APRIL
2001
Issue 69
RECENT EXPLORATION FOR MASSIVE SULPHIDE DEPOSITS
IN CENTRAL MEXICO
Roger Moss and Brian V. Hall sources Ltd. The discovery of two large sic to Cretaceous oceanic island arc se-
Golden Temple Mining Corp. massive sulphide deposits (Francisco I. quence (Ruiz and Centeno-Garcia, 2000;
1592 Eaglecliff Road, Madero and San Nicolás) in Zacatecas Hall and Gomez-Torres, 2000a). The ter-
Bowen Island, British Columbia, State over the space of two to three years rane was accreted to the North American
V0N 1G0, Canada in the mid-nineties (Table 1), confirmed continent in the Late Cretaceous, under-
email: roger.moss@sympatico.ca the potential of Central Mexico to host went deformation during the Laramide
large volcanogenic massive sulphide Orogeny, and experienced the magmatism
bvhbowen@intergate.ca (VMS) deposits. associated with the Sierra Madre Occiden-
Golden Temple Mining Corp. has been tal and Trans Mexican volcanic arcs (Ruiz
Web: http://www.goldentemple- actively exploring for VMS deposits in and Centeno-Garcia, 2000).
cdnx.com Mexico since 1996. VMS deposits were Rocks of the Esperanza Formation
selected as the target type after recognizing
host massive sulphide mineralization at the
INTRODUCTION that the Los Gavilanes prospect, on the Apolo/Venus and El Gordo Properties
Apolo/Venus property, was an unexplored (Fig. 2). In the Leon-Guanajuato Massive
VMS deposit that contained economic Sulphide District, these rocks consist of
Although silver and gold have dominated
grades (1.14% Cu and 1.78g/t Au) over a carbonaceous argillite, calcareous shales,
the Mexican mining industry for the past
true thickness of 31 metres. Based on this and limestone interbedded with intermedi-
450 years, exploration for massive sulfide
revelation, together with the knowledge ate and felsic flows and volcaniclastic
deposits has been increasing in recent
that known VMS deposits in Mexico are rocks. The Esperanza Formation is in-
years. In 1992, Mexico’s mining law was
hosted by rocks of the Guerrero Terrane truded by the Tertiary Comanja granite,
changed such that foreign corporations
(Campa and Coney, 1983), a regional pros- and overlain by conglomerate, andesite,
could, through a Mexican subsidiary, hold
pecting program was initiated focussed on and ignimbrite, also of Tertiary age. Two
a majority interest in a mineral property in
the Esperanza Formation of the Guerrero main phases of folding and a late stage epi-
Mexico (Sanchez-Mejorada, 2000). Given
Terrane in central Mexico. This initiative sode of thrusting have been recognized in
the relative political stability and the un-
led to the acquisition of two more proper- the region (Moreton, 2000).
der-explored nature of many of the depos-
ties (El Gordo and Carmen; Fig. 1) prior to Sulphide mineralization consists of
its that did not have silver or gold as their
the staking rush sparked by the San pyrite, pyrrhotite, and marcasite with lesser
primary commodities, this created an envi-
Nicolás discovery in 1997. Subsequent ex- sphalerite, chalcopyrite, galena, and bor-
ronment whereby base metal exploration
ploration by Noranda Exploracion Mexico nite. Chalcocite and digenite locally re-
could take off. This is exactly what hap-
S.A. de C.V. (Noranda), under a joint ven- place chalcopyrite and bornite at the El
pened in Mexico during the mid to late
ture with Golden Temple, succeeded in Gordo deposit. This replacement-type min-
nineties. Initial efforts, focussed in Guer-
defining a small 600m by 500m massive eralization can be high grade as shown by
rero State, included the Campo Morado
sulphide body on the Apolo/Venus prop- the 9.3m intersection grading 4.3% Cu,
project of Farallon Resources, and the
erty and a 675m by 300m body of massive 0.01% Zn, 0.01% Pb, 0.35g/t Au, and
Mamatla project of Valerie Gold Re-
and semi-massive sulphide on the El 33.5g/t Ag in hole EG99-03. Supergene
Gordo property (Fig. 2). copper mineralization occurs as chalcocite-
,QVLGH WKLV LVVXH
malachite-chrysocolla at El Gordo and as
GEOLOGY chalcanthite (CuSO4.5H2O) –malachite -
3UHVLGHQW·V 0HVVDJH The massive sulphide deposits and pros- azurite at Los Gavilanes. Sampling of un-
pects of central Mexico are hosted by rocks derground workings at Los Gavilanes pro-
*RUGRQ &RQIHUHQFH of the Guerrero Terrane, typically exposed duced an intersection of 1.14% Cu, 0.02%
as erosional windows in Tertiary volcanic Pb, 0.03% Zn, 1.78g/t Au and 20.0g/t Ag
%RRN 5HYLHZ rocks (Fig. 1). The Guerrero Terrane con- over a true thickness estimated at 31m
sists of two tectonic assemblages: Triassic (Hall and Gomez-Torres, 2000a).
%DWKXUVW *HRSK\VLFDO $WODV to middle Jurassic oceanic volcanic rocks Quartz-sericite is the dominant altera-
6XSHULRU 3*( )LHOG &RQIHUHQFH and ocean-floor sedimentary rocks derived
(Continued on page 4)
from continental sources, and a late Juras-
0,1( 5$/ '(32 6,7 6 ',9, 6,21 (;(&87,9 ( /, 67
0,1(5 '(326 ',9,6 ;(&87,9( /,6 MDD Goals and Objectives
Chairperson: Andrew Conly The Gangue is published quarterly by the Min-
Dept. of Geology, Univ. of Toronto, 22 Russell St. Toronto, ON M5S 3B1; Tel: eral Deposits Division of GAC and is distrib-
(416) 978-0657; FAX: (416) 978-3938; email: aconly@quartz.geology.utoronto.ca uted to its members. The Mineral Deposits Di-
vision of the Geological Association of Canada
Past Chairperson: Jason Dunning is Canada’s foremost society for promoting the
Hudson Bay Exploration and Development Co. study of mineral deposits by supporting local
800-700 Pender St. W., Vancouver, BC V6C 1G8; and national meetings, symposia, short courses
Tel: (604) 684-1454; FAX: (604) 689-3480; email: hbed@istar.ca and field trips. We sponsor the publication of
research relating to ore deposits and metallog-
Vice Chairperson: Stephan J. Piercey eny, and recognize the contributions of out-
MDRU, Dept. of Earth & Ocean Sciences, University of British Columbia, 6339 standing Canadian economic geologists by an-
Stores Rd., Vancouver, BC V6T 1Z4; Tel: (604) 822-6654; FAX: (604) 822-6088; nually awarding the Duncan Derry and Wil-
email: spiecey@eos.ubc.ca liam Harvey Gross medals and the Julian
Boldy Certificate.
