I'm Andrew Jackson I'm the economic geologist with global resource Investments and I'm responsible for technical evaluations of the mineral companies and their properties that Global invest in I put together this or deposits 101 series of talks to help non-technical people understand all deposits the talks highlight some of the features of the main deposit types that invest in the resource actor may come across and provide an introduction introduction to the jargon that you will find in press releases put out by expiration and mining companies this is the seventh talk in the a deposits 101 series and today we'll cover volcanogenic massive sulfides or VMS deposits as they're often abbreviated to and sedimentary exhalative or sedex deposits they're both products of seaf FL smokers but they differ in their geological settings let's start where we always do in this series showing how the VMS and setex deposits fit into the overall scheme of things you remember that nature concentrates the me Metals by a process of partially melting crustal rocks at depth letting the Melt rise through the crust and cool dumping the valueless material such as F Spar and Amper bows on the way and concentrating the really useful Metals in the remaining magma or hydrothermal fluid cool dump the dull stuff and skim off the useful Metals BMS deposits are some of the last deposits to form in terms of the upward migration of metals and the mineralization drops out of the fluids either right at the surface of the seaf Flor or within a two few tens of meters of there so they form at even shallower depths than the shallow epithermal or Carin deposits sedex deposits are not directly related to volcanic activity and so don't fit in directly to the Sur framework however their mode of formation is just so similar to that of the VMS deposits that have Clump them together for these talks comparing VMS and setex deposits both are submarine equivalents of the epithermal hot spring deposits that I discussed in part five of order deposits 101 with minerals deposited from geothermally heated water at or near this rock water interface the mineralization in both VMS and setx deposits is deposited pretty much at the same time as the rocks that host the mineralization this is termed sing gentic mineralization as opposed to epigenetic mineralization which is deposited long after the surrounding host rocks the main difference between the VMS and sedex deposits is that VMS deposits are dominantly copper and zinc rich and are associated with volcanic activity where aex deposits are dominantly lead and synr and rely mainly on the heat caused by the depth of burial in deep sedimentary Basin to drive the hydrothermal system Bashi deposits named after an area in Japan where these are well known are a hybrid of the two kinds with a metal mix of VMS deposits but hosted in sediments like the seted X deposits so let's start with the VMS deposits this image shows some of the sulfide chimneys associated with a modern black smoker VMS deposit if I Fade Out the text you can just make out the black plume of hot water venting from one of the chimneys you'll remember this cross-section from my earlier talks on both P free deposits and epithermal in the case of VMS deposit we're looking basically looking at a submarine High sulfidation epithermal deposit venting from an underlying hot chamber into the sea as I said VMS deposits are dominated by copper and zinc but there are a number of other minor Metals uh including lead silver gold Cobalt tin selenium manganese and cadmium and a whole host of other ones that are sometimes associated with them the deposits consists of a massive sulfide cap that formed on the seaf Flor and certied parallel to stratigraphy and an underlying feder zone or Stringer Zone as it is usually called uh so VMS is basically mushroom shaped Stringer Zone tends to be copper rather than zinc Rich VMS deposits often form in clusters over a large intrusive heat Source if the heat chamber is long lived you may get stacked lenses of massive sulfide each fed from the same fault but getting successively younger as you go up through through the strateg graphy the deposits are pretty common although as with any deposit type there are only a few big enough or high enough grade to be economic in spite of that they really are economically significant with 207% of Canada's copper production and almost half of its historical zinc production having come from this group of deposits VMS deposits have formed throughout geological history and they're still actively forming on the seaf Flor today here's a bunch of of some of the better known deposits you may have heard of as you can see they're scattered all around the world uh but I'm going to talk a little bit more about the distribution later on this is a cartoon 3D view of an active VMS black smoker developing on oceanic crust on the sea floor some of the metals are contributed by the underlying magma chamber but as the hydrothermal fluid rises above the hot magma it sucks in cool sea sea water this is then heated and mixing with magmatic water rises to the vent returning to the Sea and forming large circulation cells that may be several kilometers across it is this seawater circulation through the host volcanics that provides the remainder of the metal inputs leeching Metals particularly iron but also base metals and sulfur on the volcanics metal concentrations in the hydrothermal fluids volcanics and cycled recycled sea water are really low just fractions of a percent so how do we end up with ore that may contain 20 to 30% metal the next slide zooms into the vent area on the sea Flor to explain this you can see that there is a funnel-shaped uh neck of fractured rock below the seaf floor caused by the violent boiling of the hot fluids as the pressure is reduced that in turn is surmounted by a series of chimneys that allow the fluid to escape into the cold Sea and the bottom of the sea below the thermocline really is very cold it's often only a few degrees above freezing even in the tropical areas surrounding this chimney is an exhalative lens of sulfidic