Sedimentary exhalative (sedex) zinc-lead-silver deposit model

Scientific Investigations Report 2010-5070-N

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This report draws on previous syntheses and basic research studies of sedimentary exhalative (sedex) deposits to arrive at the defining criteria, both descriptive and genetic, for sedex-type deposits. Studies of the tectonic, sedimentary, and fluid evolution of modern and ancient sedimentary basins have also been used to select defining criteria. The focus here is on the geologic characteristics of sedex deposit-hosting basins that contain greater than 10 million metric tons of zinc and lead. The enormous size of sedex deposits strongly suggests that basin-scale geologic processes are involved in their formation. It follows that mass balance constraints of basinal processes can provide a conceptual underpinning for the evaluation of potential ore-forming mechanisms and the identification of geologic indicators for ore potential in specific sedimentary basins. Empirical data and a genetic understanding of the physicochemical, geologic, and mass balance conditions required for each of these elements are used to establish a hierarchy of quantifiable geologic criteria that can be used in U.S. Geological Survey national assessments.  In addition, this report also provides a comprehensive evaluation of environmental considerations associated with the mining of sedex deposits.

Suggested Citation

Emsbo, Poul, Seal, R.R., Breit, G.N., Diehl, S.F., and Shah, A.K., 2016, Sedimentary exhalative (sedex) zinc-lead-silver deposit model: U.S. Geological Survey Scientific Investigations Report 2010–5070–N, 57 p.,

ISSN: 2328-0328 (online)

Table of Contents

  • Introduction
  • Deposit Type and Associated Commodities
  • Historical Evolution of Descriptive and Genetic Knowledge and Concepts
  • Regional Environment
  • Physical Description of Deposit
  • Geophysical Characteristics
  • Hypogene Ore/Gangue Characteristics
  • Relations Between Alteration, Gangue, and Ore
  • Weathering/Supergene Processes
  • Geochemical Characteristics
  • Petrology of Associated Igneous Rocks
  • Petrology of Associated Sedimentary Rocks
  • Petrology of Associated Metamorphic Rocks
  • Theory of Deposit Formation
  • Exploration/Resource Assessment Guides
  • Attributes Required for Inclusion in Permissive Tract at Various Scales
  • Geoenvironmental Features
  • Pre-Mining Baseline Signatures in Soil, Sediment, and Water
  • Past and Future Mining Methods and Ore Treatment
  • Volume of Mine Waste and Tailings
  • Knowledge Gaps and Future Directions
  • References

Additional publication details

Publication type:
Publication Subtype:
USGS Numbered Series
Sedimentary exhalative (sedex) zinc-lead-silver deposit model
Series title:
Scientific Investigations Report
Series number:
Year Published:
U.S. Geological Survey
Publisher location:
Reston, VA
Contributing office(s):
Central Mineral and Environmental Resources Science Center
ix, 57 p.
Larger Work Type:
Larger Work Subtype:
USGS Numbered Series
Larger Work Title:
Mineral deposit model for resource assessment (Scientific Investigations Report 2010-5070)
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