Issue 54 October 1996

Tectonostratigraphic And Depositional Setting Of Paleoproterozoic Volcanogenic Massive Sulphide Deposits, Flin Flon, Manitoba

MDD - 1996 Julian Boldy Award Winner

Eric C. Syme1, Alan H. Bailes1, Stephen B. 2 2 (~30%), and minor (<10% total) ocean pla- abundances in the estimated mantle source of Lucas and Richard A. Stern teau, ocean island and ‘evolved’ plu- modern N-MORBs, probably due to their 1 Manitoba Energy and Mines, 2 tonic arc. All of the VMS deposits mined to derivation from a highly refractory mantle Geological Survey of date are associated with juvenile arc tectonos- source. tratigraphic assemblages: no economic Cu-Zn The historically non-productive juvenile The Flin Flon greenstone belt in the ju- deposits have been found in the voluminous ocean-floor assemblages include basalt/di- venile (internal) zone of the Paleoproterozoic back-arc basaltic sequences. The first-order abase sequences and related kilometre-scale Trans-Hudson Orogen, northern Manitoba association between juvenile arc rocks and layered mafic-ultramafic bodies. U-Pb zircon and Saskatchewan (Fig. 1), is one of the larg- VMS deposits provides a powerful screen to ages for both the and cumulate com- est volcanic-hosted massive sul- focus exploration in the Flin Flon belt. Con- plexes indicate that the ocean-floor assem- phide (VMS) districts in the world. Produc- sequently, knowledge of the physical (li- blage is coeval with tholeiitic arc volcanism tion plus reserves in 25 Cu-Zn-(Au-Ag) past- thologic, stratigraphic), geochemical and geo- at Flin Flon (ca. 1.904 Ga). The basalts occur and presently-producing mines totals 110 Mt chronological characteristics of the as laterally coherent ‘formations’, 4 to >60 km of sulphide, with a further 23 Mt contained in assemblages in the Amisk collage is crucial in strike length with stratigraphic thicknesses 20 subeconomic deposits.The Flin Flon belt for effective base metal mineral exploration. of 0.3 to 3.0 km, each having characteristic has been calculated to contain more base and 2 The 1.9 Ga juvenile arc assemblages are weathering colour, flow morphology, altera- precious metals per km than any other VMS dominantly mafic (basalt, basaltic andesite), tion assemblage and geochemistry. The ba- district in Canada (J. Franklin, GSC). with <10% rocks of andesite-rhyolite compo- salts are dominantly subalkaline with MgO The local depositional and regional tec- sition. Tholeiitic arc suites tend to be older contents typical of modern MORBs, falling tonic setting of VMS deposits in the Flin Flon (1903-1886 Ma) than calcalkaline (1886- mostly in the range 6-10 wt.%. They have belt have been the focus of investigations for 1882 Ma) and shoshonitic (1885 Ma) suites; higher TiO2, Zr, and Ni compared to the coe- many years. Most recently, the five-year boninites (>1886 Ma) occur only in the Snow val arc volcanic rocks of equivalent MgO. The GSC-Manitoba-Saskatchewan NATMAP Lake arc assemblage. The arc rocks were de- ocean-floor basalts can be subdivided into two Shield Margin Project has built on an exten- posited in a subaqueous environment, but main types, using the ratios of the immobile sive existing geological database to result in a there is clear morphologic evidence (e.g., trace elements: N-type (similar to ‘normal’ much improved understanding of the compo- presence of bubble wall shards, pumice) that MORB);2)E-type(similarto‘enriched’ nents and evolution of the Flin Flon belt. This resedimented pyroclastic rocks may have MORB). Some show no evidence of either a work has demonstrated that the Flin Flon been erupted in a very shallow marine or greenstone belt comprises 1.92-1.88 Ga tec- subaerial setting. Arc sequences commonly tonostratigraphic assemblages derived from a represent a proximal facies with respect to variety of tectonic environments that were source vents, comprising abundant pillowed amalgamated to form an accretionary collage and massive flows, coarse volcaniclastic de- (‘Amisk collage’) prior to the emplacement of bris flow deposits, rare sedimentary interbeds, 1.87-1.83 Ga granitoid plutons (Fig. 1). The and abundant synvolcanic dikes and sills. plutons, and rarely preserved coeval volcanic Stratigraphic sequences are complex and typi- rocks, are associated with younger arc(s) im- cally display a wide variety of rock types with posed on the collage, resulting in the develop- interfingering relationships, lenticular units, ment of a microcontinent by 1.85-1.84 Ga. and abrupt facies variations. Relative to mod- VMS deposits in the Flin Flon belt are ern MORBs, Flin Flon belt arc assemblage hosted by the earlier (1.9 Ga) tectonostrati- rocks have low abundances of Ti, Zr, Hf, Nb, graphic assemblages forming the Amisk col- Y, middle and heavy REEs, Ni and Cr, and are lage. The 1.9 Ga assemblages include juvenile similar to modern oceanic island arc suites. Flin Flon Belt - arc rocks (~60% of the exposed supracrustal For the most primitive Flin Flon arc assem- rocks), juvenile ocean-floor/back-arc rocks blage rocks these values are only 1-2.5x their Manitoba, Canada

October 1996 1 1996 – 1997 MDD EXECUTIVE The Gangue No. 54

Following are the MDD Executive and Directors for the 1996-1997 term. Please contact The Gangue is published quarterly by the Mineral Deposits Division, GAC, and is dis- any of these individuals for enquiries, or to suggest initiatives for MDD. tributed to members as part of their member- ship. Chairperson: Cominco Ltd., David Moore 7th Floor 409 Granville St. Vancouver, BC, V6C 1T2. Tel: 604-685-3064; FAX: 604-685-3069 MDD Goals and Objectives The Mineral Deposits Division of the Geo- Vice Chairperson Geological Survey of Canada logical Association of Canada is Canada’s fore- Al Galley 661 - 601 Booth Street most society for promoting the study of mineral Ottawa, ON, K1A 0E8 deposits by supporting local and national meet- Tel: 613-992-7867 E-mail: [email protected] ings, symposia, short courses and field trips. We sponsor the publication of research relating to Past Chairperson & Membership DIAND ore deposits and metallogeny and recognize the Jennifer Pell 4-4914 50th Street, Bellanca Bldg. contributions of outstanding Canadian eco- PO Box 1500, Yellowknife, NT, X1A 2R3 nomic geologists by annually awarding the Tel: 403-669-2640 FAX: 403-873-5763; Duncan Derry and William Harvey Gross med- E-mail: [email protected] als and the Julian Boldy Certificate.

Secretary: Inmet Mining Corporation Publication Schedule: Gary S. Wells 3-311 Water Street, Vancouver, BC, V6B 1B8 Tel: 604-681-3771 FAX: 604-681-3360 SUBMISSION PUBLICATION DEADLINE DATE Treasurer: Cathro Exploration Corp. Robert J. Cathro RR#1, Site U-39, Bowen Is., BC, V0N 1G0 December 15 January Tel: 604-947-0038 FAX: 604-947-0038 March 15 April June 15 July Publications: Wolverton Securities September 15 October Art Ettlinger 17th Floor - 701 W. Georgia Street Information for contributors: Vancouver, BC, V7Y 1J5 Tel: 604-662-5248; FAX: 604-662-5205 The objective of this newsletter is primarily to provide a forum for members and other pro- Professional Development Univ. of Windsor, Dept. of Earth Sciences fessionals to voice new ideas, describe interest- Short Courses: 212A Memorial Hall, Windsor, ON ing mineral occurrences or expound on deposit Iain M. Samson Tel: 519-253-4232 ext 2489; FAX: 519-973-7081 models. Articles on ore deposits, deposit mod- E-mail: [email protected] els, news events, field trips, book reviews, con- ferences, reprints of presentations to Professional Development BC Geological Survey companies, mining groups or conferences, or Field Trips: 5 - 1810 Blanshard Street; Victoria, BC, V8T 4J1 other material which may be of interest to the Tel: 604-952-0412 FAX: 604-952-0381; economic geology community are welcomed. Dani Alldrick E-mail: [email protected] Manuscripts should be submitted on IBM- Program Chair: Ottawa ‘97 Mineral Resources Division, GSC, 601 Booth St., formatted diskettes in any major word proces- Al Sangster Ottawa, ON, K1A 0E8. Tel: 613-992-8603; sor format. A printed version should be FAX: 613-996-9820; E-mail: included. Illustrations must be camera-ready [email protected]. (ideally as CDR digital files); photos should be of good quality. Short items dealing with news Program Chair: Quebec City ‘98 Sainte-Foy, Quebec events or meetings can be submitted by FAX, Benoit Dubé Tel: 418- 654-2669 FAX: 418- 654-2615; postal mail or E-mail. E-mail: [email protected].

Newsletter Editor The Gangue, PO Box 8076, Victoria, BC, V8W 3R7 Contributions may be edited Brian Grant Tel: 604-952-0454; FAX: 604-952-0451 for clarity or brevity. E-mail: [email protected] For Information & Submissions: MDD DIRECTORS Brian Grant Terence J. Bottrill (1994 - 1997) Oakville, Editor - THE GANGUE Tel: 905-842-2893; FAX: 905-842-3614 PO Box 8076, Victoria, BC, V8W 3R7 Pamela L. Schwann (1994 - 1997) La Ronge, Saskatchewan Tel: 604-952-0454 FAX: 604-952-0451 Tel: 306-425-4211 FAX: 306-425-4349 E-mail: [email protected] Marcos Zentilli (1994 - 1997) Halifax, Nova Scotia Tel: 902-494-3873 FAX: 902-494-6889; E-mail: [email protected] Dani Alldrick - Associate Editor Dan Brisbin (1995 - 1998) Timmins, Ontario. E-mail: [email protected] Tel: 705-267-1188 ext 253; FAX: 705-264-6080 E-mail: [email protected] *** Michael J. Downes (1995 - 1998) , Ontario. The MDD encourages geoscientists to join Tel: 416-869-3578; FAX: 416-869-3359 E-mail: [email protected] the division and contribute to the various Kerry Sparkes (1996 - 1999) St. John’s, Newfoundland programs and activities. Tel: 709-758-1700; FAX: 709-758-1717 Malcolm Robb (1996 - 1999) Yellowknife, Northwest Territories Tel: 403-873-6301; FAX: 403-873-2914 E-mail: [email protected] Paul Archer (1996 - 1999) Quebec City, Quebec Tel: 418-694-9832; FAX: 418-692-3969 Michael Marchand (1996 - 1999) Calgary, Alberta Tel/FAX: 403-282-5105 E-mail: [email protected]

2 The Gangue No. 54 NAIN <1.8 Ga Orogens Archean Cratons RAE SLAVE Paleoproterozoic Orogens Hudson HEARNE Bay 55° 20' N THO 50 N ASSEMBLAGE MAP OF THE FLIN FLON BELT 50 N 60 W 130 W SUPERIOR TF Atlantic Ocean SOUTH FLANK OF WYOMING KISSEYNEW DOMAIN Snow Lake assemblage

SW S Flin Flon ML F assemblage Hanson L. Block AMISK COLLAGE

W. Amisk W 99° 10' assemblage Elbow-Athapap. assemblage 15 km Amisk Lake Athapapuskow Lake Phanerozoic cover Sandy Bay

PRE-ACCRETION ASSEMBLAGES (>1.88 Ga) POST-ACCRETION ROCKS (<1.88 Ga) JUVENILE ARC ASSEMBLAGES FELSIC-MAFIC PLUTONS major faults (>1840, <1840 Ma) (<1840 Ma) OCEAN FLOOR ASSEMBLAGES SEDIMENTARY & VOLCANIC ROCKS OCEAN PLATEAU ASSEMBLAGE (successor basin deposits) West Reed-North Star shear zone EVOLVED ARC ASSEMBLAGE COLLISIONAL TECTONITES & GNEISSES OIB ASSEMBLAGE PRE- & POST-ACCRETION ROCKS VMS deposit BASEMENT

Figure 1: Simplified map of the Flin Flon belt showing the extent of the Amisk collage, major tectonostratigraphic assemblages and plutons, and location of mined VMS deposits. F: Flin Flon; S: Snow Lake; TF: Tabbernor fault; SW: Sturgeon Weir shear zone; ML: Morton Lake fault. Inset diagram: location of the Flin Flon belt in the Trans-Hudson Orogen (white box in THO). continental crust or arc signature, confirmed Within the arc assemblage a number of fluids, is associated with upwelling astheno- by their strongly positive initial εNd values. characteristics are common to all VMS depos- sphere and resulting high heat flow, and may Other basalt formations, however, show dual its: result in the production of observed geo- features of MORB-like major element geo- • they occur in tholeiitic and calcalkaline chemically unique rift basalts. We speculate chemistry and arc trace element signature suites dominated by basalt and basaltic an- that transient lower crustal melting induced by (e.g., lower TiO2 and higher Th/Nb ratios), desite; arc extension and underplating by basaltic characteristics of some basalts in modern in- • they are stratigraphically associated with magmas may have also resulted in the infre- tra-oceanic back-arc basins. ε quent high-temperature rhyolites observed in isotopically primitive (positive initial Nd ) mine sequences. The significance of exten- It is important to note that the large-scale rhyolite, commonly the most primitive rock tectonic interleaving and juxtaposition we ob- in the sequence; sion may explain why VMS deposits are par- serve between assemblages (Fig. 1) are repro- • titioned so strongly into arc environments. Ta- they occur at major stratigraphic and com- ble 1 shows that arc suites, as opposed to duced at a more detailed (camp) scale. Within positional ‘breaks’, recognized by contrast- a 20 km radius of Flin Flon, 14 VMS deposits back-arc basaltic sequences, contain the stra- ing major element, trace element and tigraphic, geochemical, and mineralogic evi- occur in a number of tectonically juxtaposed isotopic characteristics of the underlying arc slivers, separated by major accretion-re- dence consistent with extensional synvolcanic and overlying mafic rocks; deformation. lated shear zones, slivers of ocean-floor ba- • most are underlain by volcaniclastic rocks; salts, and slivers of successor basin sedimen- • Two examples from Flin Flon serve to tary deposits. As a result, VMS-hosting many have discordant footwall chloritic al- demonstrate the importance of arc extension stratigraphy usually cannot be correlated be- teration zones. in localizing mineralization: the Flin Flon- tween deposits. Detailed mapping, geochem- Integrating these empirical observations Callinan deposits and the Cuprus-White Lake istry and geochronology are required to define into a process-related model, we suggest that deposits. the various tectonostratigraphic components many of the VMS deposits are related to ex- The Flin Flon (62.4 Mt) and Callinan and their bounding structures. tension and rifting in the arc environment. (2.8 Mt) deposits are emplaced in a highly Such intra-arc deformation provides deposi- proximal setting within a 4 km thick tholeiitic, tional basins and conduits for hydrothermal basalt-dominated sequence. The deposits are

