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Geoscience Canada

Geothermal Power, The Canadian Potential J. G. Souther

Volume 3, Number 1, February 1976

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Publisher(s) The Geological Association of Canada

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Cite this article Souther, J. G. (1976). Geothermal Power, The Canadian Potential. Geoscience Canada, 3(1), 14–20.

All rights reserved © The Geological Association of Canada, 1976 This document is protected by copyright law. Use of the services of Érudit (including reproduction) is subject to its terms and conditions, which can be viewed online. https://apropos.erudit.org/en/users/policy-on-use/

This article is disseminated and preserved by Érudit. Érudit is a non-profit inter-university consortium of the Université de Montréal, Université Laval, and the Université du Québec à Montréal. Its mission is to promote and disseminate research. https://www.erudit.org/en/ through west-central kilometre of depth but locally, where hot and southern Yukon. They correspond or molten rock has risen into the upper to well-defined belts of Ouaternary as plutons or breached the sudace volcanoes including more than 100 In volcanic erupttons the thermal post-glacial eruptive centres. Within gradlent may be many times hlgherthan these broad thermal zones specific normal. Only these rare "hot spots" targets based on local heat flow where anomalously high temperatures anomalies and spring water exist at shallow enough depths to be geochemistry are closely associated reached by drilling can be classified as with those volcanic centres that have potentlal energy resources. But high produced or domes and temperature and shallow depth are only Geothermal pumice. One of these (Meager two 01 several criteria that must be met Mountain) was selected for more before heat can be extracted in Power, The detailed study, including the drilling of commercial quantities. The reservoir two 50m holes in 1974. Subsequently. rock must be permeableenoughtoallow Canadian this target was chosen as the focus of a adequate circulation of fluid andthe fluid Potential more detailed geothermal resource ttself must be relatively free of corrosive evaluation commissioned by the British salts. Columbia Hydro and Power Authority. Five types of geothermal reservoirs J. G Souther are commonly recognized: 1) molten Geological Survey 01 Canada lntroduclion rock. 2) hot dry rock. 3) dry steam, 4) hot 700 West Pender Street Ut~lizatlonof geothermal energy for water. 5) geopressured brine. Vancouver. B.C. generating electric~tyis not a new The feasibility of extracting energy concept. The first turbines to use natural from molten 1s in a very early stage Summary steam were put into operation in of lnvest~gation.Similarly, the hot dry The technology lo produce electricity Larderello, Italy in 1904 and the fteld 1s rockconcept which involvesthe art~fic~al from the natural heat of the earth was st111produc~ng. Today more than a dozen fractur~ngof hot impermeable rock developed more than 70 years ago yet nations have operating geothermal lollowed by in]ectton of water to produce today total world production is less than electric plants and world production is steam has yet to be demonstrated 1500 Megawatts. Slow growth of nearly 1500 Megawatts. The largest experlmentally. The power potent~al01 geothermal eleclrlc generating capaclty development. at the Geysers In Northern geopressured brines such as those of can be attr~butedpartly to the former Cal~tornta,has an installed capacity of the Gull Coast of the US. is enormous abundance of low-cost fossll fuel and, 550 Megawatts, enough to supply the but development has so far been more recently, to the disproportionate total needs of San Francisco. curtailed by failure to produce a allocation of tunds to nuclear research. The spectacular success of conversion machine capable 01 Most of the earth's heat is too diffuse geothermal power developments In the wlthstandlng the h~ghlycorrosive brines. ever to be recovered by man. Only those Un~tedStates, Italy, Japan. New Only two types of reservoirs, dry rare thermal anomalies where htgh Zealand. Mextco and Iceland has placed steam and hot water have been brought temperatures