Secretary: Gary S. Wells
Inmet Mining Corporation, 3rd Floor, 311 Water Street, Vancouver, B.C. V6B Publication Schedule:
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Treasurer: Robert J. Cathro
September 15 October
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or, Arizona, Tel/Fax: (602) 423-1006; email: bobcat@direct.ca Information for contributors:
The objective of this newsletter is primarily to
provide a forum for members and other profes-
Publications: Dirk Tempelman-Kluit sionals to voice new ideas, describe interesting
4697 West 4th St., Vancouver, BC;
mineral occurrences or expound on deposit
Tel/FAX: (604) 224-5582; Fax: (604) 224-6903; email: dirktk@telus.net
models. Articles on ore deposits, deposit mod-
els, news events, field trips, book reviews, con-
Professional Development – Short Courses, etc.: Robert Linnen ferences, reprints of presentations to compa-
Department of Earth Sciences, University of Waterloo, Waterloo, ON N2L 3G1; nies, mining groups or conferences, or other
Tel: (519) 888-4567 (ext. 6929); Fax: (519) 746-7484; material which may be of interest to the eco-
email: rlinnen@uwaterloo.ca nomic geology community are welcome.
Manuscripts should be submitted by email in
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ity. Short items dealing with news events or
Program Chair for St. John’s 2001: Derek Wilton meetings can be submitted by FAX, postal
Department of Earth Sciences, Memorial University of Newfoundland, St. John's, mail or email. Contributions may be edited for
NF A1B 3X5; Tel: (709) 737-8389; Fax: 709-737-2589; clarity or brevity.
email: dwilton@sparky2.esd.mun.ca
For Information & Submissions:
• Medals Committee: Dan Marshall David Lentz – THE GANGUE
Dept. of Earth Sciences, Simon Fraser Univ., Vancouver, BC
Tel: (604) 291-5474; Fax: (604) 291-4198; email: marshall@sfu.ca Dept. of Geology, Univ. of New Brunswick,
Fredericton, NB E3B 5A3
Email: dlentz@unb.ca
NEW MDD Website:
Steven McCutcheon – THE GANGUE
http://mdd.harbour.com/ N.B. Geological Survey, PO Box 50,
495 Riverside Drive, Bathurst, NB E2A 3Z1
Email: Steve.McCutcheon@gnb.ca
April 2001 – Gangue No. 69
MDD DIRECTORS President’s Message
• Georges Beaudoin (2000-2003) Dear Members,
Dept. de geologie et de genie geologique,
l’Universite Laval, Quebec City, QC; Tel: As the GAC-MAC in St. John’s quickly approaches my term as MDD Chair is com-
(418) 656-3141; Fax: (418) 656-7339; email: ing to an end. For me serving as your Chair has been a tremendous experience and I
beaudoin@ggl.ulaval.ca look forward to continuing my service in the more sedate role as Past-Chair.
• Mike Lesher (2000-2003) As always the Division had an active year. Highlights include the release of the
Dept. of Earth Sciences, MERC, Laurentian Latin American VMS Volume (January) and co-sponsorship and participation in the
Univ., Sudbury, ON; Tel: (705) 675-1151 NUNA Conference on Future Directions in Mineral Deposit and Metallogenic Re-
ext 2276; Fax: (705) 673-6508; email: search (March). Unfortunately, the Sullivan Volume has been further delayed.
lesher@@sympatico.ca However, we are hoping the volume will be sent to the printers sometime in the
summer, so it will be available prior to the closing events at the Sullivan Mine in
• Tom Lane (2000-2003) October/November. Of course the MDD is involved in the GAC-MAC meeting
Consultant., Toronto, ON with sponsorship of two field trips (Metallic Mineral Deposits of Central Newfound-
email: tom.lane@sympatico.ca land and Base-Metal Deposits of the Bathurst Mining Camp), the Special Session on
Geochemistry of Inorganic Sedimentary Rocks and The Geology of North Atlantic
• Dan Marshall (1999-2002) Mineral Deposits that is part of the North Atlantic Minerals Symposium. Unfortu-
Dept. of Earth Sciences, Simon Fraser Univ., nately, the MDD/GAC-sponsored short course on Inorganic Geochemistry of Sedi-
Vancouver, BC; Tel: (604) 291-5474; Fax: ments and Sedimentary Rocks: from Research to Exploration Applications had to be
(604) 291-4198; email: marshall@sfu.ca cancelled because of insufficient numbers. However, the MDD and GAC Publica-
tion Committee are currently discussing alternative formats for publishing the
• Dave Peck (1999-2002) course notes. Apart from the above trips and sessions, the St. John’s meeting has a
Falconbridge Exploration Ltd. strong economic geology component that includes sessions on Archean-
21C Murray Park Road, Winnipeg, MB; Paleoproterozoic Crustal Evolution and Metallogeny, Geology of the Voisey’s Bay
Tel.: (204) 888-9860; Fax: (204) 885-4152; Deposits, Environs and Analogs, and The Henry Longerich Session: New Develop-
Email: dpeck@falconbridge.com ments in LAM-ICP-MS Analytical Techniques, as well as a diverse general eco-
nomic geology session.