October 1996 3 contained within a 200 m thick rhyolitic flow complex (1903 +7/-5 Ma) at the stratigraphic Table 1: Flin Flon Belt - Comparison of Arc and Ocean-floor (back-arc) Environments contact between footwall and hangingwall Bearing on the Potential to Host VMS Deposits. basalts. Mapped facies in the footwall basalt ARC BACK-ARC sequence display an abrupt lateral transition Composition Heterogeneous (mafic-felsic), dominantly basaltic Homogeneous (basalt). from pillowed flows to mafic volcaniclastic andesite. rocks; the breccias underlie the massive sul- Lithologies Lithologically variable: pillowed and massive Lithologically simple: aphyric and plagioclase phide deposits and are overprinted by the aphyric and porphyritic mafic flows, felsic flows, phyric pillowed and massive flows, synvolcanic footwall hydrothermal alteration zone. A heterolithologic breccias, mafic-felsic tuff, diabase dikes and sills. plausible explanation for this facies relation- synvolcanic mafic-felsic dikes and sills, ship, and an angular unconformity exposed in volcaniclastic sedimentary rocks. the footwall succession, is that the rhyolite Stratigraphy Complex stratigraphy. Monotonous basaltic piles. complex hosting the Flin Flon and Callinan deposits occurs in an intra-arc rift basin. The Facies Subaqueous; proximal volcanic constructs. Subaqueous. Thin pillow selvages, few amygdales, trace element characteristics of the VMS- Subaerial source for some resedimented rare radial pipe amygdales. hosting rhyolite flow complex, marked by pyroclastic rocks. Flows commonly highly amygdaloidal. low [La/Yb]n and Zr/Y ratios, and high initial Geochemistry Tholeiitic, calc-alkaline, shoshonitic and boninitic N-type MORBs (depleted to flat REE patterns, high εNd, suggests that the felsic magmas were products of high heat flow. High heat flow magma series. Low HFSE and REE abundances, Zr/Nb, variable Th/Nb); E-type MORBs (slightly may also have been important in sustaining a chondrite-normalized LREE depletion to slight enriched REE patterns, lower Zr/Nb). hydrothermal system long enough to produce enrichment. High Al/Ti and Ti/Zr, low Ti/V and a deposit the size of Flin Flon. Zr/Y: arc mantle source strongly depleted. The Cuprus (0.5 Mt) and White Lake Synvolcanic Dynamic tectonic environment: Back-arc basin origin; rift-related structures (0.8 Mt) deposits occur in a particularly well- deformation apparently not preserved in the geologic record. exposed and well-preserved sequence 5.5 km - intra-arc rifts, fault-bounded depositional basins, - thick, monotonous sequences of pillowed and thick. The lower 4 km of this sequence com- calderas massive basalt flows prises a mildly calcalkaline sequence domi- - volcaniclastic sequences, rift basalts nated by a caldera-forming subaqueous ba- ¤ metals scavenged at least in part from porous, saltic andesite shield volcano, intracaldera permeable volcaniclastic rocks rhyolite and caldera-fill intermediate-felsic ¤ cross-stratal structures provide focused focused volcaniclastic rocks. Graphitic mudstones, pathways for hydrothermal fluid flow cherts and stratabound massive sulphides ¤ rift environments provide elevated heat flow were deposited at the top of the caldera-fill Rhyolitic Rhyolite flows, domes, breccias ~ 7% of arc Few if any associated rhyolites. sequence, in sub-basins which may have her- magmatism assemblages: alded an intra-arc rifting event. This rift event - SiO2 73-82% is clearly represented by a 150-200 m thick - low (La/Yb)n and Zr/Y ratios, suggesting high ferrobasalt formation with N-MORB trace temperature magmas element characteristics. The age of rifting, ¤ products of high heat flow established from inter-flow rhyolite crystal Synvolcanic Large, shallow synvolcanic intrusions associated Large-scale, shallow, synvolcanic intrusions are not tuff beds, is 1886 ±2 Ma. Deposition of the intrusions with some VMS deposits (e.g., Snow Lake; present. Associated plutonic rocks coeval with sulphides may have occurred in the earliest intrusions of the appropriate size and age have not ocean-floor basalts are layered gabbro-ultramafic stages of arc extension, and are thus plausibly been found at Flin Flon). complexes interpreted as ocean associated with an episode of high heat flow ¤ provide ‘heat engine’ for large-scale Layer 3. subsequently manifest by the extrusion of ba- hydrothermal systems Alteration Abundant evidence for large-scale hydrothermal Limited, low T seafloor alteration (epidosite salts derived from a MORB-like mantle. The systems: disconformable and semi-conformable, domains). resulting arc-rift basin was subsequently high T alteration zones. filled with 900 m of fine-grained shoshonitic ¤ manifestations of high heat flow pyroclastic material deposited from VMS deposits 25 mines / 110 Mt sulphide No economic deposits to date. subaqueous density currents. This shoshoni- tic material has a U-Pb age of 1885 ±3 Ma, greenstone belts of all ages, suggesting that indicating that the rifting and shoshonitic vol- similar complexities may be present in less ered in order to understand the origin of green- canism were virtually coeval. well understood belts. Our work indicates that stone belts, and ultimately to understand how The Flin Flon belt has lithologic, struc- tectonostratigraphy, geochronology, defor- continental crust and its endowment of min- tural and metamorphic similarities with mation and metamorphism have to be consid- eral deposits were generated and preserved.

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4 The Gangue No. 54 By the MDDddh Trolls Secondary core logging is usually carried out back at camp under more amenable conditions, such as a full stom- Supervising drill programs and logging core are two fun- ach, improved lighting, access to more sophisticated geo- damental skills of an exploration geologist. However, most logical tools, and hopefully sufficient time to properly ex- universities fail to address such skills, leaving geologists to amine and consider the core in the boxes. Critical to the learn on the job - sometimes with excellent tutoring, sometimes whole exercise is that the core should be thoroughly with none at all. washed to remove all drill cuttings, grease and other extra- Being confronted by a 3 am wake-up call, a mad trip neous materials. At this point a geologist should be making through the bush by snowmobile, piles of greasy drill rods, a detailed notes on all geological aspects of the core, while silent drill on “standby” at $500/hr, and a sullied driller drinking ensuring that the measurements are all accurate and reason- coffee beside the core boxes and anxiously hoping to shut down able. Rock types, textures, mineralogy, presence and abun- the hole so he can move to the next site, set up and resume dance of economic minerals (particularly mineralogy, tex- drilling for his bonus, can indeed be an intimidating experience ture, relationships to rock types, or other economic or for a green geologist. The need for a quick, but accurate, ap- gangue minerals) structures, or other obvious features, praisal of the core is critical. An error in interpretation can mean should be th principle focus of the core logger. Conversely, missing a deposit or drilling a lot of country rock at $130 a recording the absence of common features, such as miner- metre. This is not the time for scientific research into the mean- als and/or alteration, can also be an extremely important ing of life, or to identify the chemistry and ultimate origins of part of the core logging process. Drilling artifacts should the rocks on display in the core box. The geologist needs to be identified as such, not misinterpreted as significant geo- know: what rock types are present; is there mineralization of logical features: surface features and metallic markings economic interest or a possibility for it; has the hole reached its may be from drill bits or casing; strange organic looking planned target or gone beyond any reasonable chance of pro- ‘dikes’ may in fact be nothing more than the product of a viding useful information; and critically, should the hole be driller with a twisted sense of humour; and, fracturing may terminated or kept going till after breakfast? be real or induced by drilling techniques. Missing core, either justifiable or resulting from an excess of zeal by the It should be kept in mind that core logging is equivalent to driller, may be an important clue to ground conditions, geologically mapping a very long, thin outcrop. Many of the faults, and particularly economic mineralization if it’s as- skills used in regional mapping should be applied to drill core. sociated with highly altered zones. Before splitting core for Any geologist undertaking such a job must have a reasonable geochemical analysis, core should be photographed and grasp of geological fundamentals such as; mineralogy, petrol- logged radiometrically if appropriate. Remember, the pur- ogy, structure, geochemistry, sedimentology, volcanology, and pose of a drilling program is to find mines, not to log core economic geology. Armed with such skills, logging core should at a set production rate, and not to set drilling records. be an exciting and rewarding experience - particularly if your company benefits include stock options! Core should preferably be marked for sampling and analysis during the process of logging, not as a secondary Core logging is typically done in two stages. Initial inspec- task. Reluctance or accidental failure to sample can easily tion at the drill site must be cursory but thorough. Core is lead to a missed ore intersection, particularly with precious examined for rock type, alteration and textures, presence and metals as they are rarely apparent during visual inspection abundance of economic minerals, ground conditions, and such of core. administrative details as depth and core recovery. It is critical Before splitting core for analysis the geologist should to confirm that the drill meterage matches the actual core avail- ensure that such information as fracture density and orien- able, since drillers do not measure the core itself but take meas- tation(s), contact relationships, gross textures, and struc- urements from the length of their drill string. Metre, or footage, marker placement may be affected by lost core and broken ground. An inexperienced drill helper can inadvertently place core in the box backwards thus giving the impression of thin, repeating rock types when in fact the stratigraphy is much simpler. From this initial core examination most geologists can make reasonable judgements regarding the progress of the drill- ing, and whether to terminate a specific hole or let it continue so that a predefined target can be properly accessed. It is there- fore important that some master plan be in place to help guide the drill geologist in making such decisions. For example, is the program simply looking for economic mineralization, are all holes to be drilled to 200 metres regardless of rock types, or is the likely ore-bearing horizon a specific lithology in which case it is imperative to drill through it but not extensively into foot- wall rocks.

October 1996 5 tural features are properly documented. After core splitting pression that an ore zone is open when in fact there is problem much of this type of information will be lost. Particular atten- in the sampling procedure. tion should be paid to ensuring that all features are propor- tionally represented in the split core samples. If a sampler It is important that the geologist not get into a routine of tends to favour the more cohesive, resistant bits of core for describing rock types without close examination of the core. the samples, it will negatively influence the analytical results This is a real concern in larger drill programs with repetitive - particularly if economic mineralization happens to occur intersections of the same lithologies from hole to hole. Be within softer, altered zones within the core. constantly on the alert for subtle changes, particularly in mineralogy and alteration. Core logs done by rote, rather than Sample length for individual samples should be selected critical examination will prove worthless during interpretive using reasonable criteria: those from a porphyry setting stages. Each piece of core should be systematically removed should tend to be collected over much longer intersections from the box and rotated to examine all surfaces. If core is than those taken to identify high-grade vein deposits. A sam- logged as it lies in the box, then geological observations will ples from too long a length of core will, in many cases, give be based on observation of roughly 40% of the total core little information to the relationships of ‘ore grade’ to rock surface. Mineralogical and textural features that may best be type, they will also tend to dilute economic mineralization so displayed on the freshly broken end surfaces of each piece of that only low grade values are returned. Samples should never core will go unnoticed. include more than one rock type, otherwise it will be impos- sible to determine which lithologies are potentially ore hori- Drill logs and samples are the most important records of zons and which are not. Samples must always be collected to a drill program and it is worthwhile to ensure they are the best well within adjacent barren ground to ensure the boundaries possible under the program circumstances. With this in mind of economic mineralization are defined. High grade assays it is important to any large drill program that one geologist with no adjoining barren samples will always leave the im- either log all the core, or be assigned to set the basic logging standards and closely supervise all core logging from a specific property. Sec- Colin Spence tions logged by a number of geologists, Memorial Graduate Scholarship with a variety of backgrounds and basic skills, will commonly provide a won- in Geology derful puzzle for the poor geologist who tries to reinterpret the geology from the at The University of British Columbia drill logs at a later date. Before the drill is moved, all holes Rio Algom Exploration Inc. is pleased to an- longer than about 100 metres should be nounce that a scholarship of $6000 per annum has been surveyed downhole for dip and azimuth set up at The University of British Columbia in mem- (usually by acid test, Trepari or Sperry- Sun instruments). After the drill rig has ory of the late Colin D. Spence, former exploration man- moved on, the drill hole collars should ager for the company, whose tragic death occurred be surveyed in and the collar azimuth recently while on assignment in the Philippines. The confirmed. Data from such surveys award is to be offered on a two year basis to a graduate often yield surprises! The geologist student at the Masters level in Geological Sciences, Geo- also needs to be aware of all other com- ponents of the exploration program. For logical Engineering or Geophysics. example, drill holes should not be Rio Algom’s goal is to establish an Award Endow- cased, cemented for environmental pur- ment Fund sufficient for this purpose. Those contribu- poses, or shut down if geophysical log- ging is part of the program. tions which have been received to date have been transferred to UBC and will be receipted by the University. Acquiring drill core is an expen- sive, but informative, undertaking. The All further contributions to this fund should be made products of this investment should be payable to “The Colin Spence Memorial Fund” and treated with respect - it is usually forwarded to: cheaper to build permanent core storage than to have to redrill the target. It is UBC Development Office also usually cheaper and far more infor- 6253 NW Marine Drive mative to do a proper job of core log- Vancouver, BC, V6T 1Z1 ging than to have to go back and redo Attn: Elizabeth Ko, Awards Coordinator the job because the records weren’t kept or supervision of the logging activity wasn’t consistent. All core logging re- cords should be computerized for long term storage and availablity.

“If you haven’t got the time to do the job right; When will you have the time to do it over?”

6 The Gangue No. 54 Letter to the Editor Dear MDD Members: Rock Detective Inc., a nonprofit based group based in Virginia and Maine, is looking for rock and mineral samples to help enhance elementary school earth science education. We use the samples to teach cool, basic earth science concepts such as, sea level hasn’t always been where it is today. The concepts are developed by an experienced research geologist and peer-reviewed. At the present time we are looking for magnetite, and slag (yes, slag!), and ore minerals. We need several boxes of the same material, and will gladly pay the shipping costs (as inexpensively as possible please). If anyone can contribute such material we would also like to know the mineral composition, age, and location that the samples are from. Any other geological information on the samples which is interesting would be welcome. Our program has been heartily endorsed by the Smithsonian Institution, Reading is Fundamental, Sea World, and the U.S. Geological Survey. We can supply more information on request. Thanks in advance for your assistance and we look forward to your support. Ruth Deike, Journey’s End Farm, RR #1, Box 13, Dresden, ME 04342, USA. Tel: 207-737-4612

Ottawa ‘97 - Mineral Deposits Program

Symposium Examples to be discussed include: Kidd Creek, Iberian Pyrite Belt, Canadian contributions to Latin American Mineral Deposit Eskay Creek, Windy Craggy and others. Geology: M. Zentilli (Dalhousie University) and R. Jannas (Met- Topics include: allica Resources Inc.). Canadian based mineral deposit research • Classification of VMS deposits, based on world-wide compilation and mineral exploration activity are at an all-time high in Latin • Subaqueous volcanism: environments and controls America. • Structural aspects of hydrothermal venting in seafloor/ophiolite Special Sessions settings • Atypical Gold Deposits: A. Sangster (GSC) and J.-F. Couture Magmatic and Hydrothermal controls on seafloor venting (MRN, PQ). Session will consist of papers on gold deposits or their • Hydrothermal alteration of oceanic crust aspects, plus occurrences that don’t fit well within existing classi- • Fluid chemistry, base and precious metal transport and deposition fications. One section of the session will deal with deposits to be • Stratigraphy and alteration of bimodal VMS systems visited on the “Atypical Gold Deposits of the Abitibi Area” trip. • Semi-conformable alteration patterns in VMS systems Geology of the Kidd Creek Orebody, Timmins, Ontario: M. • Stable isotopes and VMS systems Hannington, T. Barrie and W. Bleeker (GSC). The results of a joint • multidisciplinary research project involving the GSC, Falcon- Heat and fluid flow modeling and VMS systems bridge Ltd. and Laurentian Univ. will be presented, covering the Field Trips geology, geochemistry, geochronology, alteration and isotope geo- Geology and Mineral Deposits of the Balmat-Edwards District, chemistry of the Kidd Creek deposit. New York: W. deLorraine (Zinc Corp of America) and A. Sangster Tectonic, Magmatic and Hydrothermal Evolution of Back-Arc (GSC). Participants will receive an overview of the geology and Rifts with Emphasis on the Bathurst Mining Camp, New dolomite marble-hosted zinc deposits in the Sylvia Lake Syncline, Brunswick: W. Goodfellow and C. van Staal (GSC). This session including an underground visit to the Number 4 Mine. will present a synthesis of the geology of back-arc rifts and their Atypical Gold Deposits of the Abitibi area, Quebec and On- role in the formation of massive sulphide deposits as exemplified tario: J.-F. Couture (MRN, PQ) and F. Robert (GSC). Field trip by the Bathurst Mining Camp. The papers will focus on the joint will focus on Archean gold occurrences that don’t fit well into Geological Survey of Canada and New Brunswick Dept of Natural existing classifications, and will compliment papers in the Special Resources Extech II project. Session. Short Course Geology and Massive Sulphide Deposits of the Bathurst Camp, Volcanic-associated Massive Sulphide Deposits in Ancient & New Brunswick: S. McCutcheon, J. Langton and D. Lentz (NB Modern Settings: Classification, Processes and Examples: T. Bar- Dept Natural Resources). This trip will provide an overview of the rie and M. Hannington (GSC). This course will review current geology and mineral deposits of the Bathurst Camp, New Bruns- studies on critical aspects of VMS formation, with an emphasis on wick, and is designed to compliment the Special Session on back- relevance to mineral exploration. It will present the results of recent arc basins and massive sulphide deposits. studies on important VMS deposits and districts around the world. Timmins to Sudbury Transect: New Developments in the Set- Course will be accompanied by an Economic Geology, Reviews in ting of Massive Sulphide Deposits: D. Ames, W. Bleeker, K. Economic Geology volume (available at the door). It is co-spon- Heather and N. Wodica (GSC). This trip will highlight new devel- sored by the Mineral Deposits Division - GAC and Society of opments in the geology of massive sulphide deposits within the Economic Geologists. Emphasis will be on audience participation Timmins Camp, the Swayze Belt, the Levack Gneiss Complex, and and speakers will be from , Europe and Australia. the Early Proterozoic Whitewater Group within the Sudbury struc- ture.

