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THE RIVER JORDAN LEAD ZINC DEPOSIT,

REVELSTOKE MINING DIVISION, B. C.

by

Christopher Riley

SUMMARY

A relatively unexplored lead zinc deposit liesabout 12 miles northwest of Revelstoke, B.C., in the highlymetamorphosed Monashee Group of rocks of the ShuswapTerrane, Pre-cambrian in age. Host'rocks are of sedimen­tary origin and consist of gneisses, schists, marbles andquartzites with intermediary types. The marbles andquartzites provide good horizon markers.

Using these it is possible to interpret the con­trolling structure which is a syncline overturn~d to thenorth, dipping south at about 450, and plunging east atabout 120 • The syncline is truncated at about halfway ofits length on a peak on the west side of which a partialcross section togethor with superimposed minor folds maybe seen. The quartzites and tho two marble beds may betraced over much of tho structure.

There are two lodes, above the marble and belowthe quartzite, which converge eastward and which are theexposed edges of the same host bed - an impure limestone.The south or No. 1 lode is the thicker and is consideredto be the chief potential ore source. This lode is ex­posed at intervals for 7,200 feet from an elevation of5,800 to 7,900 feet and has an average thickness of 5 feet.

Due to freshness of exposures, surface samplingwas carried out on four separate sections of the No. 1 lodefor'a total length of 3500 feet without preliminary surfacework of any kind.

This sampling, together with the cross sectionalexposures at the west end, permitted grade and roughtonnage estimates to be made of No.1 lode, not countingthe potential tonnages of the superimposed folds. This was2,873

1°00 tons having a grade of 1.1 ounces of silver,

5.1% ead and 5.6% zinc.

PROPERTY FILE

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There is evidence of zoning, particularly of thelead, zinc and local barite gangue with suggestions of azinc envel-epe at the extremities of the lode. The synclineappears to have been truncated by erosion at about half­way of its length to the west. 'This, with the strengthof mineralization at this place, suggests that it couldhave formed a lode originally 14,000 feet long and if itm~intained its original width of 5 foet which it couldwell have done, it would have been an almost unique de­posit. Erosion appears to have removed over three milliontons from the present No. 1 lode so that the originaltonnage could have been 12,000,000 tons. Other depositsof great length in relation to their widths are known inthe Shuswap Terrane in both the Revelstoke and KamloopsMining Di.visions.

The ease of preliminary evaluation is compen­sated for in difficulties presented to secondary stagesof development due to paucity of good drill locations andlength of cross cut tunnel to the lode. However, somedrilling can b e done in the central part and second stepsshould be taken at an early date so that production shouldnot be unnecessarily delayed in case of an increase inlead and zinc prices.

P)POO~RTY Fil E..... ij \ I ~..",?,' i ~. ,~

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INTRODUCTION AND HISTORY

The River Jordan property was discovered in thelate 90's by two prospectors who did some work prior toleaving it for the Yukon Gold rush. As it Was not men­tioned in the B.C •. Minister of ~dnes reports, it remainedunknown except in Revelstoke, some of whose residentsstaked it at intervals. The early owners drove threeshort tunnels and an operator from the United States com­pleted a well cut out trail to it in the 1940's. It wasdiscovered independently by Alfred Br~wer in 1955 whileit was still staked. He waited till the claims lapsed,ro-staked it and in the fall optionod it to AmericanStandard Mines Limited•.

This paper is based on work done in 1956, atwhich time the writer employed geologist J.S. Ives tomap and sample the deposit. Circumstances lirrited avail­able time so that the plans and sections presented do notrepresent mapping of every outcrop.

LOCATION, ACCESSIBILITY AND TOPOGRAPHY

The property is situated twelve miles northwestof Revelstoke, a divisional point on the main line of theC.P.R. It may be reached by road and trail up the JordanRiver for ten miles, thence up Copeland Creek to a branchcreek leading to the showings. The last part of the routeup the branch rises 2800 feet in about one and one halfmiles so requires switchbacks. The lode is exposed atelevations from 5800 feet to 7900 feet in a rugged areaabove timberlino. As it is on the northern slope of Cope­land Mountain, it is covered in two parts by glaciors andanother part ~s snow covered until August.

With the developmont of sufficient tonnage towarrant the cost, the deposit could be exploited by meansof a low level tunnel from Copeland Croek and a raise tothe ore bodies. The stoep part of the route up thebranch could thus bo avoided.

GEOLOGY

Tho area has not yot been mapped by governmentsurveys which extend only to the 51st. parallel, 12 milesto the south. However l there is every indication thatthe geology described ~n that location can be extended to

F1f{OPEf~l"iY F~LE

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cover the property. The area to the south is described inthe recently published Memoir 296 of the Geological Surveyof Canada, which makes an intensive study of the rocks ofthe Shuswap Terrane, the bedrock geology of this part ofBritish Columbia.