• Jeremy Richards (1999-2002)
I thank all the members of the Executive Council and Board of Directors for their
Dept. of Earth Sciences, Univ. of Alberta,
hard work and advice over the year, your dedication and efforts made my job easier
Edmonton, AB; Tel: (403) 492-3430; Fax:
and ensured the continued success of the MDD. Also I want to acknowledge the
(403) 492-2030;
work of all people involved in organizing the MDD-sponsored events over the year,
email: Jeremy.Richards@ualberta.ca
for it is they who take MDD support and turn it into a tangible benefit to our mem-
• Derek Wilton (1999-2002) bers. The Board of Directors is seeing a change of face with Mike Sweeney and
Dept. of Earth Sciences, Memorial Univ. of Bob Friesen completing their terms and welcomes the recent appointments of Jan
Nfld., St. John’s, NF; Tel: (709) 737-8389; Peter and John Thompson. As for Executive Council, Charlie Jefferson is stepping
Fax: (709) 737-2589;email: dwil- down as Award Co-ordinator, but Dan Marshall, who is also a MDD Director and
ton@sparky2.esd.mun.ca our new Webmaster, has offered to oversee MDD awards. Jason Dunning is vacat-
ing the position as Past-Chair, marking the end of his three-year term on Executive
Council. At present we are still searching for a new Vice-Chair, but will have a
• Bob Friesen (1998-2001) nomination(s) in place for the annual MDD business meeting. And finally, Steve
Teck Exploration, Kamloops, BC; Tel: (250)
Piercey will be taking over as Chair. Steve has served the MDD well as Vice-Chair
372-0032; Fax: (250) 372-1285;
and I expect him to provide excellent leadership for the coming year.
email: gfriesen@wkpowerlink.com
I thank all the membership for their continued support and hope that you are well
• Mike Sweeney (1998-2001) served by the Division.
Falconbridge Exploration, Falconbridge,
ON; Tel: (705) 693-2761 ext. 3655; Fax: Sincerely,
(705) 699-3600; email:
Mike_Sweeney@sudbury.falconbridge.com Andrew Conly
Andrew G. Conly
MDD Chairman 2000-2001
April 2001 – Gangue No. 69 3
Figure 1. Distribution of massive sulphide deposits of the Guerrero Terrane, Mexico (modified from Hall and Go-
mez-Torres, 2000b).
Figure 2. Regional geology of the Leon-Guanajuato massive sulphide district (after Hall and Gomez-
Torres, 2000a).
April 2001 – Gangue No. 69
Year Property Company Work Results Ref.
1976 - Francisco I. Consejo de Recursos Min- Geophysics & Drilling Dropped property in 1983Giles & Ga-
1983 Madero erales vier –Garcia,
2000a,b
1994 El Salvador Minera Dolores, Angustias Trenching Discovered new zone of cop- Johnson et al.,
y Anexas per oxide mineralization 2000
1994 - Francisco I. Industrias Penoles 135,000 metres of diamond Calculated proven and prob- Giles & Ga-
1996 Madero drilling able reserves of 40Mt of 40g/t vier –Garcia,
Ag, 0.8% Pb and 5.2% Zn 2000a,b
1996 Apolo/Venus Golden Temple Mining Project generation and acqui- Recognized potential for Hall and Go-
sition VMS-type mineralization at mez-Torres,
Los Gavilanes 2000a
1996 El Salvador Teck/Western Copper Detailed mapping, geochem- 2.1m of massive sulphide grad- Johnson et al.,
istry and drilling ing 2.07% Cu, 1.53% Pb, 2000
16.57% Zn, 3.68g/t Au and
213 g/t Ag in hole SAL-5.
1996-1997 El Salvador Teck/Western Copper Reconnaissance prospecting, Several targets outlined Johnson et al.,
geochemistry and mapping, 2000
and airborne geophysics
1997 El Gordo Golden Temple Mining Regional prospecting focus- Discovery of 50m wide out- Hall and Go-
sed on finding windows of crop of massive sulphide mez-Torres,
Esperanza Formation in Terti- hosted by felsic volcanic rocks 2000b
ary cover
1997 El Salvador Teck/Western Copper Orientation geophysical sur- Time-domain gradient array Johnson et al.,
veys carried out over the El induced polarization (IP) deter- 2000
Salvador deposit mined to be most effective fol-
low up technique
1997 Carmen Golden Temple Mining Regional Mapping and Pros- Recognition of VMS potential This Paper
pecting
Mid. 1997 El Salvador/San Teck/Western Copper Gradient array IP surveys A large (500 × 500m) anomaly Johnson et al.,
Nicolás characterized by high charge- 2000
ability and low resistivity
found at San Nicolás
Nov. 1997 San Nicolás Teck/Western Copper Drilling Discovery of the San Nicolás Johnson et al.,
main sulphide zone 2000
1998-2000 El Gordo Golden Temple Mining/ Geochemistry, geophysics Outlined a 675 × 300m body This paper
Noranda and drilling of massive & semi-massive
sulphide
1998-2000 Apolo/Venus Golden Temple Mining/ Geochemistry, geophysics Succeeded in outlining a small This paper
Noranda and drilling (600m by 500m) VMS body
and developing several pros-
pects
included geochemical, geological and geophysical surveys and
tion type on both properties and occurs in both hanging wall and diamond drilling.
footwall rocks, although it is stronger in the footwall. Silicifica-
tion is particularly intense immediately below mineralized inter-
Geochemical Surveys
vals, commonly with strong chloritization. The chlorite appearsA stream sediment survey over the Apolo/Venus property, at a
to be restricted to mineralized zones, whereas the quartz-sericite
sample density of approximately 2 samples per square kilometre,
alteration is more widespread. was successful in defining six areas with anomalous Ag, Cu, Pb
and Zn. These areas coincide with the occurrence of the favour-
EXPLORATION PROGRAMS able Esperanza stratigraphy (Fig. 3). Regional (1:250,000) scale
Exploration carried out by Noranda, under option agreements on stream sediment data released in 2000 by the Consejo de Recur-
the Apolo/Venus and El Gordo properties during 1999 and 2000, sos Minerales (the Mexican Geological Survey) further indicate
A pril 2001 – G angue N o. 69 5
Figure 3. Regional geology and stream sediment geochemistry of the Apolo/Venus property. (after
Hall and Gomez-Torres, 2000a).