material that forms on this on the floor the secret of the high grade of the or lies in rapid cooling of the hydrothermal fluid when it reaches the cold sea Flor as in porree deposits the main trigger for precipitation is a drop in temperature rather than changes in eh or pH different metal sulfides tend to drop out of solution at different temperatures copper and gold first followed by zinc then lead and finally iron there's an overlap of the metal deposition but that's the broad Trend the copper salts to drop out as the temperature drops from 400° C down to 300° the iron and the copper drops out before the fluids actually even reach the seaf Flor precipitate precipitating as a stockwork of veins in the breated funnel So-Cal Stringer Zone beneath the sulfide lens the fluids are hot and because they are from a high sulfidation source they're moderately acid this acidity Alters the F spars in the host rocks to Clays some of which are washed out of the Rock and others metamorphosed form serde M the dissolved silic in the hot Solutions is deposited as quartz along with the iron sulfide you may hear geologists referring to this characteristic bleached quartz serite pyite assemblage that results as either qsp or philic alteration uh but either way um it's all same stuff and they basically mean mean exactly the same as the hydrothermal fluids reach the cold seawater the temperature BL drops within seconds from 300° down to 100° and less the lead and the zinc sulfides precipitate along with the remainder of copper the sulfides deposit on the sides and the tops of the vents extending them and then bow out into the to form black and white smokers that you see in National Geographic pictures the fine cloud of uh sulfides cools and settles on the sea floor building up a finely banded layers of pure sulphides chalkar closest to the vent galiner and salite next pyite deposits throughout the sequence uh and most disly from the vent that is the sulfide still available to deposit beyond that the sulfur is exhausted an iron oxide or hematite and silica is all that's left to precipitate the mass of sulfide is made up of a combination of those finely bedded sulfides that settle out of the black smokers and fragments of chimneys that have broken off and roll down the slope here are a couple of shots of massive sulfide in our crop note the typical fine rhythmic banding just below the hammer on the left hand photo the photo in the bottom right shows abanded iron formation developed very distantly to a VMS vent and you can see it's made up almost entirely of just uh hematite or magnetite which is iron oxide rather than sulfide and white silica the fluids that form PMS deposits usually reach the SE floor up fults and because those fults represent zones of weakness when the stratigraphy is subsequently subjected to deformation the area around the fals is often particularly deformed combine this with a highly ductile nature of massive sulfides and we find that massive sulfide lenses themselves often exhib exhibit extreme deformation very often the Stringer cap which started off at a high angle to the mass of sulfide mushro cap is flattened and rotated to a much more acute angle and the mass of sulfine may end up squeezed into a cigar shaped Rod so now we know a little bit about how vmss deposits form let's consider where they occur how common they are and more importantly to investor how big they are and what metal grades can we expect VMS deposits have been forming since the earliest of times in Earth's history and they're still forming today on the sea Flor as you might expect they're found all over the world and in all ages of rocks however there are a few periods in those history when they seem to be particularly prevalent the lat Aran and the terer seem to be in particularly prolific times the blue green and red symbols Mark some of the more important VMS deposits worldwide okay what about size and grade there are a number of different classes of VMS each with somewhat different characteristics but I won't go into the details in this talk suffice to say that economic VMS deposits generally range in size from 4 to 25 million tons with an average of about 5 million tons although there are a few monsters such as King Creek in Ontario which is 50 million tons grades average 5% copper 4% zinc just under 1% lead and perhaps one gram per ton of gold again there are a few outliers with far higher grades than these let's look now at a few examples of VMS deposits neon's bisha deposit in nria is a superb example of a VMS deposit it was discovered in January in 2003 construction began in 2008 and production in 2011 this is a view of the bisha gosan looking South before development began the dark brown material in the foreground is a zrich gossen the weathered outcrop of the mineralization not surprisingly the weather in the mineralization has been folded and it plunges to the South with the Stringer Zone smeared out parallel to the massive sulfides the mass of sulfide material varies from 1 to 70 M thick this is unusual as most VMS deposits are less than 20 m in thickness bisha has a footprint that's about a kilometer long and 200 M wide in spite of the spe steep dip to the mineralization which results in a pit with a High stripping ratio the deposit has one big Advantage all zoned so there is a leech gold Zone at surface underlay by a secondary enriched copper Zone with a primary zinc dominated primary Zone below that the advantage of this is that the expensive concentrator did not have to be built by startup but it could have been could be constructed just a few years later when the primary self tiddes are reached and funded most importantly from cash flow rather than debt most attractive of all in bisha is the size with reserves of 26 million tons uh at 1.8% Copper 6.3% zinc .9 GS of ton gold and 41 G of ton silver this is five times the average VMS size as I've mentioned VMS deposits occur in clusters and beer is no exception with a last at least seven other VMS deposits discovered within 20 kilometers although bisher is the only one in production so far the second