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Kansas Geological Survey, Open-file Report 2010-14

Feasibility of Delineating a Volcanic Ash Body Using Electrical Resistivity Profiling

Jianghai Xia, Greg Ludvigson, Richard D. Miller, Lindsay Mayer, and Adel Haj

KGS Open-file Report 2010-14
Oct. 2010

Report to Kansas Minerals Inc., Mankato, Kansas


Volcanic ash production in Kansas has not lived up to its potential since limited production began in the early 1900s (Hardy et al., 1965). Between 1920 and 1940 Kansas was the largest producer of volcanic ash products in the US. Since 1945, commercial production has steadily declined and in 1960 only two producers operated in Kansas. Applications and therefore markets exist for both raw and popped or bloated ash products. Uses for refined ash include filtrate media, plaster wallboard, thermal (low-temperature) insulation, and lightweight fireproof acoustic tile. Markets for raw ash include: ceramic components, glass products, mild abrasives, road construction, concrete aggregate, and as a component of granular fertilizer. Both bloated and raw ash have been used as oil and grease absorbents and inert filters.

Key to exploiting this resource is identification of viable products and associated markets for the raw and processed material. However, before this near-surface product can be marketed, viable means must be developed for estimated volumes, geometries, and characteristics of the ash deposits. Most important is the development of cost-effective techniques for locating, sampling (for assay), and delineating volcanic ash deposits with great enough certainty to allow the accurate resource projections necessary for securing long-term contracts based on known reserves and thereby deliverable product.

Exploitation of volcanic ash deposits currently mined in northern Kansas has been limited to sparse subsurface data from drill cuttings and exposures in shallow pit walls. Continued extraction of ore from operating mines has been guided by operator observations of successive fresh exposures that appear during the mining process, interpolated to the nearest drill hole with cuttings. To estimate mineable tonnage and characteristics of ore, the geometry of the ore body(ies) must be delineated and representative, and intact samples extracted for assay. To ensure the highest accuracy and reliability of these estimations, drill holes need to be optimally placed to allow reliable extrapolations from these borings within a threshold percentage.

With so little known about the site-specific geology and the characteristics of the ash as well as the overburden and basal contact, an integrated geophysical (electrical resistivity, magnetic, and ground penetration radar) survey was conducted with borehole verifications in search of these ore bodies. Both geophysical test data and borehole samples were acquired at sites in close proximity to an existing mine face. Electrical resistivity profiling provides most encouraging results in delineating volcanic ash bodies and addressing the following questions.

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Kansas Geological Survey, Geophysics
Placed online March 31, 2011
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