In 1994, British Columbia Geological Survey Geologist Jennifer Pell released a report on the potential for exploration of several minerals in British Columbia.

1. ,.., ~ ~~~~ ~
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) and reader
the
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 Mountain Snpergroupstrata(Hovdebo,19.57). It out-
northwest of Elkford (latitude 5O0O5'24'W, longitude crops on steep face and an of approxitmate1:y by 15
a area 55
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 the other intrusions in the Elk River dolomitic sandstones (Figure 82). Aminor s:hearzone 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-drivevehicle 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 3 .
00
03 + Crorrtng Creek
25.00 kirnberllte
@ Averoga klrnberlile
20.00
1 ponolitlc
barmillto
lephrite
Iarnprophyre
50
.0
bora11
0.00 "
20.00 30.00 40.00 50.00 60.00 70.00
SI02
Figure 83. Major element discriminant
plots, Cross kirnberlite. Figure 84. Major element ternaryplots, Cross kinlberlite
-
Bulletin 88 103

2. ~~ ~
Ministry of Energy, Mines and P e t r o o Resources
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 sourceniobiumand rare-eartb elements
of the discovery of other carbonatites with potential ore-grade
among the metals and of nepheline, barite, vermiculite, co- niobium concentrations.
rundum and diamond among nonmetals. Molybdenum,
the Tantalum is not abundant British Columbi:l carbona-
in
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
economicallysignificant 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, theniobium grades Blue River are
at
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 equipment pipeline applications. Nio-
and
binm also has important potential as a superconductor of RARE-EARTH ELEMENTS AND
electricity at cryogenic temperatures (Cunningham, 1985a).
The principal niobium mineral carbonatites is pyrochlore,
in 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 grades 0.5 to 0.67% NbzOs.
are parisite, or phosphate minerals such as monazit: or xeno-
Tantalum is a relatively rare, heavy, inert metal that is time, may also be present in alkaline suites a.nd contain rare-
used in electronics, chemical processing equipment, metal- earth elements. Yttrium, although not strictly a rare earth, is
cutting tools and high-temperaturesteel alloys. It is recov- commonly grouped with them its chemical properties are
as
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 may also cracking catalysts, iron, steel and other metal-alloying
be present in significant amounts in carbonatites, generally agents, glass-polishing compounds and glass add Itives, per-
in the mineral pyrochlore. In alkaline rocks the Nb:Taratios manent magnetsand phosphors for television and lighting
commonly exceed 100,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 Aley carbonatite complex appears have the
to (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 recovery the U.I .A. comes
in
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 7 8% total rare-earth oxides, predominiatly of the
to
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 which rival the St. Honor6 complex
easily 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 and placers (Lee, 1970). Recently, the
tin
bium is present mainly in the minerals fersmite and pyro- greatest demand has been for samarium and nedymium to
chlore; columbite is also present in minor amounts (Pride et be used inthe magnet industry and for yttrium in:?hosphors,
- _"
Bullelin 88 107

3. _"
British Columbia "
The diatreme is lithologically heterogeneous and, lo- between phases be gradational or sharp. Athin dike, 10
may
tally, very friable. The west end o the outcrop is a light
f to 30 centimetres wide, cuts the central breccia phase
green, strongly foliated rock containing some red hematized Ultramafic xenoliths are almost entirely serpentinized
clasts, abundant pelletal lapilli and cobble-sizedpellets, as pseudomorphs of olivine and pyroxene. The original pres-
well as autobreccia fragments (western breccia 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. 1 ser-1
This grades eastwards to a massive, inclusion-poor light pentinized. Some relict pyroxene, with characteristic c:leav-
green unit (western massive phase) in turn grades into
which age and birefringence, 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 minor amounts.
