A GEOCHEMICAL AND STATISTICAL INVESTIGATION OF THE BIG FOUR SPRINGS REGION IN SOUTHERN MISSOURI

The Big Four Springs Region hosts the four largest first-order magnitude springs in Missouri and Arkansas. These springs are Big Spring (Carter County, MO), Greer Spring (Oregon County, MO), Hodgson Mill Spring (Ozark County, MO), and Mammoth Spring (Fulton County, AR). Based on historic dye traces, these springs drain an area of approximately 1500 square miles and collectively discharge an average of 780 million gallons of water per day. The Big Four Springs are found within Ordovician and Cambrian dolomite formations that make up the majority of rocks exposed throughout southern Missouri and Arkansas. Mammoth Spring forms the Spring River in Arkansas, which was recently found to host about 90 tufa dam deposits with each dam being about 1-2 meters thick stretching across the river and 1-2 meters tall. No other significant tufa deposits are known within Missouri. An investigation of water chemistry of the Big Four Springs is occurring to better understand what makes the Mammoth Spring water unique to host these tufa deposits and to better characterize these major groundwater resources of southern Missouri.

Key questions being answered are (1) What are the geochemical characteristics of the Big Four springs? And, (2) is the geochemistry related to the formation of tufa deposits in the Spring River, Arkansas? Initial field measurements suggest that the water chemistry of Mammoth Spring and Hodgson Mill show relatively high conductivity and alkalinity compared to Greer Spring and Big Spring. Statistical analysis to determine potential unique geochemical signatures for each spring will also be presented. The data available for each of the Big Four Springs includes: Field measurements of temperature, conductivity, pH, and alkalinity, and lab analyses for: Ca, Fe, Mg, B, Na, K, Ti, Sn, Sr, Pb, Mn, Zn, Hg, and V. Using Geochemical models with full spring water analyses will also allow the calculation of saturation indices of calcite and dolomite in these waters.