List of questions to be addressed by the IGCP-502 Global VMS teams
The aim of this questionnaire is to create a comprehensive database on VMS districts that will
enable comparisons among VMS districts, based on the same criteria.. We aim that the
database will contain much more geological and interpretative information than a simple
database of tonnage, grade and host rocks. Comparisons among VMS districts are one of the
main goals of IGCP-502 and will help us ascertain which are the key geological events,
common to all major VMS districts, that result in high-value VMS deposits. Specifically we
seek answers to the fundamental question: what controls the distribution and timing of major
VMS deposits and VMS districts? The database should also be useful for other research and
mineral exploration applications.
The leaders of IGCP-502 invite each research team to fill in the following questionnaire for
the VMS district that the team is working in. Fill in a new questionnaire for each VMS district
if you want to include more than one district from the same country. Please contact the
regional co-ordinator for IGCP-502 in your country (see list below) if you wish to participate
in this questionnaire.
Answers to the questions should provide the current state of knowledge in your district;
provide evidence and references where possible. It is anticipated that not all questions can be
answered for all VMS districts; in some cases the necessary work may not have been carried
out yet. Consequently, this questionnaire will also show what work has been done and what
work needs to be done in the future in each VMS district.
Please look at the GEODE 2000 Global VMS Questionnaire as an example of how this new
questionnaire should be completed. The results for the Iberian Pyrite Belt (available as a PDF
file from this web site) are particularly good to use as a template for filling in the
questionnaire.
VMS Districts in the IGCP-502 project and Regional Co-ordinators
VMS Districts for which the previous GEODE questionnaire was completed (please also
complete the new questionnaire).
Iberian Pyrite Belt
Skellefte
Bergslagen
Abitibi
Bathurst
Mount Read Volcanics
Southern Urals
Lau and Manus Basins
Fernando Tornos
Rodney Allen
Rodney Allen
Harold Gibson
Steve McCutcheon
Bruce Gemmell, Ross Large
Valeriy Maslennikov
Sven Petersen
VMS Districts for which the earlier GEODE questionnaire was not carried out. Regional coordinators for the IGCP-502 project are listed.
Andes (Peru, Equador)
Argentina
Green Tuff Belt, Japan
VMS Questionnaire 2006
Lluis Fontbote, Dick Tosdal
Diana Mutti, Ricardo Acevedo
Tetsuro Urabe
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China (1-3 main VMS districts)
East Pontide Belt, Turkey
Finland (Vihanti-Pyhasalmi)
West Greenland
Saudi Arabia
India
Namibia-Damara Orogen
Morocco (Variscan Belt)
Nunavut (North Slave Province)
Cuba-Carribean Belt
Central Mexico
Western Mexico
Venezuela
Jun Li
Namik Cagatay, Ramazan Dogan
Krister Sundblad
Peter Appel
Mohammed Sahl
Ritesh Purohit
Fred Kamona, Gregor Borg
Abdelhay Belkabir
Jan Peter
Xiomara Cañazas
Carlos Canet
Pedro Zarate
Simon Rodriguez
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1.
Age and tectonic/structural setting
1.1
What is the age of your VMS district?
 Extent, type and precision of geochronology? (belt scale and deposit scale). Make a
table indicating the more relevant data with type of sample (ore, host rock,
alteration), method and precision.
 Palaeontological control
1.2
What are the current interpretations of the tectonic setting of your VMS district?
(include a time-sequence diagram if available)
1.3
What is the tectonic interpretation based upon? Provide a summary of main results
and/or references:
 Structural mapping and interpretation? Is there a comprehensive district-scale
structural interpretation (quality of mapping?)
 Regional stratigraphic, facies and paleogeographic interpretation? (quality of
mapping?)
 Gravity and/or magnetic data (has it been used?)
 Any seismic sections ?
 Chemistry of volcanic rocks? What geochemical-tectonic classification was used?