prevall wlthln reach 01 it among the elite group of "alternate into commerctal product~on.Dry steam drill~ngcan be exploited for power energy" sources that are expected to fields, as the name implies, produce product~on.Techniques for locating augment and eventually replace our superheated steam that can be fed htdden geothermal reservoirs are only diminishtng reserves of fossil fuel. The directly into conventional turbines Such now belng developed and there is an appeal 01 geothermal energy lies in its fields (Larderello. Italy: Geysers, U S.: urgent need lor new wells totest the apparent simplictty. Unlike nuclear and Matsukawa, Japan) are relatively validity of existing geological concepts reactors it does not require the efficient and the volume of condensate and prospecting methods. development 01 a new and sophisttcated from the turbines is small enough to be In 1972 the Department of Energy. technology and unlikecoal-liredthermal reinjected thus minimizing Mines and Resources began an plants and hydroelectric dams it environmental damage investtgat~onofthegeothermal resource presents little risk of environmental In hot water fields (Wairaket. N Z.; potentlal of western Canada, Initial work damage. Unfortunately, f~ndingand Cerro Prieto, Mexico; Namafjall, Iceland) included: 1) expansion 01 the regional harnessing geothermal power involves the pore fluid IS water at a temperature heat llow program.;!) comp~lat~onoldata much more tnan drilllng bllndly Into the below 11sbotllng polnt at the hydrostatic on the distr~bution,age and earth. pressure prevailing In the reservoir. petrochemistry of The natural heat of the earth is When such water is brought to the volcanoes: 3) systematic sampling and produced by the decay of radioactive surface in a well. part of it flashes to chem~calanalysis of water from all elements in the crust and mantle and. steam and the temperature of thewater- known thermal sprlngs. like these rare elements. most steam mixture drops accord~nglyThe Integration of this new data with geothermal heat ts too diffuse to ever be Steam 1s separated and put through low existing geological and geophysical recovered and used by man. Over most pressure turb~nes.The hot water is information on the crustal structure of of the earth the temperature increases usually discarded and may pose a the Canadian Cordillera Indicates flve only a few degrees centigrade per dlsposal problem, not only because of broad thermal anomalies extending Geo~cienceCanada.Volume3. Number 1. February. 1976 15

the large amount ol waste heat but also (Wilson. 1965). Offsets on the The Pembertonvolcanic belt (Fig. 1 )is because of dissolved toxic salts. Fairweather Fault, an extension of the defined by a group of epizonal plutons Unlike petroleum reservoirs, which Queen Charlotte Fault Into , and two deeply eroded cauldron may persist in the earth for several indicate right lateral displacements of as Complexes. Mt. Silverthrone and geological epochs, geothermal much as 150 miles since mid-Eocene Franklin Glacier complexes (Ney. 1968) reservoirs have a relatively short "shelf tlme and strike slip movement of up to that lie along a NW trending belt life''. As soon as a thermal anomaly is 21 5 feet during a single event on July extending from near theU.S. border east introduced into the upper crust of the 10,1958 (Plafker. 1972).Where the of Vancouver to King Island on the BC earththe heat beginstoseepaway tothe coastline of turns west coast. Potassium-argon ages on four ol surface along temporarily high thermal into the curving arc of the Alaska these plutons range from 18 to 7.8 my. gradients. Thus the geological record Peninsula the northwesterly moving Or approximately the same age as the abounds with "fossil geothermal Pacific crust again impinges on the late of central systems" that long ago lost their heat. continental margin and moves down a British Columbia. The plutons are Active systems are rare and transient zone beneath central Alaska believed to be subvolcanic bodies phenomena confined almost entirely to and the Aleutian arc. The present associated with a Miocene volcanic regions of late Tertiary and Quaternary dynamic relationship between western lront that was active during early stages tectonism. Canada and the