Newsletter #4, November 2000
The McGill University Student Chapter of the SEG had a busy and successful 1999-2000 year. Twenty-two students registered as members. Corporate donations enabled the chapter to organize subsidized activities for its members. The new officers elected for the 2000-2001 year are: Olivier Grondin (President), Oliver Schatz (Vice-President), Gabrielle Plandowski (Treasurer), and Chris Wright (Secretary).
Activities during last session included a field trip to Aur Resources' Louvicourt mine in the Abitibi region. Eight members attended this trip to one of Canada's most modern mines in November 1999. In February 2000, eight Chapter members and two industry representatives spent two weeks in Arizona and Nevada on the SW USA Mineral Deposits Field Trip. In March, the Chapter subsidized members who attended the PDAC meeting in Toronto. Four speakers were invited during the academic year. Herb Helmsteadt (diamonds and lamproites), Michel Gauthier (mineral deposits of the Eastern Townships), Tyson Birkett (Olympic Dam-type deposits), and Jeff Hedenquist (epithermal systems of the Pacific region) presented talks of great interest. We were also very pleased with the turnout for our VMS Mineralization Associated with Submarine Calderas symposium held in late March. We hope to organize a symposium every two years. This fall, seven Chapter members attended a gold panning trip to the Eastern Townships. Everyone came back with gold.
This year's planned activities include a three-day field trip to Sudbury, with a visit to Inco's North mine, Clarabelle mill and smelter, and a transect of the basin's surface geology. The highlight for the current year will be a two-week field trip to New Mexico and eastern Arizona. Numerous mineral deposit types will be studied, such as world class Cu-Mo porphyries, Zn-Pb-Ag skarns, uranium and coal, and gypsum. Several speakers have been invited to talk to Chapter members, including Bruce Hart (petroleum industry), Jay Hodgson (Archean gold deposits), Pascal Prince (Raglan nickel deposit), and Benoit Dubé (Appalachian gold deposits). The schedule will be completed with talks on isotopes in mineral deposits, and the diamond potential of Québec.
SEG Seminar Series
The Tectonic Setting of Diamonds in the Canadian Shield
The first talk of the session was presented by Prof. Herb Helmstaedt, from Queen's University, and focused on diamond exploration in Canada. After a brief introduction on various diamondiferous host-rocks (e.g., kimberlite, lamproite, eclogite-peridotite and paleoplacers), Prof. Helmestaedt focused on exploration methods to find kimberlite-hosted deposits in Canada. These methods included identifying pipes from aerial and satellite photographs, geophysical methods (including geomagnetism, and reflection seismic in the case of the Buffalo Hills kimberlite field) and having found a potential intrusion, dating it using paleontology! - Canadian kimberlites tend to have Jurassic plant material in the matrix of the breccia since intrusion took place when the area was covered by swamps. Prof. Helmestaedt gave case studies on areas of diamond exploration in Canada which included Kirkland Lake (ON), Buffalo Hills (AB/BC), Smeaton (SK), Ungava Bay (QC/NF), and of course, Lac de Gras (NWT).
Mineral Deposits of the Eastern Townships
In late January, Professor Michel Gauthier from Université du Québec à Montréal (UQAM) presented "Mineral Deposits of the Eastern Townships, Québec". In his talk, Dr. Gauthier integrated the genetic models, regional geology and tectonic setting of volcanogenic massive sulphide, Mississippi Valley-type, placer gold, and sediment-hosted copper deposits occurring in Appalachian orogenic belt. Opinions on the exploration potential for each deposit type were also key points of the presentation. It was suggested that sediment-hosted copper deposits might be the best exploration targets in the Eastern Townships. Since many attendees were familiar with the area, an interesting question period followed the talk.
