USGS Science in Alaska
Application of Secular Trends and Continent-scale Geophysics to Mineral Resource Assessment
This pilot project merges two research efforts meant to improve techniques of mineral resource assessment.
Bradley, Dwight C.
Bradley, Dwight C., firstname.lastname@example.org, 907-786-7434
Start Year: 2004
End Year: 2006
USGS Mission Area and Program:
Energy and Minerals → Mineral Resources
Solid Earth > Tectonics > Plate Tectonics
This pilot project merges two research efforts meant to improve techniques of mineral resource assessment. Tasks 1, 2, and 3 involve documenting geologic secular trends in earth history and in two broad groups of ore deposits, in order to better use geologic age as a primary constraint in resource assessment. Task 4 involves the use of continent-scale geophysics in improving mineral assessment techniques through improved continental reconstructions, and through improved coverage and interpretation of buried and/or poorly known bedrock. The kickoff for this project was a Penrose Conference on Secular Variation in Tectonics and Allied Fields, organized by Bradley in October 2004, attended by scientists from 9 countries. Conventional assessments of undiscovered mineral resources rely on (a) the distribution of known deposits, (b) geologic setting, and (c) generalized geologic models for the various deposit types. The conventional approach barely makes use of the fact that, without exception, all types of ore deposit are time-bound. There are times in Earth history when a particular deposit type is absent, times when these deposits are present but scarce, times when they are abundant, and still other times for which we yet lack sufficient data. We propose to develop this property "secular variation" as a tool for resource assessment and exploration. One of the biggest problems with analysis of secular trends is the lack of robust plate reconstructions prior to about 300 million years ago, when the last supercontinent (Pangea) came together. Toward this end, continent-scale magnetic and gravity data will be compiled and used to develop and test reconstructions of the older supercontinents (e.g. Rodinia).
Project metadata record