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 toward top and
the centre 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 not abundant, are : m e t
as €
Pyrite is present as discrete grains in the groundmass and as lherzolites and glimmeritexenoliths (Hall et al., 1986,).
rims surrounding clasts where it may, in turn, be enveloped The macrocryst population (0.5 to 5.0 mm insize:)con-
by ragged, bright red hematite spotted phase). Contacts
(red sists of completely serpentinized olivines, partially altered
garnets, garnets with kelyphitic rims andphlogopites. They
may be or
round, oval lath shaped in random orientation and
TABLE 18 make up 10 to 20% of the rock volume. Garnets sf~ow a
CHEMICALANALYSIS moderate to high degree alteration or dissolution in reac-
of
CROSSING CREEK KIMBERLITE
tion with the matrix. None are enhedral. They are rounded
~~~
~
and irregular in shape and surrounded kelyphitic rims or
by
_wr %
_ 1 2 3 reaction coronas of opaque iron oxides (Ijewliw, 198711.The
Si02
Ti02
A1203
Fe203T
30.04
1.28
2.23
6.89
30.74
1.45
2.31
8.28
30.02
1.29
2.21
5.31
1.44
2.10
7.48
I;:
7.70
garnets arepyrope rich. Phlogopites are occasionally zoned,
with rims darker and morestrongly pleochroic than cores
and often displayingreversepleochroism (Halletal., 1986).
The phenocryst population comprised of completely
is
MnO 0.12 0.16 0.09 0.11
MgO 25.03 27.72 23.54 27.75 0.151
23.84 serpentinized olivine, together with phlogopite and :;pinel
CaO 13.48 9.78 14.94 9.55 14.21 (Plate 56). Phlogopite grains vary insize, 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 17.87
15.38
17.04 15.4 17.37
no5 0.99 1.06 1.03 0.99 in the groundmass and show magnetite reaction rims
- 0.14
S 0.23 0.09 0.12 (Ijewliw, 1987). The groundmass composed ofca1ci:e and
is
Total 98.68 98.22 97.88 98.35 serpentine with minor apatite and anatase.
ppm
Ni 1000 1000 10W 1300 X90
Cr 12941398
1369 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 na
na na na
Yb 2 1 3 0 .:-I
sc 20.323.1 23.7 20 25.1
Ta 7 14 9 11 11
iu
!"c
j u
Th
14
73 1
18
14
196
54
19
196
24
15
208
50
2
18
;
51
All amlyss'8 b;vXRF, B.C. G.S.B.analytical laboraforv
4
41
1. .CX5-6 K n
i . . 0.00 400.00 800.00 1200.00 1600.00
2. - CX57BHemotire-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 Wederhal Maramatsu 1979.
and
5. - CX5.7Micaceouskimberlite, red-sparfedphase. Ni vs Cr plot, Cross kimberlite.
104 Geological Survey Itranch

4. Ministry of Energy, Mines and Petroleum Resources
GEOCHEMISTRY GEOCHRONOLOGY
TheCrossdiatreme is the only trne kimberlite so far Rubidium-strontiumdating of micaseparateshas
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 and 84;
Cross kimberlite (Grieve, 1982; Smith, 1983; F:all et al.,
Table 18 ). Although it appears to bequite a heterogeneous
intrusion, analyzed were all v e 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

5. ~-
106 Geological Survey Eranch

6. engineering ceramics and superconductors(Roskill Infor- he 1 to 4 metres wide and over metres long. Mafic syenite
30
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, both Rocky Monn-
in the Russell, 1990). Very little work has been done the IvIount
in
tains; the Wicheeda Lake area along the Rocky Mountain Bisson area and preliminary results indicate some potential;
Trench near Prince George; Kechika River area in the
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. Aley narrow
At dikes enrichedin 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 minerals as bast-
such
naesite, burbankite, cordylite and huanghoite (Miider, ZIRCONIUM
1987). These dikes are thin and sporadically developed and,
although worthy ofnote, not of major economic interest. Zirconium is strongly concentrated in some alkaline
At Rock Canyon Creek a metasomatically altered (feni- rocks and comprise up 2%. The main zirconium
may to min-
tized) zone rich in rare earths and fluorite, measuring ap- erals present in these rocks are zircon, eudyialite (Na-Zr sili-
proximately 1000 by 100 metres, has been identified. cate) and haddeleyite (ZrOz), with alkaline rocks beir,g the
Samplescontaininginexcessof 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 outcrops this zone.The rare-earth fluoro-
of where it is in mineral form facing for molds for metal
used as
carbonate minerals hastuaesite and parisite, and gorceixite, casting. It is also used in refractories, nuclear powerappli-
a phosphate mineral, have been identified. At RockCanyon cations and chemical processing equipment. increasing
Of
Creek, locally high rare-earth values at surface, the size of importance is the application of zirconium inadvanccd ce-
the zone and lack of extensive work suggest that further
the 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
including carbonatites, syenites and leucitites are exposed. nium placer deposits and haddeleyite produced as a copro-
duct from apatite mining ofthe Palabora carhonatite, Sonth
Work by TeckCorporation has indicated that one carhona-
