Quick
Search: 		  
advanced search
 GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help 
Economic Geology Email Content Delivery
JOURNAL HOME HELP CONTACT PUBLISHER SUBSCRIBE ARCHIVE SEARCH TABLE OF CONTENTS
Economic Geology; November 2004; v. 99; no. 7; p. 1509-1532; DOI: 10.2113/99.7.1509
© 2004 Society of Economic Geologists
This Article
Right arrow Figures Only
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow An erratum has been published
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in Web of Science
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Web of Science (17)
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Kelley, K. D.
Right arrow Articles by Ridley, W. I.
Right arrow Search for Related Content
GeoRef
Right arrow GeoRef Citation

Textural, Compositional, and Sulfur Isotope Variations of Sulfide Minerals in the Red Dog Zn-Pb-Ag Deposits, Brooks Range, Alaska: Implications for Ore Formation

K. D. Kelley{dagger} and D. L. Leach

U.S. Geological Survey, Box 25046, MS 973, Denver, Colorado 80225

C. A. Johnson

U.S. Geological Survey, Box 25046, MS 963, Denver, Colorado 80225

J. L. Clark

Teck Cominco American Inc., 15918 East Euclid Avenue, Spokane, Washington 99216

M. Fayek

Oak Ridge National Laboratories, P.O. Box 2008, Oak Ridge, Tennessee 37831

J. F. Slack

U.S. Geological Survey, National Center, MS 954, Reston, Virginia 20192

V. M. Anderson

1175 C Bear Mountain Drive, Boulder, Colorado 80305

R. A. Ayuso

U.S. Geological Survey, National Center, MS 954, Reston, Virginia 20192

W. I. Ridley

U.S. Geological Survey, Box 25046, MS 973, Denver, Colorado 80225

{dagger} Corresponding author: e-mail, kdkelley{at}usgs.gov

The Red Dog Zn-Pb deposits are hosted in organic-rich mudstone and shale of the Mississippian Kuna Formation. A complex mineralization history is defined by four sphalerite types or stages: (1) early brown sphalerite, (2) yellow-brown sphalerite, (3) red-brown sphalerite, and (4) late tan sphalerite. Stages 2 and 3 constitute the main ore-forming event and are volumetrically the most important. Sulfides in stages 1 and 2 were deposited with barite, whereas stage 3 largely replaces barite. Distinct chemical differences exist among the different stages of sphalerite. From early brown sphalerite to later yellow-brown sphalerite and red-brown sphalerite, Fe and Co content generally increase and Mn and Tl content generally decrease. Early brown sphalerite contains no more than 1.9 wt percent Fe and 63 ppm Co, with high Mn (up to 37 ppm) and Tl (126 ppm), whereas yellow-brown sphalerite and red-brown sphalerite contain high Fe (up to 7.3 wt %) and Co (up to 382 ppm), and low Mn (<27 ppm) and Tl (<37 ppm). Late tan sphalerite has distinctly lower Fe (< 0.9 wt %) and higher Tl (up to 355 ppm), Mn (up to 177 ppm), and Ge (426 ppm), relative to earlier sphalerite. Wide ranges in concentrations of Ag, Cu, Pb, and Sb characterize all sphalerite types, particularly yellow-brown sphalerite and red-brown sphalerite, and most likely reflect submicroscopic inclusions of galena, chalcopyrite and/or tetrahedrite in the sphalerite. In situ ion microprobe sulfur isotope analyses show a progression from extremely low {delta}34S values for stage 1 (as low as –37.2{per thousand}) to much higher values for yellow-brown sphalerite (mean of 3.3{per thousand}; n = 30) and red-brown sphalerite (mean of 3.4; n = 20). Late tan sphalerite is isotopically light (–16.4 to –27.2{per thousand}).

The textural, chemical, and isotopic data indicate the following paragenesis: (1) deposition of early brown sphalerite with abundant barite, minor pyrite, and trace galena immediately beneath the sea floor in unconsolidated mud; (2) deposition of yellow-brown sphalerite during subsea-floor hydrothermal recrystallization and coarsening of preexisting barite; (3) open-space deposition of barite, red-brown sphalerite and other sulfides in veins and coeval replacement of barite; and (4) postore sulfide deposition, including the formation of late tan sphalerite breccias. Stage 1 mineralization took place in a low-temperature environment where fluids rich in Ba mixed with pore water or water-column sulfate to form barite, and metals combined with H2S derived from bacterial sulfate reduction to form sulfides. Higher temperatures and salinities and relatively oxidized ore-stage fluids (stages 2 and 3) compared with stage 1 were probably important controls on the abundances and relative amounts of metals in the fluids and the resulting sulfide chemistry. Textural observations and isotopic data show that preexisting barite was reductively dissolved, providing a source of H2S for sulfide mineral formation. In stage 3, the continued flow of hydrothermal fluids caused thermal alteration of organic-rich mudstones and a build-up of methane that led to fluid overpressuring, hydrofracturing, and vein formation. Barite, red-brown sphalerite, and other sulfides were deposited in the veins, and preexisting barite was pervasively replaced by red-brown sphalerite. Hydrothermal activity ceased until Jurassic time when thrusting and large-scale fluid flow related to the Brookian orogeny remobilized and formed late tan sphalerite in tectonic breccias.