Olympic Dam-Kiruna Deposit Continuum
Tyson Birkett of SOQUEM Inc. visited the McGill Student Chapter in March from Québec City to present a talk detailing characteristics of Olympic Dam-type, ferrous breccia-hosted Cu-Fe-U-REE deposits. The model discussed by Birkett included elements from the classic South Australia example, as well as other deposits with similar mineralization styles, tectonic settings and ore mineral assemblages (e.g., Sue Diane, Boss-Bixbee), and deposits with links to alkaline volcanism (e.g., El Laco, Chile; Durango, Mexico). The continuum with Kiruna-type Fe-P deposits and the importance of regional-scale crustal lineaments for the location of the Cu-Fe-U-REE deposits was also emphasized. The presentation included a humorous and informative comment on the precision and accuracy of commercial analytical laboratories across the country. Unfortunately, due to concerns closer to home Tyson was unable to discuss the potential for Olympic Dam-type, ferrous breccia hosted deposits in eastern Canada.
Volcanoes, Geothermal Systems and Ore Deposits
Our final speaker of the year was Dr. Jeff Hedenquist, a consultant geologist from Ottawa, who presented "Volcanoes, Geothermal Systems and Ore Deposits" in early April. The lecture featured examples of high- and low-sulphidation precious metal deposits and their link to volcanic and geothermal systems in the circum-Pacific region. Particular emphasis was given to the Lepanto deposit in the Philippines, where it is possible to see the relationship between a porphyry-copper deposit at depth and the near-surface high-sulphidation system. Jeff also showed examples of other deposits such as Summitville (Colorado), McLaughlin (California), Yanacocha (Peru) and Hishikari (Japan), and looked at some key characteristics, such as alteration and mineralogy, between these deposits and their modern analogues.
VMS Symposium
The McGill Student Chapter, in conjunction with the department of Earth and Planetary Sciences, held a very successful one-day symposium entitled "VMS Mineralization Associated with Submarine Calderas" on March 27th. The goal of the symposium was to relate volcanological processes of calderas with the formation of VMS deposits. Over eighty delegates (including members from UQAM, Carleton, Laurentian and the University of Western Ontario SEG Student Chapters) attended this free event. The first speaker of seven was Prof. John Stix, McGill University, who presented "An Overview of Caldera Systems: Current Knowledge, Unresolved Problems, and Future Prospects". This was followed by Ben Kennedy, who spoke on "Experimental Studies Related to Fault Development in Calderas". This experimental study forms part of Ben's M.Sc. thesis at McGill University. Moving to the economic geology side of the conference, Dr. Jim Franklin, of Franklin Geosciences, gave the audience "A Tectonic Overview of VMS Settings". The last speaker in the morning, Dr. Mark Hannington, Geological Survey of Canada, concentrated on "Seafloor Hydrothermal Systems in Modern Submarine Calderas: a Global Perspective". Mark showed many examples, especially from the Pacific, which demonstrated associations between calderas, VMS and epithermal gold deposits.
Dr. Richard Fiske (Smithsonian Institute) started the afternoon session with a discussion of
active calderas in the Pacific. Dr. Fiske's talk was entitled "Submarine
Silicic Calderas South of Japan: Targets for Volcanological Studies and Economic
Breakthroughs". In his presentation he showed many examples of felsic
calderas containing appreciable mineralization. Prof. Harold Gibson,
Laurentian University, introduced the audience to ancient examples of VMS
mineralization from the Abitibi district of Canada in his talk entitled "Calderas,
Cauldrons and Volcanogenic Subsidence Structures in Ancient Successions: Recognition,
Problems, and Relationship to VMS Deposits". The final speaker of the
symposium was Prof. Wulf Mueller, University of Québec at Chicoutimi,
who also spoke about ancient examples, in "Mineralized Central Cauldron
Structures: Examples from the Hunter Mine and Normetal of the Archean Abitibi
Greenstone Belt".
The consensus was that conference participants thoroughly enjoyed the topic
and format of the symposium. Based on our success this year, the McGill Student
Chapter hopes to hold similar meetings either annually or every two years.
Potential topics for the next symposium include epithermal gold mineralization,
or carbonate-hosted base-metal deposits, and may include an accompanying field
trip.
The McGill Student Chapter would like to thank the delegates who attended the symposium and especially the invited speakers who made this event so successful. Financial sponsorship and support was provided by the Department of Earth and Planetary Sciences and the Faculty of Graduate Studies and Research at McGill University, by the Géosonde Research Group at the University of Montréal/Ecole Polytechnique, and personal donations by Prof. J. Stix and Prof. A.E. Williams-Jones.