Assuming the above projection is correct, theJordan River rocks belong to the Monashee Group which lieat the base of the Shuswap of Archean or later Pre-cambrianage. There are three groups in the Shuswap -- the Monasheewith a thickness of 50,000 or more feet, the overlyingMount Ida group with at least 60,000 feet and the topmostChapperton group with 5,000 feet. All are highly meta­morphosed, the Ivlonashee more intensely than the later Shuswapgroup.

The rocks on the Jordan River property consist ofgneisses, schists, -- marbles, quartzites and transitionaltypes. The gneisses occur in beds from 20 to 100 feetthick with one prominent bed of rusty gneiss 150 feet thick.The schists are interbedded with the gneisses. There aretwo lime beds, both underlying the lode, one is a thin,fetid lime, the other is a marble much thicker up to 40feet. There aro two main quartzite bods from 20 to 100feet thick overlying the lode. Both lime and quartziteform good horizon markers, the white marble in particularis prominent and may be traced around the main structureand so has provided a means of its interpretation. A thinbed of impure lime forms the host rock for the ore. Itwas an incompetent bed and its close folding and breccia­tion provided access to the mineralizing solutions.

One main structure forms the host for the lodes,which is a syncline overturned at an angle of about 45° tothe north. This syncline is closed to the east but istruncated at about one half its length to the west whorea partial cross section may be S08n on the steep slope ofCopoland Mountain, the marble bed being especially welldefined. The syncline strikes about N. 620 w. has ageneral dip of 450 southward and an eastward piunge of120 • The western cross section shows a strong superimposedfold on the southern flank near the bottom of the fold andthere are indications of a keel-like structure at the base.In addition, there are numerous minor drag and cross folds.Near the eastern and on the north limb there are severalnormal faults with a horizontal displacement of about 80feet, but are largely marked by small deprossions.

f~ROPERer'YFiLE

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THE LODE

The potential ore deposits consist of two zoneswhich are convergent eastward and which are here consideredto be the same bed in either limb of the syncline, No.1being the southerly. Tracing No.1 from east to west, thefirst outcrop, called the East Section, is exposed for290 feet over a transverse saddle or north-south rock ridgeat an elevation of 5800 feet. From this place westward itis covered by 3080 fect of talus and ice of which the first750 is talus. It ~merges from the ice and is then exposedfor 2200 feet to the western side of MOunt Copeland at7900 feet. Here follows 400 feet of glacier from whichit emerges, dipping vertically, thence dipping easterlymore flatly, till at 500 feet it is nearly flat. It con­tinues through two rolls to a bond into a koel whero itagain dips almost vertically. This part around tho crosssectional end of the synclino has an exposed longth of1200 feet and is called the West Section.

The ~est Section is different in that it consistsof two parallel zones in the host bed separated by aboutten feet of brecciated and silicified rock, the wholeaveraging 15 to 20 feet. No. 1 lode lies at the top ofthe bed and consists chiefly of galena with minor sphalerite,the gangue is barite, not SOGn elsewhere in tho lode. Theparallel zone is mostly sphalerite and iron pyrites, andlies on the footwell of the host bed.

Tho thickness of the No. 1 lode varies in accordancewith its position in the syncline. It is narrow at theeastern closed end, at the Peak Section noar its probableoriginal top, and at the western end in those parts whereit becomes nearly flat. It widens on the flanks particu­larly where it changes in dip from southerly to northerlyand also in superimposed minor folds. It has been sampledover minimum thicknesses of 1.0 feet and 1.8 feet at theEast and West ends to a maximum of 12 feet in the Cliffsection. A probable average width throughout would be5 feet.

The possible original extent and volume of No. 1lode forms an interesting subject for speculation. Atleast one half of the original longth of the syncline ismissing due to erosion. The veins are strong at thotruncated WGstorn end and could edsily have extendedthroughout the structure. If this had been so, the totall~ngth of the lode would have been 14,000 fest. If theaverage thickness were five feet throughout as seems likely,

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SAlfJ'LING

Another remarkable feature of the deposit isthat a good preliminary evaluation could be made upon itwithout any sort of work such as stripping or rock trench­ing, except at the East Section of No. 1 where some oldwork remained in good enough condition to permit sampling.Otherwise the exposed surface was unoxidized and samplingcould be carried out at once. Later, when surface blast­ing and ro-sampling was dono, the results were not signi­ficantly differont. Singularly enough, no easy andeffective secondary exploration could be carried out exceptfor a few diamond drill holes in the covered part west ofthe East Section. Otherwise drilling would be difficultand costly and a crosscut of 1300 feet would be requiredto intersect the lode.

Plans show the weighed averages of sampling. Inthe calculations, narrow widths have been expanded to awidth of 3 feet in the steeper parts of the zone and 4 feetin the flatter. The results are as follows:

Section Longth Ft. Average Width Recalculated Values

OZ.A~ ~ Pb. %Zn.

