Arizona Geological Society

Bell Copper's Big Sandy Copper Porphyry Discovery by Tim Marsh, Ph.D.

  • 06 Sep 2022
  • 6:30 PM - 8:00 PM
  • ZOOM: Passcode: AGS-2022


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Arizona Geological Society

Speaker Series -2022

Tim Marsh, Ph.D.

President/CEO, Bell Copper Corporation

Tuesday, September 6, 2022

Time - 6:30 PM MST (PT) (zoom event opens at 6:15 PM)

ZOOM Presentation is available at


Bell Copper's Big Sandy

Copper Porphyry Discovery

Abstract.   Exploration for the faulted, down-dropped top of the Laramide Diamond Joe porphyry stock northwest of Wikieup, Arizona, has led to the discovery of porphyry-style Cu-Mo-Re-Ag mineralization beneath 600 to nearly 1200 meters of post-faulting, valley-filling gravel cover.  Three diamond drillholes separated by 1.2 to 1.8 kilometers have each cut rocks subjected to copper mineralization and related alteration typical of porphyry copper systems.  The continuous 820 meters of pervasively sericitized and veined quartz monzonite porphyry in drillhole BS-3, the latest hole completed on the project, compare well with the multi-kilometer dimensions of the porphyry system preserved in the inferred footwall of the system at Diamond Joe.  Horizontal offset between the Big Sandy drill intersection and the center of the Diamond Joe system is on the order of 13 kilometers.  Dips of the overlying gravel beds fan westward from about 15 degrees at surface to over 40 degrees near the Laramide basement.  The horizontal offset is attributed to a small number of buried, east-facing Basin and Range normal faults.  Future drilling targets a chalcocite enrichment blanket overlying the inferred copper shell internal to the sericitic/pyritic zone that was cut in BS-3.

Image.  Core from drillhole BS-3 at an inclined depth of 1213 meters. This is fertile hematitic leached capping overlying 200 meters grading 0.42 percent copper and 2.4 gpt Ag, all hosted in 74 Ma, pervasively sericitized quartz monzonite porphyry. The hole stayed in the QSP zone for 820 meters before the mechanical limits of the drill were reached.

Bio.  Dr. Marsh has a 30+ year career in mine geology and exploration, with a focus on porphyry copper deposits.  Experience includes former Chief Geologist of Resolution Copper Company (Rio Tinto Company), where he helped to drill the first 20 deep drill holes into what is now America's largest copper deposit.  A true explorationist whose favorite place is in the field.  Along the way he has earned a B.Sc. Geological Engineering from Colorado School of Mines, and A Doctorate of Philosophy in "Ore Deposits and Exploration from Standford University.

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