the range of chemistry seen in the groundwater.

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Page publiée le 20 octobre 2016, mise à jour le 9 décembre 2019