Figure 4. Lead distribution in soil samples, Apolo/Venus property. (after Hall and Gomez-Torres, 2000a)..
April 2001 – Gangue No. 69
Figure 5. Compilation map of the El Gordo grid (after Hall and Gomez-Torres, 2000b).
very anomalous values in streams draining the area between Paz de Mexico and El Gato (Fig. 3).
The highest values in the stream sediment survey came from the Los Gavilanes and Cerro Colorado areas in the south of the
property, and these were selected for detailed follow up by soil sampling, ground geophysics, and mapping. Soil sampling on a grid
covering the Los Gavilanes and Cerro Colorado areas outlined four regions of anomalous copper, lead, zinc, gold, and silver (Fig. 4).
Geological mapping revealed that all four of these anomalies are underlain by gossans representing oxidized sulphide mineralization.
A stream sediment survey was attempted on the El Gordo property, but was abandoned after only eight samples were collected.
Soil sampling, undertaken on a grid covering the immediate vicinity of the discovery outcrop, resulted in a large (1700m × 800m)
Cu-Pb-Zn-Au-Ag anomaly (Fig. 5). The highest copper values (up to 4,806 ppm) were found to be associated with chalcocite, mar-
casite, and chrysocolla mineralization in subcrop, revealed during construction of a drill road. Channel samples across this mineral-
ized interval averaged 1.31% Cu over a 29m true width.
Geophysical Surveys
An airborne geophysical survey consisting of electromagnetics, magnetics, and radiometrics was carried out at a line spacing of 200
metres over the Apolo/Venus and El Gordo properties. Unfortunately, the lines were flown too high and the results of the survey
were of limited use. However, an aeromagnetic anomaly in the vicinity of Los Gavilanes, associated with an induced polarization
April 2001 – Gangue No. 69
Figure 6. Induced polarization results, Apolo/Venus property (after Hall and Gomez-Torres, 2000).
(IP) anomaly, was drilled and returned a 7.8m intersection of semi-massive to massive sulphide consisting dominantly of pyrrhotite
(Hall and Gomez-Torres, 2000a).
A dipole-dipole IP survey with a 50m electrode separation was carried out over the Los Gavilanes and Cerro Colorado area.
This survey resulted in four main chargeability anomalies parallel to stratigraphy and approximately coincident with the soil
anomalies (Fig. 6). A Max-Min electromagnetic survey on the El Gordo grid outlined four conductors sub-parallel to the regional
strike and slightly offset from the soil anomalies (see Fig. 5).
Diamond Drilling
Drilling of the electromagnetic conductors on the El Gordo property produced mixed results. The largest conductor, located in
the central part of the grid, was drill tested by hole EG99-01, but failed to intersect the favourable stratigraphy. The cause of this
conductor and a parallel conductor to the northeast remain unexplained. However, drilling of a very weak conductor farther to the
north (drill hole EG99-03) revealed several massive and semi-massive sulphide units totaling 39.15m, with a 9.3m intersection
grading 4.3% Cu. This copper-rich mineralization is dominantly pyrite and chalcocite, with lesser digenite, chalcopyrite, and bor-
nite.
Results from the drilling of combined IP and soil geochemistry targets on the Apolo/Venus property were more consistent.
Most holes in the drill program intersected massive and/or semi-massive sulphide and a small (800 × 600 m) massive sulphide
body, which remains open in three directions, was successfully delineated.
Comparison to Other Massive Sulphide Deposits in Central Mexico
The Francisco I. Madero and San Nicolas deposits, discovered in the mid to late nineties, are perhaps the best known massive
sulphide deposits in Central Mexico. The exploration of the San Nicolás - and the earlier discovery, San Salvador - has been well
documented by Scammell et al. (1999, 2000) and Johnson et al. (2000).
April 2001 – Gangue No. 69
The San Nicolás deposit is overlain by 100m of conductive overburden (Scammell et al., 2000) and the descriptions of the ex-
ploration for this deposit are understandably biased towards geophysical techniques. As in the case of exploration on the El Gordo
property, electromagnetic surveys (including UTEM) gave inconclusive results over the San Nicolás area. Reconnaissance IP/
resistivity surveys were likewise ambiguous (Scammell et al., 2000). A gradient array IP/resistivity survey was found to be the most
cost-effective exploration tool. Drill testing of a high chargeability / low resistivity anomaly measuring 500 × 500m resulted in a
179.7 m intersection of massive sulphide and the discovery of the San Nicolás deposit (Scammell et al., 2000; Johnson et al., 2000).
There is little description of the exploration techniques used in the discovery and delineation of the Francisco I. Madero mas-
sive sulphide deposit. However, Industrias Peñoles favours aeromagnetics, ground magnetics, IP, and gravimetry combined with soil
sampling as valuable techniques for defining drill targets (Giles and Garcia, 2000a,b).
CONCLUSIONS
Recent exploration for massive sulphide deposits in central Mexico may have been inspired by the recognition that many de-
posits previously classified as skarn or vein-type deposits have characteristics analogous to those found in exhalative massive sul-
phide systems. This was the thinking behind the acquisition of the Apolo/Venus property and, together with knowledge of the distri-
bution of such deposits, resulted in the discovery of massive sulphide mineralization on the El Gordo and Carmen properties during a
regional prospecting program.
The results of exploration programs carried out on these properties, combined with published data describing exploration pro-
grams on the San Nicolás and Francisco I. Madero suggest techniques that may be useful in exploring for volcanogenic massive sul-
phide deposits in Central Mexico.
