To analyze where hotspots of element signatures are located we first needed to calculate the background concentration. Since our project focuses on the provenance of the concentrations we calculated the background value of every signature relative to each lithologic unit. We accomplished this through the calculation of the weighted mean element concentration in every unit. In figure 3, these formulas are found at the bottom.
Once the relative concentrations per lithologic unit are calculated, these are used to find the background value we suspect to find in each watershed based on the area coverage of each lithology.
Using the calculated background value and the actual measured value we, were able to find which watershed contained the largest chemical anomaly.
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Figure 3​
In studying the provenance of the sediments we wanted to use the geochemical data and correlate the amount within each watershed to the relative areas of each lithologic unit within the watershed. A regression analysis is the easiest way to analyze the relationship and using the chemical signatures as the dependent variable and the relative calculated areas as the explanatory variables. Using a regression we hope to see to what degree each lithologic unit has on the relative concentration of certain elements.
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Arc Map is well equipped with regression tools, but we instead ran the regression in Excel on our target elements due to complications with data within Arc Map.