Geochemical Signatures and Environmental Impacts of Ore and Trace Mineralization in the Southern Midcontinent

Science Center Objects

The overall project objective is a comprehensive analysis of the natural and anthropogenic consequences of extensive ore and trace mineralization in the southern midcontinent of the U.S. with a focus on Missouri. This will be conducted at two scales: 1) landscape and 2) process-level.

1) Landscape scale using geospatial and machine learning techniques to combine multiple geochemical and geologic data sets and identify patterns associated with Mississippi-valley Type (MVT) mineralization and its historic mining.

2) Process-level scale using combined Mineral Resources Program expertise on mineralogy, stable-isotope systematics, redox-speciation, and microbially-mediated transformations of element residence to futher understand the mobility and bioaccessibility of lead and other potentially toxic elements related to naturally mineralized and mining-related terrain.

Science Issue and Relevance

The ancient (Paleozoic) carbonate rocks that dominate the subsurface of the U.S. southern midcontinent including southern Missouri and adjacent states are mineralized with lead, zinc, cobalt, nickel, copper, fluorine and iron ores. This mineralization ranges from world-class ore districts to numerous smaller ore fields. Previous research has established that, in addition to ore grade mineral accumulations, subsurface midcontinent Paleozoic rocks distal to ore-grade mineralization acted as regional conduits for ancient ore-forming fluids. These ore fluid-bearing aquifers now contain trace levels of mineralization including lead and other potentially toxic elements such as arsenic and cadmium. Centuries of mining and the interaction between modern groundwater and trace-metal-bearing aquifers resulted in creation of exposure pathways for these toxic elements to impact modern sedimentary, hydrologic, and biotic environments. The list of known and potential environmental impacts is long.

This project will provide map products together with knowledge of hydrogeochemical and biogeochemical processes allowing decision makers to address continuing and emerging environmental threats. We will also collaborate with ore genesis and mineral assessment projects in the region to identify potential signatures of undiscovered ore deposits using an array of existing data.

Methodology to Address Issue

This project plants to comprehensively analyze and integrate the extensive data available and utilize the Mineral Resources Programs' scientific expertise to provide land managers and citizens with the information they need to help mitigate these natural and anthropogenic environmental concerns. This will be accomplished by two tasks.

  1. Geochemical and Environmental Impacts Mapping - integrate relevant USGS rock, water, soil, and USGS/other agency groundwater data with geologic and hydrologic data to address environmental and mineral assessment issues on a broad regional scale. 
  2. Integrated Studies of the Mobility and Bioaccessibility of Mississippi-valley Type (MVT) Elements - conduct regionally focused (county level) research on the biotic and human health impacts of major and trace elements to fully characterize the pathways linking natural and mining-related elemental sources and biotic receptors.

 

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