1.4
What is the regional structural interpretation for the district? Provide a summary of the
main regional structures and/or styles of structures, including folds, thrusts, faults and
shear zones. Include a summary structural geology map or 3D sketch/model if available.
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1.5
Is there a comprehensive and high quality database of volcanic geochemistry to assist
with tectonic interpretation?
 How many whole-rock (with trace element) analyses on least-altered rocks?
 Type and quality of trace element data? How many analyses include REE data?
 What isotope data are available?
1.6
Have the district-scale and deposit-scale ore-fluid plumbing structures been identified?
Size of structures? How were they defined (mapping? alteration? aeromagnetics?
geochemistry? Isotopes?)
1.7
Have detailed structural studies of the deposits been undertaken? Which deposits?
1.8
What further research is needed to improve the tectonic interpretation
1.9
List key references
2.
Volcanic architecture
2.1
What are the scales of geological maps available for the district and the deposits? Has
the whole district been mapped?
2.2
Has a comprehensive systematic stratigraphy been established for the district? Provide a
summary.
2.3
What is the metamorphic grade, and how strongly deformed are the rocks? Is there a
penetrative cleavage in most rocks? Can primary volcanic and sedimentary
textures/structures be identified?
2.4
Has volcanic facies mapping been carried out on the regional scale, at individual VMS
deposits, and/or in specific parts of the district? Summarise the main results.
2.5
How do the VMS deposits relate to volcanic facies? Provide some sketch diagrams if
available. Do the VMS deposits occur in proximal or distal volcanic facies? Percentage
of volcaniclastic rocks versus coherent flows or intrusions?
2.6
Do the VMS deposits occur at a single stratigraphic level/horizon? If not, how many
different stratigraphic levels do VMS ores occur on? What is the evidence for a single
or several ore horizons (stratigraphic correlation? fossil control? radiometric dating?).
How are the main ore horizon(s) or ore-host stratigraphic unit(s) identified, both close
to ore, and 1 km along strike from ore?
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2.7
What is the stratigraphic or facies sequence from 200 m into the footwall to 200 m into
the hanging-wall at the major VMS deposits (for example: rhyolite dome  rhyolite
pumice deposit  VMS  siltstone  basalt lava)? Is this sequence the same at
distances of 1 km and 5 km from ore. Is there a change in volcanic and/or sedimentary
facies at, or close to, the ore position?
2.8
What is the composition (rhyolite?, basalt?) of the VMS host package? Is there a change
in volcanic composition at, or close to, the ore position?
2.9
Have original volcanic compositions of the altered volcanic rocks around the ore
deposits been verified/identified using immobile element chemistry (e.g. ratios of Ti/Zr,
Al2O3/TiO2, Zr/Al2O3….)? How many high quality lithogeochemical analyses with
immobile trace elements (Zr, Y, Nb…) exist? Do these include REE?
2.10 What is the interpreted range of water depth during deposition of the volcanic
succession, and immediate host rocks? What criteria were used to estimate water depth
(eg. volcanic facies, sedimentary structures, fossils, fluid inclusions)?
2.11 What further research is needed to define the relationship between ore formation and
volcanic architecture?
2.12 List key references
3.
Styles of ore deposits
3.1
Provide a table of tonnes and grade for major deposits (>1 million tonnes) (include
economic and sub-economic or barren massive sulphides). How many additional
deposits of less than 1 million tonnes are known in the district?
3.2
What is the degree of metamorphism, deformation and recrystallization in the ores.
Does it vary from deposit to deposit in the district?
3.3
What VMS deposit types occur within the belt (eg polymetallic Zn-Pb-Cu-type, Cu-Zntype, Cu-type, Au-only, barite-only, pyrite-only)? Give a cartoon model of each type
present, showing simple geology, morphology of the deposit and metal zones. Do not
use genetic classifications such as kuroko type or Cyprus type, but use metal content
and ratios – Cu/(Cu+Zn) and Zn/(Zn+Pb). (eg. Large , 1992 : ECON. GEOL. V87, p
473 ).
