Fritz, Frank P.¹, Kern, Richard R.², and Lide, Chester S.³, (1) Fritz Geophysics, 560 Quillan Gulch Road, Loveland, CO 80537, (2) Klondex Mines, Ltd., 530 Melarkey Street, Suite 202, Winnemucca, NV 89445, (3) Zonge Geosciences, Inc., 924 Greg Street, Sparks, NV 89431
The Fire Creek project is located in Lander County, Nevada, in the northern part of the Shoshone Range and is associated with the Northern Nevada Rift (NNR). Fire Creek currently contains a 43-101-compliant, 1.6 Moz gold resource. Ore grade gold mineralization occurs in, and disseminated near, steeply-dipping epithermal veins within Tertiary basalt flows and intrusives. It is reasonably well known that economic mineralization associated with the NNR (Fire Creek, Mule Canyon, Buckhorn) exhibit well-defined IP highs. Due to the loss of resolution with depth inherent in all IP electrode arrays, the thin vein-type mineralization at depth is difficult to target for drilling. Historically, dipole-dipole and gradient-array IP/Resistivity and limited gravity data were collected over much of the property. Many of the well-defined IP sources were associated with potentially-economic mineralization, while the coarse gravity data indicated a possible basement high and structural control.
In the spring and summer of 2009, Klondex collected detailed gravity, CSMT, and MT data on four lines over previously-defined IP highs and known shallow, as well as, deeper mineralization, with the expectation of defining the deeper volcanic sources and basement structures. High-resolution, tensor-array CSMT data collection was used to define the shallower geologic section and locate specific resistivity contrasts for follow-up to depth with MT data. In the limited area covered by the four lines, there were well-defined resistivity contrasts associated with the several volcanic units and pre-mineral dikes, with a less well defined contrast between the volcanic section and Paleozoic basement. Paleozoic basement was defined to depths of 1,000m. Perhaps most interesting was that the mineralized late-stage basalt dikes, an important host, were defined in detail. While the combined CSMT and MT data collection was relatively expensive it was less than the cost of a single typical drill hole and allowed much better target definition for the subsequent drill program. Drill testing of these new potentially mineralized zones is in progress.