adjacent Pacific crust of subduction of . Potential for geothermal power does not appear to have changed With the notable exception of King development in Canada is confined to Significantly during the last 10 to 15 m.y. Island, all the plutons and eruptive rocks the Cotdillera. The shield and stable are calc-alkaline, mainly granodioritic platlorm of the continental interior have Vdunidty bodies and dacite ejecta, whereas the unilormly low thermal gradients and no Volcanic activity in western Canada coeval plateau lavas are uniformly evidence of young tectonic or igneous duringthepast 15 million years has been alkaline , suggesting a paired activity. Similarly the Appalachian localized along five distinct linear belts relationship analogous to an arc, back- orogenic region of eastern Canada is (Fig. 1) that appear to be related to plate arc association. geologically old, with no record of boundaries. The N-NW trending The Miocene volcanic front iscrossed igneous activity younger than lower Pemberton of southern at an acute angle by a line of Cretaceous el 10 my.). In contrast, the British Columbia is a late Miocene approximately 32 Quaternary centres

Cordillera of British~ Columbia.~ ~~, Yukon~ ~ volcanic front related to an earlvstaae, - of that comorise the Garibaldi~ ~ volcanic~ ~ and western Alberta is part of the spreading from the Juan de Fuca - belt The few analyses available plot seismically active Circumpacific Explorer system and subduction of mainly in the calc-alkaline field of the orogenic belt in which youngvolcanoes, Juan de Fuca plate. Garibaldi volcanic alkali-silica diagram. Dacite and hot springs and zones of high heat llow belt is a Quaternary front related to are the predominant rock attest to recent tectonic activity and recent spreading from Juan de Fuca types, associated with minor rhyoliteand local concentrations of heat in the ridge. runs east- high-alumina . Mt. Garibaldi earth's crust. It is tempting to equate the west between latit~de52~and 53' north (Mathews. 1958) is an intraglacial dacite Canadian segment of the Pacific margin and may be an expression of deep dome that erupted about 10.000 years with that of the United States, Mexico or fracturezones along the northern ago. Other domes in the same belt, Japan. where geothermal power has boundary of the downgoing Juan de including Mt. Cayley and Meager been successfully developed, but there Fuca plate. The north-south trending Mountain, exhibit a similar degree of are important geological differences that Stikine volcanic belt of northern British dissection and are considered to be make it impossible to project the Columbia is associated with approximately the same age. The geothermal resource potential from one structuresthat are believed to have youngest activity occurred less than segment of the Pacific margin to opened in response to right lateral shear 2.500 years ago from a vent near another. In assessing this potential the between the continent and Pacific crust Meager Mountain. of tectonic events of the last 10 to 15 my. (Souther, 1970). Wrangell volcanic belt dacitic pumice produced a thick welded are of greatest Importance and it was ol southern Alaska and southwestern ash flow in upper Lillooet valley and a during this time, from mid-Miocene to Yukon lies above the Benioff zone plume of air-fall pumice that settled over , that the tectonic setting of assoc~atedwith subduction of Pacific a wlde area of southern British western Canada differed markedly from crust at the eastern lhmlt of the Aleutian Columbia. The latter, called the Bridge other parts of the Pacific margin. Arc system. The type of Quaternary River ash (Nasmith el a/,1967) gives in each ol these belts differs Carbon-1 4 ages of 2440+140 years Tectonic Setting according to the tectonic setting. B.P. The distribution of earthquake Moreover the composition of lavas and The Anahim volcan~cbelt runs epicentres in western Canada can be style of eruption in each belt appears to approximately east-west along latitude used to infer the present position and have remained uniform not only durlng 52"N and includes 37 Quaternary sense of movement between the the Quaternary but also throughout the volcanic centres plus a large number of continental margin and adjacent