Africa and of niobium mining Araxa and Pocos C aldas
at de
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 nephelinesyenite gneiss complexesin 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 and area this plex, Paradise Lake syenite, Verity carhonatite, Tjident
might warrant further work in the future, particularly ifthe Mountain syenite and Lonnie and Vergil 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. Althoughit 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 excess of 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 mylonitized syenitekrachyte 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 suggest additional
that des, 1989). Grades as low as 4% P2O5 are currently recov-
work is warranted. ered. Approximately 90% all the phosphatemined i:; used
of
Light rare-earth elements, particularly cerium and lan- in the fertilizer industry; other uses include organicm d in-
thanum, are concentratedin 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 Bisson area. 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

7. ~ ~
M n s r of Energy, Mines and P e t r e Resources
iity
In British Columbia, all carbonatites contain some apa- 1989). The remote location 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 and and averaging
9) 3.5
to 5%. The Ren carbonatite also has an average1'20s content Vermiculite is a mineral which expan& whm heated.
of approximately 3.5%, with maximum values of 4.2% (Ta- It is formed from alteration o biotite or phlogopite and a
f is
ble 12). Carbonatitedikes 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 amounts asso-
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. contin.uity of
The these 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 c a w , 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 recovery apatite might
of the Mount Copeland showings the focns of r.ignificant
were
prove feasible, particularly in the case of Aley, if niobium exploration and development work inthe late 1960s (Fyles,
were to be mined. 1970). Current economics,however, do natfavour exploi-
tation ofmolybdenum from such deposits.
NEPHELINE AND NEPHELINE SYENITE WOLLASTONITE
Nepheline and nephelinesyenite are of major impor- Wollastoniteis an important mineral nscd primar-
filler
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 amounts also used in
are 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 are located 25 kilometres northwest ognized. As well, knopite, a rare-earth emiched variety of
of Revelstoke, may be reached by old mining 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 aluminum than 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 Copeland syenites 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 discovered Briti:;h Colum-
in
fore, has good potential to produce a commercial-grade bia, the Cross diatreme, but no results of laboratoly research
a
nepheline syenite product with brightness of 85% (White, or
on mineral composition diamond recovery have been re-
_"
Bulletin 88 109

8. ~
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 Surveyo Canada, Paper 82-2.
f 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 Ceramics Canada;
in Canadian In-
83,pages 1345-1360. stitute ofMining 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 o Canada, Map 43-1
f 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 Surveyo Canada, P a p 62.32.
f
Symons, D.T.A. and Lewchuk, M.T. (in press): Paleomagnetism Wheeler,J.O.(1965):BigBendMapArea,BritishColumhia;Geo-
of the MississippianHP Pipe the Western Marginof the
and 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;
File Report 630.
GeologicalSurvey o Canada, Open
f xo1.
White, G.P.E. (1 982):Notes on Carbonatites in
CentralBriti ;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 o Canada, Open File Report
f 536. 68-69.
(1987)Extension and
Thompson, R.I., Mercier, E. and Roots, C. 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, MansonCreek Area, Omineca istry o Energy, Mines and Petroleum Resources. Paper
f
Mining Division; B. C. Ministry ofEnergy, Mines and Petro- 1989-1, pages 483-487.
leum Resources, Assessment Report7515.
Wooley, A.R. (1982):ADiscussion of CarhonatiteEvoluticm 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 Mineral Weatk ofthe
of
Geology and Mineral Wealth 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-
.
the
position of Kimberlites Compared with Average Compo-
-~
124 Geological Branch

9. ported by industry.Microdiamonds have, however, report- have also been reportedfrom alkaline lamprophyre dikes in
edly been recovered from of the lamprophyre diatremes
two Montana.
in the Golden - Columbia Icefields area. One of the pipes Nepheline syenites are known from a localities in
few
reported to have yielded microdiamonds from concentrates 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 amount additional research
of 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.