East 290 3.0 1.48 6.2 1.5

Cliff 890 6.7 1.0 5.3 7.4

West cliff 530 4.0 0.5 2.0 11.3

Peak 550 3.0 0.49 1.0 6.8

v~est

(1) Main Structure 920 5.3 2.0 6.7 3.2(2) Cross fold 300 3.0 0.2 4.0 3.3

-3480

NO. 2 LODE

The No. 2 Lode was sampled at intervals over adistance of 2100 feet. Much of the vein is covered in thisdistance but where exposed is narrower than No.1. Recal-

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culated average values for this vein give an average widthof 3.0 feet at 1.28 oz. of silver, 3.2% lead and 4.3% zinc.

POTENTIAL ORE RESERVES

Due to the clear cut structural character of thedeposit, it is possible to make a preliminary estimate ofthe potential tonnage to be expected from the No. 1 lode.This has been done by taking only the south half of thefold down to the center of the trough as shown in theaccompanying diagram. To do this, surface widths and valueshave been projected downward where the lodo is exposed, andwhere covered, valuos and widths have been projected hori­zontally and vertically and weighted with the adjoiningexposed sections.

All narrow samples in the trough of the synclinehave been brought to a minimum of 4 feet and recalculated,using 8 cubic feet per ton for ore and 12 cubic feet perton ~r waste. Narrow samples in the steeper portions ofthe vein have been recalculated to a minimum width of 3feet using 8 cubic feet per ton for ore and 12 cubic feetper ton for waste. In estimating tonnage, a value of 10cubic feet per ton was used.

Ore roserves have been divided into blocks asshown in the figure A, B, C, D, E, F, G, and H. Block"H" which is the thin, zinc-iron portion of the limb isnot considered to be economic and is not included in theestimates. All estimates are on the conservative sideand it is probable that both grade and tonnage will befound to be substantially greater during mining operations.Additional tonnages will probably be found in the lowerlimb of the structure and in possible cross folds.

Onere insert Page 18 of Ive's Report(See following page)

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(page 18 of Ive's Report)

THE FOLLOWING TABLE SHOWS THE ESTIMATED TONNAGE IN THE VARIOUS BLOCKS

Estimated Undiluted Grade *Estimated Diluted GradeUndiluted Oz. % % Diluted Oz. % %

Block Tonnage Width ~ Pb. Zn. Tonnage ~ Pb. Zn.

A. 172,200 5.3 2.0 6.7 3.2 189,420 1.82 6.1 3.0B 885,200 5.0 1.2 5.6 6.7 973,720 1.1 5.1 6.1C 603,500 6.7 1.0 5.3 7.4 663,850 0.9 4.9 6.7D 548,000 5.0 1.0 5.3 7.4 602,800 0.9 4.9 6.7

ABCD 2,208,900 1.2 5.6 6.7 2,429,800 1.1 5.1 6.1

E 260,400 4.0 1.2 5.6 4.4 286,400 1.1 5.1 4.0F 53,500 3.0 1.5 6.2 1.5 58,800 1.4 5.6 1.4G 88,800 3.0 1.5 6.2 1·.5 97,700 1.4 5.6 1.4

EFG 402,700 1.3 5.8 3.4 442,900 1.2 5.3 3.1

Ato G 2,611,600 1.2 5.6 6.2 2,872,700 1.1 5.1 5.6

Blocks A, B, C, and D, therefore contain an estimated2,429,800 tons of ore.

Blocks A to G inclusive contain an extimated 2,872,700 tons.

...~ A dilution factor of 10% has been used to obtain the"...final estimated diluted tonnage and grade.

PROPEt<'l'Y FILE

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CONCLUSIONS

The River Jordan deposit possesses several un­common features, the chief of which is its unusual lengthin relation to its breadth, and in particular to its pro­bable original length. This phenomenon appears to be acharacteristic of the Shuswap Terrane deposits. The writerknows of three other localities where this is found. Onthe Adams Plateau, the Lucky Coon group consists of threenarrow lead-zinc replacement zones of about 3 feat widthwhich extend en echelon for 15,000 feet, and the MosquitoKing zone has a similar character. Another is the MountSeymour Mines lead-zinc veins near Seymour Arm of theShuswap Lake and the other the J and L deposit on CarnesCr6ek north of Revelstoke.

Another unusual feature of the deposit is itsprobable U-shape in which the Nos. 1 and 2 lodes form oneand the same mineralized bed. Other featuros are thetype of exposures which permit of immediate sampling andapproximate estimate of reserves. It is also strange thata zone of this size should romain unknown for so long atime and that it should be so close to transport thatit should remain undeveloped. Both the latter are larg81ydue to the fact that it is relatively inaccessible.

This and the difficulty of easy preliminary under­ground examination has prevented its exploration since 1955.This is unfortunate bocause nothing is known of the actualkGel of the syncline except for the nearly vorticallydipping limb exposed for a short distnnce to the west priorto its disappearance under talus cover. Nothing is knowneither of the potontiality of the superimposed minor foldsthat are likely to occur throughout, with consequent in­crease in reserves. It is hoped that the second steps inexploration could be undertaken in tho near future so thatproduction plans could be finalized quickly in case ofimprovement of base metal prices.

July 28, 1960.

PROPERTY FILE

PROPERTY FILE

12~V~1-s-rOK.E. MINING DIVISION, B.C.

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