,.., ~ ~~~~ ~

Ministry of Energy, Mines and Petroleum Resouxes

KIMBERLITES IN BRITISH COLU1M:BIA

THE CROSS KIMBERLITE (82J/2) et al., 1986; Ijewliw,1986,1987; Pell, 1987) andthe reader is referred to those works for additional details. The Cross diatremeis exposed at an elevation of 2200 The Cross diatreme intrudes Pennsylvanian-Pennian metres on the north side of Crossing Creek, 8 kilometres Rocky MountainSnpergroupstrata(Hovdebo, 19.57). It out- northwest of Elkford (latitude 5O0O5'24'W, longitude crops ona steep face and anarea of approxitmate1:y55 by 15 114"59'48'W). It is 60 kilometres east of the Rocky Moun- metres is exposed. Its western contact is wall exposed and tain Trench, or approximately20 kilometres east of the axis clearly crosscuts shallow-dippingcrinoidal dolo!:tones and of the zone containing theother intrusions in the Elk River dolomitic sandstones(Figure 82). Aminor s:hear zone forms - Bull River areas (Figure 73). It represents the only true the eastern contact. No thermal effects 011 the wallrocks were observed. kimberlite known in the province to date. Access is by heli- copter or by four-wheel-drive vehicle and a hike along an undriveable road. It has previously been reported on (Meeks, 1979;Robertsetal., 1980;Grieve. 1981,1982;Hall

@ Creek f Crossing kirnberllts /\

10.00

I

5.00

0.00 0.00 5.00 10.00 15.00 20.00 -25.00 30.0

03 + Crorrtng Creek 25.00 kirnberllte @ Averoga klrnberlile 20.00 1 ponolitlc

barmillto lephrite

Iarnprophyre 5.00 bora11

0.00 " 20.00 30.00 40.00 50.00 60.00 70.00 SI02

Figure 83. Major element discriminantplots, Cross kirnberlite. Figure 84. Major element ternaryplots, Cross kinlberlite

- Bulletin 88 103 ~~ ~

Ministry of Energy, Mines and PetrooResources

ECONOMHC CONSIDERATIONS AND EXPLORATION POTENTIAL

Many metals and industrial minerals are either pro- al., 1986). The other British Columbia carbonatite com- duced from alkaline rocks or are known to occur in eco- plexes which have been examined all have averageNbzOs nomically significant amounts in alkaline rocks. Alkaline values of 0.30% or less, but there is excellent potentia1 for rocks are a major sourceof niobium and rare-eartb elements the discovery of other carbonatites with potential ore-grade among the metals and of nepheline, barite, vermiculite, co- niobium concentrations. rundum and diamond amongthe nonmetals. Molybdenum, Tantalum is not abundantin British Columbi:l carbona- zirconium, copper, fluorite, wollastonite and apatite are also tites. Most of the complexes have NLxTa ratios typical of recovered from alkaline rocks. The important features of carbonatites, approaching 1OO:l or more ana niobium economically significant materials in alkaline rocks in Brit- grades are never sufficient to result in signifi.cant concentra- ish Columbia are outlined in the following summary. tions of tantalum. Carbonatites in the Blue 'River area have anomalous Nb:Ta ratios, in the order of 4:l and tantalum NIOBIUM AND TANTALUM analyses of up to 2400 ppm are reported (Aaqui:.t, 1982b). On average, however, the niobium gradesat Blue River are Carbonatites contain the bulk ofthe world's reserves of low, ranging between 0.06 to 0.1% NbzOs and, therefore, niobium, a metal whichis used in the production of high- even with anomalous NbTa ratios, currently suteconomic temperature speciality steels and superalloys for nuclear, with respect to tantalum. aerospace, heavy equipmentand pipeline applications. Nio- binm also has important potential as a superconductor of RARE-EARTH ELEMENTS AND electricity at cryogenic temperatures(Cunningham, 1985a). The principal niobium mineralin carbonatites is pyrochlore, YTTRIUM although other niobium-bearing species such as columbite Rare-earth elements are concentratedl in all alkaline and fersmite may also be present. The majority of the rocks. In carbonatites they are present main'lyin the form of world's niobium, approximately 85% of total production, the cerium subgroup, or light rare earths. A considerable comes from Araxa, Brazil, where pyrochlore has been con- concentration of rare-earth elements may be contained in centrated by residual weathering and grades arc in the order common minerals such as calcite, dolomite, pyrochlore, of 3% NbzOs. In Canada, niobium is mined by Niobec Inc. fluorite, apatite, sphene and zircon. Rare-earth carbonate (Teck Corporation and Cambior Inc.) at St. 1Ionor6, near and fluorocarbonate minerals such as bastnaesite and Chicoutimi, Quebec, where gradesare 0.5 to 0.67% NbzOs. parisite, or phosphate minerals such as monazit: or xeno- Tantalum is a relatively rare, heavy, inert metal that is time, mayalso be present in alkaline suites a.nd contain rare- used in electronics, chemical processing equipment,metal- earth elements. Yttrium, although notstrictly a rare earth, is cutting tools and high-temperaturesteel alloys. It is recov- commonly grouped with themas its chemical properties are ered principally as a coproduct of other metal mining, similar to the heavy rare earths. associated with tin lodes, tin placers and beryllium-tin-nio- These elements are used principally in petroleum- biumpegmatites (Cunningham,1985b). Tantalum mayalso cracking catalysts, iron, steel and other metal-alloying be present in significant amounts in carbonatites, generally agents, glass-polishing compounds andglass add Itives, per- in the mineral pyrochlore. In alkaline rocks the Nb:Taratios manent magnetsand phosphors for television and lighting commonly exceed100, whereas in granitic rocks theyaver- (Hendrick, 1985). The rare earths also have importantpo- age 4.8 (Cume, 1976b). tential in the manufacture of superconducsm ar.d applica- Carbonatites in British Columbia areall anomalous in tions in advanced ceramics and lasers, piuticnlarly yttria niobium. The Aleycarbonatite complex appearsto have the (Wheat, 1987). The U.S.A., Australia and China are the ma- greatest niobium potential of any of the complexes so far jor producers of rare earths (Griffiths, 1984; Hendrick, discovered. Work by Cominco Ltd. since 1982, which in- 1985). Most of the economic recoveryin the U.I .A. comes cludes surface exploration and diamond drilling, has de- from the Mountain Pass carbonatite in Califonia, which fined extensive zones in both the rauhaugite core and grades 7to 8% total rare-earth oxides, predominiatly of the sovites, containing between two-thirds and three-quarters of cerium subgroup. Bastnaesite is the principal ole mineral. a percent NbzOs (K.R. Pride, personal communication, InAustraliarareearthsarerecoveredfromnlonaziteplacers; 1986) and grades whicheasily rival the St. Honor6 complex in China rare earths are recovered fromtabular magnetite in Quebec. Local areas containing greater than 2% Nbz0s iron ores, fluorite-quartz-carbonate and tungsten-quartz have been outlined in the Aley complex. At Aley,the nio- veins, pegmatites andtin placers (Lee, 1970). Recently, the bium is present mainly in the minerals fersmite and pyro- greatest demand has been for samarium andnedymium to chlore; columbite is also present in minoramounts (Pride et be used inthe magnet industry and for yttrium in:?hosphors,

- _" Bullelin 88 107 "_ "_

British Columbia "

