Investigating Changes in Surface Water Chemistry Across the Llano Uplift and the Balcones Fault Zone in Central Texas Using Strontium and Uranium Isotopes
Abstract
The landscape of central Texas is shaped by over one billion years of Earth's history. An array of lithology lies within central Texas along with two large geological structures. The Llano Uplift, characterized by Proterozoic metamorphic and igneous rocks dating back to 1.37 billion years ago, is encircled by Paleozoic and Mesozoic sedimentary rocks. To the southeast of the Llano Uplift lies the Balcones Fault Zone (BFZ), an extensional structural system of mostly normal faults that delineates the transition between Paleozoic-Mesozoic sedimentary rocks and Cenozoic sedimentary cover, which are influential to the regional hydrogeology. This study investigates the hydrogeological dynamics influenced by these geological features, focusing on spatial variations in surface water chemistry across these two features. In this region, rivers traversing through Paleozoic-Mesozoic carbonate rocks exhibit elevated electrical conductivity (EC) and bicarbonate (HCO3) concentrations due to chemical weathering processes, while those flowing over Proterozoic crystalline rocks demonstrate lower EC levels. This study also reveals significant trends in strontium and uranium isotopic ratios, providing insights into water-rock interactions and potential groundwater influences in the BFZ and the Llano Uplift. These insights advance our understanding and knowledge of the hydrogeological processes and implications for water resource management, groundwater sustainability, and contamination mitigation efforts in central Texas.
Subject Area
Geology|Geochemistry|Environmental science|Water Resources Management
Recommended Citation
Pham, Hao Tuan, "Investigating Changes in Surface Water Chemistry Across the Llano Uplift and the Balcones Fault Zone in Central Texas Using Strontium and Uranium Isotopes" (2024). ETD Collection for University of Texas, El Paso. AAI31295981.
https://scholarworks.utep.edu/dissertations/AAI31295981