Louvicourt Fieldtrip
Immediately following Dr. Helmstaedt's presentation, eight Chapter members departed on the five-hour journey to our fall field trip destination, the Louvicourt mine. Louvicourt, operated by Aur Resources, is a Cu-Zn-Au-Ag VMS deposit located 25 km east of Val d'Or, Quebec. Mine geologist Ron Leber was our host during the visit. Before starting the excellent underground tour, Ron gave a short talk on the exploration history and geology of the Louvicourt mine. Mining operations commenced in 1995 and, as of January 1997, the reserves were calculated to be 12.5 million tonnes grading 3.6 % Cu, 1.7 % Zn, 28 g/t Ag and 0.8 g/t Au. The mine lies in the SE region of the Archean Abitibi Sub-Province with the local geology consisting of elongated E-W-trending, overturned and steeply dipping volcanic sequences. These sequences, consisting of alternating units of massive rhyolite, rhyodacite, tuff and breccia, are thought to have been deposited in a back-arc rift environment. Orebodies occur as several distinct massive sulphide lenses and stringer zones adjacent to a major syn-volcanic fault. The deeper ore lenses within the mine are dominated by chalcopyrite while the shallowest lenses are massive and polymetallic, containing sphalerite, pyrite and chalcopyrite. The underground tour commenced by observing the footwall stratigraphy, changes in alteration, volcanic facies, mineralization, and finally deformation textures caused by subsequent tectonism as we worked our way up stratigraphy. On the surface, we were given an opportunity to examine mineralized and altered core from different parts of the mine. The McGill Student Chapter would like to thank Aur Resources and especially Ron Leber at Louvicourt Mine for an informative and well-organized tour.
Participants on the Louvicourt mine visit. Back row
from left to right: Olivier Grondin, Christian Sasseville, Mark Nelson,
Zha-Zha Plandowski, Lea-Marie Bowes-Lyon, David Dolejs, Sandy Archibald.
Front row: Jae Jong (Jane) Kwak and mine geologist Ron Leber.
Arizona-Nevada Fieldtrip
The McGill University Student Chapter of the SEG held a two-week field trip to Arizona and Nevada in mid-February. Seven Chapter members, together with two industry representatives, Victoria Yehl (Cominco Ltd.) and Grant Arnold (Noranda Ltd.) participated in the excursion. The main objective of the trip was to give participants exposure to classic porphyry Cu-Mo deposits of the American southwest, as well as to other environments such as low-sulfidation gold and volcanogenic massive sulphide (VMS) deposits. An ambitious 4700 km route was planned to take in as many ore deposits and spectacular geological features as possible.
The first ore deposit visited was ASARCO's Mission Complex mine, located 30 km south of Tucson. Our guide during the tour of this giant (3.2 km long by 2.8 km wide) porphyry Cu deposit was mine geologist Bob Smith. The Mission Complex is an end-member of the classic Guilbert and Park model for porphyry mineralization as its ore was deposited almost entirely in sedimentary rocks. Mineralization in the Mission Complex orebody occurs as disseminated and veinlet sulfides in a wide variety of calc-silicate altered sedimentary rocks (tactites). Since 1959, 700 Mt of ore grading 0.67% Cu have been mined, with a reserve of 400 Mt (grading 0.65% Cu). The ore also contains molybdenum (0.019%) and silver (0.11 oz/t).
The following day the group visited the historic mining town of Bisbee, located 130 km SE of Tucson. The day was essentially a rest day, but the first stop was the lookout over the abandoned Lavender open pit, formerly mined by Phelps Dodge. The Lavender pit is unlike other porphyry copper deposits in Arizona in that the pit is in a fluidized breccia pipe, and is Nevadan (130 Ma), not Laramide, in age. Mineralization occurs as a sulfide/oxide matrix to exotic sedimentary and metamorphic clasts. A large supergene blanket is still visible in the pit walls. It is estimated that 151.7 Mt of ore, grading 2.35% Cu, 20.9 g/t Ag, and 0.58 g/t Au, was mined in the Bisbee area.