The diatreme is lithologically heterogeneous and, lo- between phasesmay be gradational or sharp. Athin dike, 10 tally, very friable. The west end of the outcrop is a light to 30 centimetres wide, cuts the central breccia phase green, strongly foliated rock containing some redhematized Ultramafic xenoliths are almost entirely serpentinized clasts, abundant pelletal lapilli and cobble-sizedpellets, as pseudomorphs of olivine and pyroxene. Theoriginal pres- well as autobreccia fragments (westernbreccia phase). Fo- ence of olivine is indicated by the typical olivine outlin e and liation is at a high angle to bedding in adjacent sediments. fracture pattern; the grains, however are completel.11 ser- This grades eastwards to a massive, inclusion-poor light pentinized. Some relict pyroxene, withcharacteristic c:leav- green unit (western massive phase)which in turn grades into age andbirefringence, is preserved. Talc replaces pyroxene a rock with 40% inclusions, 5 to 10% of which are ul- to a limited extent and also rims and veins sapentinized tramafic xenoliths (central breccia phase). The inclusions grains. Interstitial spinels are also present in minoramounts. often form the cores of accretionary lapilli (Plate 55). Far- ther east the rock is a dark green, massive, unfoliated unit The interstitial spinels analysed on the energy dispersive withfewerclasts but containing abundant,randomly distrib- system of the scanning electron microscope are in the chro- uted phlogopite books and ultramafic xenoliths (eastern mite-hercynite solid solution series and can best be ~epre- massive phase). Bright red hematization is progressively sented by the formula (Fe, Mg) (Cr, A1)204 (Ijewliw, 1987). more evident towardthe top andcentre of the outcrop where The xenoliths may be broadly classified as spinel lher- entire mineral or xenolithic fragments may be hematized. zolites. Also preserved, although notas abundant, are€:met Pyrite is present as discrete grains in the groundmass andas lherzolites and glimmeritexenoliths (Hall et al., 1986,). rims surroundingclasts where it may, in turn, be enveloped The macrocryst population (0.5 to 5.0 mm in size:)con- by ragged, bright red hematite(red spotted phase). Contacts sists of completely serpentinized olivines, partially altered garnets, garnets withkelyphitic rims andphlogopites. They may beround, ovalor lath shaped in random orientation and TABLE 18 make up 10 to 20% of the rock volume. Garnets sf~owa CHEMICAL ANALYSIS moderate to high degreeof alteration or dissolution in reac- CROSSING CREEK KIMBERLITE tion with the matrix. None are enhedral. They are rounded

~~~ ~ and irregular in shape and surroundedby kelyphitic rims or __wr % 1 2 3 reaction coronas of opaque iron oxides (Ijewliw, 198711. The Si02 30.04 30.74 30.02 garnets arepyrope rich. Phlogopites are occasionally zoned, Ti02 1.28 1.45 1.29 1.44 with rims darker and morestrongly pleochroic than cores A1203 2.23 2.31 2.21 2.10 :::;I and often displayingreversepleochroism (Halletal., 1986). Fe203T 6.89 8.28 5.31 7.48 7.70 MnO 0.12 0.16 0.09 0.11 The phenocryst populationis comprised of completely MgO 25.03 27.72 23.54 27.75 23.840.151 serpentinized olivine, together with phlogopite and :;pinel CaO 13.48 9.78 14.94 9.55 14.21 (Plate 56). Phlogopite grains vary in size, are randomly ori- Na20 0.07 0.09 0.03 0.02 ented, square to rectangular in shape and relatively unal- K20 1.37 1.01 1.47 1.26 1.22 0.05I tered. Reddish brown translucent spinels are disseminated LO1 17.8715.3817.04 15.4 17.37 no5 0.99 1.06 1.03 0.99 in the groundmass and show magnetite reaction rims -S 0.14 0.23 0.09 0.12 (Ijewliw, 1987). The groundmassis composed ofca1ci:e and Total 98.68 98.22 97.88 98.35 serpentine with minor apatite and anatase. ppm Ni 1000 1000 10W 1300 X90 Cr 12941369 1398 1747 1728 co 60 56 54 70 55 Rb 56 40 53 57 54 Sr 1177 1073 1171 1452 14921 Ba 3237 2642 3497 2648 3442 Zr 292 322 301 313 367 Nb 187 207 200 199 %30 Y 18 22 21 21 La 134 157 126 132 197 Ce 258 300 239 266 363 Nd na nana na na Yb 2 1 3 0 .:-I sc 20.323.1 23.7 20 25.1 Ta 7 14 9 11 11 Th 18 19 24 18 41 iu 14 14 15 !" 196 196 208 2; j cu 731 54 50 51 4 All amlyss'8 b;vXRF, B.C. G.S.B.analytical laboraforv 1. .CX5-6 Kin .. 0.00 400.00 800.00 1200.00 1600.00 2. - CX57B Hemotire-spotred kimberlite: red-sparredphase: Cr ppm ~- 3. - CX5-8A Kimberlife, easrem massivephase: 4. - CX6-Dl Fine-grained crosscutting, inclusion-free dike; Figure 85. "Average" values from Wederhaland Maramatsu 1979. 5. - CX5.7Micaceouskimberlite, red-sparfedphase. Ni vs Cr plot, Cross kimberlite.

104 Geological Survey Itranch Ministry of Energy, Mines and Petroleum Resources

GEOCHEMISTRY GEOCHRONOLOGY TheCross diatreme is the only trne kimberlite so far Rubidium-strontiumdating of micaseparates has recognized in the province. It fits both the petrologic and yie,ded Pemo-T~assicages of 240 244 k,a for the geochemical definitions of a kimberlite (Figures 83 and84; Cross kimberlite (Grieve, 1982; Smith, 1983; F:all et al., Table 18 ). Although it appears to bequite a heterogeneous intrusion, analyzed were all ve~similar geochemi- 1986 ). Both the Cross kimherlite and its hostrocks are sig- cally. It is characterizedby low silica, high magnesium, high nificantly younger than other British Cohtmbia diatreme strontium and high nickel and chrome(Figure 85; Table 18). suites.

~~- Bulletin 88 105 ~- 106 Geological Survey Eranch engineering ceramics and superconductors(Roskill Infor- he 1 to 4 metres wide and over30 metres long. Mafic syenite mation Services, 1988). dikes in the area generally contain lower concentrations of Significant enrichment in rare-earth elements is re- rare earths than the pegmatites; local concentrations up to ported from five localities in British Columbia, the Aley 4.26% total rare earths have been found (Halleran and complex and Rock Canyon Creek, bothin the Rocky Monn- Russell, 1990). Very little work has been donein the IvIount tains; the Wicheeda Lake area along the Rocky Mountain Bisson area and preliminary results indicate some potential; Trench near Prince George;the Kechika River area in the this area might warrant further work in the future, particu- Cassiar Mountains; and the Mount Bisson area in the larly if the demand for cerium and lanthanum incream. Omineca Mountains.At Aley narrowdikes enriched in rare- The presence of these five highly anomalous occur- earth elements, and locally fluorite, cnt the altered sedi- rences indicates that British Columbia is highly prospwtive ments peripheral to the main complex. Samplescontaining for economic accumulations of carbonatite-related rare- in excess of 2.1% total rare-earth oxides are present. The earth elements. rare earths are contained in carbonate mineralssuch as bast- naesite, burbankite, cordylite and huanghoite (Miider, ZIRCONIUM 1987). These dikes are thin and sporadically developed and, although worthy ofnote, not of major economicinterest. Zirconium is strongly concentrated in some alkaline At Rock Canyon Creekmetasomatically a altered(feni- rocks andmay comprise upto 2%. The main zirconiummin- tized) zone rich in rare earths and fluorite, measuring ap- erals present inthese rocks arezircon, eudyialite (Na-Zr sili- proximately 1000 by 100 metres, has been identified. cate) and haddeleyite (ZrOz), with alkaline rocks beir,g the Samplescontaininginexcess of 2.7% total rare-earthoxides only known source of substantial amounts of haddele yite. (predominantly cerium and lanthanum oxides) have been The major application of zirconium is in four dries obtained from outcropsof this zone.The rare-earth fluoro- where it isused in mineral formas facing for molds for metal carbonate mineralshastuaesite and parisite, and gorceixite, casting. It is also used in refractories, nuclear powerappli- a phosphatemineral, have been identified. At RockCanyon cations and chemical processing equipment.Of increasing Creek, locally high rare-earth values at surface, the size of importance is the application of zirconium inadvanccd ce- the zone andthe lack of extensive work suggest that further ramics which have suchdiverse uses as heat-resistant tiles, work is warranted. sensors and automobileexhausts. The principal sources of zirconium are zircon recovered as a hyproducl. from tita- In the