Pacific late Miocene, suggesting that the Miocene and Pl~ocenecentres. The crust. The linear belt of epicentres present tectonic framework has not Quaternary centres have all produced extending northwest from the north end undergone major changes during the alkali olivine basalt that forms small of Vancouver Island (Fig. 1 )mark the last 15 million years. pyroclastic cones and thin blocky intra- trace of the Queen Charlotte transform valley flows overlying eventhe youngest The relatively broad Stikine volcanic activity during which one or more Small glacial features. Near the centre of the belt cuts diagonally across older. pyroclastic cones were built and a small belt, north of Anahim Lake, the post- northwesterly-trending structures of the volume of alkali olivine basalt issued to glacial cones are satellitic tothreeolder. northern and form thin blocky flows. The youngest very large shield volcanoes comprising Belt. Scattered within it are dated eruption of this type issued from the Ilgachuz, ltcha and Rainbow ranges. more than 50 post glacial eruptive fissures in the central Coast Crystalline The lower flows of each shield appear to centres plus at least as many of late Complex near the southern end of the be continuous with adjacent Plateau Miocene to late Pliocene age. The lavas. Stikine belt. The flows, which extend for lavas that rest on sediments containing like thoseof the Anahim belt, are mainly 15 km along Lava Fork valley, have late Miocene or early Pliocene flora alkaline. Most of the Quaternary centres surrounded and charred trees, the (Mathews and Rouse, 1963). have been the locus of a single pulse of stumps of which still project through the

Figure 1 Schemalrc map showrng lhe d!slrlbulron of late Terlrary andouafernary volcanrcand p~ufoncrocks, oceanfc rrdges earthquake epcenlres and lhe ,nferredposrf~on01 the Oueen Charlolfe Farweather lranslorm laulr syslem Geoscience Canada. Volume 3, Number t . February, 1976 17

flow. Carbon-14 ages on these indicate overthrust by pre-Wrangell Springs in the Rocky Mountains of that they were killed by thelava less than rocks and intruded by large plutons of eastern B.C. and western Alberta are 200 years ago (E.W.T.Grove, pers. dacite. South of Kluane Lake. typical of the first class (Van Everdingen, comm.). The slightly older Aiyansh flow in the Alsek River area similar high-level 1972). They are linked to deep flow and also near the southern plutons are associated with a volcanic- systems along intersectingthrust faults end of the Stikine belt, produced a total tectonic depression occupied by or along thrust faults and porous, mainly of 0.45 km3of basalt during two closely eruptive lava domes and surrounded by carbonate, aquifers. Meteoric water spaced pulses of activity about 220 a thick apron of explosion and entering fractures in topographically- years B.P. (Sutherland Brown. 1969). welded ash flows. high recharge areas passes through The MI. Edziza - Spectrum Range flow systerns controlled by geological complex, near the centre of the belt has Thermal Structure structure and porosity and eventually a long. nearly continuous record of Data on temperature distribution in the discharges as springs at lower activity that spans most of post Miocene Canadian Cordillera are sparse and elevations. High local relief provides the time. The earliest flows give KIAr dates confined mainly to southern B.C. hydraulic head that drives the system of nine my, whereas charred wood Existing heat flow and relevant and the water temperature is simply a covered by from satellitic cones geophysical data have been compiled function of the depth of circulation and gives a Carbon-14 age 1340 years B.P. and interpreted by Hyndman(1975) who cooling rate on returntothesurface.The Most of the Edziza pile comprises defines a coastal zone 200 km wide of Banff springs, for example, issue from alkali olivine basalt. The basalt, however. low heat flow separated by a narrow several points along the trace of the is interlayered with a significant volume transition zone from a central belt of high Sulphur Mountain thrust fault. They are of sodicrhyoliteand peralkalinetrachyte heat flow. Steacy (1973). using gravity believed to originate from surface that form domes, flows, pumice and and seismic data, calculated crustal and waters that have travelled down a subvolcanic intrusions (Souther. 