The following day saw the party travel 200 km to spend the afternoon touring Phelps Dodge's Miami-Inspiration mine. Leading the tour for this Cu-Mo porphyry was geologist Zean Moore. The mine at Miami showed another variation of the porphyry model, this time hosted within metamorphosed rocks of the Precambrian Pinal schist. Mineralization consisted of pyrite and chalcopyrite, with a grade of 0.30 to 0.40% copper. Minor amounts of molybdenite, bornite, sphalerite and galena are also present. Tertiary to Recent weathering of the Miami-Inspiration ore body has led to the development of extensive oxidation and supergene zones. The leached cap is composed of limonite, hematite and remnant chrysocolla. Beneath this cap occurs a thick copper oxide zone. At the present rate of extraction, the Miami-Inspiration mine life is expected to be five years.
Our next mining area visited was
the inactive Jerome VMS district, 60 km southwest of Flagstaff. Hosts for the
day were consultant geologists Paul Lindberg and Will Wilkinson (Phelps Dodge). Paul started the tour by taking the party to the local museum
where he gave an overview of the geological history of the Jerome District.
A display, designed and built by Paul, at the museum illustrated clearly the
3D geometry of the United Verde orebody, and the satellite UVX orebody, in context
of the local geology.
The United Verde mine was the largest VMS deposit in the district with a total
tonnage of 33.7 Mt, producing 1.68 Mt Cu, 24000 t Zn, 47 t Au, and 1.74 t Ag.
Paul explained that the richest copper mineralization was present in the supergene
UVX orebody, where an oxidizing event during Tertiary times led to enrichment
from 4.3 to 10.3 wt. % Cu. Mining at the United Verde mine commenced in 1883
and ceased in 1953. Recent exploration has focused on an 18 Mt lens of ore containing
6.4 % Zn and <1 % Cu on the mine property.
The next stage of the tour was at the United Verde open pit were Paul and Will showed the participants a variety of diagnostic features of VMS mineralization displayed on the pit walls. Some of the features observed were the jasperoid bed (representing a post-ore exhalative horizon), intense Mg-chlorite alteration of the Lower Cleopatra rhyolite, chalcopyrite veins and stockwork cutting the footwall "black schist", and bedded pyrite (containing black smoker chimney fragments). After lunch, Paul led a tour of roadside outcrops in the immediate vicinity of the mine that concentrated on structural and stratigraphic relationships.
The Round Mountain gold mine in Nevada was our next stop (after a few days rest). Round Mountain Gold Corporation geologist Craig "Slim" Pickins was our guide for a whistle-stop tour of this vast heap-leach, low-sulfidation gold mine. The Round Mountain mine is located 80 km north of Tonapah, Nevada. The orebody is hosted in tuff units associated with a 26.5 Ma caldera that formed in and on Paleozoic metasediments overlying Cretaceous granite. Fracturing associated with caldera collapse led to the upward migration of mineralizing fluid, and of gold and silver precipitation and quartz-adularia alteration in the permeable tuff.
Most of the ore currently being mined is classified as "Type 2" (mineralized porous and permeable non-welded tuff) and has an average grade of 0.45 g/t Au. It is estimated that there are 3.7 million ounces of gold present as Type 2 ore. Also present are bonanza veins that contain between 5 and 206,000 oz per pocket! This material is taken directly to the smelter. The group was fortunate to witness a routine blast from the safe distance of the dispatch tower shortly after arriving. Unfortunately, we are unable to visit the floor of the pit and after briefly looking at the huge cyanide heap-leach pads, had to content ourselves with samples from the core-shed.