October 1996 7 The Geology of Australia An introduction to earth sciences and a OTTAWA ’97 – SHORT COURSE comprehensive guide to the geology of Aus- tralia is now available on CD-ROM for per- BIOLOGICAL/MINERALOGICAL sonal computer users. This is an invaluable INTERACTIONS resource in the teaching of geology and earth sciences from high school to university. It is an unparalleled reference source for libraries, Date: 16-17 May 1997 and anyone interested in a detailed under- standing of the evolution of the Australian continent. A two-day Short Course organized by Julie M. McIntosh and Lee A. Groat (De- partment of Earth and Ocean Sciences, The University of British Columbia) and spon- The 2 CD-ROM pack includes a guide to sored by the Mineralogical Association of Canada, will provide an introduction and the geology of Australia with accompanying review of the rapidly expanding field of geomicrobiology. geological and topographical maps. It also in- Topics will include a review of bacteria, growing and maintaining bacterial cultures, cludes an introduction to general earth science techniques used to study bacterial/mineralogical interactions, bacteria and the break- concepts, a database of earthquakes in Austra- down of sulphide minerals, bacteria and acid rock drainage, bacteria and the weathering lia, a database of over 250 minerals with pic- of silicate mineral, biomineralization, and lichens. tures and detailed descriptions, and most im- portantly for economic geologists a database This course will be relevant to researchers from academia and government, and to of key mineral deposits across Australia. geoscience professionals. Discussion among the speakers and attendees will be an important component of the course. Participants will include B.S. Davis, M. Easton, F.G. The CD-ROMs sell for AUS$125 for a Ferris, G.D. Ferroni, L.G. Leduc, D. Gould, R. Guay, and H.W. Nesbitt. single user, AUS$295 for a single network, Registration $350 CAD for professionals, $200 for students. and AUS$695 for a site license, plus AUS$4 postage & handling. Information and orders For additional information; can be placed through: AGSO Sales Centre, GPO Box 378, Canberra ACT 2601, Austra- Julie M. McIntosh or Lee A. Groat, lia. Tel: 61-06-249-9519; FAX: 61-06-249- Earth & Ocean Sciences, University of British Columbia 9982; E-mail: [email protected]. Vancouver, BC, V6T 1Z4

th GAC 50 Anniversary World Gold: A Minerals Availability Appraisal 50 Ottawast '97 GAC AGC May 18 - 21 , 1997 This Special Publication of the US Geo- logical Survey, summarizes a number of in- GEOMINE depth studies of the major gold mining regions of the world. The mining geology discussion group is finally ready to roll!! GEOMINE is an electronic mailing list serving as a platform for discussion on mining and mine-exploration related issues. Gold resources and reserves and produc- It is envisaged as a world-wide network of mine-based geologists, and mining related geologists, tion costs are estimated and compared for the that interact through discussion to exchange information, solve problems, and advance the major producers, and in US dollars, to facili- applied science of mining geology. tate the comparisons. Dramatic changes in re- The list has been the result of efforts of Craig Morley, Senior Mine Geologist, Boddington source development and mining and process- Gold Mine, W. Australia, [email protected]. Thanks to the generosity of Robertson Info-Data Inc, in Vancouver, BC, Canada, there is a server now up and running to maintain the group. ing technologies that have occurred in the gold industry since the early 1980s are docu- The site can be visited on the WWW to see a list of mentors, other info, and to access a subscription form at: http://www.info-mine.com/technomine/ege/geominesrv.html mented. Future growth areas such as the for- mer Soviet Union, the Asia-Pacific region, Those with E-mail, but without WWW access, can subscribe by sending an E-mail message to: [email protected] with the words “Subscribe GEOMINE, plus your E-mail address” and Latin America are reviewed. Finally, this in the content of the message. publication identifies factors that may influ- Once subscribed you will receive all messages posted on GEOMINE via your E-mail. There ence the future of worldwide gold supply, and is no cost to belong to and participate in the group. any impacts on the economy of the United Messages, articles, questions, etc., can be posted to the GEOMINE audience by sending an States. E-mail message to: [email protected], with your message in the main body of the E-mail. Copies of World Gold, SP 24-94, US$13 This site is intended for critical discussion of topics related to mining and mining geology and active participation is encouraged. Members can use the group as a sounding board for or US$16.25 for foreign orders, can be or- research or ideas, arranging mine visits, making contacts, finding out about practices and dered through the US Government Printing techniques used at mines, conducting surveys, etc. Office at Tel: 202-512-1800 and ask for pub- lication stock number 024-004-02372-4.

8 The Gangue No. 54 MEETINGS, WORKSHOPS & FIELDTRIPS

October 1996 Vancouver, BC, V6C 1C8. Tel: 604-681- Geochemical Exploration. Toronto. Work- 5328; FAX: 604-681-2363. shops Sept 8-12th. Contact: Jon Baird, 28 - 31 Argentina Mining ‘96 - A New Frontier Publicity Chair, c/o CAMESE, 101-345 of Opportunity. Mendoza, Argentina. Ex- February 1997 Renfrew Drive, Markham, ON, L3R 9S9. ploration, Geology, Mine Development, Tel: 905-513-0046; FAX: 905-513-1834; Business Opportunities Conference. Con- 24 - 27 SEG Meeting with Society for Mining, Email: [email protected]. Ab- tact: Conference Mgr., c/o E&MJ, 29 North Metallurgy & Exploration. Denver, Colo- stracts by Sept 1/96 to Ian MacLeod, Chair, Wacker Drive, Chicago, IL 60606-3298, rado. One-day symposium “Characteristics Technical Prgm Comm., c/o Geosoft Inc., USA. FAX: +1-312-726-2574. of Successful Exploration Organizations”, Suite 500, 204 Richmond St. W., Toronto, & six exploration & geology sessions. Con- ON, M5H 2G4; Email: [email protected]. November 1996 tact: S. Hamilton, 7490 Robb Court, Arvada, CO 80005-3542, USA. Tel: +1-303-420- October 1997 6-29MINERALDEPOSITSDIVISION- 3056; FAX: +1-303-420-3056. Bolivia - Chile - Argentina Field Trip. Join 9-12Prospectors & Developers Asoc of Can- 20 - 23 SEG Annual Meeting with Geological the MDD in La Paz, Bolivia for another of ada - International Convention & Trade Society of America. Salt Lake City, Utah. the renowned MDD fieldtrips. Dr. Al Sang- Show. Royal York & Metro Toronto Con- Contact: R.W. Schafer, BHP Minerals, ster, GSC, Ottawa, trip leader.Contact: Dani vention Centre, Toronto, Canada. Contact 14062 Denver West Parkway, Suite 150, Alldrick, MDD Fieldtrip Coordinator, PDAC 34 King St E, 9th Floor, Toronto, Golden, CO 80401. Tel: 303-277-0707; Email: [email protected] OUT ! M5C 2X8. Tel: 416-362-1969; FAX: 416- FAX: 303-277-0620. 362-0101 Nov. 15 Mapping and Resource Evaluation 20 - 24 Heavy Mineral Conference. Marshall- Using Regional Airborne Geophysical April 1997 town, South Africa. Sponsored by SA Datasets and Gravity. One-Day Workshop. Institute of Mining & Metallurgy: Zululand Soc. Expl. Geophysicist’s Annual Meeting, 21 - 25 EACM ‘97: East Asian Continental & Natal Branchs. Contact: HM Conference, Denver, USA. Contact: P. Gunn, Head, SAIMM, PO Box 61127, Marshalltown AGSO, GPO Box 378, Canberra, ACT 2601, Margin - Geology and Development. Hong Kong. Sponsored by Univ. of Hong Kong, 2107, SA. Tel: +27-11-834-1273; FAX: +27- Australia. Tel: +61-6-249-9226; FAX: 61+- 11-838-5923; E-mail: [email protected]. 6-249-9986; Email: [email protected] . H.K. Geological Survey, & Geological So- ciety of Hong Kong. Contact: EACoM ‘97, 21 - 22 Advances in Saskatchewan Geology & Earth Sciences Dept, Univ. of Hong Kong, January 1998 Mineral Exploration. Saskatoon, Sask, Pokfulam Road, Hong Kong. FAX: 852- Canada. Contact: Sask. Geological Survey, 25176912; Email [email protected]. MINEXPO ’96, PO Box 234, Regina, Sask, 28 - 30 Exploration Methods ‘98 - Pathways S4P 2Z6. Tel: +1-306-787-9181; FAX: +1- April 27 - May 1 CIM ‘97 - . New Frontiers for to Discovery. Hotel Vancouver, Vanc. BC. 306-787-24 8 8; E-mail : the Next Century. Vancouver, BC. Contact: Sponsored by the BC&YCM, SEG, BCGS, [email protected]. Chantal Murphy, Meetings Dept., CIM, GSC. This will be a special version of the 3400 de Maisonneuve Blvd. West, Suite traditional Cordilleran Roundup. Contact: 27 - 29 Nickel ‘96 - Mineral to Market.Kal- 1210, Montreal, PQ, H3Z 3B8. Tel: 514- BC & Yukon Chamber of Mines, 840 W goorlie, Australia. Sponsored by the 939-2710; FAX: 514-939-2714. Hastings St., Vancouver, BC, V6C 1C8. Tel: Australasian Institute of Mining & Metal- 604-681-5328; FAX: 604-681-2363. lurgy, Australian Institute of Geoscientists, May 1997 and W Australian School of Mines. Contact: Dr. Eric Grimsey, WA School of Mines, Box 17 - 18 Short Course: Volcanic-Associated March 1998 597, Egan St., Kalgoorlie, WA 6430, Austra- Massive Sulphide Deposits in Ancient and lia. Tel: 090-80-5182; FAX: 090-80-5181. Modern Settings: Classification, Processes March - TBA Mineral Deposits Division- & Examples. Sponsored by SEG and MDD SEG-BCYCM Fiel d Tri p to December 1996 - immediately preceding the Ottawa ‘97 AUSTRALIA. See Ad page 24, this issue! GAC-MAC Annual Meeting. Contact: T. 2-6 Mining and the Environment: Northwest Barrie or M. Hannington, GSC, 601 Booth June 1998 Mining Association - Spokane Convention Street, Ottawa, ON, K1A 0E8. Tel: 613-947- 2793 or -996-4865; FAX: 613-996-9820; Centre, Washington. Annual meeting, short- June 29 - July 18 IAGOD/CODMUR 8th In- courses, core-shack, technical sessions and E mail: [email protected], or [email protected]. ternational Platinum Symposium. major trade show. Contact: NWMA, 10 N Johannesburg, South Africa. Field excur- Post St., Ste 414, Spokane, WA 99201, USA. 11 - 14 NEVES CORVO Field Conference. sions and technical meeting. Contact: Dr Tel: 509-624-1158; FAX: 509-623-1241; Univ of Lisbon, Portugal. Conference will C.A. Lee, PO Box 68108, Bryanston 2021, WWW: http://www.ior.com/nwma/ be organized around the Neves Corvo mine South Africa. Tel: +1-2711-411-2253; FAX: & other points of interest in the Iberian Py- +1-2711-692-3693. January 1997 rite Belt. Contact: Geoffrey Snow, Barranca Resources, c/o SEG Offie, 5808 Rapp Street 8-11 IGCP 356 & Mineral Deposits Studies #209, Littleton, CO 80120, USA. Tel: 303- Future GAC/MAC Meetings: Group Meeting. Univ. of Glasgow, Scot- 797-0332; FAX: 303-797-0417; WWW: land. Fee £30, reduced fees for members & http://NevesCorvo.geo.fc.ul.pt. May 19 - 21, 1997 Ottawa ‘97. GAC/MAC Joint students. Contact: A.J. Hall, Dept of Geol- Annual Meeting. Ottawa Congress Centre, ogy, Univ. of Glasgow, Glasgow G12 8QQ. August 1997 Ottawa, Ontario. Details: Tel: 613-947- E-mail: [email protected]. 7649, FAX: 613-947-7650, Email: 11 - 13 Fourth Biennial Meeting, Society of [email protected] 13 - 15 Mexico Mining ‘97. Conference & Ex- Geology Applied to Mineral Deposits hibition. Puerto Vallarta, Mexico. Contact: (SGA). Turku, Finland. Contact: Congress May 18 - 20, 1998 Quebec ‘98 - Quebec Con- L. Feeney, Randol International Ltd., Gold- Office, SGA Meeting 1997, Lemmnkais- gress Centre, Quebec City. Contact: Mme en Colorado, USA. Tel: 303-526-1626; enkato 18-18B, FIN-20520, Turku, Finland. Agathe Morin, Laval University, Sainte- FAX: 303-526-1650. Foy, PQ, Tel: 418-656-2193; FAX: Tel: +358-21-333-6342; FAX: +358-21- 418-656-7 3 39 ; e-mai l: q ue- 28 - 31 CORDILLERAN ROUNDUP ‘97. Ho- 333-6410; E-mail: [email protected]. [email protected]; WWW: tel Vancouver, BC. Sponsored by the BC http://www.ggl.ulaval.ca/quebec1998.html. Geological Survey, BC&Yukon Chamber of September 1997 Mines and Geological Survey of Canada. May 1999 GAC/MAC 1999 - Sudbury Contact: Jack Patterson, BC & Yukon Cham- 14 - 18 Exploration ‘97. 4th Decennial Inter- ber of Mines, 840 W Hastings St., national Conf. Geophysical & May 2000 GAC/MAC 2000 - Calgary

October 1996 9 PALEOPROTEROZOIC VOLCANIC-RELATED MASSIVE SULPHIDE DEPOSITS: TECTONIC AND DEPOSITIONAL ENVIRONMENTS: NOTES FROM A GAC’96 SYMPOSIUM by Alan Galley, Geological Survey of Canada Robert Cathro pointed out upon completion of have formed in suprasubduction arc terranes. tokumpo, Vihanti-Pyhaslmi and Orijarvi-Ai- the GAC’96 symposium on Paleoproterozoic The development of these various arc envi- jala-Attu mining districts (Railainen, 1996) of massive sulphide deposits that a summary ronments includes a spectrum of tectonic set- the Svecofinnian Orogen, and the Ladysmith- presentation was needed at the end of the tings from oceanic through to continental Rhinelander Belt of Wisconsin (Brown and session to compare and contrast some of the margin to continental rift. In each environ- Mudrey, 1996). Deposit characteristics were tectonic and depositional settings described ment, VMS deposits have specific temporal described for the Petiknäs-Renstrom district over the course of the 13 papers presented. As and spatial relationships whose recognition of the Skellefte Belt (Jonsson and Nordin, penance for this omission I have put together allow the explorationist to identify fertile Pa- 1996), the Bergslagen district (Lundström, the much-needed summary. This allows the leoproterozoic base metal terranes. As 1996), the Snow Lake camp (Bailes and Gal- opportunity to add some observations that the pointed out in talks by Steve Lucas and Eric ley, 1996) and the Sudbury district (Gibson et authors did not have time for, and a reading Syme, volcano-sedimentary assemblages tra- al., 1996). These mining camps are hosted list for those interested in finding out more ditionally called greenstone belts are actually within multiply deformed and metamor- about Paleoproterozoic massive sulphide met- tectonic collages containing juxtaposed ac- phosed terranes, as is typical for Proterozoic allogenesis. creted arc and ocean floor terranes. Within any and Phanerozoic orogenic belts. Some of the Introduction one of these tectonic collages there may be problems involved in defining synvolcanic more than one depositional environment in hydrothermal alteration patterns in highly The period in the earth’s history from 2.0 which significant massive sulphide deposits metamorphosed terranes was examined by to 1.8Ga involved the amalgamation of sev- are most likely to form. These prospective Menard and Gordon (1996). eral Archean microcontinents, previously terranes can be identified through regional Intraoceanic Arc Environments separated by oceanic basins, into a supercon- geologic mapping and airborne magnetic sur- tinent known as Laurentia (Hoffman, 1988) veys, coupled with selected high quality geo- Although each of the volcanic domains (Fig. 1). The process of amalgamation in- chemical and geochronological studies. In all hosting the various mining districts are com- volved ocean closure, with attendant develop- of the symposium presentations the emphasis posed of arc-ocean floor collages, they can be ment of destructive plate margins with over- was placed on geologic mapping and strati- crudely categorized as representing different lying suprasubduction arc environments. graphic correlation in identifying optimum settings for arc development. The Outokumpo Whereas the Trans-Hudson Orogen was the settings for VMS deposition. District, Flin Flon Belt and Ladysmith- main Paleoproterozoic event stitching to- A tectonic overview for the Flin Flon Rhinelander volcanic complex represent juve- gether the Canadian Shield, the Svecofinnian Belt was presented by Lucas et al. (1986). The nile intra-oceanic environments. Kalevi Rasi- Orogen was the main event welding together massive sulphide districts described included lainen’s presentation defined Outokumpo the Baltic Shield (Fig. 1). Volcanogenic mas- the Flin Flon Belt (Syme et al., 1996; Reilly rocks as representing a primitive early oce- sive sulphide (VMS) deposits formed in a and Maxiener, 1996) and Rusty Lake Belt anic/back arc rift environment in which Cu- number of depositional environments during (Ames, 1996) within the Trans-Hudson Oro- Co-Zn deposits are hosted within dolomite- the various stages of submarine arc develop- gen, the Swedish Skellefte Belt (Weihed, skarn units surrounded by greywacke. The ment within these two orogens (Table 1). The 1996) and Bergslagen mining district (Lund- succession can be termed a “sedimented- Paleoproterozoic is one of the earth’s most ström and Allen, 1996) and Finnish Ou- ophiolite”, and the massive sulphide deposits prolific periods of VMS development, with more massive sulphide tonnage developed per 2 km in the Trans-Hudson Orogen than in any Skellefte comparable Archean terrane with over 160 million tonnes of massive sulphide ore pro- duced from 24 deposits. This includes two of Canada’s five largest massive sulphide depos- its: Flin Flon (62 Mt) and Ruttan (57 Mt). 3 Nearly all of Sweden and Finland’s massive Rusty sulphide production has come from arc terra- Lake nes within the Svecofinnian Orogen. Berslagen The purpose of the GAC’96 VMS sym- posium was to present a number of papers 1 Outokumpo- summarizing the tectonic environments for Flin Sudbury Orijari VMS deposition within the major Paleopro- Flon terozoic volcano-sedimentary terranes, and to characterize the massive sulphide types with ca 1.1 Ga continental rift respect to their depositional environments and 1.3-1.0 Ga imbricated crust alteration characteristics. The purpose of this 1.8-1.6 Ga juvenile crust article is to summarize some of the material 22 1.9-1.8 Ga juvenile crust presented at the symposium in such a manner 1 Trans-Hudson 2 Penokean as to allow the reader to understand the vari- 3 Svecofennian ous submarine environments in which these 2.0-1.8 Ga continental deposits formed. magmatic arcs Ladysmith 2.0-1.8 Ga thrust-fold belts Setting of Paleoproterozoic Rhinelander VMS Deposits 2.3-2.1 Ga juvenile (?) crust Archean greenstone- granite-gneiss provincesprovinces Numerous geological and geochemical (variable deformation) studies over the last 15 years (Swindon, 1990; Campbell et al., 1982; Lesher et al., 1985; Figure 1. Archean and Paleoproterozoic elements of Laurentia, with the Baltic Shield shown in pre-Iapetus Barrie et al., 1993; Bailes and Syme, 1994) position, and Greenland restored prior to rifting from North America. VMS mining districts discussed have shown that throughout geological time during the GAC’96 symposium are labeled, along with the principal VMS-hosting orogenic terranes. most economic massive sulphide deposits Modified from Hoffman (1988).