Blue corundum crystals (star sapphires) up to 1 to 2
GEMSTONES centimetres in size, have recently been discovered in the
Corundum (sapphire, ruby) is a common accessory Slocan Valley withina syenitic phase o the Valballa Gneiss
f
mineral in silica-undersaturated, alumina-rich rocks as
such 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 occurs nepheline-
in fenites in the Blue River and Perry River (Z.D. Hora,
areas
of
bearing rocks and marginal zones 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 for
should be prospected gem corundum.
_"
110 Geological Survey 3ranch

10. 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 and syenite gneisses crop out inthreebelts There appears to be a relationship between depth of
parallel to the Rocky Mountain Trench. The intrusions in the emplacement, degreeof associated metasonratism and en-
eastern Rocky and Cassiar Mountain are middle Paleo-
belt richment in economically interesting elements suchas nio-
zoic, predominantly Devono-Mississippian in age, hosted bium or rare earths. All of these 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 have significant 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
or
(e.& Rock Canyon Creek showing), be extensive linear Rocky Mountains and some regions 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 considered when assessing the niobium or me-earth
nificantly enriched in niobium, fluorine, yttrium and rare- potential of any prospects.
earth elements. Commercial-grade nepheline syenite could pcttentially
The central belt lies within the Omineca Belt, immedi- be produced from the Trident Mountain syenite, however,
ately west ofthe Rocky Mountain Trench. The intrusions in current inaccessibility precludes immediate exploitation. 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 loggingroads, 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 compositionally similarsyenites 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 Mount Bis-
(the tested.
son intrusions), they are not enriched in niobium,
as 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 recognized areas
in five
nepheline syenite gneisses hosted by the autochthonous of British Columbia; the Kechika River and Ospika River
cover sequence of the Frenchman Cap gneiss dome. The areas of northern British Columbia, the Goldan, Bull River
enclosing metasedimentary rocks of uncertain age, how-
are -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 spans Precambrianto Eocambrian
late 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-
tling gneiss succession, indicates an age of emplacementof gopite, green diopside, spinel and olivine, 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 c f 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

11. . ~~
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 from volatiles and
the beddedepiclasticorpyroclasticrocks.Anumhert~fthe])ipes
actually formed the ‘bubbles’, as indicated by the spherical -
in the Bull River Elk River area intrude Ordovician-Silu-
stmctures (or globular segregations) and armoured xeno- rian Beaverfoot carbonate rocks and contain 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) suggesting anl3arly
nificant recognizable igneous component, are present.
also 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 have been 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 inDevono-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 bedded tuffs 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. In area,
that 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 Creek yielded concordant
area lead- ting porphyritic dikes and flows, characterized by the pres-
lead ages of 469 Ma; ifthese zircons are not xenocrystic, it ence of phenocrystic olivine and titanaugite, with ahwdaut
may indicate that there was athird 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 Kechika are dis-
areas mass. These rocks are extremely difficult 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 and feldspathoids.
olivine, altered pyroxene, feldspars and chromian spinel They may have originated in volatile-enriched systems, but
macrocrysts and by theabsence 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 position diaEemes, B - Bush River;C -Lens Mountain; D - Mons Creek;E - Valenciennes River;P HP pipe; G
of
- 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

12. Ministry of Energy, Mines and Petrnleum Resourres
the reverse. In some cases they maybe tentatively classified North America, it is unlikely that significant concentrations
as limburgites, in others they appear to be most similar to of diamonds can found in nonkimberlitic rock!: originat-
be
members of the alkaline basalt family, but gmerally are ing so far from the stable craton; however, the we.;tern con-
more basic than typicalalkaline basalts which suggests that tinental margin at the time of diatreme emplacement was
they are verging towardsnephelinites. probably significantly more complex than 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 of
westem edge 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 pipe remnant 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 and rifting along t t e western
At this point it is difficult to completely assCss the depth continental margin that produced and deepened the basin
of origin and diamond potential 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 pyrope garnets 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 appear have behaved entirely in a passive man-
to
cient to be in the diamond field; however, diamond genesis ner and therefore may not be strictly analogous lo the pre-
apparently depends on oxygen fugacity as well as pressure sent day Atlantic margin, as earlier workers proposed
and depth origin alone is not sufficient to predict thedia-
of (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 Creek kimberlite.