The final mine visited on the two-week field trip was the Bagdad Cu-Mo porphyry deposit also operated by Phelps Dodge. Mine engineer Pete Blakeley was on hand to guide us through the geology of this "classic" porphyry. Having visited two other Cu-Mo porphyries, we were under the naive impression that we might know what was going on. Alas, our preconceived ideas of porphyry mineralization were dashed again as we found that all of the ore at Bagdad is present within the potassic zone. Since mining first began at Bagdad in 1927, 514 Mt of ore has been mined with a grade of 0.497% Cu. Reserve calculations estimate that 750 Mt of ore remain with a grade of 0.372 % Cu and 0.022 % Mo, which amounts to a mine life of 25 years, at the current extraction rate. The mine has also produced 12 million ounces of silver. After a brief, but lucid, explanation to the geology of the deposit, Pete showed the group representative samples of alteration and ore in the core-shed. In the pit, several stops were made to compare different styles of mineralization present in the potassic altered quartz monzonite and porphyritic quartz monzonite intrusives. Of the three porphyry Cu-Mo mines visited during the field trip, Bagdad had the richest hypogene ore, where chalcopyrite was particularly abundant in stockwork veins, accompanied by minor supergene chalcocite.
The McGill Student Chapter would like to thank the Society of Economic Geologists, Cominco Ltd., Noranda Ltd., Barrick Gold Corp. and Québec Cartier Mining for their generous donations which made this trip possible. We would also like to extend our thanks to the companies (Phelps Dodge, ASARCO and Round Mountain Gold Corp.) and their staff in Arizona and Nevada, who facilitated our mine visits.
Click HERE to see pictures of the field trip.
Gold Panning at Mining Brook, Eastern Townships
The first activity organized by the Student Chapter for the academic year 2000-2001 was a gold panning trip to Mining Brook on October 1st. This famous gold panning location is situated between La Patrie and Chartierville in the Eastern Townships, close to Lac Mégantic and the Canada-US border. The native population first discovered gold in the Mining Brook in 1863. Commercial gold panning and sluicing began in 1866. Gold nuggets weighing more than 100 g were discovered. That was enough to convince seven Chapter members that the Mining Brook was the place to go. The party included six graduate and one undergraduate students.
Besides the possibility of collecting gold flakes, the main objective of the trip was to teach Chapter members how to use a pan. Panning is a great tool to concentrate heavy minerals, a method that is also applicable to diamond exploration when in search of indicator minerals. Sandy Archibald, whose experience in panning gold in Scotland proved to be quite useful, gave a panning lesson. Other members learned quickly enough to pan their own load of gravel after the first demonstration.
Although Sandy's first pan did not contain any gold, participants panned happily with hope in their eyes, during a beautiful autumn day in southern Québec. Sandy first found gold probably because of a special Scottish technique, which he kept to himself! By lunchtime, half the group had found at least one flake and put it in a sealed vial. Again, the "sticky finger" technique to transfer the gold from the pan to the vial was taught by Sandy.
Different material was panned during the day. Gravel behind boulders in the brook, soil and gravel from the riverbank, and weathered bedrock were all sampled. The schistose nature of the latter creates an excellent trap for gold flakes. A homemade sieve was used to accelerate the first stages of panning. Some participants took a back-pain-relieving break to look for large pyrite cubes (~ 1cm) in the schistose bedrock. Several pans later, just before leaving, everyone had found gold. Mysteriously, Sandy found the largest piece of gold (a micro-nugget). He must be hiding a secret!
This was the second time the McGill Student Chapter of the SEG conducted a gold panning trip. Everyone had a great time and the activity will be on the schedule again next year. The trip was good fun and an excellent learning experience re-enacting the golden years of mining in Canada.
Participants (L to R): Olivier Grondin, Chris Wright,
Azin Zangooi, David Dolejs, Oliver Schatz, Sandy Archibald, Guillaume Daniel.
The McGill Chapter of the SEG would like to thank the following corporate members for sponsorship during 1999-2000:
ALCAN
Barrick Gold Corp.
Cogema
Cominco Ltd.
Falconbridge Ltd.
INCO
SOQUEM Inc.
and the following companies who provided financial assistance for the Arizona and Nevada ore deposit trip:
Barrick Gold Corp.
Cominco Ltd.
Noranda Ltd.
Québec Cartier Mining Company
Interested in becoming a sponsor?
Should your company wish to sponsor our student chapter, then as a thank you, we shall be pleased to advertise your logo on our website and in our future promotional efforts. For more information, please contact us.