• In areas without significant overburden, such as El Gordo and Apolo/Venus, regional stream sediment surveys provide a means
for targeting areas for more detailed follow up. Sample densities as low as one sample per 35 km2 (based on Government sur-
veys) picked up mineralization on the Apolo/Venus property.
• Prospecting is still a valuable exploration technique in much of Mexico, as indicated by the discovery of a 50m wide outcrop of
massive sulphide on the El Gordo property.
• Soil sampling resulted in anomalies that were later found to be underlain by mineralization, and which broadly correspond to
geophysical anomalies.
• Ground electromagnetic surveys produced ambiguous results at El Gordo and San Nicolás.
• Induced polarization methods have fared better. For example, the discovery hole of the San Nicolás deposit tested an anomalous
zone of high chargeability and low resistivity and intersected 179.7 m of massive sulphide.
• Subsequent to the discovery of the San Nicolás deposit detailed gravity, real section IP and controlled source audio magnetotel-
lurics (CSAMT) were conducted over the deposit. All of these techniques successfully imaged the deposit. (Scammell et al.,
2000).
An integrated exploration program making select use of the above techniques together with detailed geological mapping and
lithogeochemistry appears to be the most effective way of exploring for VMS deposits in central Mexico.
REFERENCES
Campa, M.F. & Coney, P.J.,1983. Tectono-stratigraphic terranes and mineral resource distributions in Mexico. Canadian Journal of
Earth Science, v.20, p. 1040-1051.
Giles, D., A. & Garcia F. J., 2000a. Volcanogenic deposits in Mexico: the producing mines: In Sherlock, R., and Logan, M.A.V. eds.
VMS deposits of Latin America. GAC Mineral Deposits Division, Special Publication No. 2, p. 135-140.
Giles, D., A. & Garcia F. J., 2000b. VMS orebodies in Mexico: the producing mines. GAC-MAC Annual Meeting, Calgary 2000,
Program with abstracts.
Hall, B.V. & Gomez-Torres, P.P., 2000a. Geology and exploration of the Los Gavilanes deposit, Leon, Mexico – a bimodal-
siliciclastic volcanogenic massive sulphide deposit: In Sherlock, R., and Logan, M.A.V. eds. VMS deposits of Latin America. GAC
Mineral Deposits Division, Special Publication No. 2, p. 167-182.
Hall, B.V. & Gomez-Torres, P.P., 2000b. The El Gordo volcanogenic massive sulphide deposit, Leon-Guanajuato District, central
Mexico: In Sherlock, R., and Logan, M.A.V. eds. VMS deposits of Latin America. GAC Mineral Deposits Division, Special Publica-
tion No. 2, p. 163-166.
April 2001 – Gangue No. 69
Johnson, B.J., Montante-Martinez, J.A., & Canela-Barboza, M, 2000. Geology of the San Nicolas deposit, Zacatecas, Mexico: In
Sherlock, R., and Logan, M.A.V. eds. VMS deposits of Latin America. GAC Mineral Deposits Division, Special Publication No. 2,
p. 71-85.
Moreton, C., 2000. Structural analysis at El Gordo. Unpublished Internal Report, Noranda Exploration, 13 p.
Ruiz, J. & Cento-Garcia, E., 2000. The Guerrero Terrane of western Mexico: geology and massive sulphide deposits: In Sherlock,
R., and Logan, M.A.V. eds. VMS deposits of Latin America. GAC Mineral Deposits Division, Special Publication No. 2, p. 47 -
56.
Sanchez-Mejorada, R., 2000. Mining law in Mexico. Mineral Resources Engineering, v. 9, p. 129-139.
Scammell, D.R., Johnson, B., Motante, A., Kearvell, G., & Janzen, J., 1999. Geology and exploration of San Nicolas polymetallic
(Zn-Cu-Au-Ag) volcanogenic massive sulphide deposit, Zacatecas State. Proceedings with abstracts, Cordilleran Round up Van-
couver, January, 1999, p. 64-65.
Scammell, D.R., Pawluk, C.R., & Mertens, R., 2000. Successful integrated exploration applied in Mexico: A case history of the
San Nicolás VMS deposit. Proceedings Mining Millennium 2000, PDAC – CIM joint annual meeting, Toronto, March, 2000.
ACKNOWLEDGEMENTS
Pedro Pablo Gomez Torres of Templo Dorado S.A. de C.V. and Curt Hogge, Noranda Exploracion, Mexico S.A. de C.V. are
thanked for their significant contributions to the Apolo/Venus and El Gordo exploration programs.
FORMATION, MODIFICATION AND PRESERVATION OF ORE DEPOSITS
August 19-24, 2001, Proctor Academy, Andover, New Hampshire
John Thompson & Jeff Hedenquist, Co-Chairs
Jean Cline, Vice-Chair
The theme of the 2001 Gordon conference will be the formation, modification and preservation of ore deposits, with a particular
focus on geochemical processes related to tectonic, climatic and surficial factors. The conference is scheduled for August 19-24,
2001 at Proctor Academy, New Hampshire. Space will be limited and the organizers will be seeking expressions of interest from
those in academia, government, and industry with interests in this general topic. Students will be encouraged to attend and subsi-
dies for students are anticipated. Formal announcements will follow later this year with registration details in early 2001. If you
wish more information in the meantime, please contact Jeff Hedenquist - Gordongeochem@aol.com
Website: www.grc.uri.edu. Click on 2001 Meetings, "Inorganic Geochemistry" for session and speaker updates.