and Simony, 1987; Thompson e t 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,
whichultimatelyresultedinalkalinemagmatism(Tab1e19).
chrome spinels and very rare pyrope garnets (Northcote,
1983a, 1983b). This suggests an origin in the spinel lher- The earliest event recorded alkaline activi:y in west-
by
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 (craton and
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 Windemlere depo-
When comparedto current models, it appears that the
probability of British Columbia diatremescontaining eco- sition (Armstrong et al., 1982). Slightly younger datas of
nomic concentrations of diamonds is low. From craton to 728 and 741 Ma (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 Supergroup strata 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 an attempt to establish the original positions al., 1984). This implies that rifting began as early as 770 Ma
in some areas, but that the event spanneda pericd of time
of the diatremes relative to the North Americancontinent,
and, locally,Windermere sedimentation not beginuntil
did
theirpositions have beenprojectedonto cross-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 synsedimentary faulting (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 Pass thrust. The alnoitic rocks and Simony, 1983; Pell and Simony, 1987; Sevigny, 1987).
alkaline lamprophyres north of Golden are carried on a Extrusion of theMount 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

14. Minisfry of Eneqy, Mines and Pet,%l Resources
1988). These rocks occur a relatively thin cover-succes-
in 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 coincided with foundering of an 1965).
extensive Lower Cambrian platform 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 with Antler
the orogeny. 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 inthe Canadian Cordillera and Alaska (Okulitch et
carbonatites of Eocambriau to Early Cambrian age are re- ab, 1975; Dillonefal., 1980; Montgomery, 1985: Okulitch,
ported from a number localities (Figure 87); for example,
of 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 C o b 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, termed Eagle Bay assemEdage, was
the form-
).
1984; 1987; Although these intrusions are structurally in- ing o f fthe western contintental margin; these rocks record
board of the Mount Grace carbonatite, their emplacement a change from an island arc environment at the base of the
may be related to the same large-scale extensional tectonic sequence, where calcalkaline volcanics wen: forning above
event. a subductingplate, to a rift environment wbicb alkaline
in
Anumberofperiods ofPaleozoic extension 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
dovician to Ordovician-Silurianin age (circa 450 Ma) and have pertained at the end of the Devonian and it was not
that
is recorded by the emplacementof some ultra'basic diatre- simply a timeof extension. A more complex mollel 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
originally proposed by Taylor and Stott (1980). who be- Cariboo and Alaska approximately the same timeas ex-
at
lieved it to be a subvolcanic pluton related 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 culminated in
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 found Lemitar Moun-
in the
ized obduction (and possibly subduction) occurred to the
tains of New Mexico (McLemore,1987).
south and outboard. Subduction probably resulted 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. Diatremebreccias in the Yukon Territory Eisbacher (1983) and Gordeyet al. (1987:1; however, this
(e.g., Mountain diatreme, R.L. Armstrong, personal com- scenario does notexplain the intrusion of g:raniter.
munication, 1988) of the same age. In a more continental
are
setting (Figure 87). Early Devonian kimherlites are reported The last Paleozoic extensional event is inferred liom
from thecolorado-Wyoming State-Linedistrict (McCallum the presence of Permo-Triassic kimberlite in the Rocky
et al., 1975; McCallum and Marbarak, 1976; Hauselet al., Mountains. Although only one example known, it is
is pos-
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 regime established on the
was
this major Devono-Mississippian extensional event is also Pacific margin whilerifting and the opening: ofthe Atlantic
evident in the stratigraphic record (Thompsonet 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 telascoped the
and
mentary block faults and chert-pebble conglomerates are re- alkaline igneous rocks were deformed, metamorphosed and
Bulletin 88 115

15. ; Tom
LEGEND
WILLIAM HENRYBAY
.