example we're going to talk about today is kind of unusual it's actually a group of deposits that have only recently been formed in fact they're so young they're still on the ocean floor and will have to be mined remotely for floating platforms they were discovered by naus a TSX and aim listed company using combination of petrics and EM geophysics the data gives a fascinating insight to the nature of these black smoker Fields this image is taken from Nas's 4311 report and shows an amazing isometric view of the chimneys of the salara 1 Target off the coast of Papa New Guinea derived from bimmetry the image covers about 800 meters from left to right and the individual chimneys are clearly visible the small image shows a remote operating vehicle's Clause removing a sample of a smoker chimney foras for environmental reasons only extinct smokers were targeted once the hot water stops flowing the cold and lack of nutrients cause the ab abundant sea life to move away or to die extinct smokers are therefore devoid of significant sea sea life and environmentally uh not an issue in a cross-section of the salara 1 VMS based on mapping and uh in and drilling of the deposits we can see the massive sulf Ides in red the alterations associated with Stringer zones in pale green although the resource is relatively small just 2 and a half million tons the grades are exceptionally high with a copper grade of almost 8% and a gold grade of over six gram per ton as is typical there have been at least other 18 other deposits discovered in this particular cluster the Solara 1 VMS is at a depth of 1600 M below sea level submarine VMS deposits have never been mined before but the equipment that in naus plans to use has a proven record Excavating trenches for submarine cables and Mining Marine diamonds off the South African Coast its practicality is well established this is another piece of uh mining equipment that nless is considering having custom built you'll notice the proposed completion date in this old material to my knowledge this construction is still on hold which gives an indication that funding and Mining will not be straightforward once the material has been remotely mined it's planned to pump it to the surface as a slurry and then it begin then to transfer to barges for transport to a LW or Shore based concentrator the project is a fine example of outof thebox thinking but it still remains to be seen just how economic the process will be okay now we move on to the second group of Submarine Sy gentic sulfide deposits the sedimentary exhalative or sedex deposits these are very similar in Genesis to the VMS deposits except that they are not primarily driven by intrusions below but are instead products of dewatering and metamorphism of thick piles of accumulated sediments in ocean basins hence the said part of the name the exhalative portion of the name refers to the geological process of venting hydrothermal Solutions into a submarine environment here's a list of some well-known examples of stics deposits that you may have heard of including Sullivan in British Columbia and broken Hill in Australia I'll talk about Sullivan in a little more detail in a few minutes time but what are the similarities and differences between setex deposits and VMS deposits let's start with the similarities both are sing gentic that is they're deposited at the same time as the enclosing rocks again the majority of the metalin heex deposits is in the form of bedded exhalative mass of sulfides with an underlying fedus zone They too often occur in clusters in both deposit types the methyls are carried in solution as chloride complexes rather than tho complexes so the main trigger for precipitation as I mentioned earlier is a drop in temperature lastly the massive sulfide lenses are often highly deformed but now the differences firstly sedex deposits generally form in fault-bounded sedimentary basins on continental crust rather than in volcanic piles on oceanic crust for SED for sedex deposits the Basin needs to accumulate several kilometers or tens of kilometers of oxygen deprived sediments usually shells secondly the heat drives the hydrothermal system is dominantly from depth of burial rather than a felic intrusion although there may be a deep mafic intrusion for the same reason the metals are not derived from felc Magnus so copper is largely missing instead the metals are purely derived from leeching the sediments themselves and Lead zinc and silver dominate instead to form sedex deposits you require the Deep sedimentary basins so distribution is more limited than that of VMS deposits however they're still found on all continents and there are around 125 sedex deposits of note and these are marked in red on the map they vary considerably in both size and GR this graph shows that range in tons and percent metal size along the x-axis varies from 1 million tons up to a huge 400 million tons with the mean sitting around about 20 million tons leaden zinc grades that's uh the Y AIS range from 3% up to 30% with a mean of about 10 to 12% so you can see that zedex deposits are generally both much bigger than VMS deposits and have better grades making them highly desirable expiration targets the problem of course is that they are much less common in spite of this scarcity they are a source of a large proportion of the world's lead and zinc sedex deposits range in age from the mid protozoic that's uh 1,800 million years ago to to the ferk 150 million years ago the Sullivan deposit in southeast British Columbia is 150 million tons making it a larger than average said X deposit but the grades are pretty much average with about 11% combined lead and zinc this is a cross-section through the Sullivan deposit it displays most of the typical characteristics of sediment deposits sedex deposits you can see the massive bedded leaden zinc sulfides in red the deposit is underl by a maic sill that may be partially responsible for driving the hydrothermal system shells the shells contain highest amount of boron of any rock type and this is leeched out along with the lead and zinc by dewatering fluids