10 The Gangue No. 54 as of the “Besshi” type (Slack, 1993). The fines shallow water massive sulphide devel- gillite and abundant subvolcanic intrusions. presence of serpentinzed ultramafic rocks opment accompanied by well developed argil- Synchronous with the development of this within the sedimentary succession is ex- lic alteration and skarn development. The de- basinal succession are several calcalkaline plained as either infolded ocean floor, or sills. velopment of Carbonate units early in the felsic volcanic centres with associated chemi- In the latter case, the alternative to an imma- hydrothermal history, followed by shallow cal and volcaniclastic sediments. ture rift is a transfer fault-related basin at the sub-sea floor replacement of the carbonate by VMS deposits occur in three distinct geo- termination of a back-arc, or oceanic, spread- massive sulphide is characteristic of parts of logic environments (DeMatties, 1996). Only ing ridge (Koski, 1993). several Paleoproterozoic camps, including one deposit is situated in the lower mafic flow The Flin Flon Belt represents a series of Skellefte, Bergslagen, Ladysmith-Rhinelan- section (Thornapple), and it is associated with juxtaposed intra-oceanic island arcs and oce- der and Sudbury (Galley et al., 1993). iron formation. Most of the other deposits and anic terranes that were assembled relatively The other massive sulphide-rich arc ter- occurrences are spatially associated with fel- early in the evolution of the Trans-Hudson rane within the juvenile core of the Trans- sic eruption centres (Flambeau, Bend, Cran- Orogen. The setting is analogous to the more Hudson Orogen is the Rusty Lake belt. Intra- don, Lynne and Ritchie Creek), whereas a few modern arc settings in northern Honshu and oceanic arc volcanism had terminated by 1.88 (Kivela Zone: Ritchie Creek, Spirit and Horse Hokkaido, Japan, or Luzon, northern Philip- Ga in the Flin Flon Belt, but the more north- Shoe) occur at the contact between footwall pines (Lucas et al., 1995). The Flin Flon and erly Rusty Lake appears to have been one of basalt and hangingwall volcaniclastic sedi- Snow Lake terranes represent two early island the last juvenile arcs to form at 1.87 Ga. At ments. The Cu-rich Ritchie deposit consists arc successions separated by ocean least one of the four structural domains iden- principally of sulphide vein stockwork. floor/back-arc basins. Tholeiitic to transi- tified in the belt formed subaerially. The un- Brown and Mudrey pointed out the dif- tional tholeiite-calcalkaline arcs formed be- usual aspect of this arc terrane is that it con- ficulties involved in not only exploring in this tween 1.88 and 1.92 Ga, followed by succes- tains only one significant massive sulphide overburden-rich terrain, but of also develop- sor arc volcanism at 1.87. All of the significant occurrence, and this is the 64 Mt Ruttan Cu- ing any deposits discovered due to strict land massive sulphide deposits, including the 62.4 Zn deposit (Ames, 1996; Ames and Taylor, use regulations presently in force in Wiscon- Mt Flin Flon Main Mine, formed within 1996). The deposit appears to have formed sin. This example emphasizes that successful primitive arc environments (Syme and Bailes, near the end of active submarine volcanism, exploration for VMS deposits can be out- 1993), which can include fore-arc, back-arc, and is situated within a small fault-controlled weighed, or even negated, by an unfavourable or rifted arc regimes. This may be due to the basin infilled with redeposited felsic that is development climate. fact that these primitive environments repre- directly overlain by a thick turbiditic se- Arc-Continental Margin Environment sent extensional regimes in which periods of quence. A structural juxtaposition of N- episodic magmatism are interspersed with pe- MORB and fractionated arc tholeiite vol- The 1.80 - 1.89 Ga Skellefte Belt in riods of extension through normal faulting. canics at the base of the volcanic succession north-central Sweden is representative of Whereas high level magmatism results in may indicate a rifted arc environment (Ames, either a continental margin arc, or an accreted steep thermal gradients that instigate sub-sea 1996). The presence of abundant large gas island arc system (Weihed, 1996). The over- floor seawater convection, deep-seated fault- cavities in associated volcanic units, As-Au- whelming felsic nature of the calcalkaline vol- ing allows for incursion of large volumes of rich quartz-microcline-sericite (metamor- canic strata (>70% rhyolite-dacite) is indica- seawater that can react with the cooling vol- phosed low sulfidation quartz-adularia?) al- tive of a continental regime. The 85 massive canic strata and underlying intrusions to form teration along the margins of the sulphide deposits occurring in the belt appear metal-rich hydrothermal fluids. deposit-hosting basin, and the high Hg con- to have formed near the top of various vol- Several different depositional environ- tent of the Ruttan ore are suggestive of a shal- canic and volcaniclastic successions. The belt ments can occur within these tholeiitic arc low water depositional environment. As with does not contain any significant Cu VMS de- regimes (Table 1). In the Flin Flon district many large tonnage VMS deposits, the inter- posits, which are more commonly associated Cu-rich massive sulphide deposits are hosted pretation of Ruttan’s tectonic and depositional with mafic-dominated volcanic regimes. In by basalt-gabbro dominated, E-MORB to environments are complicated by the late tec- the western part of the belt there is the felsic tholeiitic arc successions proposed in Maxe- tonic truncation of much of it’s deep footwall volcaniclastic-hosted 10 Mt Kristeneberg Zn- iner’s presentation to represent back-arc ba- strata. Cu deposit, with metal grades and morpho- sins. The rhyolite-hosted Flin Flon and Calli- The 1.89 Ga Wisconsin Magmatic Ter- logical characteristics typical of proximal nan Cu-Zn deposits in the Flin Flon mining rane of northern Wisconsin and southern massive sulphide deposits (Lydon, 1994) (Ta- camp occur at the top of an intra-arc (rifted) Michigan consists of a number of oceanic and ble 1). This deposit contains the most metal of depleted tholeiitic basalt-dominated succes- intra-oceanic arc terranes accreted unto the any in the belt, and is spatially associated with sion (Syme and Bailes, 1993). Rhyolite-re- southern margin of the Archean Superior a shallow rhyolite stocks and underlying sub- lated Cu-rich deposits in the Snow Lake min- Province during the 1.83 - 1.86 Penokean volcanic intrusive complex (Viterliden por- ing camp are restricted to arc tholeiite, largely Orogeny (LaBerge, 1996; DeMatties, 1994, phyry) (Rickard, 1986). Also in the western bimodal, succession containing subordinate 1996). The south margin of the orogen is un- part of the belt are two Zn-Pb-Cu deposits refractory boninite lavas typical of fore-arc derlain by quartzites derived from an Archean (Hornträsk and Räveliden) that consist of in- regimes (Stern et al., 1995). In all of these microcontinent to the south (LaBerge, 1996). terlayered massive sulphide, carbonate and ar- cases, the preponderance of thick sequences The southern part of the Wisconsin Magmatic gillite. The central and eastern parts of the of mafic volcanic rocks is indicative of a rift Terrane is so far barren of significant massive Skellefte Belt are dominated by felsic vol- environment in which a thinned crust results sulphide mineralization, but the northern part, canic successions characterized by shallow in rapid decompression of the underlying known as the Ladysmith-Rhinelander vol- water rhyolite porphyry cryptodome-tuff mantle and formation of shallow (1000 to canic complex, is host to 13 VMS deposits and cone formations. The Zn-Pb-rich deposits 2000 mbsf) magma chambers. The resultant major occurrences, including the 65.8 Mt themselves have shallow water VMS-epither- steep thermal gradient results in high tempera- Crandon deposit (Table 1). The poorly ex- mal characteristics (so-called high sulfidation ture (Cu-rich) deposits. posed 230 km long Ladysmith-Rhinelander VMS; Sillitoe et al., 1996), which includes Also present in the Snow Lake camp are complex includes a tholeiitic Main Volcanic high Au-As-Sb values and related acid-sulfate rhyolite-hosted Zn-Pb-rich deposits anoma- Arc Sequence containing amphibolites with type alteration. The Renström-Petiknäs de- lous in Au, Ag, As and Hg. They are associ- thin continuous oxide-facies iron formations posits are well-described examples of this ore ated with thick sequences of felsic volcani- and serpentinized ultramafic intrusions, type (Jonsson and Nordin, in press). The As- clastic rocks and small felsic eruptive centres, which has been classified by Schulz (1984) as Au-rich Boliden massive sulphide deposit is and characterized by well layered, chert-car- a suprasubduction ophiolite suite at the base not a stratiform orebody, but rather a discor- bonate-rich ores. This ore type is typified by of an island arc. This primitive arc succession dant pyrite-arsenopyrite-pyrrhotite body that the Chisel-Lost-Ghost deposits in the Snow is overlain by a thick sequence of volcanic transects a high level intrusive dacite stock Lake camp (Bailes and Galley, 1996) and de- sediments, calcalkaline to tholeiitic basaltic (Bergman-Weihed, 1995). This is suggestive and andesite flows, sulphide-bearing meta-ar- of an epithermal origin. The eastern part of the

October 1996 11 Table 1: Tonnage and Grades for Paleoproterozoic VMS Deposits belt is also characterized by several more typi- Deposit Status Type Cu Zn Pb 100 Cu/ Au Ag Au:Ag Prod+Res. cal epithermal gold deposits. % % % Cu + Zn g/t g/t (tonnes) Continental Back-Arc Environment SPREADING RIDGE ENVIRONMENT (SEDIMENTED OPHIOLITE) OUTOKUMPO REGION, FINLAND The Bergslagen and Orijarvi-Aijala-Attu Outokumpo - Cu 3.8 1.07 - 78 0.8 8.9 0.09 28 500 000 mining districts of Sweden and Finland con- Luikonlahti - Cu 0.99 0.5 - 66 - - - 7 500 000 Vuonos - Cu 2.45 1.6 - 60 0.1 11 0.01 5 890 000 stitute a broad zone of continental platform or Saramaki - Zn-Cu 0.71 0.63 - 53 - - - 3 400 000 back-arc volcanism that entailed crustal ex- Kylylahti - Cu 2.9 0.72 - 80 0.64 10 0.06 1 550 000 tension, intense magmatism and thermal dom- Perttilahi - Cu 2.15 1.39 - 61 - - - 1 320 000 ing, followed by waning extensional volcan- Riihiahti - Cu 0.72 0.09 - 89 - - - 700 000 ism, sedimentation and thermal subsidence ( Source of tonnage and grade data from Gaal and Parkkinen, 1993 Vivallo and Rickard, 1984; Allen et al., in INTRAOCEANIC ARC ENVIRONMENTS press). The Bergslagen region has a long his- FLIN FLON BELT, MANITOBA tory of mining for both iron and copper, with Flin Flon CL Zn-Cu 2.19 4.2 - 34 2.6 41.5 0.06 62 446 734 the Falun VMS deposit continuously mined Trout Lake OP Zn-Cu 2.11 4.79 - 31 1.41 15.43 0.09 10 180 608 Chisel Lake CL Zn-Pb-Cu 0.6 10.94 1.4 5 2.17 56.3 0.04 7 299 816 from about 900 A.D. until the early 1990s. Stall Lake CL Cu 4.39 0.5 - 90 - - - 7 000 000 The 1.88 - 1.90 Ga Bergslagen-Orijarvi ter- Osborne Lake CL Cu 3.14 1.52 - 67 - - - 3 380 061 rane is characterized by thick sequences of Anderson Lake CL Cu 3.41 0.1 - 97 - - - 3 189 601 felsic pyroclastic flows and their resedi- Callinan OP Zn-Cu 1.43 3.7 - 28 1.68 20.57 0.08 2 800 000 mented equivalents. The base of the sequence Spruce Point CL Zn-Cu 2.36 2.8 - 46 2 25 0.08 1 931 000 Schist Lake CL Zn-Cu 4.21 7 - 38 1.4 37 0.04 1 877 813 contains interlayered continent-derived sand- Centennial CL Zn-Cu 1.41 2.48 - 36 0.05 0.59 0.08 1 624 550 stones containing older Paleoproterozoic to Westarm CL Cu 3.34 1.25 - 73 - - - 1 579 403 Archean detrital zircons as evidence for the Coronation CL Cu 4.25 0.03 - 99 1.87 4.68 0.4 1 282 088 presence of an older basement. The explosive Dickstone C Zn-Cu 2.47 3.13 - 44 - - - 1 083 590 nature of the volcanic rocks, and presence of Chisel pit CL Zn-Pb-Cu 0.23 10 0.4 2 2.74 54.86 0.05 1 140 000 White Lk CL Zn-Cu 1.97 4.63 - 30 - - - 849 598 abundant accretionary lapilli, indicate initial Rod No. 2 CL Cu 6.2 2.3 - 73 - - - 667 702 shallow water deposition from a series of cal- Photo Lake OP Zn-Cu 5.6 6.2 - 47 5.1 20 0.26 660 000 deras. Rapid subsidence of this rift system Ghost L./Lost L. CL Zn-Pb-Cu 1.34 8.87 - 13 - - - 605 690 resulted in the deposition of deeper water ash- Cuprus CL Zn-Cu 3.24 6.42 - 34 1.37 28.69 0.05 462 002 siltstone deposits interlayered with extensive Flexar CL Cu 3.75 0.47 - 89 - - - 305 940 Birch CL Cu 6.15 ------278 825 Fe-Mn iron formation. The massive sulphide North Star CL Zn-Cu 6.11 ------241 643 deposits occur within the ash-siltstones in the Mandy CL Zn-Cu 5.63 13.95 - 29 - - - 123 116 upper part of the volcanic pile. The presence Don Jon CL Zn-Cu 3.07 ------79 313 of Fe-Mn iron formations temporally associ- Rod No. 1 CL Cu 5 4.5 - 53 - - - 22 675 ated with massive sulphide mineralization ap- RUSTY LAKE BELT, MANITOBA pears typical of continental rift environments, Ruttan OP Zn-Cu 1.27 1.37 - 48 0.56 10.89 0.05 57 000 000 and are also present in the Ordovician Sources of grade and tonnage information: Bailes and Galley, 1996; Ames, 1996 Bathurst camp (Peter and Goodfellow, 1996) LADYSMITH-RHINELANDER VOLCANIC COMPLEX, WISCONSIN as well as in the Iberian Pyrite Crandon ND Zn-Cu 1.04 5.56 0.48 16 1.08 38.9 0.03 65 800 000 Belt (Barriga, 1990). The 10 developed Lynne ND Zn-Pb-Cu 0.64 8.7 1.65 7 0.76 76.2 0.01 6 800 000 Bergslagen Zn-Pb-Cu-Ag-Au deposits (Table Flambeau OP Cu 4.1 1 tr 80 2.89 29.92 0.10 5 900 000 Eisenbrey ND Zn-Cu 1.5 3.4 - 31 tr tr - 2 700 000 1) fall into two categories: The Zinkgruvan Catwillow ND Zn-Cu 1.5 2.6 - 37 0.62 14 0.04 2 600 000 deposit type are well layered sphalerite-ga- Pelican ND Zn-Cu 1 4.5 tr 18 tr 15.9 - 2 000 000 lena ores interbedded with siliceous silt- Hawk ND Zn-Cu 0.8 2.7 - 23 - - - 1 400 000 stones, with mineralization extending for kil- Ritchie Creek ND Cu 2.11 0.37 - 85 0.3 - - 800 000 ometres as thin, sheet-like deposits with Horse Shoe ND Zn-Pb-Cu 2.45 5.35 0.9 31 1.86 32.6 0.06 650 000 Source of grade and tonnage information DeMatties, 1996 well-spaced, Cu-rich discordant stockwork feeder zones (Hedström et al., 1989). The CONTINENTAL MARGIN ARC ENVIRONMENT Garpenberg type consists of skarn-rich im- SKELLEFTE BELT, SWEDEN pregnation ores formed by replacement of Rakkejaur ND Zn-Cu 0.2 2.9 0.2 6 1.1 62 0.02 10 400 000 previously existing hydrothermally-derived Renström OP Zn-Pb-Cu 0.8 6.5 1.5 11 2.8 155 0.02 9 100 000 carbonate units (Vivallo, 1985). Kristineberg OP Zn-Cu 1.2 5.2 0.4 19 1.4 53 0.03 8 900 000 Boliden PD Cu-Au 1.42 - - - 15.2 49 0.31 8 341 550 Submarine Impact Structures Petiknäs S OP Zn-Cu 1.1 4.9 0.9 18 2.3 108 0.02 6 500 000 Långdal PD Zn-Pb-Cu 0.14 5.7 1.7 2 1.9 160 0.01 4 000 000 One of the most unusual Paleoprotero- Petiknäs N PD Zn-Cu 1.3 5.6 0.9 19 5.6 103 0.05 1 300 000 zoic settings for massive sulphide deposition Kimheden ND Cu-Au 1.1 0.08 - 93 0.4 6 0.07 1 000 000 is within the 1.85 Ga Sudbury meteorite im- Bjurliden ND Zn-Cu 0.11 3.5 0.36 3 0.3 46 0.01 670 000 pact crater, where two Zn-Pb-Cu deposits Hornträsk PD Zn-Pb-Cu 0.9 7.4 1 11 0.6 113 0.01 400 000 (Vermilion and Errington) formed as shallow Holtjärn PD Zn-Cu 0.4 4.8 0.6 8 8 120 0.07 200 000 subsurface replacement deposits within coe- Näsliden OP Zn-Cu 1.1 3 0.3 27 1.3 35 0.04 - val hydrothermal carbonate units (Gray and Source of grade and tonnage information from Rickard, 1987; Nordin and Jonsson, in press Gibson, 1993). The deposits occur at the con- CONTINENTAL BACK-ARC ENVIRONMENT tact between a submarine crater-fill sequence BERGSLAGEN MINING DISTRICT, SWEDEN of andesitic composition (Onaping Forma- Zinkgruvan: Nygruvan PD Zn-Pb-Cu 0.9 10 1.5 8 - 45 - 43 000 000 tion) and overlying pelagic and chemical sedi- : Knalla PD Zn-Cu-Pb - 6 5.5 - 100 - - ments. Harold Gibson’s presentation pointed Falun CL Zn-Cu 2.4 4 1.5 38 2 to 4 13 to 24 - 28 100 000 out the similarities between the Errington- Garpenberg PD Zn-Pb-Cu 0.3 5.3 3.3 5 0.65 98 - 21 500 000 Saxberget - Zn-Pb-Cu 0.9 7.1 2.2 11 0.4 42 - 6 800 000 Vermilion and Garpenberg deposit type found Stollberg - Zn-Pb-Cu - 1 to 4 0.5 to 15 - 10 to 320 - 6 700 000 in the Bergslagen region of Sweden, including Sala - Zn-Pb-Cu tr 12 1 to 2 - - 150 to >3000 - 5 000 000 deposition of massive sulphide during shal- Ryllshyttan - Zn-Pb-Cu ------1 000 000 low sub-sea floor replacement of carbonate Oster Silvberg - Zn-Pb-Cu 0.9 5.6 to 22.51.2 to 2.9 - 4.5 to 7 45 to 70 - 200 000 sediments, a footwall sequence of clastic Utö - Zn-Pb-Cu - 4 1 - - 40 - 200 000 Source of grade and tonnage information Allen et al., in press Grades quoted are production grades rocks of explosive origin, and associated re- Status: OP = present producer; CL = past producer, ND = not developed Deposit size includes production plus drill indicated reserves