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3.4
Are stringer zones present? Are they economic? What is their mineralogy? Are there
any deposits that comprise only stringer sulphides?
3.5
Are there deposits that contain large volumes of semi-massive to strong
disseminated/impregnation ore types (25-75% sulphides and 10-25% sulphides
respectively)? What is their mineralogy? Are these economic? Are these ore types
localised in particular volcanic or sedimentary facies?
3.6
What are the major textures in the massive sulphides – massive featureless, banded,
brecciated? Are these textures interpreted to be primary or deformation-related. Key
evidence?
3.7
Did most deposits form on the seafloor or by replacement below the seafloor or a
combination of both? Key evidence (see Doyle and Allen, 2003. Ore Geology Reviews,
v. 23, p. 183-222)? If sub-seafloor, how far below the seafloor? Evidence?
3.8
Did the seafloor deposits form in brine pools, or as mounds, or are both types
represented, or did they form by some other mechanism? Key evidence? Is there general
agreement on the mechanism of formation?
3.9
Relationships between anoxia and exhalative ore deposits; are there studies on the local
environment of deposition of the massive sulphides?
3.10 List key references for each deposit
4.
Exhalites
4.1
Are “exhalites” (Fe, Si , Mn… units) present at the same stratigraphic level as the ores?
Are other styles of ore-equivalent horizons developed, eg; sulphide-bearing clastic
facies, pyritic black shales, limestones? Are the exhalites true seafloor precipitates or
simply alteration (silicification?) of tuffaceous sediments? Key criteria?
4.2
Are exhalites developed at other stratigraphic levels above or below the ore position?
How far above or below?
4.3
Can the exhalites be mapped along strike from the deposit (how far?), and are they
useful for exploration? How do you distinguish ore-associated exhalites from barren
exhalites.
4.4
Is there a geochemical database for exhalites in your belt (how many samples, REE
data, isotope data)?
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4.5
List key references
5.
Alteration facies
5.1
Have hydrothermal, regional diagenetic, and regional metamorphic mineral
assemblages and textures been identified? Criteria used for discrimination?
5.2
What (if any) is the immediate footwall alteration mineralogy and zonation? Does the
footwall alteration occur as stratabound zones or as pipes? What is the depth extent and
surface area of footwall alteration in absolute terms (metres) and relative to the deposit?
5.3
What (if any) is the extent and mineralogy of hangingwall alteration? Give morphology,
dimensions and mineral zonation.
5.4
What particular alteration indices (vectors to ore) have been tested or proposed?
5.5
Has a single database of alteration geochemistry been compiled for the district?
(number of samples?). By whom? and is it available?
5.6
Is there a database of whole rock oxygen isotopes? (number of samples?) Is data
available on H/D, C or Sr-Nd isotopes of the hydrothermal alteration?
5.7
Have deep semi-conformable alteration zones been identified ? What is their dimension,
mineralogy, and chemical characteristics? Is there evidence for metal depletion?
5.8
Is alteration geochemistry used to assist exploration in the district?
5.9
List key references
6.
Hydrothermal geochemistry
6.1
Are there systematic published studies on the mineralogy, mineral paragenesis and
mineral chemistry of the ores and altered host rocks. Which deposits?
6.2
Are the temperature, salinity and chemistry of the ore fluid well constrained from
deposit data? What is the quality of primary fluid inclusion data?
6.3
Is there any evidence for fluid boiling, give details?
6.4
What hydrothermal thermodynamic modelling has been attempted? What modelling
software was used (if any)?
6.5
What additional information is required to develop robust geochemical models?
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6.6
List key references
7.
Source of fluids, sulfur and metals
7.1
How extensive is the S isotope database on ores, sulfates and host rocks (numbers of
analyses)? What is the range of del 34S? Do the massive sulphides and stringer zones
have the same mean value and range? What is the interpreted source(s) of sulfur?
