Central Mineral Resources Team
Updated National Mineral Resource Assessment - Planning Phase
Large Mineralizing Systems in the U.S.
Task Objectives
Given that most of the production for any commodity comes from the very largest mining
districts or systems and that most new discoveries are made within known districts, this
Task aims to synthesize what is known about such systems in the U.S. and fill data gaps as
a contribution to updated mineral deposit models, resource assesment procedures, and
ultimately, mineral resource estimates.
Important questions to be addressed include:
- Where are the country's economically most important mining districts/systems, what are
their attributes, how did they form, how do they fit into the geotectonic evolution of the
country? (compilation)
- What remains to be learned about these systems that could ehhance the Updated National Mineral Resource Assessment?
(research)
- What proportion of the identified resources in these systems remains and could be mined?
- How do we use the concentration gradients in these systems to estimate the amount of
marginal reserves present therein?
- How do we use our understanding of these systems to delineate varying mineral resource
favorability and estimate undiscovered resources within them? (assessment)
More generalized questions to be addressed include:
- What over arching geotectonic environments or system types generate most of the
deposits of the types to be assessed?
- How do these systems operate and what secular or local factors strongly influence
formation of associated deposits?
- How can we use known occurrences of one deposit type in these systems to estimate the
size and number of related deposit types?
- How can we use a reported grade and tonnage for a deposit together with the
concentration gradient for a deposit type to estimate the amount of marginal reserves or
subeconmic resources present ?
Task objectives include:
- Compile pertinent information on large mineralized systems and display this information on a USGS web site.
- Identify large mineralized systems in need of additonal research and fill knowledge gaps that otherwise would inhibit the effectiveness of the Updated National Mineral Resource Assessment.
- Where possible, establish commodity concentration gradients for deposits within these systems.
- Map favorability within these sytems and estimate undiscovered resources.
Statement of Work
The initial focus will be to identify the major systems in the country and begin work on a few of them (e.g. Carlin trend, Coeur d'Alene, etc.) as described in the summary narratives.
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U.S. Geological Survey