12 The Gangue No. 54 gional-scale alteration systems (Ames and sium. This article was much improved Massive Sulfide Deposits of Northern Wisconsin: A Gibson, 1995). The presence of massive sul- through review by Doreen Ames. Commemorative Volume, (ed.) G.L. LaBerge, Insti- phide deposits within a submarine meteorite References/Reading List tute of Lake Superior Geology, V. 42, Part 2, 31-66. impact crater fill sequence should not come as Galley, A.G., Bailes, A.H. and Kitzler, G. 1993. Geological Allen, R.L., Lunström, I., Ripa, M., Simeinov, A., and setting and hydrothermal evolution of the Chisel Lake a surprise, as it is an environment that contains and North Chisel Zn-Pb-Ag-Au massive sulphide all the necessary ingredients for developing a Christofferson, H., in press. Regional volcanic facies interpretation of 1.9 Ga metasediment- and metavol- deposit, Snow Lake, Manitoba; Exploration and Min- convective hydrothermal system. This in- canic-hostedZn-Pb-Ag-(Cu-Au)sulphideandFeOx- ing Geology, v. 2, p. 271-295. cludes: a) a high level heat source in the form ide ores, Bergslagen region, Sweden; Economic Gibson,H.L.,Jonasson,I.R.,Gray,M.J.,Paaki,J.J.,Rogers, of an impact melt sheet and/or sub-surface Geology Special Issue. D.F., Stoness, J.A., Ames, D.E., 1996. The geological intrusion; b) a thick permeable sequence of Ames, D.E., and Gibson, H.L. 1995. Controls on and setting of the Paleoproterozoic Errington and Vermil- geological setting of regional alteration within the ion massive sulphide deposits; in Geological Associa- glassy, readily altered clastic material; c) tion of Canada/Mineralogical Association of Canada seawater to circulate through the pile and react Onaping Formation, footwall to the Errington and Vermilion base metal deposits, Sudbury Structure, Annual Meeting 1996, Program with Abstracts, v. 21, with the crater-fill material; and d) discrete Ontario; inCurrentResearch1995-E,GeologicalSur- p.A-50. sill-dike-dome complexes (“melt bodies”) vey of Canada, p. 161-173. Gray, M.J., and Gibson, H.L., 1993. Geological setting of whose intrusion into the shallow sub-sea floor Ames, D.E., 1996. Stratigraphic and tectonic setting of the the Vermilion Cu-Zn-Pb-Au-Ag massive sulphide locally steepened the thermal gradient to Paleoproterozoic Ruttan Cu-Zn VHMS deposit, deposit, Sudbury Basin; in Geological Association of Rusty Lake belt, Trans-Hudson Orogen; in EXTECH Canada/Mineralogical Association of Canada, An- forms hydrothermal upflow zones. nual Meeting, Program with Abstracts, A37 In Conclusion . I: A Multidisciplinary Approach to Massive Sulfide Research in the Rusty Lake-Snow Lake Greenstone Hedstrom, P.,Simeonov,A.,andMalmstrom,L.,1989.The Zinkgruvan Ore Deposit, South-Central Sweden: A The Paleoproterozoic contains abundant Belts, Manitoba; (ed.)G.F.Bonham-Carter,A.G. Gal- ley, and G.E.M. Hall, Geological Survey of Canada, Proterozoic, Proximal Zn-Pb-Ag Deposit in Distal volcanogenic massive sulphide deposits Bulletin 426, p. 15-44. Volcanic Facies; Economic Geology, 84, 1235-1261. hosted within a variety of suprasubduction en- Ames, D.E., and Taylor, C., 1996. Geology of the West Hoffman, P.F., 1988. United Plates of America, The birth vironments. These range from Cu-rich depos- Anomaly orebody, Ruttan volcanic-hosted massive of a craton: Early Proterozoic assembly and growth of its within mafic extrusive volcanic-dominated sulphide deposits, Proterozoic Rusty Lake belt; in Laurentia; Annual Review of Earth and Planetary fore-arc arc regimes, through Zn-Cu deposits EXTECH I: A Multidisciplinary Approach to Mas- Science Letters, v. 16, p. 543-603. sive Sulfide Research in the Rusty Lake-Snow Lake Jonsson,R.,andNordin,R.,1996.ThePetiknäsProterozoic in bimodal rifted arc to back arc regimes, to volcanic-hosted massive sulphide deposits -Case his- Zn-Pb-Cu deposits within more evolved and Greenstone Belts, Manitoba; (ed.) G.F. Bonham-Car- ter, A.G. Galley, and G.E.M. Hall, Geological Survey tory and a comparative genetic study; in Geological fractionated felsic dominated volcaniclastic of Canada, Bulletin 426, p. 45-76. Association of Canada/Mineralogical Association of successions in island arc and back-arc set- Ames, D.E., 1996. Stratigraphic and tectonic setting of the Canada Annual Meeting 1996, Program with Ab- tings. Sedimented-ophiolite terranes may be Paleoproterozoic Ruttan Cu-Zn VHMS deposit, stracts, v. 21, p.A-48. associated with any setting where sea floor RustyLakebelt,Trans-HudsonOrogen; inGeological Jonsson, R., and Nordin, R., in press. The Paleoproterozoic Association of Canada/Mineralogical Association of Petiknäs volcanic-hosted massive sulphide deposits, spreading centres develop. A range of massive Skellefte field, Sweden; Economic Geology Special sulphide compositions are found within each Canada Annual Meeting 1996, Program with Ab- stracts, v. 21, p.A-2. Issue. accreted arc collage, but the predominance of Koski, R.A., Lamons, R.C., Dumoulin, J.A., and Bouse, Bailes, A.H., and Galley, A.G., 1996. Setting of Paleopro- one compositional type, i.e. Cu, Zn-Cu or Zn- terozoic volcanic-hosted massive base metal sulphide R.M., 1993. Massive sulphide metallogenesis at a late Pb-Cu, is controlled by whether the suprasub- Mesozoicsediment-coveredspreadingaxis:Evidence deposits, Snow Lake; in EXTECH I: A Multidiscipli- from the Franciscan complex and contemporary ana- duction environment was intra-oceanic, mar- nary Approach to Massive Sulfide Research in the logues; Geology, v.21, p. 137-140. ginal continental, or continental arc (Table 1). Rusty Lake-Snow Lake Greenstone Belts, Manitoba; LaBerge, G.L., 1996. General characteristics and geologic There appears to be abundant evidence for (ed.) G.F. Bonham-Carter, A.G. Galley, and G.E.M. setting of the Wisconsin Magmatic terranes; in Vol- shallow water environments for many Paleo- Hall, Geological Survey of Canada, Bulletin 426, p. canogenicMassive SulfideDepositsofNorthernWis- 105-138. consin: A Commemorative Volume, (ed.) G.L. proterozoic deposits. This includes epither- Bailes, A.H., and Galley, A.G., 1996. Tectonostratigraphic mal characteristics such as high Hg, As, and LaBerge, Institute of Lake Superior Geology, V. 42, setting of Paleoproterozoic massive sulphide deposits, Part 2, p. 17-30. As-Au contents, as well as associated high- Snow Lake, Manitoba; in Geological Association of (aluminosilicate) and low- (quartz-adularia) Lesher, C.M., Goodwin, A.M., Campbell, I.H. and Gorton, Canada/Mineralogical Association of Canada Annual M.P. 1985. Trace element geochemistry of ore-asso- sulfidation alteration assemblages. Meeting 1996, Program with Abstracts, v. 21, p.A-5. ciated and barren felsic metavolcanic rocks in the As we continue to study and understand Barriga, F.J.A.S., 1990. Metallogenesis in the Iberian Pyrite Superior Province, Canada; Canadian Journal of Belt; in Pre- Geology of Iberia, (ed.) R.D. Earth Science, v. 23, p. 222-237. the controls on massive sulphide deposition Dallmeyer and G.E. Martinez, Springer-Verlag,Ber- during this period of extensive orogenic activ- Lucas, S.B., Stern, R.A. and Syme, E.C., 1995. Flin Flon lin, p. 369-379. Greenstone Belt: Intraoceanic tectonics and the devel- ity, we will gain a better understanding on how Barrie, C.T., Ludden, J.N., and Green, A.H., 1993. Geo- opment of Continental crust (1.92-1.84 Ga); Geologi- to effectively evaluate and explore for specific chemistry of Volcanic Rocks Associated with Cu-Zn cal Society of America Bulletin. depositional environments within specific arc and Ni-Cu deposits in the Abitibi Subprovince; Eco- Lucas, S. B., Stern, R.A., Syme, E.C., Bailes, A.H., and regimes. In order to optimize the exploration- nomic Geology, 88. 1341-1358. Reilly, B.A., 1996. Regional tectonic setting of the Bergman-Weihed, J., 1995. Structural and textural evolu- 1.9-1.8 Ga Flin Flon belt; in Geological Association ist’s understanding of where and when signifi- tion of the Paleoproterozoic epigenetic (?) Boliden cant massive sulphide deposits form, it is nec- of Canada/Mineralogical Association of Canada An- VHMS deposit, Skellefte District, northern Sweden; nual Meeting 1996, Program with Abstracts, v. 21, essary to have a basic (but not too basic!) level in ’95, International Conference on Tec- of understanding of belt-scale tectonic proc- tonic & Metallogeny of Early/Mid Precambrian Oro- esses, igneous petrology and geochemistry, genic Belts, Montreal Canada, Program with physical volcanology and hydrothermal geo- Abstracts, p. 45. The Earth chemistry. As these are evolving disciplines, Brown, B.A., and Mudrey, M.G., 1996. Tectonic/strati- graphic setting of volcanogenic massive sulphide de- “Some of us still get all weepy when one must be prepared to continuously update posits in the Early Proterozoic Penokean terrane of we think about the Gaia Hypothe- one’s knowledge through reading of relevant northern Wisconsin; in Geological Association of sis, the idea that earth is a big furry periodicals and short course attendance. Canada/Mineralogical Association of Canada Annual Acknowledgements Meeting 1996, Program with Abstracts, v. 21, p.A-13. goddess-creature who resembles Campbell, I.H., Coad, P., Franklin, J.M., Gorton, M.P., everybody’s mom in that she knows I would like to thank all of the speakers Scott, S.D., Sowa, J. and Thurston, P.C. 1982. Rare what’s best for us. But if you look at the symposium for taking the time and ef- earth elements in volcanic rocks associated with Cu- fort to present their material on what is an Zn massive sulphide mineralization: a preliminary at the historical record—Krakatoa, report; Canadian Journal of Earth Sciences,v.9,p. Mt. Vesuvius, Hurricane Charley, important time in the earth’s history with re- 619-623 spect to massive sulphide formation. I would DeMatties, T.A., 1994. Early Proterozoic volcanogenic poison ivy, and so forth down the also like to thank Doreen Ames, Harold Gib- massive sulphide deposits in Wisconsin: an overview; ages—you have to ask yourself: son and Pär Weihed for chairing the sessions, Economic Geology, 89:1122-1151. Whose side is she on, anyway?” and to the Mineral Deposit Division of the DeMatties, T.A., 1996. A geological framework for Early GAC for allowing us to put on this sympo- Proterozoic volcanogenic massive sulphide deposits in Wisconsin: an exploration model; in Volcanogenic Barbara Ehrenreich (b. 1941)

October 1996 13 p.A-59. Lundstrom, I., and Papunen, H. (eds), 1986. Mineral de- Geological Survey of Canada posits of southwestern Finland and the Bergslagen GEOLOGY OF CANADIAN MINERAL DEPOSIT TYPES Province, Sweden; 7th IAGOD Symposium and Nordkalott Meeting, Excursion guide no. 3, Sveriges Geologiska Undersokning Ca 61, 1-43. Lundström, I, and Allen, R., 1996. Tectonic setting of the edited by O.R. Eckstrand, W.D. Sinclair and R.I. Thorpe, 1995 Bergslagen mining region, S. Central Sweden; in Geological Association of Canada/Mineralogical As- sociation of Canada Annual Meeting 1996, Program This recently released volume summarizes the essential charac- with Abstracts, v. 21, p.A-59. teristics of all economically significant Canadian metallic and some indus- Lundström, I., 1996. Alteration patterns and ore genesis in W. Bergslagen, S. Central Sweden; in Geological trial mineral deposits. It has been authored by 28 mineral deposit specialists Association of Canada/Mineralogical Association of at the Geological Survey of Canada, and three external authors. The volume Canada Annual Meeting 1996, Program with Ab- is also one of nine that make up the latest Geology of Canada, the seventh stracts, v. 21, p.A-60. Lydon,J.W.,1984.Volcanogenicmassivesulphidedeposits such overview by the Geological Survey of Canada since its inception in Part 1: A descriptive model; Geoscience Canada,v. 1842. The volume contains 640 pages, including 16 pages of colour plates, 11, p. 195-202. and is available in either English or French. Menard, T., and Gordon, T.M., 1996. Laser-ablation ICP- MS study of REE alteration during metamorphism of Copies can be ordered from the Geological Survey of Canada Book- VMS deposits, Snow Lake, Manitoba; in Geological Association of Canada/Mineralogical Association of store in Ottawa (Tel.: 613-995-4342; FAX: 613-943-0646). Price: $70 Canada Annual Meeting 1996, Program with Ab- (Canada), $91 (Other Countries) stracts, v. 21, p.A-65. Peter, J,M., and Goodfellow, W.D., 1996. Genesis of mas- Information about this volume, is available on the Geological Survey sive sulphide-associated hydrothermal sediments along the Brunswick Belt, Bathurst Camp, New of Canada internet home page at http://www.NRCan.gc.ca/gsc/. Brunswick; Canadian Journal of Earth Sciences,v. 32. Rasilainen, K., 1996. Paleoproterozoic massive sulphide deposits of Finland; in Geological Association of Special Session on Back Arc Continental Rifts Canada/Mineralogical Association of Canada Annual Meeting 1996, Program with Abstracts, v. 21, p.A-77. May 18 - 21, 1997 - Geological Association of Canada/ Reilly, B.A., and Maxeiner, R.O., 1996. Geological setting of volcanogenic massive sulphide deposits of the Flin Mineralogical Association of Canada ’97 - Ottawa Flon-Amisk Lake-Hanson Lake area, Trans-Hudson Orogen, Saskatchewan; in Geological Association of A Special Session entitled “Tectonic, Magmatic and Hydrothermal Evolution of Canada/Mineralogical Association of Canada Annual Continental Backarc Rifts and Methods of Sulphide Exploration, with Emphasis on the Meeting 1996, Program with Abstracts, v. 21, p.A-78. Bathurst Mining Camp”, will be held at the Geological Association of Canada/Mineralogi- Rickard, D., 1986. The Skellefte Field; 7th IAGOD Sym- cal Association of Canada Annual General Meeting. A post-conference trip to the Bathurst posium, Excursion Guide No. 4, p. 46-52. Mining Camp, northern New Brunswick will be offered as part of the Session. Co-spon- Schulz, K.J., 1984. Early Proterozoic Penokean Igneous Rocks of the Lake Superior Region: Geochemistry sored by the GAC-Mineral Deposits Division, CIM-Geology Section, and EXTECH-II th and Tectonic Implications: Abstracts, 30 Annual project:GSC and NB Dept of Natural Resources. Institute on Lake Superior Geology, Wausau,Wiscon- Technical Program: Two days of presentations and one day of posters will run sin, v. 30, p. 55-56. concurrently on the first day. Emphasis will be on new research emanating from EXTECH- Sillitoe, R.H., Hannington, M.D., and Thompson, J.F.H., II in the Bathurst Mining Camp. The session will draw on the extensive research of modern 1996. High sulfidation deposits in the volcanogenic massive sulphideenvironment; Economic Geology,v. continental rifts, and similar ancient backarc rifts that host seafloor massive sulphides. 91, p. 204-212. Over 50% of the presentations are by invitation, and will feature international experts Stern, R.A., Syme, E.C., Bailes, A.H. and Lucas, S.B., in tectonics, and magmatic & mineralizing processes in backarc rifts. Day 1 will focus on 1995. Paleoproterozoic (1.90-1.86 Ga) arc volcanism the genetic relationship between extensional tectonism, anoxic sedimentation, felsic mag- in the Flin Flon Belt, Trans-Hudson Orogen, Canada, matism, metalliferous fluid generation & discharge, and seafloor depositional processes. Contributions to Mineralogy and Petrology, v. 119, p. 117-141. Day 2 will focus on the development, testing and application of exploration methods in Swinden, H.S., 1991. Paleotectonic settings of volcano- the Bathurst Camp. genic massive sulphide deposits in the Dunnage Zone, Field Trip: “Geology & Massive Sulphide Deposits of the Bathurst Mining Camp”. Newfoundland Appalachians; Canadian Institute of This 3-day trip will examine the characteristics of various VMS deposits, and relate their Mining and Metallurgy Bulletin, v. 83, p. 59-69. Syme, E.C. and Bailes, A.H., 1993. Stratigraphy and tec- formation to the stratigraphic and tectonic evolution of the Bathurst Camp, recently re-in- tonic setting of Early Proterozoic volcanogenic mas- terpreted as a preserved backarc basin accretionary complex. sivesulphidedeposits,FlinFlon,Manitoba;Economic Organizers: Wayne Goodfellow and Cees van Staal - Geological Survey of Canada Geology, v. 88, p. 566-589. Syme, E.C., Bailes, A.H., Lucas, S.B., and Stern, R.A., 1996. Tectonostratigraphic and depositional setting of BATHURST MINING CAMP Paleoproterozoic volcanogenic massive sulphide de- posits, Flin Flon, Manitoba; in Geological Association ~466 million years ago of Canada/Mineralogical Association of Canada An- Subduction nual Meeting 1996, Program with Abstracts, v. 21, Oceanic Zone and Back-Arc Rift Shelf Margin Crust Island Arc p.A-59. Sea Level Vivallo, W., 1985. The geology and genesis of an Early Massive Proterozic massive sulphide deposit at Garpenberg, Felsic Sulphides VoVolcanicsolcanics central Sweden; Economic Geology; v. 80, p. 17-32. Vivallo, W., and Rickard, D., 1984. Early Proterozoic OCEANIC CRUST ensialic spreading-subsidence: Evidence from the CONCONTINENTAL Garpenberg enclave, Central Sweden; Precambrian Magma BASEMENT Research, v. 26, p. 203-211. Weihed, P., 1996. The tectonic setting of volcanic-hosted CONTACT: massive sulphide deposits in the Paleoproterozoic Ottawa '97 c/o GSC Skellefte district, northern Sweden; in Geological As- 601 Booth St., Ottawa, ON,K1a 0E8 sociation of Canada/Mineralogical Association of Tel: 613-947-7649 FAX: 613-947-7650 ASTHENOSPHERE Canada Annual Meeting 1996, Program with Ab- E-mail: [email protected] stracts, v. 21, p.A-101.