I: LEGEND
MOUNTAIN DIATREME
i SALMON BAY KECHIKA PIPE
! KECHIKA
, ALEY
i LONNIE
F MOUNT BISSON
1 WICHEEOA LAKE
i BEARPAW RIDGE
IO BLUE RIVER AREA
II 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 MONTE LARGO
24 LEMITAR MOUNTAINS
!5 MOUNTAIN PASS
SYMBOLS SYMBOLS
19+ 0 Age unknown Age unknown
v Tertiary (-50 & -30Ma)
01Tsriiary (Eocans) -50Mo
+ UpperCretocsour -90-95Ma
X Oevono-Mirrirrlplon -350Ha
# Permo-Trioaric -245Mo
UNITED X Dewno-Uisriraippian
0 Ordorician-Silurian -450Ma
350-375Ma A EarlyDevonian -4OOMo
OCEAN 0 Ordoviclon-Silurlon -45OMa
STATES t Placediamond
r Ioc~lity
I Lower
Cambrion-EoCombrlon :D) MlsrodlomondIoEOlity
520-58OMo
t L o bp r o t e r o r o l s -770Mo
A Mid-Pmlerozolc 1400-15OOM
23
M C o r d l l l e r o n front
,---Western limit of the
.. miageoc1ino1 rtrato
.
I
MEXICO
0 . "
:i KILOMFTRLI
1 I
:!

16. Minisfry o Energy, Mines and P e t r e Resoumes
f
transported eastwards in thrust sheets. Their present distr- Cordillera, however, young calcalkaline lamprophyres,
bution near the Rocky Mountain Trench 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

17. British Columbia "
118 Geological S~rrvey
3ranch

18. Ministry of Enevy, Mines andP e t l w Resources
REFERENCES
Aaquist, B.E. (1981): Report on Diamond Drilling on the AZ-1 Barlow, A.E. (1902): Nepheline Rocks of Ice River, British Co-
Claim Group,Kamloops Mining Division; B.C. Ministry of lumbia; Ottawa Naturalist, June 1902, page 70.
Energy,MinesandPetroleumResources,Asse!;smentReport Bending, D. (1978): Fluorite Claims, Golden :Minin,: Division;
9923. B.C. Ministry of Energy, Mines and Petndeum Resources,
Aaquist, B.E. (1982a): Assessment Report on Verity First I, 2, 3 Assessment Report 6978.
B.C.
Claims, Blue River, British Columbia: Ministry of En-
Betmanis, A.I. (1987): Report on Geological, Geochemical and
eqy, Mines and Petroleum Resources, Assessment Report Magnetometer Surveys on the Prince and George Groups,
10955. Carib00 Mining Division; B.C. Ministry of Encrgy, Mines
Aaquist, B.E. (1982b): BlueRiver Carbonatites, BritishColumbia, and Petroleum Resources, Assessment Report1.7 944.
Final Report 1981; B.C. Ministry of Energy, Mines andPe-
Betmanis,A.I.(1988):SamplingEvaluation,l?G.NiobiumProject
troleum Resources, Assessment Report 10 274.
(Prince and George Groups); unpublished repixi for Teck
Aaquist, B.E. (1982~): Assessment Report, Blue River Carbona- Explorations Limited.
tites, 1982; B.C. Ministry of Energy, Mines and Petroleum
Bond, G.C. and Kominz, M.A. (1984): Constnlction of Tectonic
Resources, Assessment Report 11 130.
Subsidence Curves for the Early Paleozoic Miogeocline,
Adams, W.T. (1985): Zirconium and Hafnium; in Mineral Facts Southern Canadian Rocky Mountains: Implications for Suh-
and Problems, 1985 Edition, United States Department of sidence Mechanisms, Age Breakup and C N S ~ Thinning;
of ;.~
the Interior, Bureau ofMines, Bulletin 675, pages 941-956. Geological Society ofAmerica,Bulletin 95, pag:s 155-173.
Ahroon, T.A. (1979): Airborne Helicopter Magnetometer-Spec- Bonney, T.G.(1902): On a Sodalite Syenite (Ditroit:) from Ice
trometer Survey on the Blue River Carbonatite Project, Brit- River, British Columbia; Geological Ma(:azine Volume 9,
ishCo1umbia;B.C. MinistryofEnergy, MinesandPetroleum pages 199-213.
