Thesis (Ph. D.)--University of Wisconsin--Madison, 1988. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 169-188).

Thesis (M.S.)--University of Montana, 2008. / Title from title screen. Description based on contents viewed Aug. 26, 2008. Includes bibliographical references (p. 64-69).

There are four distinguishable groundwater systems in the Boise area, Idaho, U.S.A., identified as modern batholith, thermal batholith, Boise frontal fault, and Nampa-Caldwell systems (Figure 1). Modern batholith and thermal batholith groundwaters are located in Tertiary to Cretaceous aged granites and granodiorites of the Atlanta lobe of the Idaho Batholith. The frontal fault system near Boise, ID defines the southeastern edge of the Idaho Batholith, and divides the batholith from the western Snake River Plain. The Nampa-Caldwell system is in the volcanic, fluvial and pluvial sediments of the western Snake River Plain. Groundwater ages for these systems are modern, 5-15 ka, 10-20 ka, and 20-40 ka respectively. Local meteoric water lines (LMWL) using the delta 2H and delta 18O composition of the groundwater were defined for each system using linear regression techniques. LMWL had variable and defined single slopes of 6.94 and 8. Deuterium excess values (d) were found for each system for each linear regression method. Relative differences of the deuterium excess value assuming the two single slope methods were similar. Changes in moisture source humidity and temperature, and Boise area recharge temperatures calculated from stable isotopic data and the deuterium excess factor agree with other published data. At the moisture source there was a 9% humidity increase and a 7-6 °C decrease of sea surface temperature between the present and the last glacial maximum (LGM). The local temperature decreased 4-5 °C from the present to the LGM for the Boise area.

The thermal springs along the Middle Fork of the Boise River (MFBR) within the Atlanta lobe of the Idaho batholith discharge in discrete locations that appear to be part of self-organizing flow systems. Infiltrating water flows through Basin and Range fractures to depth where it is heated and ultimately discharged at the intersection of trans-Challis oriented faults along the MFBR. Isotopic compositions of the thermal waters have a linear trend with elevation suggesting that the recharge locations are near each thermal spring and the hydrothermal system is not one large interconnected system, but rather multiple individual hydrothermal systems. Water chemically evolves along the hydrothermal flow paths dissolving feldspars and precipitating secondary minerals. PHREEQC inverse modeling of the chemical evolution based on identified minerals within the system predicts positive volume changes in the pore space within the hydrothermal flow systems can occur. Precipitation of secondary minerals is likely to occur in the cooler, subsidiary, less-efficient fractures of the hydrothermal system. Flow areas calculated using heat flow, exponential decay, and a combination of the two, show that the topographic watershed is inadequate to accommodate the water supporting the thermal springs indicating that water is being captured from outside the watershed. The positive volume changes coupled with the water capture is evidence of positive feedback loops are active within the hydrothermal system providing a mechanism for self-organization to occur in the hydrothermal systems of granite.