14 The Gangue No. 54 1996 Julian Boldy Awards

The Julian Boldy Award is presented by the Mineral Deposits Clifford R. Stanley - Division - GAC to the author(s) of the paper(s) presented at the Annual A Lithogeochemical Analysis of Host Rock Composi- GAC meeting, that are judged to best describe significant and prag- tional Variability at the Citronen Fjord Zn-Pb Sedi- matic advances in mineral deposit research or exploration. The win- ment-Hosted Massive Sulphide Deposit, Peary Land, ning papers are more than excellent technical writing; they are also Greenland elegantly and concisely presented. Eric C. Syme Alan H. Bailes - At the recent GAC annual meeting held in Winnipeg, a total of 60 Stephen B. Lucas Richard A. Stern - papers were presented to two MDD-sponsored sessions, one on the Tectonostratigraphic and Depositional Setting of Paleo- Geological Setting of Nickel Deposits, and another on PaleoProtero- Proterozoic Volcanogenic Massive Sulphide Deposits, zoic Volcanic-related Massive Sulphide Deposits: Tectonic Setting and Flin Flon, Manitoba Depositional Environments, as well as to general sessions on Economic Following the Boldy Award tradition, expanded abstracts of each Geology. Three papers are being recognized with awards in 1996. of these papers will appear in this and upcoming issues of The Gangue These are, in alphabetical order by presenter’s name (in bold type): for the benefit of those unable to attend the meeting. Each author will receive a wall certificate, a book plate and a small cash prize. MDD extends its gratitude to the following, who served as judges Bruce Ryan - at the Winnipeg meeting: Mario Joly and Charles Tarnocai of Placer Dome (Val D’Or & Cochenour offices, respectively), Gary Wells of The Voisey’s Bay Massive Sulphide Deposit: Inmet, Vancouver, and Ed Debicki of MITEC, Sudbury. It’s Geological Setting within Androgenic Plutonic Rocks of the Nain Area, Labrador Bob Cathro, MDD Treasurer

GAC Travel

The Geological Association of Canada has recently signed a 3-year agreement with Ottawa Travel to act as a corporate travel agent. Ottawa Travel promises to offer excellent service to all GAC members in either English or French, real rock-bottom pricing, and free delivery Mark Twain (1835–1910), of tickets anywhere in North America.

This dedicated agency agreement will benefit GAC in a number of ways such as free tickets for GAC Headquarters staff travel, travel Epithermal Gold Deposits: for unsupported Councillors to business meetings, some free tickets for Styles, Characteristics and annual conventions and hopefully, several thousands of dollars to GAC’s annual income (to help keep dues at a minimum). GAC will Exploration receive 2% of the pre-tax value of all air tickets purchased by members by J.W. Hedenquist, E. Izawa, or executive for travel to business meetings and annual conventions. A. Arribas Jr. And N.C. White GAC will also receive one free ticket for every 30 purchased by GAC The Society of Resource Geology wishes members. to announce the publication of Special Publi- cation No. 1, 1996, a wall poster, 146x103 It is essential that as many members as possible be encouraged cm), full colour, with 41 figures, 21 photo- to use Ottawa Travel for GAC-related travel. If you wish to support the graphs, 4 tables, 8 case studies. All text and captions translated to Spanish, French, Japa- GAC with your next trip, contact Ottawa Travel at 1-800-267-8866 and nese and Chinese in an accompanying book- mention that your bookings are GAC related. The account coodina- let. tor is Jean-Guy Lamadeleine. Ottawa Travel will also compile a Per- Poster plus booklet US$30 each, airmail sonal Profile detailing airline & seating preferences, address for postage included; 20% discount for orders of sending out tickets, and credit card particulars for billing. 5 or more. Student discounts. Send mailing address with credit card name (VISA or MC Ottawa Travel can be contacted through several routes: only), card number, and expiration date to: The Society of Resource Geology Nogizaka Building, 9-6-41 Akasaka 1-800-267-8866; Tel: 613-563-1494; FAX: 613-563-8070 Minato-ku, Tokyo 107, Japan E-mail: [email protected]; WWW: http://www.magi.com/~ottrvl/index.html FAX: +81-3-3475-0824; E-mail: [email protected]

October 1996 15 MDD Publication: Downhole Seismic Imaging

Pubication price: MDD members - $45.00 Cdn/US Non-members - $55.00 Cdn/US Thirty researchers and managers from three mining Order from:Geological Association of Canada Dept. of Earth Sciences, Memorial Univ. of Nfld. companies, five universities, St. John’s, Newfoundland, Canada A1B 3X5 Atomic Energy of Canada Ltd. Tel: 709-737-4062 FAX: 709-737-2532 E-mail: [email protected] and the Geological Survey of Canada attended a workshop on downhole seismic imaging at the ATLAS OF ALTERATION MDD GSC in Ottawa, Sept. 6/96. A Field & Petrographic Guide Alteration Atlas Preliminary surveys by to Hydrothermal Alteration Minerals MDD Alteration Atlas 1996 GSC staff have demonstrated that this technique has practical Anne J.B. Thompson, John F.H. Thompson and Kathryn P.E. Dunne, Editors application for mapping geologi- cal structure and delineating This 8.5x11”, soft-covered book facilitates recognition of major altera- massive sulphide deposits from tion minerals in both field and laboratory settings. It provides an intro- instruments deployed in exist- duction to major types of alteration, referenced to the environment of ing, neighbouring deep bore- formation and the relationship to ore deposits. It covers standard altera- holes. tion types & textures using colour photographs and concise, short de- scriptions. The atlas is for professional geologists and students. The workshop partici- pants agreed to form a five-year, The volume contains 50 contributions by international authors and 50 multi-agency consortium to de- colour plates. Each colour plate is complemented by a facing page of velop and test computer hard- text describing common mineral alteration type, characteristics in out- ware and software associated crop, hand sample and thin section, related and accessory minerals, environments of deposition, example deposits, references and photo with downhole seismic imaging, captions. A cross-reference table links alteration minerals to deposit with the ultimate goal of trans- types. Charts of standard mineral optical properties are included. ferring this technology to indus- try.

MINERAL DEPOSITS DIVISION - GAC Membership Information &Application

16 The Gangue No. 54 often inconspicuous and difficult to detect. The explored but still interesting deposits include: Tintaya: Tintaya’s reserves are estimated at 10 Mt of 2.29% Cu in oxide ore, and 41 Mt of 2% Cu in chalcopyrite-magnetite ore. Coroccohuayco: A blind, magnetite-chalcopyrite skarn deposit, 15 km from Tintaya. It was discov- ered through geophysics and drilling has out- lined 15.2 Mt of 2.89% Cu with a cutoff grade of 1% Cu. Chalcobamba: Undeveloped Cu skarn de- posit in southeastern . Its reserves are reported as 13.7 Mt of 2.1% Cu, mostly in sulphides. Compiled by B. Grant, Victoria, BC Antamina: A Cu, Zn, Ag and Mo skarn de- posit in central Peru. Calculated ore reserves are: 34.6 Mt of 1.7% Peru, dominating the west-central coast of , faces Cu, 2.13% Zn, 24.8 g/t Ag, and 0.05% Mo. the new millennium with some of the richest mineral potential on earth. STRATABOUND CU DEPOSITS Peru’s mining tradition dates to well before Europeans sailed to Only a small portion of Peru’s Cu production is obtained from the New World , when metallic minerals were mainly used by native stratabound sulphide deposits. The leading stratabound producers are peoples for tools and in the arts. Its gold and silver production became Condestable and Ra. Together, they produced some 10 493 t of Cu legendary in 1532, when on behalf of the Spanish Crown, Francisco concentrate in 1993. Both mines are on the coastal strip, 100 km south Pizarro received Atahualpa’s ransom, consisting of 3 rooms full (~24 of Lima, where there is good potential for similar deposits. tons) of gold and silver objects. Peru’s stratabound-Cu potential is largely undefined because these The country is now a major international producer of silver, bis- deposits are usually flat-lying, low-profile ore bodies that are not ob- muth, copper, lead, zinc and gold. It also produces a wide range of other vious to the prospector. However, in Tambo Grande, a large Cu-Zn metallic and industrial minerals from a great many mines concentrated rich stratabound massive sulphide deposit in northern Peru, drilling has particularly within the Andes which run through the country, parallel outlined 42.3 Mt of 2.06% Cu, 1.47% Zn and 30 g/t Ag. It also contains to the Pacific coast for about 3000 kilometres. The Pervian Andes are 30 Mt of nearly barren pyrite. almost 300 km wide, rise an average of 3000 metres ASL and include high plateaus, valleys and canyons. PRECIOUS METALS Mining, always one of the country’s main economic activities, Silver: Historically, the most important Ag-vein deposits have presently accounts for about 11% of the GDP. The mining sector also been, Millotingo, Julcani, Uchucchacua, Arcata, San Genaro, Cayl- generates the highest amount of foreign currency from exports, ~50% loma, Caudalosa and San Juan de Lucanas. Production from these of Peru’s total exports. In the 1990s the country has concentrated on mines ranges from 400 to 1000 t/day, depending on the grades of the modernizing its economic structure, ensuring security for its people, veins. Some mines, like Orcopampa and Arcata, have succeeded in and reviving the historically important mineral resource sector of the achieving head grades as high as 435 g/t Ag. economy. Gold: Gold was Peru’s third largest export in 1995 with a value PORPHYRY CU DEPOSITS of US$463 million (copper was the second at a value of US$1.2 billion). Most of Peru’s copper production is obtained from two porphyry Statistics indicate production of 56 tonnes gold in 1995, about half of deposits located in southern Peru: Toquepala, which produced 105 623 which came from the Yanacocha and Buenaventura mines. Government t of Cu in 1993; and Cuajone, which mined 135 602 t. Both deposits officials predict Peru’s output will rise to about 100 tonnes by the year are mined by Southern Peru Copper Corporation, a company owned by 2000, and new discoveries such as the Pierina deposit by Arequipa/Bar- Asarco, Newmont, Phelps Dodge and Marmon Corporation. The Cerro rick, appear to justify such an optimistic view. Verde mine is also located in this area. A line of porphyry deposits runs for about 2500 km, from southern Peru into Chile along which there is a strong potential for new Cu production. Porphyry Cu deposits located in central and north-central Peru, also offer a good potential. Significant deposits, already measured Iquitos but still undeveloped, are: Quellaveco: Southern coast; 385 Mt of 0.85% Cu with a 0.45% cutoff. Talara Michiquillay: Northern highlands; 544 Mt of 0.69% Cu with some precious metals. Toromocho: Central highlands; 365 Mt of 0.67% Cu, with some Ag. Cerro Verde and Santa Rosa: North of the southern porphyry de- posit belt; 810 Mt of 0.66% Cu. In all, over 50 porphyry Cu deposits have already been identified. In addition to the above, La Granja, Caariaco, Pashpap and Almaçn Trujillo are also important. All of them have supergene deposits that appear large and rich enough for solvent extraction and electrowinning. CU SKARN DEPOSITS An important Cu-skarn deposit occurs in the central Andean high- Lima Cusco lands - Tintaya. In 1993, production from Tintaya stood at 48 927 t of Cu concentrate. Another leading Cu-skarn mine in the region is Co- briza, with production of 27 310 t in 1993. Arequipa Much of Peru’s Cu potential is associated with such skarn deposits. A large section of the Peruvian Andes is underlain by limestones and dolomites and is densely spotted with igneous intrusives, some of which have associated hydrothermal mineralization. Such mineralization is

October 1996 17 Peru has several old high-grade Au districts. Pataz, Parcoy and The line of Au mines and placer deposits that runs south to Rin- Buldibuyo, with rich Au-quartz veins, located on the eastern slopes of conada and Santo Domingo, shows several “bonanza-type” Au veins, the Andes in northern Peru. The line of Au mines, prospects and asso- with good prospects. According to Minero Peru’s estimates, there are ciated placer deposits runs farther south, where there are amazingly rich 90 Mm3 of dredgable ore reserves grading about 0.28 g/m3. These placer deposits close to the border with Bolivia. reserves are located in Puno, close to the Bolivian border. There may be great placer potential in southern Peru; however, this potential has Exploration Potential not yet been explored with modern techniques. Peru’s metallogenetic provinces have not been adequately inves- Similarly, on the western slopes of the Andes, there is a line of Au tigated until recently due to a variety of reasons such as lack of access deposits, typified by the string of Au mines between Sol de Oro and to the geoscience database, undeveloped infrastructure, and a restrictive Andaray. These Au deposits are found mostly along the edge of the legal and investment environment. Changes in the political environ- coastal batholiths and also in their roof rocks. Au vein districts typified ment therefore make grassroots exploration, using modern concepts by Guanaco, San Cristobal and others, have bulk-tonnage ore bodies and technology, a good investment opportunity, particularly in the as well as veins. search for porphyry Cu deposits and bulk-tonnage Au deposits. The Andean metallogenetic province in Peru is one of the most To the east of the line of porphyry Cu deposits that runs south from attractive areas to explorers in Latin America. In general, Peru’s epi- Cerro Verde to Cuajone and Toquepala - and farther south into Chile - thermal Au districts are still unexplored and there are possibilities of there is an elongate field of middle to late Tertiary volcanic centers. finding important scattered Ag and Au deposits. This field is peppered with color anomalies that bear the same relation- It should also be noted that the mineral resource and geological ship to the Peruvian porphyry Cu belt as the relationship borne between database is being aggressively upgraded and made more easily avail- the Maricunga Au district color anomalies and underlying ore bodies, able to the public by INGEMMET (Instituto Geológico Minero y and the Chilean porphyry Cu belt. Metalúrgica Resú), the national geological, mining and metallurgical The geologic provinces where Cu-rich skarn deposits may exist institute. Similarly, recent changes to the Peruvian mining laws and are large and scattered in the south-central and southern Peruvian An- mineral tenure system have been made in order to attract foreign invest- des. Thus, there are very good possibilities that similar deposits will ment. As a result Peru is the focus of major interest from the interna- continue to be discovered. tional mining community and exploration is booming in this South American country. Bulk-tonnage Au deposits that are missing in the Peruvian Andes References may yet be discovered. Before 1975, there were no known major Au deposits in Chile and the prevailing idea among exploration geologists Fornari, M and Herail, G. (1991): Lower Gold Occurrences in the Eastern was that no such deposit existed. However, a careful exploration pro- Cordillera of Southern Peru and Northern Bolivia: A Genetic Model; Brazil Gold ’91, Ladeira, E.A. Editor, Proceedings of the Symposium Brazil Gold ’91, pp 135-142. gram revealed the existence of important and feasible Au-Cu prospects, Noble, D.C. and Vidal, C.E. (1994): Gold in Peru; Society of Economic Geologists, SEG like El Indio and Escondida in Chile. The Chilean exploration experi- Newsletter No. 17, April 1994. ence indicates that further Cu and Au exploration work in the Peruvian Various, (1990): Economic Geology, Vol85, No. 7, A Special Issue Devoted to the Mineral Andes could be just as productive. Deposits of Peru. International Mining Highlights