1973). mantle densities and depth to the M secondary fault that intersects the The complex lies across a system of discontinuity across the southern Sulphur Mountain thrust at about 21.000 north-south trending normal faults and is Cordillera. He concludes that both crust feet. At this depth, even in aregionoflow bounded on the west by a rift valley that and mantle densities must be relatively to moderate thermal gradient, the water shows evidence of collapse during low under central B.C. and high beneath will encounter temperatures of about construction of the adjacent volcanic the coastal zone. The possibility that the tOO°C or 50% hotter than the hottest of edifice (Souther. 1970). , low densities are due to thermal the Banff springs. Springs of this class 60 km northwest of MI. Edziza comprises expansion is supported by the electrical are dominantly of the calcium sulphate a large Miocene-Pliocene shield of properties. Caner (1969) has identified a type with less than 50 ppm silica (Fig. 3). mainly alkal~olivine basalt, but small zone that extends from near the Rocky They indicate the presence of an segments of rhyolite flows are exposed Mountain Trench westward beneath unusually deep natural groundwater in the central part of the shield and large central B.C, in which the lower crust and flow system but they arenot indicativeof domes and subvolcanic intrusions of uppermost 10 to 25 km of mantle are thermal anomalies. In the far norlhsome rnyo le an0 tracnyle occur on ao acent n gnly cono-ct ve he aur b,les In s to of tnese aeep flow systems may have rlearl Peatcs hvarat on ano n on temoeratjre. 750UC I mtled polenl~afor space healing b-l The Wrangell volcanic (Souther and ai 35 km, and c&cludes that the they have no potential forthe production Stanciu. 1975) belt runs across combined effect is sufficient to initiate of power. southwestern Yukon northwesterly into partial melting in the conductive zone. Springs of the second class are central Alaska. The lavas are related to flow systems through more predominantly basaltic and Hot Springs diverse rock typesand this is reflected in andesites of the calc-alkaline rock Approximately 60 thermal springs are the chemistry of their waters. Those series and. in Alaska, they range in age known in western Canada (Souther and issuingfrom other clasticsedimentary or from Miocene to Recent. Explosive Halstead. 1973). None are boiling and volcanic are predominantly of eruption of pumice from a vent near there are no associated fumeroles, mud the calcium bicarbonate type whereas Whlte River, Alaska (Lerbekmo and pots or extensive alteration zones such those issuing from granitic terranes are Campbell. 1969) produced two lobes of as are commonly found near producing mostly chloride waters high in alkalis. tephra, one of which extends northeast geothermal fields. Spring locations are Both total dissolved solids and silica are tothe Arcticocean and the other shown on Figure2. intermediate between the class 1 and eastward into Alberta. Tree-ring and On the basis of their geological class 3 springs. All of them are believed Carbon-14 dates have established that association and water chemistry the to be discharging from flow systems the northernlobeisabout 1500yearsold springs have been broadly grouped into driven by differential hydraulic pressure and the eastern lobe 1200 years B.P. three classes (Souther, in press): 1) rather than by thermal convection, Only two small Quaternary centres are springs associated with deep flow however, some of the systems may be known in the Canadian part of he systems in layered carbonate rocks. 2) encountering relatively high Wrangell volcanic belt. West of Kluane springs issuing from fractures in granitic temperatures at shallower depthsthan Lake the Wrangell Lavascomprisemore or metamorphic rocks of non-volcanic those associated with the class 1 than 5000 feet of flows and minor regions. 