The provisional program is as follows:
Sunday p.m.: Industry Perspective: A review of the characteristics of economic metal concentrations; Chair: Eric Seedorff
Monday a.m.: Metal mobility in the natural environment, chemical and biological processes involved in metal mobility; Chair
Gordon Southam
Monday p.m.: Climate, tectonics and metal mobility interrelationships among large-scale climatic/tectonic processes and metal
mobility and concentration ; Chair: Dick Holland
Tuesday a.m.: Supergene enrichment - Cu and Au processes leading to the near-surface concentration of Cu & Au ; Chair: Rich-
ard Sillitoe
Tuesday p.m.: Tectonics and ore deposits large-scale tectonic processes leading to metal concentration and the formation of ore
deposits; Chair: Dick Tosdal
Wednesday a.m.: Supergene enrichment - Fe, Ni and Mn processes leading to near-surface concentration of Fe, Ni & Mn;
Chair: Hiroshi Ohmoto
Wednesday a.m.: Preservation and destruction of ores processes that may preserve or destroy metal concentrations in subaerial
and submarine environments; Chair: Steve Kesler
Thursday a.m.: Crustal fluid circulation processes of fluid flow in the crust that may concentrate metals; Chair: TBA
Thursday p.m.: Research Frontiers—panel discussion; Chairs: Ross Large & Larry Cathles
April 2001 – Gangue No. 69
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April 2001 – Gangue No. 69
Book Review
Geophysical Atlas of Massive Sulphide Signatures: Bathurst Mining Camp, New Brunswick, by
M.D. Thomas, J.A. Walker, P. Keating, R. Shives, F. Kiss, and W.D Goodfellow, 2000.
Geological Survey of Canada Open File 3887/New Brunswick DNRE Open File 2000-4.
This richly illustrated, 11” by 17” atlas is a product of the EXTECH (Exploration Technology) II project which ran from 1994
to 1999 with funding from government and industry sources. The principal objective of EXTECH-II was to enhance the potential for
new mineral discoveries in the Bathurst Mining Camp of northern New Brunswick. As indicated in the preface, the volcanogenic
massive sulphide deposits of the Bathurst Mining Camp make it one of Canada’s most important mining areas accounting for ap-
proximately 25%, 30%, and 19% of Canada’s production of zinc, lead, and silver respectively. Recoverable reserves at the camp’s
largest mine, Brunswick #12, are however nearing exhaustion, making the search for new deposits especially important.
The atlas showcases results of a high resolution helicopter-borne magnetic, electromagnetic (EM), and radiometric survey ac-
quired over the Bathurst Mining Camp in 1995 and released in 1996. The survey covered a region measuring roughly 45 km by 45
km with flight lines spaced 200 m apart. The complex geology and structure of the camp, combined with the many known VMS de-
posits exhibiting a variety of physical property contrasts in well-studied geological settings, make it ideal for highlighting the capa-
bilities of a modern airborne survey. This is fitting in a historical sense as the Heath Steele deposit discovered in 1953, is widely re-
garded to have been the first airborne EM discovery in the world.
The atlas is much more however, than a series of brightly-coloured maps. The authors have added great value by integrating the
airborne data with ground-based gravity surveys and by relating geophysical signatures to the geological settings for individual de-
posits as well as for the camp as a whole. The text is also a great resource, citing more than 150 original papers, government reports,
and assessment reports listed in the references.
Section 1 presents an overview of the Bathurst Mining Camp’s geology – its stratigraphy and complex structure, the tectonic
model thought to give rise to the massive sulphide deposits, and major characteristics of the deposits themselves. Section II describes
the high resolution airborne survey and includes brief tutorials on the geophysical methods employed. Significantly, it includes ta-
bles of physical properties (density, magnetic susceptibility, and electrical conductivity), measured on core samples of sulphides and
host rocks from several deposits. Section II concludes with colour maps of the total magnetic field, the vertical magnetic gradient,
apparent conductivity, and equivalent thorium content for the entire mining camp as derived from the high resolution airborne sur-
vey. A lower resolution Bouguer gravity map based on pre-existing regional data is also provided. Superposition of geological
boundaries on the geophysical maps shows how remarkably useful the magnetic and apparent conductivity maps are for identifying
and/or confirming structural trends, geologic contacts and faults throughout the camp.
Section III presents the geophysical signatures of 20 massive sulphide deposits in the Bathurst Mining Camp and accounts for
83 of the volume’s 105 pages. Information on each deposit is given in a 4-page format. Page 1 describes the deposit’s geologic set-
ting, and points out the significance of the major features evident (or sometimes absent) in the geophysical maps and profiles that
follow. Pages 2 and 3 present a geological map of the deposit and 10 geophysical maps displayed at exactly the same scale, covering
an area roughly 2.5 by 2 km. These include maps of the topography with flight lines, the Bouguer gravity field, the total magnetic
field, the (calculated) vertical magnetic gradient, the apparent conductivity at 4433 Hz, the EM profiles and anomalies along each
flight line, and four gamma ray spectrometry maps showing %K, ppm eU, ppm eTh, and the eTh/eU ratio. The gravity maps, present
for all but four deposits, are based on detailed deposit-specific surveys and are a valuable complement to the airborne data. The maps
are followed by a geological cross section with geophysical profiles displayed above. Page 4 presents a full suite of the airborne geo-
physical profiles measured along one flight line crossing the deposit.
The authors are to be commended on the clarity and consistency of data presentation, and on their concise written summaries
for each deposit. Maps of the flight lines and (in most cases) gravity station locations show clearly how well each deposit has been
surveyed. Common map scales and sizes permit easy comparison of the geophysics to the geology and topography, while common
colour scales simplify comparisons between deposits. The utility of having several different geophysical maps in order to distinguish
a massive sulphide signature from geological noise is well illustrated by this format.
The only significant ambiguity that I noted in the case studies was an (acknowledged) uncertainty in georeferencing of the
Heath Steele gravity map. It’s unfortunate that the authors were not able to confirm whether an observed gravity high, striking paral-
lel to this noteworthy deposit, was indeed misplaced 200 m to the south.
One could easily argue that this atlas should be required reading for any geoscientist involved in or contemplating exploration
in the Bathurst Mining Camp. It should also be valuable as a source of high quality case studies for those involved in VMS explora-
tion elsewhere, and for those involved in teaching exploration geophysics. It’s utility as a teaching tool, and in the development of
geophysical modelling algorithms, could be further enhanced if the authors were to make full sets of the digital data (airborne, grav-
ity, and topographic data as well as the geologic maps) available on an accompanying CD for a few of the 20 deposits covered.