• A decree by President Boris Yeltsin,Au- activity, involving largely non-mechanized set of mineral claims and temporarily froze gust 15, dismantled the Russian Commit- operations mainly for gold and diamonds, out the private sector from the area sur- tee for Precious Metals and Stones (Rosk- can play an important role in the economies rounding the new base metal find. Several omdragment) which controlled Russia’s of developing countries. It is an important gossans sparked the staking which con- sales of diamonds and precious metals. The source of employment and income, and in- tained about 2% Ni, 2% Cu and some co- authority will be transfered to the Ministry comes are often higher than those paid in balt. Mining companies working in the im- of Finance and the new Ministry of Indus- other economic sectors. (MJ 06/09/96) mediate area of the discovery and claim try. The Committee for Metallurgy and the • staking have voiced disapproval of the Over the next six months there is a series governments approach. (NM 09/09/96) Committee for Geology and Use of Under- of mining privatizations planned right ground Resources were also disbanded and across South America. However, privatiza- • Klondike - The Last Great Gold Rush! It their functions will passed to the new Min- tion is not proving entirely smooth for istry of Natural Resources, State Commit- was 100 years ago on August 16, that these programs. There is strong trade union George Carmack discovered gold along the tee for Environmental Protection and the opposition to privatization of CVG in Ministry of Industry. (MJ 06/09/96) Klondyke (as it was then spelt) River in Venezuela. Venezuela’s opposition party, Canada’s Yukon Territory. • British Columbia and Papua New Radical Cause, controls all of the union- Guinea are the only major copper concen- ized employees in CVG’s heavy industries, • Productivity the Orapa diamond mine, in trate producers that don’t have smelting and opposes the government’s privatiza- Botswana, is to be doubled to 17 Mt/y in and refining capacity - an unusual situation tion plans. Also, the outlook for Peru has the next four years, at a cost of approxi- for a major producer of concentrate. A not been helped by indications last month mately $290 million. The expansion of looming shortage of copper smelting ca- of renewed activity by the Shining Path Orapa is expected to increase the output of pacity is breathing new life into a smelter Maoist guerrilla movement. (MJ 06/09/96) Debswana by approximately 6 Mct/y. proposed for Kitimat on BC’s north coast. • Remarkable words:“Don’t forget that Debswana, the largest diamond producer The proposed smelter would be in the 150 government can do anything”, British Co- in the world in terms of value, currently 000 to 200 000-tonne a year range and cost lumbia’s Forests Minister, 9/12/96. (VS recovers about 17 Mct/y, including dia- about $600 million, according to Tex Ene- 14/09/96) monds from the full range of categories and mark, executive of PRM Resources Ltd. It quality. (MJ 23/08/96) now seems clear that the world’s existing • Quebec added a new twist to the traditional copper smelting capacity is full and con- Canadian mining scene in which govern- • The IMF this week called on the South Af- centrate stocks are growing. (VS 14/09/96) ment geologists assist the mining industry rican Government to make a significant by mapping in virgin areas and releasing break with the past by accepting that min- • Over the past 25 years there has been a information about new discoveries. Que- ing could no longer be the lynchpin of the world-wide resurgence of small-scale bec, to the dismay of resource companies country’s economic strategy. (MJ mining, particularly artisanal mining. This working in the North Shore area, staked a 30/08/96)

18 The Gangue No. 54 Gold in Ukraine

by Boris Kotlyar and Steve Ludington The characteristics of gold deposits and The metamorphic grade of the blocks is pri- US Geological Survey occurrences correspond to worldwide deposit marily amphibolite facies, with some areas of models (Cox and Singer, 1986), and applica- granulite and greenschist. Three important Introduction tion of these models has allowed us to make a north-trending shear zones divide these general assessment of the precious-metal po- blocks. They are, from west to east, the Be- Ukraine is an independent country, rees- tential of the country. The geological and loserkov, Krivorog, and Pavlograd. The shear tablished in 1991 within the boundaries of the quantitative resource information in this paper zones are composed primarily of mafic vol- former Ukrainian Soviet Socialist Republic, is derived from published materials, from in- canic rocks and iron formations, which are belonging to the Commonwealth of Inde- formal communications with colleagues in primarily Archean or lower Proterozoic in pendent States. It is a large state, covering Ukraine, and from personal experience of the age. Most rocks in the blocks are Proterozoic, more that 600 000 square kilometers, and with senior author. The information is not official. except for some Archean greenstone areas in a population of nearly 60 million people. Most The early history of gold in Ukraine is de- the Pridneprov block. The upper Proterozic of the country has low relief, and is devoted scribed by Galetskiy et al. (1993), and some rocks of these stable blocks contain much of to agriculture, except for the Carpathian and of the deposits described here are shown on a Ukraine’s mineral wealth, especially deposits Crimean Mountains, which rise to more than metallogenic map prepared by Galetskiy et al. of titanium, uranium, beryllium, and rare earth 1500 meters in the southwestern and southern (1994). elements. part of the country. Geology of Ukraine The central shield is bounded on the west Ukraine was not known in the past for and south by marginal sedimentary basins production of precious metals, but new dis- The geologic diversity of Ukraine is in- (Volyn and Prichernomor), which are filled coveries during the last decade suggest that dicated by Figure 1. The central part is made with Mesozoic carbonate rocks that host a this perception may change. These discover- up of the Ukrainian Precambrian Shield, fluorspar deposit and exhibit indications of ies resulted from extensive geological, geo- which is composed of four stable blocks, from lead-zinc mineralization. The Volyn basin physical, and geochemical exploration pro- west to east, the Volyn-Podol, Kirovograd, also contains some trap rock, along with asso- grams. Gold prospects and deposits have been Pridneprov, and Priazov. These blocks are ciated basaltic and sediment-hosted copper discovered in the Carpathian Mountains, in composed primarily of gneiss and migmatite, occurrences. intruded by granitic plutons and complexes the Ukrainian Precambrian Shield (UPS), and On the northeast margin, the shield is in the Dneprovo-Donetzk Aulacogen (DDA). (both alkaline and subalkaline), and several massifs of rapakivi granite and anorthosite. bounded by the Phanerozoic Dneprovo- Donetzk aulacogen, which is filled with gen-

October 1996 19 Region District Deposits and Occurrences Type of Deposits Age Known Resource Gold content

tly deformed flysch, primarily of Carbonifer- been better-known for base metals and for The presence of these epithermal depos- ous age. This region contains significant de- silver. Present reserves are about 3.6 million its suggests the possibility for the existence of posits of coal, and the well-known mercury tonnes of ore, with a grade of 5 g/t Au, 15 g/t large, low-grade, hot-spring Au-Ag deposits deposits at Nikitovka. Ag, and 5% combined Pb and Zn. (Berger, 1986a; 1992). These deposits typi- cally are larger than 10 million tonnes, at The Carpathian Mountains and the Cri- Detailed descriptions of ore stages, vein grades between 1 and 2 g/t Au (table 2); they mean Peninsula, which form the southwestern mineralogy, and fluid-inclusion and isotopic might be sought in regions where the upper and southern part of the country, are Alpine characteristics can be found in Vityk and oth- parts of the Neogene volcanic pile, including mountain systems, composed primarily of ers (1994). The deposit is characterized by a the paleosurface, have been preserved from overthrust Mesozoic and rocks, classic cycle of vein mineralization that be- erosion. with some local Paleozoic uplifted areas. The gins with quartz and polymetallic sulphide Ukrainian Carpathians include part of the Car- minerals, followed by relatively barren Low sulphide gold-quartz pathian Neogene volcanic belt, composed pri- quartz-barite and quartz-carbonate stages. deposits—Rakhov district marily of silicic ash-flow tuffs and andesite The initial sulphide-mineral-depositing stage To the southeast of Beregevo, the Rak- and dacite flows, which host hydrothermal was characterized by temperatures of about hov district (Fig. 1, Table 1) is located in an precious- and base-metal deposits in nearby 250°C., and fluid salinities of 5–8% NaCl uplifted block of basement, the Marmarosh Romania, Hungary, and Slovakia, as well as equivalent. Elements found in geochemical block. The area includes one important de- in Ukraine. haloes surrounding the veins include Mn, Cu, posit, Saulyak, and several prospects known The Carpathian Mountains Pb, Zn, and Ag. Mineralized rock is found as Bun, Bely Potok, Tukalo, and Yaseniv over a vertical interval of several hundred me- (Averin et al., 1992; Galetskiy et al., 1994). Precious and base metals have been re- ters. covered from vein deposits in the Carpathian At Saulyak, ore is present in quartz and Neogene volcanic belt at least since the Holy The deposits are similar in many respects quartz-carbonate veins that are emplaced into, Roman Empire began to mint silver coins in to deposits in the western San Juan Mountains although largely concordant with, green- the 12th century. New discoveries in the 20th of Colorado. Like the Colorado deposits, schist-facies quartz-chlorite-sericite (-car- century have brought fresh attention to this those at Beregovo exhibit some charac- bonate) schist that forms part of a shear zone area, and there has been considerable explo- teristics of both epithermal-precious metal that marks the border between two strati- ration activity since the mid-1970s (Averin et and polymetallic veins. Certainly, the recently graphic sequences. al., 1992). discovered gold deposits, found in the upper The veins carry small amounts (20%) of Epithermal quartz-adularia parts of the district, should be classified as pyrite, arsenopyrite, sphalerite, and galena. deposits—Beregovo district epithermal quartz-adularia deposits. In either Gold is unevenly distributed throughout the case, when compared to the data in Mosier and veins in small grains. Alteration assemblages Deposits near the town of Beregovo (Fig. others (1986) and in Cox and Ludington 1, Table 1) are related to a large volcanic de- that surround the veins include quartz, quartz- (1996) (Table 2), the known deposits at Bere- albite-sericite, and quartz-carbonate mineral- pression, identified as a caldera in Vityk and govo are fairly large; very few quartz-adularia others (1994). The caldera is filled with an- chlorite. Elements in geochemical haloes sur- or polymetallic vein deposits are as large as 3 rounding the veins include As, Hg, Ag, Bi, desitic to rhyolitic ash-flow tuffs and sedi- million tonnes. mentary rocks. The mineral deposits consist and Cr. The deposit has been explored, and is estimated to contain reserves of about 1.6 of sulphide, quartz-sulphide, quartz-barite, Other volcanic-hosted Carpathian occur- and quartz-carbonate veins, veinlets, and million tonnes of ore at 7 g/t Au. All the char- rences are found in the Kvasov, Vyshckov, and acteristics of these deposits, including the stockworks. Individual deposits (Beregovo, Began districts (Fig. 1, Table 1). The style of Muzhievo, Kuklyan) are within a few hun- grade and tonnage estimate, suggest classifi- mineralization is similar to that at Beregovo, cation as low-sulphide Au-quartz deposits dreds of meters of each other, and are inside with the additional occurrence of some gold- and near the eastern rim of the caldera. (Berger, 1986b). Comparison to the grade and rich pipes at Began (Averin and others, 1992; tonnage model of Bliss (1986) suggests Detailed exploration by mining and drill- Galetskiy et al., 1994). Some detailed sam- Saulyak is a relatively large deposit (Table 2). ing in the last decade has revealed new ore- pling has been done in these districts, and bodies in which gold is the most important preliminary data indicate no more than 1–3 There are few signs of mineralization in metal, whereas previously, the district had million tonnes at a gold grade of 3–5 g/t. the Crimean Mountains, though the geologic

20 The Gangue No. 54 Gold, electrum, silver sulfosalts, and argentite in vuggy quartz-adularia veins hosted by felsic to intermediate volcanic rocks that overlie predominantly clastic sedimentary rocks, and their metamorphic equivalents.

Gold, chalcopyrite, sulfosalts, and argentite in vuggy veins hosted by felsic to intermediate volcanic rocks that overlie older volcanic sequences or igneous intrusions.

Gold, electrum, silver sulfosalts, and argentite in vuggy quartz-adularia veins hosted by felsic to intermediate volcanic rocks that overlie unspecified basement.

Fine-grained silica and quartz in silicified breccia with gold, pyrite, and Sb and As sulfides.

Gold in massive persistent quartz veins mainly in shear zones in regionally metamorphosed volcanic rocks and volcanic sediments. Gold in massive persistent quartz veins mainly in shear zones in regionally metamorphosed Archean volcanic rocks and volcanic sediments.

schist-facies metamorphic rocks. The veins setting is closely similar to the Carpathians tent of other elements includes Ag, 4 g/t, Cr, (Shnyukov et al., 1993). 1.25%, and Ni, 0.18%. The occurrence has are 10 cm to 2 m thick, and the mineralized area is several kilometers in length. Sulfide The —variations on been intensively prospected and probably contains about 350 000 tonnes at a grade of mineral content of the veins is 3–5 volume low sulphide gold-quartz deposits percent, and sulphide minerals, including pyr- 1.2 g/t Au (author’s estimate). Laterite depos- Much of the rest of Ukraine consists of rhotite, pyrite, loellingite, arsenopyrite, chal- flat plains covered with wheat fields, and most its like this may form from many types of precursor deposits, as is evident from the work copyrite, and native bismuth also form aure- of the Ukrainian Shield is concealed by oles as much as 20 m wide around the veins. 50–100 m of cover, along with the mineral of McKelvey (1992) and Bliss (1992) (Table 2). Quartz, chlorite, and rare graphite and tour- deposits it hosts. A major exception is Klin- maline are also found in the veins. Geochemi- tzov, described below, which is exposed. The May occurrence, in the Savran dis- cal halos are of Bi, As, Cu, and Ag. Klintzov Beloserkov deformed zone trict (Fig. 1, Table 1), is known for its coarse- has been relatively well prospected, and we grained gold, and low sulphide mineral con- In the southern part of the Beloserkov estimate a reserve of 2–3 million tonnes at a tent (Yaroshchuk and others, 1994). It is gold grade of 3–5 g/t (author’s estimate). deformed zone, a well-known chromium-, associated with a steeply-dipping shear zone nickel-, and iron-rich area known as Pobuzge in a high-grade area of mixed gneiss, This description corresponds closely to the low-sulphide Au-quartz deposit type (Ber- (Fig. 1, Table 1) is developed in an assemblage granulite, and granite. Within the shear zone, of gneiss and granulite, which surrounds nu- hydrothermal alteration may be intense, pri- ger, 1986; Bliss, 1986; Table 2). The other merous bodies of mafic and ultramafic rocks. marily silicification, with less intense devel- prospects are similar, and we expect other un- discovered deposits in this area will be found Shear zones and zones of retrograde metamor- opment of sericite, hydromica, serpentine, phism are characterized by Mn-Fe and Ca-Mg and chlorite. Gold, as well as rare pyrite and to be similar, both with respect to their geol- ogy, and their grade and tonnage. skarn assemblages, serpentine, and sericitic marcasite, is present in these zones in large altered rocks. Gold mineralization is present (up to 10 mm) grains in breccia zones and in Pridneprov block in these altered rocks, and also in lateritic veinlets. Intercepts in diamond drill holes may weathering products of mafic and ultramafic Farther east, lies the Pridneprov block, contain as much as 50 g/t Au. This occurrence, where a number of Archean greenstone belts rocks. too, has been intensively prospected, and has An important occurrence is at Kapitanov (3200–2500 Ma), are characterized by banded a tonnage of about 6 million tonnes at a grade iron formation, felsic metavolcanic and sub- (Fig. 1, Table 1), where gold is present in of 7–10 g/t Au (author’s estimate). association with a small ( square kilometer) volcanic rocks, mafic metavolcanic rocks, and Kirovograd block altered komatiite-tholeiite assemblages body of dunite and gabbro of indeterminate age (Yaroshchuk and Mel’nichuk, 1991). Hy- Farther east, in Proterozoic rocks of the pogene mineralization is confined to Mg Kirovograd block, which is well-known for its skarns near the margins of the mafic body, and important uranium deposits, the Klintzov de- consists of disseminated pyrite, magnetite, posit is representative of another group of and hematite (as much as 10% total), with gold-bearing deposits and prospects, includ- gold values commonly from 0.1–0.3 g/t and ing Chmelev, Markov, Michaylov, Yuriev, rarely as high as 80 g/t. The main Kapitanov Lipnyazh, and Adzham (Fig. 1, Table 1) occurrence is a laterite, developed along the (Metalidi et al., 1992). All these deposits and northwestern contact of the mafic body. The prospects are present in relatively narrow de- laterite is more than 500 m long, 2 to 16 m formation zones around the margins of a cen- thick, and consists primarily of kaolinite and tral granitoid massif. They all are found in montmorillonite. Metallic minerals include steeply-dipping, narrow (100–300 m), long magnetite, pentlandite, chalcocite, covellite, mineralized zones that may display anoma- sphalerite, cinnabar, native copper, and gold. lous contents of gold ( 0.1 g/t) over 20–60 km. The grain size of the gold is 0.1–0.7 mm. The At Klintzov, the deposit consists of a group of laterite contains 0.3–10 g/t Au; average con- quartz veins and cataclastic zones in green- T. S. Eliot (1888–1965)

