National mineral assessment tract AK-BR22 (Sedex Zn-Pb)

Tract AK-BR22
Geographic region Brooks Range, AK
Tract area 49,825sq km
Deposit type Sedex Zn-Pb
Deposit age Mississippian - Pennsylvanian

Rationale

Explained by Jeanine M. Schmidt, Karen D. Kelley, Richard I. Grauch, Byron R. Berger, John W. Cady, Gregory T. Spanski, James E. Kilburn
On the choice of deposit models
The geologic setting and host rocks are permissive for sediment-hosted Zn-Pb-Ag deposits (Briskey, 1986), but no occurrences are known.
Major deposits of shale-hosted Zn-Pb-Ag +/-Ba deposits (Briskey, 1986) occur in Alaska. The geologic setting, deep-water marine sedimentary host rocks and drainage geochemistry are permissive for additional deposits.
On the delineation of permissive tracts
This tract is defined by carbonate rocks of the Mississippian to Pennsylvanian Lisburne Group. These are mainly light-colored platform carbonates, but include some slope and deeper-water carbonate lithologies, and are permissive for Zn-Pb mineralization similar to the “Irish” type orebodies of Novan and Silvermines (Hitzman and Lange, 1986).
This composite tract comprises all of the individual tracts permissive for sedex deposits in Alaska. Those tracts having estimates of the number of undiscovered deposits were used as guidelines to the potential for undiscovered deposits throughout the state.
Important examples of this type of deposit
No sediment-hosted deposits are known in this tract, although time-equivalent deeper-water rocks to the west host the Red Dog and Lik deposits (Schmidt, 1997).
Known mineral occurrences of this type include the Red Dog mine (Lange and others, 1985; Moore and others, 1986; Schmidt and Zierenberg, 1988; Zierenberg and Schmidt, 1988) and the Lik (Forrest, 1983; Forrest and others, 1983; Forrest and Sawkins, 1987), Drenchwater (Nokleberg and Winkler, 1982), and Suds prospects (Schmidt, 1997).
On the numerical estimates made
Because of the lack of geologic information and mineral deposit data, no attempt was made to estimate the number of undiscovered deposits that may exist.
Based on the wide extent of appropriate host rocks, several known and drilled prospects, and widespread geochemical anomalies, the number of undiscovered deposits, consistent with the median grade and tonnage for the model (Menzie and Mosier, 1986), estimated for Alaska is:
Percentile 90 50 10 5 1
Estimated number of deposits 3 8 12 17 30
References
Briskey, J.A., 1986b, Descriptive model of sedimentary exhalative Zn-Pb, in Cox, D.P., and Singer, D.A., eds., Mineral deposit models: U.S. Geological Survey Bulletin 1693, p. 211-212
Hitzman, M.W., and Lange, Duncan, 1986, A review and classification of the Irish carbonate-hosted base metal deposits in, Andrew, C.J., Crowe, R.W.A., Finlay, S., Pennell, W.M., and Pyne, J.F., eds., Geology and genesis of mineral deposits in Ireland: Dublin, Ireland, Irish Association of Economic Geologists, p. 217-238.
Schmidt, J.M., 1997, Shale-hosted Zn-Pb-Ag and barite deposits of Alaska, in Goldfarb, R.J., and Miller, L.D., eds., Mineral Deposits of Alaska: Economic Geology Monograph 9, p. 35-65.
AK04 Sedimentary-Exhalative Zn‑Pb Alaska
Briskey, J.A., 1986, Descriptive model of sedimentary exhalative Zn-Pb, in Cox, D.P., and Singer, D.A., eds., Mineral deposit models: U.S. Geological Survey Bulletin 1693, p. 211-212
Forrest, Kimball, 1983, Geology and isotopic studies of the Lik deposit and the surrounding mineral district, DeLong Mountains, Western Brooks Range, Alaska: unpublished PhD thesis, Univ. of Minnesota, 161p.
Forrest, Kimball, Rye, R., and Sawkins, F.J., 1983, Sulfur and oxygen isotope systematics of sedimentary exhalative Zn-Pb-Ag deposition in a fault-bounded basin, Lik deposit, Western Brooks Range, Alaska, (abs.): Geol. Assoc. of Canada, Abstracts with Program , Victoria, B.C., v. 8, p. A23.
Forrest, Kimball, and Sawkins, F.J., 1987, Geologic setting and mineralization of the Lik deposit: Implications for the tectonic history of the western Brooks Range, in Tailleur, I.L., and Weimer, Paul, eds., Alaskan North Slope Geology: Soc. of Economic Paleontologists and Mineralogists Field Trip Guidebook 50, p. 295 -305.
Lange, I.M., Nokleberg, W.J., Plahuta, J.T., Krouse, H.R., and Doe, B.R., 1985, Geologic setting, petrology, and geochemistry of stratiform zinc-lead-barium deposits, Red Dog Creek and Drenchwater Creek areas, northwestern Brooks Range, Alaska: Economic Geology, v. 80, p. 1896-1926.
Menzie, W.D., and Mosier, D.L., 1986, Grade and tonnage model of sedimentary exhalative Zn-Pb, in Cox, D.P., and Singer, D.A., eds., Mineral deposit models: U.S. Geological Survey Bulletin 1693, p. 212-215.
Moore, D.W., Young, L.E., Modene, J.S., and Plahuta, J.T., 1986, Geologic setting and genesis of the Red Dog zinc-lead-silver deposit, western Brooks Range, Alaska: Economic Geology, v. 81, p. 1696 - 1727.
Nokleberg, W.J., and Winkler, G.R., 1982, Stratiform zinc-lead deposits in the Drenchwater Creek area, Howard Pass quadrangle, northwestern Brooks Range, Alaska: U.S. Geological Survey Professional Paper 1209, 22 p, 2 sheets, scale 1:20,000.
Schmidt, J.M., 1997, Shale-hosted Zn-Pb-Ag and barite deposits of Alaska, in Goldfarb, R.J., and Miller, L.D., eds., Mineral Deposits of Alaska: Economic Geology Monograph 9, p. 35-65.
Schmidt, J.M., and Zierenberg, R.A., 1988, Lateral variations of ore, and reconstruction of the Red Dog Zn-Pb-Ag deposit, Noatak District, Alaska [abs.]: Geol. Soc. of America Abstracts with Program, v. 20, no. 7, p. A-37.
Zierenberg, R.A., and Schmidt, J.M., 1988, Isotopic evidence for multiple sulfur sources at the Red Dog Zn-Pb-Ag deposit, Noatak District, Alaska [abs.] : Geol. Soc. of America Abstracts with Program, v. 20, no., 7, p. A-37.

Geographic coverage

Show this information as XML or JSON