Prof. Karl E. Butler, P.Geo., P.Eng., Department of Geology, University of New Brunswick, Fredericton, NB
April 2001 – Gangue No. 69
Geophysical Atlas of Massive Sulphide Signatures,
Bathurst Mining Camp, New Brunswick
This Open File is a product of the Exploration and Technology Research (EXTECH-II) project carried out in the period 1994-1999.
The report is a joint publication of the Geological Survey of Canada and the New Brunswick Department of Natural Resources and
Energy, and is available in both hard copy and CD-ROM versions. The former is a 105-page (11 by 17 inches) coloured document,
and the latter contains the digital counterpart in pdf file format, readable with Adobe Acrobat Reader®. Both are available from the
addresses provided at the end of this note. Costs are $125 for the hard copy (spiral bound) and $45 for the CD-ROM.
The atlas was produced primarily in response to a request by the New Brunswick Prospectors and Developers Association for a
well-illustrated volume depicting geophysical signatures associated with volcanogenic massive sulphide (VMS) deposits of different
size, geological setting, and mineralogy in the Bathurst Mining Camp. It contains a comprehensive summary of the geology and tec-
tonic history of the Bathurst Mining Camp, the geophysical techniques used to obtain the illustrated data sets, the airborne survey,
and regional (camp-wide) geophysical maps. Economic geologists will find the capsule descriptions of the geology of each of the 20
major sulphide deposits, along with a surface geology map and representative section particularly useful.
The multiparameter geophysical characteristics of each deposit are described and portrayed in a four-page layout. Each layout
includes a colour surface geological map and a cross-section showing the sub-surface distribution of the sulphide mineralization, and
colour contour maps and profiles of magnetic, electromagnetic (EM), radiometric, and gravity data. The magnetic, EM and radio-
metric data were collected by a helicopter-supported, high resolution airborne geophysical survey (200 m line spacing; 60 m mean
terrain clearance). The gravity data were obtained from ground surveys undertaken by private companies and the Geological Survey
of Canada.
The suite of geophysical images illustrated in this atlas reflects the diverse geological and structural settings, morphologies, and
mineralogical compositions of VMS deposits in the Bathurst Mining Camp. As such it provides a range of comparative geophysical
fingerprints that could help influence and enhance the planning of new exploration programs, not only in the Bathurst Mining Camp,
but also in other VMS camps where the geological setting is similar.
Copies of this report (hard copy and CD-ROM) are available from the following outlets:
1) Geophysical Data Centre
Geological Survey of Canada
615 Booth St., room 235
Ottawa, Ontario K1A 0E9
Tel : (613) 995-5326
Fax : (613) 952-8987
E-mail : infogdc@agg.NRCan.gc.ca
www: http://gdcinfo.agg.nrcan.gc.ca/toc.html?/gdc/
2) New Brunswick Department of Natural Resources & Energy
Minerals and Energy Division
P.O. Box 6000
Fredericton, New Brunswick E3B 5H1
Tel: (506) 453-2206
Fax: (506) 453-3671
E-mail : Geoscience@gnb.ca
www: http://www.gnb.ca/0078/minerals
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April 2001 – Gangue No. 69
Sullivan Mine meeting
November 9th and 10th
After roughly a century since first production, the Sullivan Mine will finally close at the end of this year.
To help mark the occasion, we are having a geological meeting in Kimberley on November 9th and 10th.
This letter constitutes a first circular for the meeting.
We are planning a day of talks on the Friday and mine tours on the Saturday. Dr. H.C. (Hugh) Morris and
Dr. F.R. (Rob) Edmunds, two well-known former employees of Cominco at Sullivan, are organizing the
talks, which will comprise a mixture of reminiscences and current synopses of the science that has come out
of government, university and our own work over many years.
The tours on Saturday will comprise underground and surface visits at the mine, as well as unstructured time
at a poster session/chat room in downtown Kimberley. Although there is not a lot left to see underground,
mine management are going all out to make this last opportunity to collect samples of folded Sullivan ore as
valuable as possible for the maximum 180 geologists we can accommodate underground that day. Fresh
material will be blasted off the wall of a drift through bedded ore in a shaft pillar on 3600 level, and left on
the floor for collecting.
Naturally, there is no registration fee for this meeting. Also, we have block booked some hotels at favour-
able rates. However, to help us plan some of the events, we seek an expression of interest at this time. The
second circular will provide more details, including hotel costs, and a registration form. If you would like to
receive it, or know of a colleague who would, please send either an email or a postal address to Helen Au-
gustin at helen.augustin@cominco.com or the above address.
We hope you can help us mark this milestone in the many decades of geologi-
cal and exploration work in and around the Sullivan orebody.
John M. Hamilton
Manager, Acquisition Evaluations
john.hamilton@cominco.com
Cominco Ltd., 500 – 200 Burrard Street, Vancouver, B.C. Canada V6C 3L7
Tel: (604) 682-0611 / Exploration Fax: (604) 844-2516
MDD members are invited to subscribe to the journal
Exploration and Mining Geology,
edited by Jim Franklin
Issues for volume 8 of CIM’s quarterly journal Exploration and Mining Geology
(EMG) are nearly ready for distribution. The first will be a special issue on
South American ore deposits and the second will be a special issue on seafloor
hydrothermal deposits. Subscriptions to volume 8 are available to members of
MDD at a special affiliated rate of $CDN 75/ $US 55. Subscription forms are
available from the EMG website (http://www.cim.org/geosoc/indexEmg.html).
April 2001 – Gangue No. 69
CIM GEOLOGICAL SOCIETY
FIELD CONFERENCE
SEPTEMBER 16 - 19, 2001
THUNDER BAY, ONTARIO
SUPERIOR PGE 2001, the CIM Geological Society Field Conference, will be held Sunday, Sept 16 to Wednesday, Sept 19, based at
the Travelodge Hotel Airlane in Thunder Bay, Ontario. The theme of the conference is PGE models and mineralization in the Lake
Superior region, which is currently a hotbed of exploration activity. Four different field trips have been arranged to demonstrate vari-
ous geological settings and deposit types. The field trips flank a full day (Monday Sept 17) of technical presentations and poster dis-
plays specifically related to the main theme.