October 1996 21 (Yesipchuk and Monakhov, 1992). At present, the Chertomlyk, Sur, and Verkhovzev belts (Fig. 1, Fig 2a, Table 1) are believed to have the most potential. Each is 150–300 square kilometers in area. The Krivorog deformed zone, which divides the Pridneprov block from the Kirovograd, is the site of world-class banded iron formation deposits. The tailings of iron deposits at Krivoy Rog contain 0.05–0.3 g/t Au (Galetskiy et al., 1994). In the Chertomlyk belt, Balka Shirokaya is the most important deposit (Fig 2B). The Chertomlyk belt forms a northwest-trending syncline about 15 km long that contains greenschist-facies volcanic and volcaniclastic rocks. The metavolcanic rocks include dacite, andesite, basalt, komatiite, and jaspilite. The central part of the syncline contains some fel- sic rocks, and is intruded by porphyritic pla- giogranite. Balka Shirokaya (Fig. 2C) is confined to a steeply-dipping shear zone, up to 500 m wide, on the eastern limb of the syncline (Yesipchuk and Monakhov, 1992). Here, al- tered rocks form narrow (5–20 m) en echelon bands within the shear zone. These pods are zoned outwards from quartz and quartz-car- bonate mineral cores through quartz-carbon- ate mineral-mica to normal propylitic assem- blages. Gold is present in three different associations within these pods: gold-sulphide minerals-quartz, gold-quartz, and polymetal- lic sulphides. The gold-sulphide mineral asso- ciation, which also contains magnetite, is found as disseminated and brecciated ore, and the size of gold grains is 50–100 microns. The Bobrikov district gold-quartz veins and veinlets (as wide as 50 suggest that many of these prospects could be cm) are mostly brecciated, and contain only a quite large. small quantity of sulphide minerals; they also Bobrikov is the best-studied (Shumlyan- contain rare native silver. The polymetallic We believe the deposits in the Pridneprov skiy and others, 1994). It is located on the crest association is less important than the other block can be adequately represented by the of an anticline above the axis of a horst (Fig. two and is characterized primarily by pyrite, grade and tonnage model for Archean low 3). The host rocks are Carboniferous coal- galena, and sphalerite. Gold mineralization sulphide Au-quartz deposits of Klein and Day bearing sediments, and there are no indica- within the altered bands may extend for as (1994) (Table 2). As these deposits commonly tions of the presence of igneous rocks that much as 2 km along strike, but consistent eco- contain 10 tonnes or more of gold, deposits in could have been the source of heat or hy- nomic gold grades are found only where these the Pridneprov block are likely to provide the drothermal fluids. The deposit consists of a mineralized structures intersect jaspilite lay- largest share of gold to be discovered in stockwork and disseminations that have ers. Actual ore bodies have thicknesses of 10 Ukraine. The major reason for uncertainty is formed on the hanging wall of a fault that is cm to 1 m and are less than 300 m long. They the fact that most of the prospective terrain is approximately parallel to the axis of the anti- have been followed by drilling beneath more covered by as much as 100 m of Mesozoic and cline. At depth, the mineralized zone is as than 600 m of cover. Detailed exploration, Cenozoic overburden. wide as 750 m and as long as 1500 m; it ex- deep subsurface mapping, trial mining, and tends to depths of 1300 m. Disseminated min- feasibility studies indicate a resource of 2.5–6 eralization is very low grade; high grades are The Dneprovo-Donetzk associated with quartz-carbonate mineral-ga- million tonnes at a gold grade of 3–5 g/t. Aulacogen—Something Different lena-sphalerite veins. Farther north, in the Sur and Verkhovzev greenstone belts (Fig. 1, Table 1), a number of The Dneprovo-Donetzk aulacogen Alteration is very subtle, and is difficult less well explored gold occurrences are forms most of the northeastern part of to discern in hand specimen. The main altera- known, including Semerenkov, Sergeev, Ukraine. It began to form in the Late Protero- tion minerals detected are sericite, hydromica, Solonyan, Krasnobalk, Petrov, Apolonov, Po- zoic, but most of the sedimentary rocks that and chlorite. The ore mineral assemblages are tok, and Pravdin. Some of these prospects are fill it are Paleozoic in age. This basin has been complex, and consist of 1) quartz, sericite, found in metamorphosed felsic volcanic and a prolific producer of coal, hydrocarbons, and ankerite, epidote, tourmaline, apatite, alunite, subvolcanic rocks, as well as the rock types salt. In addition, the Nogolny Ridge, an area barite, and vivianite, followed by 2) quartz, described for Balka Shirokaya; alteration as- of low hills underlain by a major anticline and siderite, pyrite, arsenopyrite, chalcopyrite, semblages are primarily propylitic and serici- horst, is the host to the large Nikitovka mer- tetrahedrite, tennantite, bournonite, and gold, tic. Gold is present primarily in quartz veins cury district (Fig. 1). In addition, the region followed by 3) quartz, siderite, ankerite, ga- and veinlets, and as disseminations with pyrite has long been known for silver-rich polymet- lena, boulangerite, freibergite, and gold. More and rare pyrrhotite. The Semerenkov occur- allic deposits. During the 1980s, re-examina- than 50% of the gold is in the form of free rence seems to lack structural controls, and is tion of these polymetallic districts has re- gold, which is very fine-grained, commonly characterized by a relatively even dispersion vealed that many of them have significant <0.1 mm. Microprobe studies of the gold of gold (1–3 g/t) throughout a bed of jaspilite. gold grades. Known gold-rich polymetallic show mercury concentrations as high as 6%. Sergeev is probably the most thoroughly ex- deposits include Bobrikov, Esaulov, Nagolno- Geochemical halos of As, Ag, Pb, and Cu plored. The similarities with Balka Shirokaya Tarasov, and Ostrobugor (Table 1). accompany the gold mineralization.

22 The Gangue No. 54 Preliminary prospecting and drilling in- dicate that Bobrikov contains a geologic re- source of 5–10 million tonnes at 0.3–0.5 g/t Au. It is difficult to classify these polymetal- lic gold deposits. The geochemical signature, including the close association with mercury, and the lack of evidence for an igneous source for the fluids, suggest similarities to some hot- spring Au-Ag deposits (Berger, 1986) (Table 2). The tectonic setting and the abundance of base metals contrast sharply with the low sul- phide content of most hot-spring systems. The stratigraphic and tectonic setting are reminis- cent of sediment-hosted gold deposits (Carlin type), particularly if a metamorphic source for Carlin-type ore fluids is accepted. However, if a magmatic theory of origin for Carlin de- posits is favored, the Paleozoic age and lack of igneous activity would suggest that Bo- brikov and the other deposits are not Carlin, but a new deposit type. Where are the Gold Placers? Unlike most productive gold regions, there do not appear to be significant occur- rences of placer gold in Ukraine. Although this helps explain why many of the deposits we describe were not discovered before the late 20th century, the lack of placers is not a favorable indicator for the region unless it can be explained. There are some known occurrences (Galetskiy and others, 1994). The Dnestr River, for more than 300 km along the bound- ary between the UPS and the Volyn basin, has yielded small amounts of placer gold, and some large nuggets have been found. Gold, along with native bismuth, has been found in the lowermost part of the section in the northern part of the Kirovograd block, where small amounts of placer gold exist in remnants of paleovalleys incised into Precam- brian rocks. In addition, finely-dispersed gold has been discovered in modern delta and shal- low marine sediments along the coast of the Black Sea, in the Dnepr and Dnestr estuaries. ods could be used to discover ore hidden un- Berger, B.R., (1986b): Descriptive Model of Low-sulphide And, finally, numerous subeconomic placer der tens of meters of overburden. In addition, Au-quartz Veins, in Cox, D.P., and Singer, D.A., eds., concentrations are known in Cretaceous and there remains a potential for large hot-spring MineralDepositModels:USGSBulletin1693,p.239. Berger, B.R., (1992): Grade and Tonnage Model Of Hot- Tertiary conglomerates in the Carpathian Au-Ag deposits in the Carpathian Mountains, and hot-spring or sediment-hosted Au depos- spring Au-Ag, in Bliss, J. D. Ed., Developments In Mountains. Mineral Deposit Modeling, USGS Bulletin 2004, p. Conclusions its in the Dneprovo-Donetzk aulacogen. 23–25. The amount of gold available for discov- Bliss, J. D., (1986): Grade and Tonnage Model of Low-sul- Whereas Ukraine is not well-known as a ery cannot be known, but it can be estimated. phide Au-quartz Veins, in Cox, D.P., and Singer, D.A., gold-producing region, recent exploration and From Table 1, we can see that there may be as eds., Mineral Deposit Models: USGS Bulletin 1693, development activities have resulted in the p. 239–243. much as 200 tonnes of gold already discov- Bliss, J. D., (1992): Grade and Tonnage Model of Laterite- delineation of significant gold resources. An ered. Comparison with average productivity saprolite Au, in Bliss, J. D. Ed., Developments In entirely new district in the Kirovograd block (Singer, 1995) from similar geologic environ- Mineral Deposit Modeling, USGS Bulletin 2004, p. has been discovered, the potential in the ments (Canada, Russia, Czech and Slovak Re- 50–51. Donetzk region has been substantiated, and publics, Kazakhstan) would suggest that the Cox, D. P., and Ludington S. D., (1996): Database for a the resource at Pridneprov and at Pobuzge has total amount of gold, including that in undis- national mineral resource assessment of undiscovered been reevaluated. Ukrainian experts believe covered deposits, may well be somewhat Deposits Of Gold, Silver, Copper, Lead, And Zinc. USGS Open File Report (in press). that vigorous exploration in the prospective larger (300–3600 tonnes). Only through con- Klein, T. L. and Day, W.C., (1944): Descriptive And Grade areas described here will result in further dis- tinued exploration will the full potential be And Tonnage Model Of Archean Low-sulphide Au- coveries (Averin and others, 1992). Major tar- recognized. quartz Veins And A Revised Grade And Tonnage gets will be the Beregovo and Rakhov districts References Model Of Homestake Au: USGS Open File Report in the Carpathian Mountains, districts in the 94–250. Kirovograd and Pridneprov blocks and the Averin,Yu.A.,Zaritskiy,A.I.,Lebed,N.I.,andMakivchuk, Galetskiy, L. S., Teslenko, Yu. V., Zaytsev, B. P., and Beloserkov greenstone belt in the UPS, and O. F., (1992): The Prospects of Gold Ore Potential In Kudelko, S. M., (1993): Estimation Of Gold Potential Ukraine: Geologicheskiy Zhurnal, v. 4, p. 38–44, (in In Ukraine: Geologicheskiy Zhurnal, 5, p. 26–30, (in the Nagolny are in the DDA. Perhaps the best Russian). Russian). opportunity for the discovery of large deposits Berger, B.R., (1986a): Descriptive Model of Hot-spring Galetskiy, L. S., Bochay, L. V., and Lebed, N. I., (1994): lies in the Archean rocks of the Pridneprov Au-Ag, in Cox, D.P., and Singer, D.A., eds., Mineral MapOfGoldInUkraine:Geologicheskiy Zhurnal, 3, block, where sophisticated geophysical meth- Deposit Models: USGS Bulletin 1693, p. 143. p. 14–29, (in Russian).

October 1996 23 McKelvey, (1992): Descriptive Model Of Laterite- saprolite Au, Developments In Mineral Deposit Mod- eling, USGS Bulletin 2004, p. 47–49. Metalidi, S. V., Gurskiy, D. S., Babynin, A.K., Mel’nichuk, E. V., and Lepigov, G. D., (1992): The Prospects For Gold Exploration In The Northwestern And Central Ukrainian Shield: Geologicheskiy Zhurnal, 4, p. 129–132, (in Russian). Dr. John Thompson (MDRU, Vancouver), Mosier, D.L., Singer, D.A., Sato, T., and Page, N.J, (1986): Dr. Dani Alldrick (BC Geological Survey) Relationship Of Grade, Tonnage, And Basement Li- & Australian geologists will lead a 3-week fieldtrip thology InVolcanic-hostedEpithermal Precious-And Base-metal Quartz-adularia-type Districts: Mining Geology, v. 36, no. 4, p. 245–264. Shnyukov, Ye. F., Krasnozhina, Z. V., and Sidenko, O. G., (1993): Gold And Silver Bearing Sulfide Mineraliza- tion In Volcanic Rocks In The Crimean Mountains: The tour will study geology & mineral deposits and include Geologicheskiy Zhurnal, 5, p. 36–48, (in Russian). overview lectures on prior to visiting: Shumlyanskiy, V. A., Demikhov, Yu. N., Derevskaya, Ye. I., Dudar, T. V., Zelenskiy, S. A., Zinchuk, I. N., Ivantishina, O. M., Kurilo, M. V., and Cyngayevskiy, NEW SOUTH WALES - Porphyry, VMS and Au-Ag deposits E. D., (1994): Geological-genetic Model Of The TASMANIA - VMS deposits of the Mt Reed volcanic belt & Tin skarns Bobrikov Gold-polymetallic Deposit: Geologicheskiy Zhurnal, 3, p. 96–106, (in Russian). QUEENSLAND - Pb-Zn and Cu-Au deposits of the Mt. Isa-Cloncurry Singer, D.A., (1995): World Class Base And Precious Metal Deposits—a Quantitative Analysis: Economic district; breccia-, diatreme-, and granitoid-hosted Au Geology, v. 90, p. 88–104. deposits; plus, a visit to the Great Barrier Reef! Vityk, M. O., Krouse, H. O., and Skakun, L. Z., (1994): Fluid Evolution And Mineral Formation In The Bere- govo Gold-base Metal Deposit, Transcarpathia, Ukraine: Economic Geology, v. 89, 3, p. 547–565. Yaroshchuk, M. A., and Mel’nichuk,E. V., (1991):Predict- ing Gold Potential In The Gneiss Granulite Com- plexes Of The Ukrainian Shield: Geologicheskiy Zhurnal, 1, p. 129–132, (in Russian). Co-Sponsored and in association with For information contact: Yaroshchuk, M. A., Dudar, T. V. and Zaborovskaya, L. P., Mineral Deposits Division - GAC Dani Alldrick (1994): Gold-bearing Mineralization Of The May MDD Fieldtrip Coordinator Occurrence In The Pobuzhe District Of The Ukrain- Society of Economic Geologists Tel: 604-952-0412 FAX: 604-952-0381 ian shield: Geologicheskiy Zhurnal, 3, p. 50–55, (in BC & Yukon Chamber of Mines E-mail: [email protected] Russian). Yesipchuk, K. Ye., and Monakhov, V. S, (1992): Gold ore occurrences in greenstone structures in Ukraine and Finland: Geologicheskiy Zhurnal, 4, p. 155–66, (in Russian). Exploration Methods ‘98 -

January 28 - 30, 1998 Sponsored by Society of Economic Geologists, and the B.C. - Yukon Chamber of Mines in conjunction with the annual Cordilleran Roundup - Hotel Vancouver, Vancouver, BC, Vancouver, British Columbia, Canada, will be the site of this international exploration conference in January 1998. The theme for this conference, Pathways to Discovery, will build on the successful meeting in Denver organized by the Society of Economic Geologists in 1993 - Integrated Methods in Exploration and Discovery. The 1998 meeting will combine technical excellence with the atmosphere of the annual Cordilleran Roundup. Vancouver, a centre for worldwide exploration and mining, is an ideal location for a major exploration-focused meeting. Technical sessions (posters and papers), forums, core shacks, short courses and field trips will highlight exploration strategies and pathways to discovery in frontier areas, explored regions, and mature mining districts. The hospitality and entertainment that characterize Roundup will be an important feature of this confer- ence, particularly in celebration of the centenary of the Klondyke Gold Rush. Vancouver is a city that reflects its position on the Pacific Rim. The cultural mix creates a vibrant atmosphere providing excellent restaurants and entertainment. Snow-capped mountains rim the active harbour and nearby is some of the world’s best skiing and sailing. Mark your calendars now - this meeting should not be missed! For further information contact:

BC & Yukon Chamber of Mines E-mail: [email protected] WWW: http://www.eos.ubc.ca/pathways98 Tel: 604-689-5271 FAX: 604-681-2363 Associated Organizations: Mineral Deposits Division - GAC § Association of Exploration Geochemists § Canadian Institute of Mining, Metallurgy & Petroleum § MDRU - University of British Columbia § British Columbia Geological Survey § Geological Survey of Canada

24 The Gangue No. 54