it is then deposited just below the vent as a stockwork of taline Rich veins although the the false mapped as uh occurring to the west of the of the vent I suspect that the uh vent itself is actually developed along the main structure although it is no longer recognizable as a fault due to the brachiation The Rock in the immediate foot wall of the massive sulfide and above the vent is fically altered I.E quartz thite pyite alteration the important thing to realize is that depositing mass of sulfides is a slow process then needs to be a break in sedimentation to allow the sulfides to accumulate undiluted by depositing sediment recognizing those time breaks in sedimentation can help with expiration for both setex deposits and VMS deposits and now I want to talk a little bit about expiration for both of them because techniques and strategy are similar for both expiration for these is like looking for the filling in a sandwich once you identify the break between the slices of bread that's the time break you know that the filling will be somewhere along that plane and that allows you to focus your efforts on just a tiny portion of the stratag graphic P package the statgraphic sequence around VMS deposits tends to follow a standard pattern It generally starts with a thick series of oceanic bassal flows then during a break in the basaltica volcanism a small felc Dome is extruded derived from the intruding felc magma chamber at depth as this called the hydrothermal fluids vent altering the foot wall and depositing the mass of sulfides horizon the sequence is then cut off by the renewal of btic flows which bury and preserve the sulfides why is it important because it can help your expiration in identifying that time break that we're looking for and the likely vent areas are near going to be near felic domes this time break in in the bass eruption May host additional VMS deposits elsewhere in the district also the faults that produced one deposit are often often leak fluids over a long time and stack lenses may exist on the same fault or in other time breaks in sediment ation although the stratag graphic indicators are not as strong uh in the case of the sedex dep deposits the same principle applies once you find the mineralization there are likely to be more occurrences Elsewhere on the same time break in the strateg graphy OR up or down strateg graphy on the same fault system so in expiration for these deposits we're trying to see through the younger deformation and we're trying to identify the early fults fults which may have been active at the time of mineralization soil and rock geochemistry and electromagnetic electromagnetic geophysics or Em are the two most useful tool expiration tools for massive sulfides although magnetics and gravity may also be of value in detecting mineralization once you're in the proximity of mineralization identification of qsp foot wall alteration may help guide you through to the S massive sulfide Plum that you're looking for as an expiration for all types of deposits the drill bit is the ultimate judger value I'm going to walk you through now typical expiration program for one of these deposits I've chosen Tarsus as M dep property in southern Yukon not because it was a great success in fact the project has been put on the back burner no but because it a simple and straightforward story and Tas tus has also published a nice set of plans on their website so on the property expiration for VMS mineralization began with a series of soil sample Services across most of the property with the lines oriented at right angles to strike with a a nominal 100 met line spacing and a sample interval of 50 m that's the black dot those are the black dots on the plan these sample points were guided and located using GPS the sampling identified large zinc soil anomaly and a coincidence slightly smaller lead anomaly the entire property was also flown with VM which stands for uh ver versatile time domain electromagnetics uh which transmits an electromagnetic pulse from a large coil suspended beneath the low flying helicopter and then it records the return signal after it's been modified by passing through the earth below EMS capable of detecting buried conductors such as SM sulfides on the property the survey identified three such conductors one of which was coincident with both the the soil lead and zinc anomalies this then became the top priority Target and six holes were cited to test that Central conductor this is a section through two of those holes and you can see that it inter they intersected three mineralized massive sulfide Horizons at depth none of these came to surface so this was entirely um followed from the GE the geochemistry and the GE particularly the geophysics in this particular case the widths of the those massive sulfides were sub economic but it shows that the expiration process was effective that's about all all the time I have this talk on volcanogenic massive sulfides and sedimentary exhalative deposits but as usual I'll end off with the main points that you need to walk away with from this talk both types of deposits are products of Submarine Hot Springs VMS deposits are volcanic hosted dominantly copper and zinc and they're fairly common sedex hosted uh sedex deposits are sediment hosted they're dominantly zinc and lead and they're bigger but less common than the VMS deposits in VMS deposits the metals are usually spatially zoned with copper near the vent and then zinc and lead more distal to that these deposit types are major Global Sources of Base Metals particularly zinc geophysics has a vital role to play in the expiration particularly em and gravity finally the next generation of this group of deposits may be from uh seaf floor Mining and the deposits are relatively small but they're also relatively easy to find as they covered only by water and they can also be very high grade that's the end of this talk the next one in the OR deposits 101 series will be on one of the most controversial topics in the geological world the V vant gold deposits of South Africa uh perhaps the greatest source of gold on earth