7.2
How extensive is the Pb isotope database on ores and host rocks (number of analyses
and range of Lead isotope ratios on ores and host rocks?). What is the interpreted source
of metals?
7.3
Is there any other isotopic data (Re/Os, Sm/Nd, Rb/Sr) that may assist in determining
the source of metals?
7.4
Is there any evidence for magmatic fluid/metal input? If so what is the key evidence?
7.5
What further research is required to determine the source of fluids, sulfur and metals?
7.6
List key references
8.
Subvolcanic intrusions
8.1
Have syn-volcanic intrusions been identified and are they associated with VMS
deposits? What are their mineralogy, composition and textures? Are they composite
intrusions?
8.2
Classify them (according to distance below the VMS horizon, and if possible according
to texture) as shallow (<1000 m from the lowest VMS horizon), epizonal (1000-3000
m) or deep (>3000 m). Is there more than one level present? What are their geometry
and dimensions.
8.3
Are they hosted by comagmatic volcanics? Or do they occur in underlying basement?
8.4
Are they identified as comagmatic to VMS-hosting strata by: a) geology; b) igneous
geochemistry, and/or c) geochronology?
8.5
Are they related to district-scale alteration zones? Key evidence?
8.6
Do they contain extensive areas of alteration? Do they contain base-metal and/or gold
occurrences?
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8.7
List key references
9.
Hydrogeological modelling
9.1
Are there any published or unpublished hydrogeological models for the district or for
individual deposits? What software package was used?
9.2
Are there any data on the original porosity and permeability of the volcanic and
sedimentary facies in the succession?
9.3
Have regional or local hydrothermal fluid pathways been defined? Using what data or
criteria?
9.4
Have any heat sources or fluid driving mechanisms been defined
9.5
What research is required to develop robust hydrogeological models? What computer
codes are suitable and available? What computer code developments are needed to
better constrain 3D heat and fluid flow modelling?
9.6
List key references
10. Exploration criteria
10.1 How were the known deposits found? Provide a list with dates and the key methods.
(eg. outcropping gossan, electromagnetic methods (EM), gravity, magnetics, soil
geochemistry etc.)
10.2 Currently, what are the key methods used by companies to identify 1) prospect areas,
and 2) drill targets?
10.3 What regional exploration data sets are available from the relevant government
departments : aeromagnetics?, gravity?, EM?, stream geochemistry?, soil
geochemistry?, till geochemistry?, rock-chip geochemistry? Give specifications and
degree of coverage.
10.4 What percentage of the volcanic district is under shallow cover? Have any deposits been
discovered in the covered areas?
10.5 What exploration methods need to be considered or further researched in your district?
10.6 List key references
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11. Research strengths for your VMS district
1
2
3
4
5
1. Tectonic and structural setting:
2. Volcanic architecture:
3. Styles of deposits:
4. Exhalites:
5. Alteration facies:
6. Hydrothermal geochemistry:
7. Sources of S, metals, fluids:
8. Hydrogeological modelling:
9. Subvolcanic intrusions
1 = Adequate database and extensive interpretation of data
2 = Adequate database but little interpretation
3 = Extensive interpretation but inadequate database
4 = Moderate database and interpretations (needs improvement)
5 = Inadequate database and little interpretation
12. List of fifteen key references
List the major references, even if the interpretations differ from those generally accepted. The
key references should include those that have the major geological, geochemical etc data
(maps and tables) and also those that contain important discussions and interpretations. Make
sure the titles of key maps or map series are included. List key unpublished references (eg.
theses) especially if they contain critical data not available elsewhere.
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Compiled by Ross Large and Derek Blundell for the GEODE project with further
modifications by R. Allen, J. Peter, N. Çagatay and F. Tornos (IGCP-502 Global VMS
project). This version 4.11.05.
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