Wicheeda Lake area a series of alkaline rocks and haddeleyiteproduced as a copro- including carbonatites, syenites and leucitites are exposed. nium placer deposits duct fromapatite mining ofthe Palabora carhonatite, Sonth Work by TeckCorporation has indicated that one carhona- Africa and of niobium miningat Araxa and Pocosde C aldas tite plug locally contains in excess of 4% total rare-earth carhonatites in Brazil (Adam, 1985). elements and one trench, across part the carbonatite, ex- posed material grading 2.60% total rare earths over its 42- Zircon is a ubiquitous phase in carbonatitc: and metre length (Betmanis, 1988). These valnes are nepheline syenite gneiss complexes in BritishCo1umb.a and predominantly in light rare earths, in particular cerium and crystals often exceed 1 centimetre in length. The Aley com- lanthanum, however, the results are favourahle andthis area plex, Paradise Lake syenite, Verity carhonatite, Tjident might warrant further work in the future, particularly ifthe Mountain syenite and Lonnie andVergil complexes all con- demand for cerium and lanthanum increases. tain coarse zircon inexcess of 1%. In the Lonnie. and 'Jergil complexes, the syenitic rocks may contain 3 to '15% zircon In the Kechika River area, alkaline rocks consisting of locally. Although it is unlikely that any of these rocks could syenites, malignites, breccias and fenites are intermittently compete with placer deposits, it is possible that zircceium exposed along a northwest-trending zone in excess of 15 could he produced as a hyprodnctof niobium 0.r rare..earth kilometres in strike length. During a recent exploration pro- mining and should hetested for. gram, samplescontainingin excessof 3.77% total rare-earth oxides (mainly cerium snhgronp elements) werecollected from carhonatite dikes; other samples containing up to PHOSPHATES 1.13% Y203, 0.30% NdzO3, 0.11% Sm2O3 and 0.14% Ultrabasic alkaline igneous complexes commonly con- Dy2O3 were taken from phosphate-richsegregations, con- tain high concentrations of phosphate, largely in the fcrm of taining upto 19.3% P2O5, in a mylonitizedsyenitekrachyte themineralapatiteandapproximately 18%ofallphos&hates (Pel1 et al., 1990). Rare-earth elements and yttrium in the mined come from igneous complexes. Apatite: from car- Kechika River area are present mainly in monazite, xeno- bonatites is mined at Palabora, South Africa; Dorowa, Zim- time and other phosphate minerals. The size of this zone, babwe; the Kola Peninsula in the U.S.S.R.; and Araxa and lack of detailed work and presence of anomalous concen- JacupirangainBrazil (Currie, 1976a;Russell, 1987; Feman- trations of heavy rare-earth elements suggestthat additional des, 1989). Grades as low as 4% P2O5 are currently recov- work is warranted. ered. Approximately 90%of all the phosphatemined i:; used Light rare-earth elements, particularly cerium and lan- in the fertilizer industry; other uses include organicmd in- thanum, are concentrated in allanite pegmatites and allan- organic chemicals, soapsand detergents, pesticides, :nsec- ite-hearing mafic syenite dikes that are associated with large ticides, alloys, animal-food supplements, ceranics, fenite zones in the Mount Bissonarea. Some of the pegma- beverages, catalysts, motor lubricants, photographic mate- tites reportedly contain up to 14.5% total rare earths and can rials and dental cements.

108 Geological Survey 1:ranch ~ ~

Ministry of Energy, Mines and PetreResources

In British Columbia, all carbonatites contain some apa- 1989). The remotelocation of this body, howeve!; severely tite. The Aley complex and carbonatites in the Blue River limits its economic potential. area are more enriched in apatite than many of the other carbonatites, containing, on average, 5 to 15% apatite, with VERMICULITE P205 contents up to 11% (Tables 1 and9) and averaging3.5 to 5%. The Rencarbonatite also has an average1'20s content Vermiculite is a mineral which expan& whm heated. of approximately3.5%, with maximum values of 4.2% (Ta- It is formed from alteration of biotite or phlogopite andis a ble 12). Carbonatite dikes cutting ultramafic rocks of the Ice characteristic accessory in ultrabasic rocks associated with River complex locally contain np to 8% PzOs (Table 3). carbonatites. Vermiculite is present in minor amountsasso- Syenitic mylonites in the Kechikaarea contain small zones ciated with carbonatites in the Blue River area, but is not which assay as high as 19.3% P20s and haveapatite as one reported from other areas. The potential for vermi<:ulite pro- of the major rock-forming minerals.The contin.uity ofthese duction from carbonatites in British Columbia is :xtremely phosphate zones is unknown and it is unlikely that they limited. would be exploited for phosphate alone. MOLYBDENUM It has been estimated that the Aley complex may con- tain as much as 15 billion tonnes of 5% P2O5, while other Molybdenum is generally associated with granitic as carbonatites probably contain only a few million tonnes of opposed to syenitic rocks, but,in some caw, it may bepre- phosphate reserves (Butrenchnk, in preparation). Produc- sent in alkaline complexes (Currie, 1976a). In British Co- tion of phosphates from these carbonatites as a primary lumbia, the nepheline syenite gneisses associate1 with the commodity is unlikely in light of competition from sedi- Frenchman Cap domecommonly contain nlolybdenite and mentary deposits, but byproduct recoveryof apatite might the Mount Copeland showings thewere focns of r.ignificant prove feasible, particularly in the case of Aley, if niobium exploration and developmentwork inthe late 1960s (Fyles, were to be mined. 1970). Current economics,however, do natfavour exploi- tation of molybdenum from such deposits. NEPHELINE AND NEPHELINE SYENITE WOLLASTONITE Nepheline and nepheline syenite are of major impor- Wollastoniteis an important mineralfiller nscd primar- tance in the glass and ceramicsindustries due to their high ily in the paint and ceramics industries. It #:an b,: found in alumina contentin the presence of abundant sodium; these two main geological environments:contact .metarnorpbicor elements act as a flux which affects the rate and temperature metasomatic (skarn) deposits and in carbonatite!:, as a pri- of melting, the flnidity of the melt andthe physical proper- mary, magmatic mineral. Most world production comes ties of the finished product. Small amountsare also used in from contact deposits (Harben andBates, 1990). paints and as fillers in plastics. Canada is currently the larg- Wollastonite has not been recognized in any carbona- est free-world producer of nepheline syenite which is all tites in British Columbia; however, it is worth looking for quarried in the Blue Mountainregion of Ontario. in fntnre discoveries. Nepheline syenite occurs in large volumes in a number of areas of British Columbia; the Ice River complex, Bear- TITANIUM paw Ridge, Paradise Lake, Trident Mountain, the Perry Titanium-bearing minerals are present in a inumber of River area and Mount Copeland.With the exception of the the carbonatite and alkaline rock complexesin Rritish Co- latter, most are relatively inaccessible. TheMonntCopeland lumbia. Sphene,perovskite and ilmenite have all been rec- syenite gneisses, which arelocated 25 kilometres northwest ognized. As well, knopite, a rare-earth emiched variety of of Revelstoke, may be reached by oldmining roads. Onav- perovskite, has been reported from the Ice R.iver area erage they contain moreiron, manganese, calcium andpo- (Ellsworth and Walker, 1926).In most cases, these titanium tassium, and less sodium, silica and aluminumthan thoseat minerals are present in relatively low concent:ations; at Blue Mountain (Table 11; Currie, 1976a). In general, the Howard Creek, however, sphene is a rock-forming mineral Mount Copelandsyenites are medium to coarse grained and in a melteigite of limited spatial distribution. It is unlikely it was considered that many of the impurities (ferromagne- that titanium could be produced from any of th,:se wcur- sian minerals - in particular biotite) could potentially be rences. removed by crushing and magneticseparation techniques; however, beneficiation tests failed to produce a product with DIAMOND a low enough iron content to meet industry specifications (White, 1989). Some of the other syenites, such asthe Para- Diamonds were traditionally considered to be prcsent disesyeniteorthelargehodyonTridentMountain,arequite in economic concentrations in kimberlites oniy. Recent similar in composition to those being minecl in Ontario. studies have shown that they may also be recosered from Beneficiation tests run on samples from Trident Mountain lamproites, and they havealso been reported fro:n such di- indicate that this syenite is low in magnetic impurities, has verse rock typesas peridotites and even carbonaites. Only a high recovery rate of nonmagnetic materials and, there- one true kimberlite has been discoveredin Briti:;h Colum- fore, has good potential to produce a commercial-grade bia, the Cross diatreme, but no results of laboratoly research nepheline syenite product witha brightness of 85% (White, on mineral compositionor diamond recovery have beenre- _" Bulletin 88 109 ~