3) springs located in or near springs. Many occur in or near potash- pyroclastic material. Though mostly flat belts of Quaternary volcanism. rich Tertiary plutons which have lying the entire section is locally folded. relatively high rates of radiogenic heat J xcrnnvr 17 not Sprxn.s Cow 1 *arhe-qul-cc~s-i-Lk 28 Flarcs l-1-d 5 old Fort I.l."d 19 lulrron 6 clavrcn Cree* 30 Xmtmay inkc ~6 I ,.ocragw ~rulc 31 st. h;"n 32 N.kus> 31 TayLor 31 lordan ~anch 35 atopvscrVrk 11 ".r".ilD" 36 rarlo rrrck I3 ntan.l luuar 37 l~nrurrh I4 suipnvr mtn. 18 Crm(ord lrrrw I5 canmrr 16 larrvnr I7 mdium 18 mlphlnr rc. IV r..,m., CLASS m SPRINGS 20 L"rrlrr cmynn 39 rivn rrrr* ?I ur Cr-k 40 laah rrrek 11 FDrdln" "t". 41 *Err i*ku 21 ",la inrr. ,'r. 42 mr. I,."* 14 rlbcrr ranyun 43 Murmn ircck 14 ivrurr ray 45 T-L~,.~ 46 RL~~~crwk 1, aii,t,... 4 My'*H.nrral rlnu I? .iralrrrrc 50 .*nur ~~u~r 5, ra.o,,. .,,.,* 51 mFa,zCr cLe*h 51 shuukmi.liu, k 11 i'irt Niulr 55 -L".iUI 56 ,I...... " 57 in..,I ,,,,. i-. 58 :1111

YoLc-&N!c wry G.V.B. (Gribaldi Volcanic Belt) P.V.B. (Pemberton Volcanic Belt) A.V.B. (Anohim Volcanic Belt) S.V.B. (Stikine Volcanic Belt) W.V.B. (Wrongell Volcanic Belt)

Figure 2 C;in;rda Springs /,sled ;ibove Tire those lor Map showmg (he drsIr~Ou1,on nl rtlerrnal wtrrch cherrr~:;ridnla nrr ;~v;nfable A Iew sprrngs and lherr reli#r!onsh!plo fate Terlrary nddirional spinngs have been reporled in and 0u;rrernary volcnn!c bells 01 weslern cenfraf Yukon ;~ndalonglhe cons1 ol B C production (T. Lewls, pers. comm.) and either bicarbonate or sulphale type with in this groupand theone w~ththehighest correspondingly high thermal gradients. dissolved silica between 80 and 250 s~licacontent (I15 ppm) issuesfrom The springs of south central B.C..for ppm In south-central BC. six groups of fractured granodiorite on Bentick Arm, example. are closely associated with thermal springs lie along the same near the 12 million year old. King Island Eocene plutons. It is unlikely that lineament as high level. Miocene. syenite stock.Thermal springs with~nthe any of the systems related lo the class 2 plutons (Figs 1 and 2). The hottest of north-south Stikine belt of Quaternary springs is hot enough to be regarded as these issue from fractured granodlorrte volcanoes are clustered around the Mt. a potential geothermal power source: at several po~ntsaround the periphery of Edzlza volcanic complex. The waters however, some may be suitable for non- Meager Mountain, a Quaternary dacite are of the sodium bicarbonate type with power applications. from whlch the 2000-year-old a relatively high silica content (190 Springs of the third class are spatially Bridge River ash waserupted. Agroupof ppm) Of all the volcanic centres in the related to belts of Quaternary igneous eight thermal springs lie along the east- Stikine belt Mt Edzrza and adjacent activity. Most yield alkaline waters of west Anahim volcanic belt. The hottest Spectrum Range have produced the Geoscience Canada. Volume3. Number 1, Februaw. 1976 19

helicopters to scout the landscape lor gossans. 110 It seems realistic to hope for the r Class I Sprtngs d~scoveryof at least one hot-water field loo I +...... Class !lSprings + such as Wairakei (New Zealand) Dl . . Class Sprlnps capable of supplying enough flash . . .,. . ,,.. . . 180 steam to oenerate electricitv. Surface manifestaiions of suchafielb may not be very dramatic in the Canadian Cordillera where high relief and heavy precipitation favor deep circulation of cold groundwater and consequent dilution of rising thermal fluids. The most promising areas of search are broadly defined by the lour belts of Quaternary volcanoes that extend across British Columbia and south-western Yukon. However, most ol the eruptive centres in these belts have produced a single pulse ol basaltic that must have been generated deep within the mantle. The lluid magma rose rapidly to the surface through relatively narrow conduit systems in which little of the thermal energy was trapped. The scores of isolated Figure 3 pyroclastic conesformed by this type of PI01 ols~licavs. lolaldissolvedsolids lor 58 eruption in British Columbia are thermal sprrnss in weslern Canada ~ -- ~robablvnot associated with thermal reservoirs within the earth's crust. Only those few volcanoes with a record of only signilicant volume of siliceous lava consistantly higher temperatures for the repeated activity and those which have that might be associated with class 3 springs. The two highest produced a significant volume of acidic SLDVO can c ntr~sons temperatures