Resources, Assessment Report 8216.
Brown, R.L. (1980): Frenchman Cap Dome, Slmswap Complex,
Ahroon,T.A. (1980): Geological Reporton theBlueRiverProject, British Columbia; in Current Research, PaR A, Geological
British Columbia: B.C. Ministry of Energy, Mines and Pe- Survey o Canada, Paper XO-IA, pages 45-51.
f
troleum Resources, Assessment Report 9566.
Butrenchnk, S.B. (in preparation): Phosphate Deposits in British
Allan, J.A. (1911): Geology of the Ice River District, British Co- Columbia: B.C. Ministry of Energy, Mims and Petroleum
lumbia; Geological Survey of Canada, Summary Report, Resouzes.
1910, pages 135-144.
Campbell, EA. (1961): Differentiation Trends: in th: Ice River
Allan, J.A. (1914): Geology theFieldMap-area, 13ritishColum-
of Complex, British Columbia;American Journal of Science,
bia and Alberta:Geological Survey of Canada, Memoir 55. Volume 259, pages 173-180.
Alonis, E. (1979): B.C.
Fluorite Claims, Golden Mining Division: Clement, C.R. and Reid, A.M. (1986): The Origin of Kimberlite
. MinistpojEnergy, MinesandPetroleum Resources,Assess- Based on a Synthesis of Geological
Pipes: An Interpretation
ment Report7830. Features Displayed by South African Occurrences; Geologi-
Armbrustmacher, T.J. (1979): Replacement and Primary Mag- cal Society of Australia,4th International Kimlmlite Con-
matic Carhonatites from Wet Mountains Area, Fremont
the ference, pages 167-169.
and Custer Counties,Colorado;Economic Geology, Volume Clement, C.R., Skinner, E.W.M. and Scon-Snuth, B.H. (1984):
74, pages 888-901. Kimberlite Redefined; Journal of Geology, Volume 92,
Armbrustmacher,T.J. (1984):
AIkalineRockCompIexesinthe Wet pages 223-228.
Mountains Area, Custer and Fremont Counlies, Colorado;
Cunningham, L.D. (1985a): Columbium; in Mineral Facts and
UnitedStates Geological Survey, Professional Paper 1269.
Problems, United States Department Interioi; Bureau of
of
Armbrnstmacher, T.J., Brownfield, I.K. and Osmonson, L.E. Mines, Bulletin 675, pages 185-196.
(1979): Multiple Carbonatite Dike at McClure Gulch, Wet
Cunningham, L.D. (1985b): Tantalum:in Mineral Fac's and Prob-
Mountains Alkaline Province, Fremont County, Colorado;
lems, United Stares Department ojrnnlerior, Bureau of
Mountain Geologist, Volume 16, Number 2, pages 37-45.
Mines, Bulletin 675, pages 811-822.
Armstrong, J.E., Hoadley, J.W., Muller, J.E. and Tipper, H.W.
(1969): Geology, McLeod Lake, British Columbia (933); Currie, K.L. (1975): The Geology and Petrologyof the Ice River
Geological Survey of Canada, 1204A.
Map Alkaline Complex; Geological Survey 01Canada, Memoir
245.65 pages.
Armstrong,R.L.,Eisbacher,G.H.andEvans,P.D.(1982):Ageand
Stratigraphic-Tectonic Significance of Proterozoic Diabase Cunie, K.L. (1976a): The Alkaline Rocks Cmada: Geological
of
Sheets, Mackenzie Mountains, Northwestern Canada; Ca- Survey of Canada, Memoir 239.
nadian Journal of Earth Sciences, Volume '19, pages 316- Cnrrie, K.L. (1976b): Notes on the Petrology of Nepheline
323. Gneisses near Mount Copeland, British
Columbia;Geologi-
Baadsgaard, H., Folinsbee, R.E. and Lipson, (1961): Potassium-
J. cal Survey of Canada, Memoir 265.
ArgonDatesofBiotitesfromCordilleranGranites;Geologi- Dawson, G.M. (1885): Preliminary Report on the Fhysical and
cal Society ofAmerica,
Bulletin, Volume 72, pages 689-702. Geological Featuresof that Portion of the Rockit Mountains
-
Bulletin 88 119