British Columbia "

Stevens, R.D., Delahio, R.N. and Lachance, G.R.(1982): Age De- sition of Three Basaltic MagmaTypes; in Kimberlites, Dia- terminations and Geological Shldies, K-AI Isotopic Ages, tremes and Diamonds: Their Geology, Petrology and Geo- Report 16; Geological Surveyof Canada, Paper 82-2. chemistry, American Geophysical Union,Procwdings ofthe Stewart, J.H. (1972): Initial Deposits in the Cordilleran Geosyn- Second International Kimherlite Conference, Volume 1, cline: Evidence of Late Precambrian (R my) Continental pages 300-312. Separation; GeologicalSociefyofAmerica,Bulletin,Volume Wheat, T.A. (1987): Advanced Ceramicsin Canada;Canadian In- 83, pages 1345-1360. stitute of Mining andMefaNurgy,Bulletin, Volume 80,Num- Stewart, J.H. and Poole, F.G.(1974): Lower Paleozoic and Upper- ber 900,pages 43-48. most Precambrian Miogeocline, Great Basin, Western Wheeler, J.O. (1962): Rogers Pass Maparea, British Col~mbia United States; in Tectonics and Sedimentation, Sociefy of and Alberta; Geological Survey of Canada, Map 43-1 962. Economic Paleontologists and Mineralogists,Special Puh- Wheeler, J.O. (1963): Rogers Pass Map-area, British Colmhia lication 22, pages 28-57. and Alberta;Geological Surveyof Canada, Pap62.32. Symons, D.T.A. and Lewchuk, M.T. (in press): Paleomagnetism Wheeler,J.O.(1965):BigBendMapArea,BritishColumhia;Geo- of the MississippianHP Pipeand the Western Marginof the logical Survey of Canada, Paper 64-32. North American Craton; American Geophysical Union, Monograph Series. Wheeler, J.O., Campbell, R.B., Reesor, J.E. and Mountjoy. E.W. (1972): Structural Style of the Southern Canadian C!ordil- Taylor, G.C. and Stott, D.F. (1979): Monkman Pass (931) Map lera; International Geological Congress, Excursion A-01- Area, British Columbia;GeologicalSurvey of Canada, Open xo1. File Report 630. White, G.P.E. (1 982): Notes on Carbonatites inCentral Briti ;h Co- Thompson,R.I.(1978):GeologicalMapsandSectionsoftheHalf- lumbia; in Geological Fieldwork1981, B.C. Ministry of En- way River Map Area, British Columbia (94B); Geological erg3 Mines and Pefroleum Resources,Paper 1!>82-1,pages Survey of Canada, Open File Report536. 68-69. Thompson, R.I., Mercier, E. and Roots, C.(1987) Extension and White, G.P.E. (1985): Further Notes on Carhonatims in C!entral its Influence onCanadian Cordilleran Passive-margin Evo- British Columbia;in Geological Fieldwork1984, B.C: Min- lution; in ContinentalExtensional Tectonics, Howard,M.P., istry of Energ3 Mines and Petroleum Resources, Paper Dewey, J.F. and Hancock, P.L., Editors, GeologicalSociety, 1985-1,pages 95-100. Special Publication 28, pages 409-417. White, G.V. (1989): Feldspar and Nepheline Syenite Potertial in Vaillancourt, P. and Payne, J.G. (1979): Diamond Drilling Report British Columbia;in Geological Fieldwork1988, B.C Min- on the LonnieRitch Claims, Manson Creek Area, Omineca istry of Energy, Mines and Petroleum Resources. Paper Mining Division; B. C. Ministry ofEnergy, Mines and Petro- 1989-1,pages 483-487. leum Resources, Assessment Report7515. Wooley, A.R. (1982): ADiscussion of Carhonatite Evoluticm and von Knorring, 0. and du Bois, C.G.B. (1961): Carbonatite Lava Nomenclature and the Generation of Sodic :md Potassic from Fort Portal Area in Western Uganda; Nature, Volume Fenites; Mineralogical Magazine,Volume 46,pages 13-17. 192, pages 1064-1065. Woyski, MS. (1980): Geology of the Mountain Pass Carbmatite Warhol, W.N. (1980): Molycorp's Mountain Pass Operations; in Complex - A Review; in Geology and MineralWeatk of the Geology and Mineral Wealthof the California Desert,South California Desert, South Coast Geological Society, pages Coast Geological Sociefy,pages 359-366. 367-377. Wedepohl, K.H. and Mnramatsn, Y. (1979): The Chemical Com- position of Kimberlites Compared withthe Average Compo-

-~ 124 Geological Branch Survey ported by industry. Microdiamonds have, however, report- have also been reportedfrom alkaline lamprophyre dikes in edly been recovered fromtwo of the lamprophyre diatremes Montana. in the Golden - Columbia Icefields area. One of the pipes Nepheline syenites are known from afew localities in reported to have yielded microdiamonds fromconcentrates B.C. (e&, Paradise Lake, Ice River, etc.). These areas have collected and processedat two different times, from differ- not been evaluated for their potential to contain gem corun- ent laboratories. Asignificant amountof additional research dum. Alkaline lamphrophyres are present in the Rcckies is necessary to establish if economic concentrations are pre- (e.g., Golden cluster) and couldalso be prospected fa: gem sent. corundum varieties. GEMSTONES Blue corundum crystals (star sapphires) up to 1 to 2 centimetres in size, have recently been discovered in the Corundum (sapphire, ruby) is a common accessory Slocan Valley withina syenitic phase of the Valballa Gneiss mineral in silica-undersaturated, alumina-rich rockssuch as Complex, part of the Passmore Dome. These gneisser also nepheline syenites and nepheline-feldspar pegmatites. In contain sphene and amphibole and, in outcrop, resemble the Bancroft area of Ontario,corundum occursin nepheline- fenites in the Blue River and Perry Riverareas (Z.D. Hora, bearing rocks and marginal zonesof nepheline syenite in- personal communication,1993). Fenites are widesprer.d, as- trusions at Blue Mountain and elsewhere. Nepheline sociated with carbonatites and syenite gneiss complexes syenites at Cabonga Reservoir, Quebec contain blue corun- within metamorphosed rocks or the Ominica Belt and dum crystals mantled by biotite (Currie, 1976a). Sapphires should be prospectedfor gem corundum.

_" 110 Geological Survey 3ranch Ministry ojEnergy, Mines and Pelruleurn Resources

SUMMARY AND CONCLUSIONS

CARBONATITESAND SYENITE are sill-like bodies with extensive fenitic aureolss. Work GNEISSES done to date indicates moderate enrichment in rare-earth elements, with or without niobium. Carbonatites andsyenite gneisses crop out inthreebelts There appears to be a relationship between depth of parallel to the Rocky Mountain Trench. Theintrusions in the emplacement, degreeof associated metasonratism and en- eastern Rocky and Cassiar Mountainbelt are middle Paleo- richment in economically interesting elements suchas nio- zoic, predominantly Devono-Mississippian in age, hosted bium or rare earths. All ofthese factors are prohabl y related by lower to middle Paleozoicstrata and therefore are rela- to the original volatile content of the magma.. The most fa- tively high-level intmsions. They can be large and elliptical vourable areas for additional exploration for these slements in shape and havesignificant alteration halos (e&, Aley car- would appear to bethose underlain by lower to middle Pa- bonatite), consist simply of metasomatic alteration zones leozoic strata of North American affinity. The western (e.