in0 care0 oy both magma have a reasonaole chance of Tne cnem strv of therma waters s oeotnermometers are a ven bv water oelng ~noerlan oy an accessble influenced by temperature dependent irom Tawah Creek and~eagerCreek. thermal reservoirl~omeof the centres reactions between water and rock Tawah Creek spring (silica 227OC and within the southern Wrangell Belt. MI. (Wh~te,1970) In rapidly flowing springs Na-K-Ca 177%) is on the eastern flank Edz~zaand Hoodoo Mountain of the retrograde reactions may be slow of Mt. Edziza near the source of an Stikine Belt, the llgachuz, ltcha and enough to prevent re-equilibration ofthe approximately 1.000 year old plume of Rainbow Ranges of the Anahim belt and water as it rises tothesurfaceandcools. rhyolite pumlce and Meager Creek the dacite domes. Mt. Garibaldi, MI. Thus spring water may inherit chemical spring (silica 228°C and Na-K-Ca Cayley and Meager Mountain of the character~sticsestablished in the hottest 187'C) is on the south flank of Meager Garibald~belt could, on this basis. have part of the flow system and these in turn Mounta~n,the volcano from which the some potential. Of these MI. Edziza and may be used to estimate subsurface Br~dgeRiver dacit~cpumice was erupted Meager Mountain are the rnost l~kely temperatures. The amount of dissolved 2,440 years ago. targets. Both have erupted showers of silica varies directly with temperature acid pumice within the last 2,000 years. and provides the slmplest means of What next for Canada? It IS reasonable to suppose that this identify~ngpotential high temperature Exploration for geothermal energy in volat~le-r~chejecta constitutes only a systems (Fourn~erand Rowe, 1966). An Canada has scarcely begun and any small proportion of the total volume of empirically derived Na-K-Ca attempt to predict its future must be magma involved in the eruption and that geothermometer (Fournier and predicated largely on theoretical subvolcan~cmasses of degassed Truesdell. 1973) is also widely used. It inference.The possibility of flnding adry magma or hot rock may be left beneath provldes not only a rough estimate of steam field such as Larderello or the the volcanic edifice It 1s significant that, temperature, but also a means of Geysers in Canada seems extremely of all the thermal springs known in discriminating between undiluted remote. Such fields are invariably western Canada, those near Mt. Edziza thermal waters and those mixed with associated with surface leakage of and Meager Mountam yield the highest cold groundwater (Fournier and stearnor boiling water Eventhesmallest estimates of subsurface temperatures Truesdell, 1973). Results of applyingthe surface expression of such thermal using both the silica and Na-K-Ca Silica and N-K-Cageothermometers to activlty could not have gone unnoticed geothermometers. Meager Mountain, thermal waters from western Canada In theCanadian Cordillera where, lor because of its proximity tothe city of Indicate low or spurious temperatures twenty years, an aggressive mineral Vancouver, is of patticular interest and, tor rnost of the class 1 springs and exploration industry has used In 1974 IheDepartmentol Energy, Mines and Resources drilled two test holes in Referenca Souther. J. G., 1973. Cordilleran the area. Both were abandoned when Volcanic Study; ~nReport of Activities. Caner. 0.. 1969. Electrical Conductivity they encountered a copious artesian April to October 1972: Geol. Surv. Can. Structure in Western Canada and flow of 60°C water at less than 200 feet Paper 73-1. p. 46-48. Petrological Interpretation: Canadian below surface. Further drilling and Contribution No, 198 to the International Souther, J. G.. in press, Geothermal detailed geophysical investigations Upper Mantle Project. Potential of Western Canada: 2nd U.N. were subsequently undertaken by B.C. Symposium on the Development and Fournier, R. 0. and J. J. Rowe, 1966. Hydroand Power Authority. use of Geothermal Resources. Development 01 geothermal power in Estimation 01 underground Canada faces some unique and temperatures from the silica content of Souther, J. G. and E. C. Halstead. 