Paper No. 2
Presentation Time: 9:15 AM


HAMMARSTROM, Jane M., U.S. Geological Survey, 954 National Center, Reston, VA 20192, ZIENTEK, Michael L., U.S. Geological Survey, 904 W Riverside Ave, Room 202, Spokane, WA 99201, BERGER, Byron R., U.S. Geological Survey, Federal Center MS 964, Denver, CO 80225-0046, BOOKSTROM, Arthur A., US Geological Survey, Spokane, WA 99201, GRAY, Floyd, United States Geological Survey, 520 North Park Avenue, Tucson, AZ 85721, LUDINGTON, Steve, U.S. Geological Survey, Menlo Park, CA 94025, MIHALASKY, Mark J., U.S. Geological Survey, 904 West Riverside Avenue, Spokane, WA 99201, ROBINSON Jr, Gilpin R., U.S. Geological Survey, 12201 Sunrise Valley Drive, Mail Stop 954, Reston, VA 20192 and ZURCHER, Lukas, United States Geological Survey, Tucson, AZ 85745,

Porphyry copper deposits are the most significant source of copper on earth. Tracts permissive for Phanerozoic porphyry copper deposits were delineated in 176 areas of North and South America, Europe, Asia, and Oceania at a scale of 1:1 million. Tracts were constructed by analyzing geologic data at various scales to identify appropriate geologic settings for porphyry copper deposits (continental-margin arcs, island arcs, postconvergent magmatic belts). Tract areas range from about 1,000 to 1,000,000 km2 with a median of 40,000 km2. The tracts host 455 known deposits (with well-defined identified resources) that contain about 1.8 billion metric tons of copper, some of which has already been produced. About 30% of the tracts contain 3 or more known deposits, whereas about 30% of the tracts contain none. The assessment predicts a mean of 812 undiscovered deposits within the uppermost kilometer of the earth’s surface. Results of combining estimates of numbers of undiscovered deposits with grade and tonnage models using Monte Carlo simulation on a tract by tract basis indicate that the estimated amount of copper (arithmetic mean) in undiscovered porphyry copper deposits is about 3.1 billion metric tons, which represents about 180 times 2012 global copper production from all types of copper deposits. The Andes region is a major source of both known and predicted deposits along with parts of Central America, the southwestern U.S. and northern Mexico, and Alaska. The Pacific margin areas of Russia and China, Tibet, the Central Asian Orogenic Belt of China and Mongolia, and the Philippines host about 60% of tracts that are estimated to contain 24 million metric tons of copper or more. Economic filters indicate that no more than 70% of the estimated resources may be economic, depending on assumptions about depth distributions of the deposits and local infrastructure. Permissive tracts, a database of deposits and prospects, and assessment results are available in a GIS.