& Rock Canyon Creek showing),or be extensive linear Rocky Mountains and someregions of the eastern 13mineca belts comprising numerous and lithologically varied sills, Belt, close to the Rocky Mountain Trench, have the best dikes and plugs (e.g. the Wicheeda Lake and Kechika River potential. Byproduct recoveryof apatite and zircon should showings). The carbonatites in the eastern belt can be sig- also be consideredwhen assessing the niobium or me-earth nificantly enriched in niobium, fluorine, yttrium and rare- potential of any prospects. earth elements. Commercial-grade nephelinesyenite could pcttentially The central belt lies within the Omineca Belt, immedi- be produced from the Trident Mountainsyenite, however, ately west ofthe Rocky Mountain Trench. The intrusions in current inaccessibility precludes immediateexploitation. If this belt are also Devono-Mississippian in age, hut are this area were everto become moreaccessible, through the hosted by Precambrian strata; they were not emplaced as development of good logging roads, the nepheline syenite high in the stratigraphic succession as those in the eastem potential of this body would warrant serious exar.lination. belt. The carbonatites in the Omineca Mountainsare thin, Other compositionallysimilarsyenites are presentin British discontinuous, sill-like intrusions generally with narrow Columbia, but are also in remote locations and remain un- fenite alteration halos. With one exception(the Mount Bis- tested. son intrusions), they are notas enriched in niobium,fluorine or rare-earth elements as their eastern counterparts. KIMBERLJTES, LAMPROPHYRES AND The western belt, also within the Omineca Mountains, OTHER ULTRABASIC DIATREMES comprises intrusive and extrusive carbonatites and Ultrabasic diatremes have been recognizedin five areas nepheline syenite gneisses hosted by the autochthonous of British Columbia; the Kechika River and OspikaRiver cover sequence of the Frenchman Cap gneiss dome. The areas of northern British Columbia, the Goldan, Bull River enclosing metasedimentary rocks of are uncertain age, how- -Elk River and Elkford areas of the Kcatenays. Iri the Os- ever, recent studies suggest that they mayhave been depos- pika River area north of Mackenzie, and in the Columbia ited in a period which spanslate Precambrianto Eocambrian Icefields area north of Golden (Figure Z), the diatrwnes are time (HOy and Godwin, 1988). A single radiometric date, characterized by macrocryst-rich breccias and dikes. The obtained on one of the alkaline intrusive bodies (Mount macrocryst population consists of clinopyroxene, phlo- Copeland syenite) which occurs near the base of the man- spinel and olivine, tling gneiss succession, indicates an age of emplacement of gopite, green diopside, with either py- roxene or phlogopite as the most abundantphase. In some circa 770 Ma for that intrusion (Okulitch et al., 1.981).This cases, microphenocrystic feldspars are present :,.nsmall gives a minimum age for the basal part of the succession. amounts. These rocks aretentatively classifi,ed as lampro- Much higher in the mantling gneiss stratigraphy, overlying phyres; the HPpipe in the Golden area and the Ospika pipe the carbonatitehorizons, a strataboundlead-zincdeposit has can he classified as aillikites, which are members cf the ul- yielded an Eocamhrian to early Cambrian lead-lead date. tramafic lamprophyreclan based on their modal mineralogy This suggests that the highest stratigraphic levels of the and, to a lesser extent, the chemistry. The other ultrabasic mantling gneiss succession are Early Cambrian and the in- intmsions in the Golden area are more difficltlt to 'classify; tervening stratigraphy was deposited between Late Protero- they appear to be most similar to amphibole-free alkaline zoic and early Paleozoic time. The extrusive carhonatites lamprophyres.In all cases the breccia pipes commonly con- are located relatively high in the mantling gneiss stratigra- tain multiple phases of intrusion characterized by variable phy, approximately 100 metres below the lead4nc layer proportions of xenoliths, macrocrysts and accretionary and, like the lead-zinc deposit, are probably Eocambrian in lapilli or spherical structules. The breccia matrix in some age. cases is clearly magmatic. These pipes are characteristic of The carbonatites in the western belt comprise high- the diatreme facies material, as described from kilnberlite level intrusions and extrusives. The carbonatite intrusions pipes and/or hypabysal-facies (Clement and Reid, 1986).

Bullelin 88 111 . ~~

Brirish Columbia “ ~~~~

They formed from extremely volatile-rich magmas, so rich, diatreme-facies tufflsitic breccias. Some pipes bneached the in some cases, that as they reached the surface and vesicu- paleosurface andthe upper parts of the crater zone contain lated, the magmatic phase exsolved fromthe volatiles and beddedepiclasticorpyroclasticrocks.Anumhert~fthe])ipes actually formed the ‘bubbles’, as indicated by the spherical in the Bull River- Elk Riverarea intrude Ordovician-Silu- stmctures (or globular segregations) and armoured xeno- rian Beaverfoot carbonate rocks andcontain bedded cl’ater- liths. At Lens Mountain, Mons Creek and Valenciennes facies material which is unconformably overlain b., the River sandy tuffisitic or gas-stream breccias, with an insig- basal Devonianunit (MiddleDevonian) suggestinganl3arly nificant recognizable igneous component, arealso present. Devonian age of emplacement of approximately 4oC Ma. Rubidium-strontium and potassium-argon dates of Other pipes and flows apparently underlie and predate the 3381r3 and 323f10 Ma havebeen obtained from phlogopite Beaverfoot Formation, but cut middleSilurian rocks and, separates from the Ospika pipe. These dates indicate that therefore, must be approximately 455 Ma in. age. The emplacement occurred in Devono-Mississippiantime, as is Kechika pipe is also hosted by Ordovician to Silnrian litrata the case for the most of the carbonatites in the eastern and and associatedwith beddedtuffs whichmust be of the Same central belts. Aillikites and alnoites arenoted for their affili- age as the host strata (possibly circa 450 Ma.). ation with carbonatites (Rock, 1986). Pipes and dikes from The craters containing these breccias are envisaged to two areas north of Golden have also been dated. Inthat area, have a ‘champagne glass’ structure, similar to that of lam- most of the diatremes were emplaced slightly earlier, in proite or basaltic craters, with no extensively developedrmt Early Devonian time (circa 400 Ma). Zircons from ultra- zone. The breccias are commonly associated with cro5 scut- basic rocks in the Mons Creekarea yielded concordantlead- ting porphyritic dikes and flows, characterized by the pres- lead ages of 469 Ma; if these zircons are not xenocrystic, it ence of phenocrystic olivine and titanaugite, with ahwdaut may indicate that there was a third period of emplacement feldspar (plagioclaseorpotassiumfeldspar),titanaugite and in the Late Ordovicianto Early Silurian. opaque oxide microphenocrystsin a fine-grained ground- Intrusions in the Bull River and Kechikaareas are dis- mass. These rocks are extremelydifficult to classify: they tinctly different than those in the Golden or Ospika areas. are ultrabasic, and locally quite potassic, feldspar-bearing They are characterized by chaotic breccias containing abun- rocks that can contain vesiculated glass lapilli and are gen- dant vesiculated glass lapilli, juvenile lapilli and rare altered erally devoid of hydrous mafic minerals andfeldspathoids. olivine, altered pyroxene, feldspars and chromian spinel They may have originated in volatile-enriched systems, but macrocrysts and by the absence of primary micas. The ma- not to the extent of the previous diatremes; as ihey n:ared trix of these breccias is not magmatic; they are crater and the surface the volatiles exsolved fromthe maglna and not

Figure 86. Structural positionof diaEemes, B - Bush River;C -Lens Mountain; D - Mons Creek;E - Valenciennes River ;P HP pipe; G - Shatch Mountain;H - Russell Peak; I - Blackfoot; J - Quinn Creek; K - Summer :L - Crossing Creek,Geology modified from Wheeler (1963),Wheeleretal., ( 1972),Leech (1979), Price(1981).

