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DESCRIPTION:The Department of Earth and Planetary Sciences Presents: \n\n 
 \n\nDr. Daniel Gregory\n\nDepartment of Earth Sciences \n\nUniversity of T
 oronto\n\n \n\nOctober 6\, 2023 \n\n11:00 am \n\nIn-person: FDA room 232 
 \n\n \n\nFrom economic geology to ocean chemistry: the wide range of infor
 mation that can be obtained from a humble pyrite grain\n\nAbstract:\n\nPyr
 ite incorporates a portion of the trace elements dissolved in the fluids f
 rom which it formed. Thus trace element analysis of pyrite grains can give
  us information of these past fluids with applications as varied as unders
 tanding changes in ocean chemistry to identifying ore deposit type. We hav
 e analysed over 1400 pyrite grains from sedimentary rocks through geologic
  time using laser ablation ICPMS. Periods in geologic time when several tr
 ace elements are enriched in pyrite match with times where whole rock anal
 yses of redox sensitive trace elements also show enrichments. This suggest
 s that pyrite chemistry\, like these traditional whole rock studies\, can 
 be used to understand changes in ocean chemistry and the atmosphere throug
 h Earth history. In this presentation we evaluate the efficacy of this by 
 investigating nano-scale zoning of pyrite framboids from euxinically forme
 d pyrite\, the most likely pyrite to retain the trace element signature of
  the water column from which it formed.\n\nPyrite also incorporates trace 
 elements from hydrothermal fluids. Because pyrite forms in many different 
 deposits and those deposits have different fluid compositions pyrite chemi
 stry should be a viable way to identify ore deposit type. This is importan
 t as near surface deposits are increasingly exploited and new\, large depo
 sits will be found at deeper and deeper depths. This requires deeper drill
 ing and increased costs\, thus we must get as much information from each d
 rill hole as possible. If pyrite can be utilized to identify ore deposit t
 ype it will allow for application of geological models early in an explora
 tion program enhancing efficiency of the drilling. In this study we presen
 t almost 4\,000 LA-ICPMS trace element analyses of pyrite from 84 differen
 t deposits (including porphyry\, hydrothermal breccia\, IOCG\, SEDEX\, VHM
 S\, orogenic gold\, and skarn) and unmineralized sedimentary pyrite format
 ions. These data are used to train a Random Forest data learning algorithm
  to identify ore deposit signatures based on the trace element composition
  of the pyrite associated with them.\n\n \n
DTSTART:20231006T150000Z
DTEND:20231006T160000Z
SUMMARY:Seminar Speaker: Dr. Daniel Gregory 
URL:https://www.mcgill.ca/eps/channels/event/seminar-speaker-dr-daniel-greg
 ory-351077
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