1973. formidable obstacles. The high cost 01 water from hot springs and wet-steam Mineral and Thermal Waters 01 Canada: geothermal exploration is aggravated by wells: Am. Jour. Sci.. v. 264, p. 685-697. Dept. Energy, Mines and Resources Paper 73-18. vast areas without roads, where aircraft Fournier, R. 0. and A. H.Truesde11.1973, provide the only means of An Empirical Na-K-Ca geothermometer Souther. J. G. and C. Stanciu, 1975, transportation. Moreover, the regions 01 for natural waters: Geochim, et Operation Saint Elias. Yukon Territory: Canada with the greatest geothermal Cosmochim. Acta. v. 37. p. 1255-1275. Tertiary Volcanic Rocks: Geol. Surv. potential are also regions with Can. Paper 75-1. Pt. A,, p.63-70. substantial reserves of fossil fuel and Hyndman, R. D.. 1975. Heat flow hydroelectric power that can be measurements in the inlets of Stacey R A. 1973. Grav~tyAnomalies. developed without assuming the high southwestern British Columbia: Jour. Crustal S(ructure, and Plate In capital risk inherent in geothermal Geophys. Res., (in press). the CanadIan Cordillera Can Jour Earth SCI , v to, p 61 5-628 drilling. However, the relatively small Lerbekmo. J. F, and F. A. Campbell, environmental impact 01 a geothermal 1969. Distribution. composition, and Sutherland Brown. A,, 1969, Aiyansh development must be taken into source of the White River Ash. Yukon lava flow, British Columbia: Can. Jour. account when considering the Territory: Can. Jour Earth Sci..v. 6, no. 1. Earth Sci.. v. 6, no. 6, p. 1461-1468. alternatives of llooding reservoirs for p. 109-116. hydroor stripping coal lor thermal plants, Van Everdingen. R. 0.. 1972, Thermal There are few precedents to serve as Mathews. W. H.. 1958, Geology of the and mineral sprlngs in the southern a guide to geothermal exploration in Mount Garibaldi map-area. Rocky Mountains of Canada: Ottawa, Canada. We have no obvious surface southwestern British Columbia. Canada; Dept. 01 the Environment,Water expressions 01 thermal reservoirs so our Part IIGeomorphology and Quaternary Management Service. volcanic rocks: Bull. Geol. Soc Am., v. search must be directed toward hidden White. D. E.. 1970,Geochemistry applied targets defined only by geological 69. no. 2. p. 179.198. to the discovery, evaluation, and concepts and by geochemical and Mathews. W. H. andG E. Rouse, 1963. exploitation of geothermal energy geophysical anomalies that are believed Late Tert~aryvolcanic rocks and plant- resources: United Nations Symposium to be temperature dependent, bearing deposits in British Columb~a: on the Development and Utilization of Reasonable first-order targets have Bull. Geol. Soc Am.. v. 74. p. 55-60, Geothermal Resources: Pisa. Sec V, already been identilied but their true Rapporteur's rept. (preprint) p. 1-25. nature can only be confirmed by drilling. Nasmith. H.. W. H. Mathews. and G. E Wilson. J. T.. 1965. Transform Faults. I1 the Canadlan geothermal program isa Rouse. 1967. Bridge River Ash and oceanic . and magnetic serious effort to develop geothermal some other recent ash beds in Braish anomalies southwest 01 Vancouver electric power capacity then it must be Columbia: Can. Jour Earth Sci.. v. 4, p. directed toward the siting and drilling of 163-170, Island: Science, v. 150. no. 3695. p. 482- 485. several deep holes. Any effort that stops Ney, C S.. 1968, Geological and short of drilling can do no more than Geochemical Report on the VAN MS received October 17. 1975 produce another theoretical paper Claims, British Columbia: B.C. model and until several such models are Department of Mines Assessment actually tested there is no justification in Report, open file. using them to assess our potential Plalker. G.. 1972, New Data onCenozoic geothermal resource. displacements along the Fairweather Realization 01 Canada's modest Fault System, Alaska ~nProgrammeand geothermal potential will be possible Abstracts. Faults. Fractures. Lineaments only if governments are prepared to and related Mineralization in the support the search either through large Canadian Cordillera: Geol. Assoc. Can. scale participation or through the Cordilleran Section Symposium, Feb. enactment of new legislation that will 1972. encourage the investment of private risk capital in geothermal exploration and Souther, J. G,1970, Volcanism and its development programs. relationship to recent crustal movements in the Canadian Cordillera: Can. Jour Earth Sci., v. 7, no. 2, p. 553- 568.