~~ 112 Geological Survey haranch Ministry of Energy, Mines and Petrnleum Resourres the reverse. In some cases they maybe tentatively classified North America, it isunlikely that significant concentrations as limburgites, in others they appear to be most similar to of diamonds canbe found in nonkimberlitic rock!: originat- members of the alkaline basalt family, but gmerally are ing so far from the stable craton; however, the we.;tern con- more basic than typical alkaline basalts which suggests that tinental margin at the time of diatreme emplacement was they are verging towardsnephelinites. probably significantly more complexthan theone proposed The last distinct rock typeis represented by one exam- in Haggerty’s model for South Africa. The locat ion of the ple, the Cross kimberlite, located at Crossing Creek, nortb westem edgeof the continental mass at that time is unknown of Elkford. As the nameimplies, it is a true kimberlite, the and the depth to the lithosphere-asthenosphere bcandary is only one so far recognized in the province. It is apparently also uncertain, therefore, the proposed constraints on dia- a deeply eroded piperemnant and contains two generations mond genesis may be not directly applicable. of olivine, phlogopite, pyroxene, garnet and spinel megacrysts as well as garnet and spinel lhemlite nodules TECTONIC IMPLICATIONS (Hall etal., 1986). Rubidium-strontiumisotopic ratios indi- cate that the pipe was emplaced in Permo-Tiiassic time, The emplacement of carbonatites, kimberlites and circa 245 Ma (Grieve, 1982; Hall etal., 1986). other alkaline rocks in the Canadian Cordillera appears to be related, in part, to extension andrifting along tte western At this point it is difficult to completely assCss the depth continental margin that produced and deepened the basin of origin and diamondpotential of theserocks. The Crossing into which the miogeoclinal succession ‘was t.eposited. Creek kimberlite apparently originated deep in the mantle, Sedimentological and stratigraphic evidence inc.icate that it contains abundant pyropegarnets and has sampled mantle the western continental margin was tectonically active lithologies including garnet lherzolites. This suggests that it throughout much of the Proterozoic and Paleozc,ic eras. It may have originated at depths generally considered suffi- does not appearto have behaved entirely in a passive man- cient to be in the diamond field; however, diamond genesis ner and therefore may not be strictly analogous lo the pre- apparently depends on oxygenfugacity as well as pressure sent day Atlantic margin, as earlier workers proposed and depthof origin alone is not sufficient to predict thedia- (Stewart, 1972; Stewart andPoole, 1974); rather it appears mond potential of a pipe (Haggerty, 1986). The pipes inthe that several superimposed ‘passive margin-type’ :;equences other arms of British Columbia do not appear to have origi- are present as a result of periodic extensional activity (Pell nated as deep in the mantle as the Crossing Creekkimberlite. and Simony, 1987; Thompson et al., 1987). During these They contain no good evidence of deep mantle xenoliths; periods of extension, deep faults and fractures in the crust the xenolith and xenocryst populationsare generally con- may have released pressure and triggered partial melting, fined to crustal material: rare eclogites, spinel. lberzolites, 19). chrome spinels and very rare pyrope garnets (Northcote, whichultimatelyresultedinalkalinemagmatism(Tab1e 1983a, 1983b). This suggests an origin in the spinel lher- The earliest event recordedby alkaline activi:y in west- zolite field of the uppermantle, which is generally consid- ern Canada is represented by the Mount Copelandsyenite ered to be at pressures below those required for diamond of Late Proterozoic in age (circa 770 to 750 Ma); it may formation. Microdiamonds reportedly found in two of the record extension or rifting of the North Ame:rican (cratonand pipes in the Golden swarm suggest that these pipes may the initiation of the Late Proterozoic Windermere basin. Di- have sampled the uppermost levels of the diamond field. abase dikes and sills of similar age (770 Ma) in northern Canada also record extension preceding Windemleredepo- When comparedto current models, it appears that the probability of British Columbia diatremescontaining eco- sition (Armstrong et al., 1982). Slightly younger datas of 728 and 741 Ma nomic concentrations of diamonds is low. From craton to (U-Pb, zircons) have been obtained from margin, a sequence of kimberlite with diamond, kimberlite granitic gneisses which appear to be basemen1 for Win- dermere Supergroupstrata in north-central and central Brit- without diamond(e&, Cross) and diamond-free ultrabasic ish Columbia ( Parrish and Armstrong, 1983;Evznchick ef diatremes (nonkimberlitic) is commonly proposed (Hag- gerty, 1986). In anattempt to establish the original positions al., 1984). This implies that rifting began as early as 770 Ma in some areas, but that the event spanned a pericd of time of the diatremes relative to the North Americancontinent, and, locally,Windermere sedimentationdid not beginuntil theirpositions have beenprojectedontocross-sections (Fig- after 730 Ma. ure 86). If these sections were restored to predeformational configurations, the pipes contained in the most westerly Sedimentary loading and synsedimentaryfaulting (Lis thrust sheet would have been the farthest outboard. The and Price, 1976; Eisbacher, 1981; Root, 1.983; Bond and Cross kimberlite is in the Bourgean thrust sheet and is the Kominz, 1984; Devlin and Bond, 1984) accoun:ed for the easternmost of the diatremes. The ultrabasic diatremes in deepening of the basin and the continuation of deposition the Bull Riverarea are carried by the Bull River- Gypsum into the early Paleozoic. Minor extensional activity is also fault (Figure 86), which is west of the Bourgeau thrust. As indicated by the presence of acid to basic volcanic andin- the faults are traced to tbe north, the Bull River- Gypsum trusive rocks throughoutthe Hadrynian to early Paleozoic thrust apparently dies out and the displacement is accom- sedimentary wedge (Simony and Wind, 1970; Raeside and modatcdby the Simpsons Passthrust. The alnoitic rocks and Simony, 1983; Pell and Simony, 1987; Sevigny, 1987). alkaline lamprophyres north of Golden are carried on a Extrusion oftheMount Grace carbonatiteandintrusion thrust (the Mons fault) which lies west of the Simpsons Pass of shallow-level carbonatites, accompanied by :he forma- thrust and apparently originated the farthest outboard of the tion of extensive zones of fenitization, probably occurred in continent. If Haggerty’s model is applicable to western Eocambrian to Early Cambrian time (Htiy and Godwin,

Bulletin 88 113

Minisfry of Eneqy, Mines and Pet,%l Resources

1988). These rocks occurin a relatively thin cover-succes- ported from the mid-Devonian to early M:ississippian se- sion above core gneisses of the Frenchman Cap dome, quence in the northern and central Canadian 'Cordillera which suggests that the dome may reflect a tectonic high in (Gordey, 1981; Mortensen, 1982; Gordey et al.. 1987) as late Precambrian to Early Cambrian time. Emplacement of well as in the southern Canadian Cordil.lera :Wheeler, the alkalic rocks may have coincidedwith foundering of an 1965). extensive Lower Cambrianplatform to the east. This period The Devono-Mississippian extension was synchronous is also interpreted by many workers as the time of the rift- with, or slightly postdated, compression to the south that to-drift transition along the western continental margin was associated withthe Antlerorogeny. Devono- Mississip- (Bond and Kominz, 1984; Devlin and Bond, 1984; pian granites and granitic gneisses have also been docu- Thompson et al., 1987). In the southwestern United States, mented in the Canadian Cordillera and Alaska (Okulitchet carbonatites of Eocambriau to Early Cambrian age are re- ab, 1975; Dillonefal., 1980;Montgomery, 1985: Okulitch, ported from a numberof localities (Figure 87); for example, 1985;Mortensen 1986;Mortensenetal.,19117).Theserocks the McClure Mountain carbonatite-alkalic complex, the crop out west of the alkaline intrusions and are believed to Gem Park and the Iron Hill carbonatite complexes in Cob have intruded near the western edge of the Paleozoic Cor- rado and the Lobo Hills syenite and carbonatite in New dilleran miogeocline (Okulitch er al., 1975). Aso during Mexico (Fenton and Faure, 1970; Olson et al., 1.977; Loring Devono-Mississippian time,a mixed volcanic and sedirnen- and Armstrong, 1980; Annbrustmacher, 1984;McLemore, tary sequence, termedthe Eagle Bay assemEdage, wasform- 1984; 1987;). Although these intrusions are structurally in- ing offthe western contintental margin; these rocks record