Please complete a Registration Form and send a cheque for appropriate fees, by August 1, 2001. Register early, as space is limited
and will be reserved on a first come-first served basis. Once received, your registration will be confirmed by email, fax or mail and
further details will be sent once field trip groups are confirmed.
TECHNICAL SESSION / POSTER DISPLAY
Monday, Sept 17, 2001, the following is a tentative list of speakers and topics:
SPEAKER AFFILIATION TOPIC
Mark Smyk & Bernie Schnieders Ontario Geological Survey PGEs and Exploration Activity in NW Ontario
Moe Lavigne North American Palladium Ltd. Lac des Iles PGE Mine
Neil Pettigrew Avalon Ventures Ltd. Legris Lake PGE Property
Jim Miller Minnesota Geological Survey The Midcontinent Rift in the Lake Superior Region
Mark Severson Natural Resources Research Inst. PGEs in the Duluth Complex
Bob Middleton East West Resource Corporation PGE Exploration Models for the Nipigon Basin
Don Hoy Freewest Resources Canada Inc. New Style of PGE Mineralization in the Coldwell Complex
Phillip Walford Geomaque Explorations Ltd. Marathon Deposit in the Coldwell Complex
FIELD TRIPS
Field Trip 1: Coldwell Alkaline Complex Sept 16
(Mark Smyk Ontario Geological Survey and Industry Geologists)
Field Trip 2: Lac des Iles Mine/Legris Lake Complex Sept 16
(M.J. Lavigne and Staff North American Palladium Ltd. and Neil Pettigrew Avalon Ventures Ltd.)
Field Trip 3: Duluth Complex Sept 18-19
(Jim Miller Minnesota Geological Survey and Mark Severson Natural Resources Research Institute)
Field Trip 4: Lac des Iles Mine/Legris Lake Complex Sept 18
(M.J. Lavigne and Staff North American Palladium Ltd. and Neil Pettigrew Avalon Ventures Ltd.)
Field Trip 5: Intrusions in the Nipigon Basin Sept 18
(Bernie Schnieders & John Scott Ontario Geological Survey and Bob Middleton East West Resource
Corporation)
Please make cheque payable in Canadian Funds to: SUPERIOR PGE 2001 and mail by August 1, 2001 to:
SUPERIOR PGE 2001
c/o Ontario Geological Survey
Ministry of Northern Development and Mines
Suite B002 – 435 James St. South
Thunder Bay, ON P7E 6S7
superiorpge2001@ndm.gov.on.ca
For more information, please contact:
Mark Smyk, Phone: 807-475-1331, Fax: 807-475-1112, mark.smyk@ndm.gov.on.ca
Karen Ree, Phone: 807-346-0404, Fax: 807-346-4233, avalon@microage-tb.com
www.cim.org/geosoc/superiorPGE_2001.html
April 2001 – Gangue No. 69
MEETINGS, WORKSHOPS, & FIELDTRIPS
2001
• August 19-24 - Gordon Conference on Inorganic Geochemistry (Formation, Modification, and
Preservation of Ore Deposits) Proctor Academy, New Hampshire. Contact: Jeff Hedenquist, email:
gordongeochem@aol.com
• August 27-29 - The 6th Biennial Society for Geology Applied to Mineral Deposits, Mineral De-
posits at the beginning of the 21st Century. Krakow, Poland. http://galaxy.uci.agh.edu.pl/~sga
• September 16-19—SUPERIOR PGE 2001, CIM Field Conference, Thunderbay, ON. Ontario Geological Survey, Ministry of
Northern Development and Mines, Suite B002 – 435 James St. South, Thunder Bay, ON P7E 6S7, superiorpge2001@ndm.
gov.on.ca
• November 5-8 - Annual Meeting of the Geological Society of America, Boston, Mass. Contact: email: meet-
ings@geosociety.org; www.geosociety.org
• November 9-10 - Sullivan Mine meeting, Kimberely BC. Contact: Cominco Ltd., 500 – 200 Burrard Street, Vancouver, B.
C. Canada V6C 3L7, Tel: (604) 682-0611, Exploration Fax: (604) 844-2516, helen.augustin@cominco.com
• December 3-7 - Northwest Mining Association Annual meeting, Spokane Washington. Contact: NWMA, 10N. Post St.,
Ste. 414, Spokane, WA 99201, Tel: 509-624-1158, Fax: 509-623-1241
Please submit your events to Dave Lentz at email: dlentz@unb.ca
GEOCHEMISTRY: Exploration, Environment, Analysis
Editor-in Chief: G.E.M. Hall (Canada)
Scope of Journal
The Journal covers all aspects of the application of geochemistry to the explora-
tion and study of mineral resources, and related fields, including the geochemis-
try of the environment. Topics include: the description and evaluation of new
and improved methods of geochemical exploration: sampling and analytical
techniques and methods of interpretation; geochemical distributions in and
around mineralized environments; and processes of geochemical dispersion in
rocks, soils, vegetation, water and the atmosphere. Papers that
seek to integrate geological, geochemical and geophysical methods of explora-
tion are particularly welcome. Given the many links between exploration and
environmental geochemistry, the journal encourages the exchange of concepts
and data; in particular, to develop mineral resources while protecting the envi-
ronment. Submission of Letters to the Editor is encouraged. This provides a
means of commenting on papers that have been published in this journal. The
Journal is be published by the Geological Society of London
Editorial Office:
Ms. Marcia Scrimgeour—Editorial Office Manager
Geochemistry: Exploration, Environment, Analysis
P.O. Box 26099
72 Robertson Road
Nepean, Ontario, CANADA K2H 9R0
Tel: 613-828-1222; Fax: 613-828-2567;
Email: geea@compmore.net
www.aeg.org
April 2001 – Gangue No. 69