Effects of intrusions on grades and contents of gold and other metals in volcanogenic massive sulfide deposits

Ore Geology Reviews
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Abstract

The reason some VMS deposits contain more gold or other metals than others might be due to the influence of intrusions. A new approach examining this possibility is based on examining the information about many VMS deposits to test statistically if those with associated intrusions have significantly different grades or amounts of metals. A set of 632 VMS deposits with reported grades, tonnages, and information about the observed presence or absence of subvolcanic or plutonic intrusive bodies emplaced at or after VMS mineralization is statistically analyzed.

Deposits with syn-mineralization or post-mineralization intrusions nearby have higher tonnages than deposits without reported intrusions, but the differences are not statistically significant. When both kinds of intrusions are reported, VMS deposit sizes are significantly higher than in the deposits without any intrusions. Gold, silver, zinc, lead, and copper average grades are not significantly different in the VMS deposits with nearby intrusions compared to deposits without regardless of relative age of intrusive. Only zinc and copper contents are significantly higher in VMS deposits with both kinds of intrusive reported. These differences in overall metal content are due to significantly larger deposit sizes of VMS deposits where both intrusive kinds are observed and reported, rather than any difference in metal grades.

Publication type Article
Publication Subtype Journal Article
Title Effects of intrusions on grades and contents of gold and other metals in volcanogenic massive sulfide deposits
Series title Ore Geology Reviews
DOI 10.1016/j.oregeorev.2010.12.003
Volume 39
Issue 1-2
Year Published 2011
Language English
Publisher Elsevier
Contributing office(s) Western Mineral and Environmental Resources Science Center
Description 3 p.
First page 116
Last page 118
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