board of the Mount Grace carbonatite, their emplacement a change from anisland arc environment at the base of the may be related to the same large-scale extensional tectonic sequence, wherecalcalkaline volcanics wen: forning above event. a subductingplate, to a rift environmentin wbicb alkaline Anumberofperiods ofPaleozoicextension areinferred volcanism and sedimentation took place 6:Schi;lrizza and along the western continental margin; however, additional Preto, 1987). dating is necessary to clearly define these periods and elimi- nate possibilities of overlap. The earliest event is Late Or- Thesedatasuggestthatacomplextectonicre,:imemust have pertained at the end of the Devonian andthat it was not dovician to Ordovician-Silurianin age (circa 450 Ma) and is recorded by the emplacement of some ultra'basic diatre- simply a timeof extension. A more complexmollel is nec- essary to explain westerly sources for Devono-:Mississip- mes and alkaline lamprophyres in the southern Rocky Mountains and the Golden area of British Columbia. The pian miogeoclinal sediments, obduction a1 the latitude of Bearpaw Ridge sodalite syenite (eastern belt, Figure 1)may present-day northern California and southern OIegon, and also prove to be Ordovician to Early Silurian in age as was emplacement of granites in southern British Colnmbia, the Cariboo and Alaskaat approximately the same timeas ex- originally proposed by Taylor and Stott (1980). who be- lieved it to be a subvolcanic plutonrelated to alkaline basalt tension and alkaline intrusion were taking placl: near the flows in the Silurian Nonda Formation. Syenites, trachytes, eastern margin ofthe Canadian Cordilleran miog:ocline. A carbonatites and ultrabasic diatremes and tuffs in the sequence of events may have occurred which culminatedin the development of an incipient continental back:arc rift at Kechika area may also be of a similar age. Carbonatites of a complex, attenuated margin (see Struik, 1987). as local- approximatelythe same age are foundin the Lemitar Moun- ized obduction (and possibly subduction) occurred to the tains of New Mexico (McLemore,1987). south and outboard. Subduction probablyresulted inpartial A secondperiod of alkaline igneous activi.ty along the melting and genesis of granite and calcalkaline volcanic western margin of North America occurred in Early De- rocks; this compressional regime was ap;parently super- vonian time (circa 400 to 410 Ma). Most of the ultrabasic ceded by an extensional regime. Alternatively, e:ctensional and alkaline lamprophyres in the Golden area and somenl- basins may have resulted from strike-slip faulting: outboard trabasic diatremes in southern British Colnmbia were em- of the preserved marginof the miogeocline, as pr,>posed by placed at this time. Diatreme breccias in the Yukon Territory Eisbacher (1983) and Gordey et al. (1987:1; however, this (e.g., Mountain diatreme, R.L. Armstrong, personal com- scenario does notexplain the intrusion of g:raniter. munication, 1988)are of the same age. In a more continental setting (Figure 87). EarlyDevonian kimherlites are reported The last Paleozoic extensional event is inferred liom from thecolorado-WyomingState-Linedistrict (McCallum the presence of Permo-Triassic kimberlite in the Rocky et al., 1975; McCallum and Marbarak,1976; Hausel et al., Mountains. Although only one exampleis known, it ispos- 1979). sible that other alkaline intrusions of simihu age exist and A third Paleozoic extensional event at the end of the that other evidence for extension may be discovered. As Devonian (circa 350 to 370 Ma)resulted in the intrusion of with theprevious event, Permo-Triassic extmsion occurred carbonatites into the miogeoclinal successionin the Fore- approximately synchronously with compression in the land and Omineca belts. Aillikite diatremes (ultramafic lam- southern Cordillera (Sonomau orogeny). prophyres) and dikes in the Ospika River area were also In Late Jurassic to Early Tertiary time, orogmesis oc- emplaced at this time. The tectonic instability resulting from curred when a compressional regimewas established on the this major Devono-Mississippianextensional event is also Pacific margin whilerifting and the opening: ofthe Atlantic evident in the stratigraphic record (Thompson et al., 1987); took place on the opposite side of the continent. During OIO- volcanic rocks (someperalkaline in composition), synsedi- genesis the continental margin prism was telascopedand the mentary block faults and chert-pebble conglomerates arere- alkaline igneous rocks were deformed,metamorphosed and

Bulletin 88 115 . LEGEND ; Tom LEGEND WILLIAM HENRYBAY I: MOUNTAIN DIATREME i SALMON BAY KECHIKA PIPE ! KECHIKA , ALEY i LONNIE F MOUNT BISSON 1 WICHEEOA LAKE i BEARPAW RIDGE IO BLUE RIVER AREA I I TRiOENT MOUNTAIN I2 PERRY RIVER-MOUNT GRACE I3 MOUNT COPELAND 14 THREE VALLEY GAP I5 ICE RIVER 16 ROCK CANYON CREEK 17 RAINEY CREEK I8 BEARPAW MOUNTAINS I9 RAVALLliLEMHl COUNTIES !O IRON HILL. GUNNISON COUNTl !l WET MOUNTAINS CUSTER AND FREMONT COUNTIES !Z GEM PARK/MsLURE MOUNTAiN !3 MONTELARGO 24 LEMITAR MOUNTAINS !5 MOUNTAIN PASS

SYMBOLS SYMBOLS 19+ 0 Age unknown Age unknown v Tertiary (-50 & -30Ma) 01 Tsriiary (Eocans) -50Mo X Oevono-Mirrirrlplon -350Ha UpperCretocsour + -90-95Ma # Permo-Trioaric -245Mo X Dewno-Uisriraippian UNITED 0 Ordorician-Silurian -450Ma OCEAN 350-375Ma A EarlyDevonian -4OOMo STATES 0 Ordoviclon-Silurlon -45OMa t Placerdiamond Ioc~lity I LowerCambrion-EoCombrlon :D) MlsrodlomondIoEOlity 520-58OMo t Lobproterorols -770Mo A Mid-Pmlerozolc 1400-15OOM

23 MCordllleron front ,---Western limit of the .... miageoc1ino1rtrato ......

I

MEXICO 0." :i KILOMFTRLI \ 1 I :! Minisfry of Energy, Mines and PetreResoumes transported eastwards in thrust sheets. Their present distr- Cordillera, however, young calcalkaline lamprophyres, bution near the Rocky MountainTrench is due to original strongly alkaline basalts and miaskitic syenite complexes location along a rifted continental margin, not to later tec- such as KrugerMountain, Copper Mountainand theCoryel1 tonics. No syn or postorogenic carbonatites or alkaline nl- intrusions are present. tramafic diatremes have been discovered in the Canadian

Bulletin 88 I17 British Columbia "

118 Geological S~rrvey3ranch Ministry of Enevy, Mines andPetlw Resources

REFERENCES

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Colorado: United States GeologicalSurvey,Bulletin 1027- Pride, K.R., Leconteur,P.C. andMawe1,A.B. (1986): Geology and 0, pages 693-721. Mineralogy of the Aley Carbonatite, Ospika I:iver Area, Olson,J.C.,Shawe,D.R.,Pray,L.C.andSharp,W.N.(1954):Rare- British Columbia:Canadian Institute ofh!ining and Metal- earth Mineral Deposits of the Mountain Pass District, San lurgy, Bulletin, Volume 79, Number 891, Ahstra:t, page 32. Bernadino County, California; United States Geological Raeside, R.P. and Simony, P.S. (1983): Stratigraphy an,iDeforma- Survey, Professional Paper 261. tional History of the Scrip Nappe, Moniishee Mountains, Parker, R.L. and Sharp, W.N. (1970): Mafic-Ultrarnafic Igneous British Columbia:Canadiun Journal of Earth Sc.ences, Vol- Rocks and Associated Carbonatites of the Gem Park Com- ume 20,639-650. plex, Custer and Fremont Counties, Colorado;United States Rapson, J.E. (1963): Age and Aspectsof Metamorphism Associ- Geological Survey, Professional Paper 649. ated with the Ice River Complex, British Colnmtia;Bulletin Panish, R.R. and Armstrong, R.L. (1983): U-Pb Zircon Ages and ofCanadianPetmleumGeology,Volumell,pag:s116-124. Tectonic Significance of Gneisses in Srmctural Culmina- Rapson,J.E.