This article has been cited by other articles:


Home page
 Geochemistry: Exploration, Environment, AnalysisHome page
G. E. Graham, K. D. Kelley, J. F. Slack, and A. E. Koenig
Trace elements in Zn-Pb-Ag deposits and related stream sediments, Brooks Range Alaska, with implications for Tl as a pathfinder element
Geochemistry: Exploration, Environment, Analysis, February 1, 2009; 9(1): 19 - 37.
[Abstract] [Full Text] [PDF]

Home page
 Geochemistry: Exploration, Environment, AnalysisHome page
K. D. Kelley and T. Hudson
Natural versus anthropogenic dispersion of metals to the environment in the Wulik River area, western Brooks Range, northern Alaska
Geochemistry: Exploration, Environment, Analysis, February 1, 2007; 7(1): 87 - 96.
[Abstract] [Full Text] [PDF]

Home page
 Economic GeologyHome page
D. L. Huston, B. Stevens, P. N. Southgate, P. Muhling, and L. Wyborn
Australian Zn-Pb-Ag Ore-Forming Systems: A Review and Analysis
Economic Geology, September 1, 2006; 101(6): 1117 - 1157.
[Abstract] [Full Text] [PDF]

Home page
 Geological Society of America MemoirsHome page
T. W. Lyons, A. M. Gellatly, P. J. McGoldrick, and L. C. Kah
Proterozoic sedimentary exhalative (SEDEX) deposits and links to evolving global ocean chemistry
Geological Society of America Memoirs, January 1, 2006; 198(0): 169 - 184.
[Abstract] [Full Text] [PDF]

Home page
 Reviews in Mineralogy and GeochemistryHome page
R. R. Seal II
Sulfur Isotope Geochemistry of Sulfide Minerals
Reviews in Mineralogy and Geochemistry, January 1, 2006; 61(1): 633 - 677.
[Full Text] [PDF]

Home page
 Economic GeologyHome page
K. D. Kelley and S. Jennings
A Special Issue Devoted to Barite and Zn-Pb-Ag Deposits in the Red Dog District, Western Brooks Range, Northern Alaska
Economic Geology, November 1, 2004; 99(7): 1267 - 1280.
[Full Text] [PDF]

Home page
 Economic GeologyHome page
C. S. Rombach and P. W. Layer
Geochronology of the Western and Central Brooks Range, Alaska: Implications for the Geologic Evolution of the Anarraaq and Red Dog Zn-Pb-Ag Deposits
Economic Geology, November 1, 2004; 99(7): 1307 - 1322.
[Abstract] [Full Text] [PDF]

Home page
 Economic GeologyHome page
J. A. Dumoulin, A. G. Harris, C. D. Blome, and L. E. Young
Depositional Settings, Correlation, and Age of Carboniferous Rocks in the Western Brooks Range, Alaska
Economic Geology, November 1, 2004; 99(7): 1355 - 1384.
[Abstract] [Full Text] [PDF]

Home page
 Economic GeologyHome page
J. F. Slack, J. A. Dumoulin, J. M. Schmidt, L. E. Young, and C. S. Rombach
Paleozoic Sedimentary Rocks in the Red Dog Zn-Pb-Ag District and Vicinity, Western Brooks Range, Alaska: Provenance, Deposition, and Metallogenic Significance
Economic Geology, November 1, 2004; 99(7): 1385 - 1414.
[Abstract] [Full Text] [PDF]

Home page
 Economic GeologyHome page
C. A. Johnson, K. D. Kelley, and D. L. Leach
Sulfur and Oxygen Isotopes in Barite Deposits of the Western Brooks Range, Alaska, and Implications for the Origin of the Red Dog Massive Sulfide Deposits
Economic Geology, November 1, 2004; 99(7): 1435 - 1448.
[Abstract] [Full Text] [PDF]

Home page
 Economic GeologyHome page
D. L. Leach, E. Marsh, P. Emsbo, C. S. Rombach, K. D. Kelley, and M. Anthony
Nature of Hydrothermal Fluids at the Shale-Hosted Red Dog Zn-Pb-Ag Deposits, Brooks Range, Alaska
Economic Geology, November 1, 2004; 99(7): 1449 - 1480.
[Abstract] [Full Text] [PDF]

Home page
 Economic GeologyHome page
J. F. Slack, K. D. Kelley, V. M. Anderson, J. L. Clark, and R. A. Ayuso
Multistage Hydrothermal Silicification and Fe-Tl-As-Sb-Ge-REE Enrichment in the Red Dog Zn-Pb-Ag District, Northern Alaska: Geochemistry, Origin, and Exploration Applications
Economic Geology, November 1, 2004; 99(7): 1481 - 1508.
[Abstract] [Full Text] [PDF]

Home page
 Economic GeologyHome page
R. A. Ayuso, K. D. Kelley, D. L. Leach, L. E. Young, J. F. Slack, J. F. Wandless, A. M. Lyon, and J. L. Dillingham
Origin of the Red Dog Zn-Pb-Ag Deposits, Brooks Range, Alaska: Evidence from Regional Pb and Sr Isotope Sources
Economic Geology, November 1, 2004; 99(7): 1533 - 1553.
[Abstract] [Full Text] [PDF]

Home page
 Economic GeologyHome page
R. M. Morelli, R. A. Creaser, D. Selby, K. D. Kelley, D. L. Leach, and A. R. King
Re-Os Sulfide Geochronology of the Red Dog Sediment-Hosted Zn-Pb-Ag Deposit, Brooks Range, Alaska
Economic Geology, November 1, 2004; 99(7): 1569 - 1576.
[Abstract] [Full Text] [PDF]


JOURNAL HOME HELP CONTACT PUBLISHER SUBSCRIBE ARCHIVE SEARCH TABLE OF CONTENTS
Copyright © 2009 by Society of Economic Geologists