Carlin Trend Field Guide now available online
Field trips to mining camps provide invaluable information on ore deposit models and applicable exploration techniques. Yet many of the guides routinely distributed to field trip participants have never been published online and are at risk of disappearing.
The guide to the Carlin Trend field trip organized by Newmont Mining following the Society for Exploration Geophysicists (SEG) conference in 1996, for example, is a comprehensive package of materials that would be impossible to replicate but remains relevant to exploration for Carlin-type deposits.
The Carlin Trend, a 60 kilometre northwest trending alignment of gold deposits in northeastern Nevada, is the most productive gold camp in North America. More than 40 separate deposits have been delineated since 1961, when Newmont discovered disseminated gold mineralization in carbonate rocks. Several companies, including Newmont and Barrick Gold, continue to conduct exploration along the trend as ore deposit models evolve.
The SEG field guide compiled by Colin Barnett and Jim Wright - who both worked for Newmont at the time - describes the geophysical techniques used at Gold Quarry, an open pit mine at the south end of the trend. A supplementary reading guide provides related papers published by the USGS and other sources. Topics range from testing the ability of IP, VLF-resistivity, and radiometrics to detect geophysical signatures that could be help find similar deposits, to techniques used to detect leaks from the leach pond.
A road log describes the geology along the bus route from Elko to Carlin, following the Humboldt River valley, where Cenozoic fluvial and lacustrine rocks lie uncomformably on top of coarse clastic rocks of Late Paleozoic age.
“This was an exceptional field trip and the materials assembled would be hard to find anywhere else,” says Ken Witherly, president of Condor Consulting, who says the Carlin Trend suffers from a paucity of datasets and analysis because companies are not required to submit assessment files in Nevada and have traditionally been unwilling to share their knowledge.
But it’s not only explorers in Nevada that are missing out on industry-generated research. Witherly is concerned that as his generation of professionals retires, informal geoscientific references from mining camps worldwide will be lost and never replaced with modern equivalents. He encourages others dig out their industry guides and reports and digitize them.
Download the 1996 SEG post-conference Carlin Trend Field Trip Guide and Supplementary Reading on Earth Explorer.