(1964):IntrusiveCarbonateintheIceRiv~rComplex, tions of the Omineca Crystalline Belt, British Columbia; BritishColnmbia;Canadian Mineralogist,Ahstr~ctVolume GeologicalSociety ofAmerica,Abstracts with Programs15, 8, page 138. page 3U. Read, P.B. and Brown, R.L. (1981): Columbia River :?aukTone: Panish, R.R., Heinrich, S. and Archibald, D. (1987): Age of the Southeastern Margin of the Shuswap and Monashee Com- Ice River Complex, Southern British Columbia;Geological plexes, Southern British Columbia; Canadian Journal of Survey of Canada, Paper 87-2. Earth Sciences,Volume 18, pages 1127-1 145. Pecora, W.T. (1956): Carbonatites: a Review; Geological Society Roberts, M.A., Skall, M. andPighin, D.L. (1980) DiaWemes in the ofAmerica, Bulletin, Volume 67, pages 1537-1556. Rocky Mountains of Southeastern British Columbia:Cana- Pell, J. (1987a): Alkaline Ultrabasic Rocks in British Columbia: dian Institute of Mining and Metallurgy, Bulletin, Volume Carbonatites, Nepheline Syenites, Kimberlites, Ultramafic 71, Number 821, Abstract,pages 74-75. Lamprophyres and Related Rocks:B.C. Ministryof Eneqy, Rock, N.M.S. (1986): The Nature and Originof Ultra'nafk Lam- Mines and Petroleum Resources,Open File 1987-17. prophyres: Alnoites and AlliedRocks;JoumlqfPetrology, Pell, J. and Simony, P.S. (1987): New Correlations of Hadrynian Volume 27, pages 155-196. Strata, South-central British Columbia;Canadian Journal Root, K.G. (1983): Upper Proterozoic andPaleozoic Stratigraphy, of Earth Sciences,Volume 24, pages 302-13. Delphine Creek Area, Southeastern British Columbia: Im- Pell, J., Culbert, R.R. and Fox, M. (1989): The Kechika Yttrium plications for the Porcell Arch;in Current Research, Part A, and Rare-earth Prospect(94Lfll,12 and 13); in Geological GeologicalSurvey of Canada, Paper 83-1.4, pages 377-380. Fieldwork 1988,B.C. Ministryof Eneqy,Mines andPetm- leum Resources, Paper 1989-1, pages 417-421. Rowe, R.B. (1958): Niobium (Columbium) Deposits of Canada; GeologicalSurveyofCanada,Economic(ieolo~ySeries18, Pell, I., Martin, L.M., Culbert, R.R., Moms, R.J. and Leighton, 103 pages. D.G. (1990): Geology of the Kechika Yttrium-Rare Earth Prospect, Northern British Columbia (abstract): Canadian Rnssell,A.(1987):PhosphateRock:TreudsinPl'ocessingandPro- Institufe of Mining and Metallurgy. duction; Industrial Minerals Magazine, Septe:nber 1987, pages 25-59. Perkins, M.J. (1983): Structural Geology and Stratigraphy of the Northern Big Bend of the Columbia River, Selkirk Moun- Schiarizza,P.andPreto,V.A.(1987)GeologyofiheAdamsPlatean tains, Southeastern British Columbia; unpublished Ph.D. - Clearwater - Vavenby Area; B.C. Mmistry of Energy, thesis, Carleton University, 238 pages. Mines and Petroleum Resources,Paper 1!)87-2. Peterson, T.D. (1983): A Study of the Mineralogy and Petrology Scott-Smith, B.H. and Skinner, E.M.W. (1984a): A New Look at of the Ice River Complex,Yoho National Park; unpublished Prairie Creek, Arkansas;in Kimberlites and Related Rocks, BSc. thesis, Universify of Calgary, 133 pages. Kornprohst, 1. Editor, Proceedings,3rd Ltremtional Kim- berlite Conference,Volume 1, pages 255-284. Pilcher,S.H.(1983):ReportontheGeologyandGeochemicalSur- veys and Physical Work Conductedon the Ren I, 11, I11 and Scott-Smith, B.H. and Skinner, E.M.W. (1984hj: Dianondifemus IV Claims, Kamloops Mining Division:B.C. Ministryof En- Lamproites, Journalof Geology,Volume 92, pages 433-438. ergy, Mines and Petroleum Resources, Assessment Report Scott-Smith,B.H.,Skinner,E.M.W.andLoney,P.E.(1986):Lam- 11 639. proites from the Luangwa Valley, Eastern Zambia:Geologi- Price, R.A. (1967a): Operation Bow-Athabasca, Alberta and Brit- cal Society of Australia, 4th International Kimberlite ish Columbia; in Report of Activities,Geolo){ical Survey of Conference, pages 87-89. Canada, Paper 67-1A, pages 106-110. Sevigny,J.H.(1987):FieldandStratigraphicRelationshipsoEAm- Price, R.A. (1967b): Golden, East Half, Map Area (82N E1/2), phibolites in the Late Proterozoic HorsethiefCxek Group, British Columbia and Alberta,in Report of Activities,Geo- Northern Adam River Area, British Columbia;in Current logical Survey of Canada,Paper 67-1B, pages 88-91, Research, Part A,Geological Survey of (:anadgr, Paper 87- Price,R.A.(1981):TheCordilleranForelandThrnstandFoldBelt IA, pages 751-756. in the Southern Canadian Rocky Mountains;in Thrust and Simony,P.S.andWind,B.(1970):Structureofth.eDogloothRange Nappe Tectonics, McCIay , K.R. and Price, N.J., Editors, and adjacent parts of the RockyMountah Tren(:h;Geologi- Geological Society of London,pages 427-448. calAssociation of Canada,Special Paper 6, pal:es 41.31. Pride, K.R. (1983): Geological Survey on the Aley Claims, Smith, C.B. (1983): Rubidium-Strontium, Uranium-Lead and Sa- Omineca Mining Division, British Columbia;B.C. Ministry marium-Neodymium Studies of Kimberlites and Selected of Energy, Mines and Petmleum Resources,Assessment Re- Mantle-derived Xenoliths; unpublished ,'Ph.D. thesis, Uni- port 12018. versify of the Witswatersrand, Johannesborg.

- _" Bulletin 88 123 Ministry of Energy, Mines and Petroleun, Resources

APPENDICES

__ Bulletin 88 125 British Columbia "

-~ 126 Geological Su:wey llranch Ministry of Energy, Mines andPet,mleumResources

APPENDIX 1 RARE EARTH ELEMENT ANALYSES FROM SOME CARBONATITE SUITES

16 14 119.7 6 3.2 8

401 1% 213

8

Bulletin 88 127 __ 128 Geological Survey Bnanch APPENDIX 2A U-Pb ZIRCON DATA, BRITISH COLUMBIA CARBONATITES AND NEPHELINE SYENITES

Pb' 2MPb3 Pbc4 Analysis No. wt.' U - '%b2 "6ph +lSEM%' Size' (mg) PPm ppm '"PS (Pg) (%) 23au

Trident Mountain nepheline syenite, PCA-307-83 NSY 1.+149ceu 1.674 45.34 5.39 2999 75 64.0 0.4698 64.0 75 2999 5.39 45.34 1.6741.+149ceu (.%) 0.3454 (.lo) 0.5332 (.06) 342.6 (1.2) 2.+149cdeu 2.295 124.6 13.56 1224 496 72.2 0.03327 72.2 496 1224 13.56 124.6 2.+149cdeu2.295 (.08) 0.2373 (.18) 0.05172 (.13) 273.2 (2.9) Paradise Lake nepheline syenite, P4-323 3.+149ceu 1.988 40.98 8.035 2458 11.4 74.7 0.05440 (.18)0.05440 74.7 11.4 2458 8.035 40.98 1.988 3.+149ceu 0.4036 (.21) 0.05382 (.lo) 363.3 (2.2) 4.+149cup 1.872 92.84 15.47 6702 89 70.4 0.05421 70.4 89 6702 15.47 92.84 1.8724.+149cup (.18) 0.4000 (.19) 0.05352 (.05) 350.7 (1.2) Lonnie carbonatite, L4-191 5.+149ceui 1.673 44.28 4.488 461 484 58.7 0.04599 58.7 484 461 4.488 44.28 1.6735.+149ceui (20) 0.34160.05386365.2 (.41)(.36) (8.2)

Vergil carbonatite, L4-241 6.+149cf 2.714 75.36 7.676 2969 236 51.7 0.05414 (.18)0.05414 51.7 236 2969 7.676 75.36 2.7146.+149cf 0.05354351.60.3996(2.0)(.07) (1.6)

Notes: 'sires (i.e., +1495) refer to length aspect of zircons in microns, e=equant, cd=somewhar cloudy, c=clear, u=euhedral, p=pink, i=contains inclusions,f=fragments and shards; 'radiogenic Pb: 3m~asuredratio, corrected for spikp andfractionation; 'total common Pb in analysis corrected forfractionarion and spike; 'corrected for blank Pb an U,common Pb, errors quoted are I standard ermr %[he mean in percent; 'corrected for blank and common Pb, ermrs are I standard error of rhe mean in Ma: *weighing ermr 0.002 mg. APPENDIX 2B URANIUM-LEAD ANALYTICAL DATA, B.C. DIATREMES

5W.7

3855 13080 2356 I II I

22910 0.132 6664 0.114

5751. 2267.8 I 9.8307! 0.665. 17.99 581.3 17.6 1579.3 4.2746 0.221 ~....

17.51 59.75 80 1W9.72.808292 4.793

28.98 931 28.04 27WMa

22 18.76 27W

a4 13.44 ZIW 0.134

11.1 0.145 B pinlimd 15080 15.1 0.116 12.4 0.115 2716 11.5 0.121

8.0 0.576 953.3 1.6294 06.70 4944 6.4 'I0.111 82.50 7485 7.5 0.101 ""*I APPENDIX 2B (continued) "-

@ MONS CREEK @ VALENCIENNERIVER

1- 1- .2[ 3 2.00 4.00 6.00 8. io 4.50 6.50 8.50 10.50 207pb/ 235u /20?pb/ 23SU

O0 A

IO 2.00 4.00 6.l 207pb/235u

I 207pb/235u

_~ Bullelin 88 131 British Columbia -

APPENDIX 2C SUMMARY OF RbISr ANALYTICALDATA, B.C. DIATREMES

Lab Mineral ppm Sr Sample 87Sr/86Sr Number Name T7Initial Rr tio lspika Pipe 33008 phlogophite AL64 103.Oi0.3 432.4i2.7 12.22i0.08 0.7646i1 351i2 Ma 0.7036 30239 phlogophite AL 5-20 134.9i0.4 407.5*2.3 8.7i0.08 0.7471+1 351i3 Ma 0.7036 30238 phlogaphitc AL 5-16 166.8i0.5 387.7S.2 6.75iO.04 0.7361il 338i3 Ma 0.7036 [P Pipe 30240 phlogophite HP- 5 359.9iO.5 8.01iO.06 0.749il 391i5 Ma 0.7040 :ushRiver (Larry) 475.9956 -I LA 6-196 156.1iO.5 F 8.86i0.11 0.7556+1 409i6Ma I 0.7040 I 32961 lphlagophife I

132 Geological Survey Branch Minisiry of Energy, Mines and Petroleum ,-

APPENDIX 2D SUMMARY OF K-Ar ANALYTICAL DATA,B.C. DIATREMES

K=X=8.2M0.01 % 40'- 139.297~10-~cc/gm) ;(94,6 zrAr40*) ;(Ar - K20= n=2 % 62.159~10"~rnol/gm)

moterial date 1oerror (Biotite) 391 *12 Ma

K=X=8.2M0.01 % 40. :(Ar = 139.297~1O-~cc/gm) :(94,6 %rAr40.1 K20= n=2 % 62.159~10-~~mol/grn)

material date loerror

(Biotite) 391 f12 Ma

OspikaPipe SampleNurnber(s) AL-5-16 AnalyticalData: (list duplicate analyses or indicaten=2, n=3, etc.) K=x=~.~o*o.o~% 40' 108:496~10-~cc/gm) :(95.8 zrAr40*) ;(Ar = K 20= n=3K20= % 48.414~10-~~mol/gm) m aterial date loerrordatematerial (Biotite) +10323 Ma

decayconstants 4.96/.581/1.167

Bulleiin 88 133 - 134 Geological Survey Branch