GEOLOGICAL RECONNAISSANCE OF THE Higher ridges range up to 600 feet above the WARBURTON RANGE AREA, Elder Creek level at the mission site, and are flanked WESTERN AUSTRALIA. by, or interbedded with, lower, less-resistant belts of similar trend. Dissection of the hilly belts has By John Sofoulis, BSc. been general with drainages mainly controlled by rock fracture systems, strike and dip features, and INTRODUCTION. lithological diversity. A geological reconnaissance of the Warburton Range area was prompted by the recent marketing In the south-west sector, lower lying breakaway of copper ores extracted from the immediate vicin- and butte features are formed by dissection of the ity of the Warburton Range Aboriginal Missioii. flat-lying Palaeozoic sediments. Earlier geological reconnaissances of the same area were conductkd by Talbot and Clarke (1917) and Outwash Plains. Porman (1932, 1933). Flat alluviated plains skirt or occupy the lower The present report discusses the physiography, lying areas of the hilly belts. These are associated stratigraphy, structure and economic potential of with the sheet drainage of the area, and appear as the area, and also suggests correlations with red loamy outwash plains (or aprons) showing little, a,djacent areas. The report is accompanied by a iL' any outcrop, but frequently mantled by veneers geological compilation based on photo index map of stoney or fragmentary material derived from Talbot, sheet 3/468, scale 1 mile = 1 inch. the upland areas. The geological reconnaissance was carried out These plains support strong stands of mulga during the period October 2nd to 12th, 1961. vegetation and (dependent on gradient) usually present regular dense grove patterns, arcuately ar- LOCATION AND ACCESS. ranged (convex downslope), and up to a half mile The Warburton Range Area is contained within in length. Intergrove areas may be bare or show the "Talbot" international oseries sheet S.G. 52-9 scantier vegetation. In some sectors, the increased delineated by latitudes 26 and 27" south and frequency of mulga banding presents a dense longitudes 126" and 127" 30' east. The locality falls thicket appearance. within a native reservation, and permission to enter Other alluviated and calcreted drainages also in- the area must be obtained from the Department cluded with this unit are separately discussed in of Native Welfare. the water supply report for this area. A native mission Station, operated by the United Aborigines Mission, is located near the junction of Sand Plains. Hughes and Elder Creeks on the north-west foot- Extensive developments of red aeolian sand hills of the Warburton Ranges, and caters for the plains, commonly formed into parallel seif dunes, welfare of the nomadic natives of the region. The appear in the north-east and south-west sectors. Station includes a store, hospital, and school, and Dunes average 30 feet in height, and can vary up is connected to the Flying Doctor radio network to 1 mile in length. General dune orientation is based at Kalgoorlie. A landing strip for light along south-west lines, but directions appear con- aircraft, and water facilities, are available at the fused, anastomising, or chain-like, where adjacent Mission. to upland belts. From t'ne West Australian side, the Warburton area may be reached by travelling eastwards along Some recent sand movements has occurred a graded dirt road from Laverton to Cosmo New- (directed towards the south-west) , but in general, berry Mission (50 miles), and thence north- the Sand plain and dune areas are now fixed by eastwards for a further 300 miles via the southern spinifex and low scrub cover. margin of Lake Throssell. In the south-west sector, sand plain areas locally A graded dirt road running north-eastwards for contain small developments of mulga-covered some 170 miles ccnnects the Warburton Mission lateritic rises and occasional low breakaways, form- with the Giles Weather Station. Forty miles along ing the Tertiary surface as developed over Palaeo- this road, a newly-constructed track branches west- zoic sediments. wards to link with Carnegie Pastoral Station and thence to Wiluna. STRATIGRAPHY. Supplies and mail are carted by the Mission Within the area, metamorphic rocks of sediment- truck which makes a trip monthly to Laverton. The ary and volcanic origins, rise abruptly out of the Giles Weather Station forms the nearest perman- sand plains to form upland areas and prominent ent settlement and has a weekly mail service from ridge belts. On lithological and structural grounds, Alice Springs. Giles is operated jointly by the these rocks bear a strong resemblance to the Nulla- Bureau of Meteorology and Weapons Research, and gine System overlying the undoubted Archean is connected by a graded dirt road running some rocks in the Pilbara and Murchison areas of West 400 miles eastwards via Mulga Park and Mount Davies pastoral Stations to meet the Adelaide to Australia. Alice Springs Highway 10 miles south of Kulgera. In the Warburton region, it is apparent that From this South Australian side, a branch track the metamorphic rocks have been mobilised to also connects to the Warburton area via the Black- form porphyry and granite bodies, and are thus stone Ranges. tentatively relegated to the Lower Proterozoic era. PHYSIOGRAPHY. These rocks form the basement and probably the From a regional aspect, the area has an average source areas for the Palaeozoic beds developed elevation between 1,500 and 2,000 feet above sea marginal to and transgressing the Wa:burton rocks level but shows a gradual fall from north-east to in the west and south-west. south-west. Consequently major drainages are con- trolled by this fall and drain westerly or southerly Younger superficial formations of Cainozoic age to terminate in outwash aprons or become lost in mask a large proportion of the metamorphic and adjacent sand plains areas. Palaeozoic terrains. Dissection of the hilly belts is influenced mainly All of the rocks appear unfossiliferous and by structural and lithological features and, with formation names which are proposed below are the exception of the higher Warburton Range purely tentative, subject to more intensive field ridges, local differences in elevation seldom exceed and petrological study and approval by the West 200 feet. Physiographic units distinguished within Australian Stratigraphical Nomenclature Commit- the area are:- tee. Dissected Hills and Ranges. Lower Proterozoic Metainorphics. Resistant ridges and dissected hills of meta- Distribution and attitudes of the metamorphic morphic rocks comprising the Warburton Ranges rocks indicate a major anticlinal flexure with the form the major positive elements of relief. These eroded core now represented by the various meta- are south-east trending in the north-west sector. morphic belts of the Warburton Range. Higher but alter to an east trend in the south-east sectoi. grades of metamorphism are confined to the axial 16 zone of the anticline, whilst 01; the east flank, From the present investigation, the Townsend upper horizons of the sequence have been further Quartzites appear more or less conformable with mobilised to yield granite and porphyry bodies. the underlying Ainslie Volcanics, but are separated From bottom to top, the formations which can from them by a low angle thrust. Isolated quartzite be distinguished are: outliers frequently appear as conformable strike remnants fused to the underlying Ainslie Volcanics Miller Volcanics (after Miller Hill) .-This name east of the main escarpment. is tentatively proposed for a sequence of some 5 000 to 6,000 feet of fine to medium grained doleritic On the eastern limb, the Townsend Quartzites are and basaltic lavas and extrusi! es appearing along metamorphosed and grade into phyllitic schists, the axial portion of the flexure The sequence also quartz schists, sericite schists, etc., whilst further contains minor intraformational volcanic breccias, east, they have been completely mobilised to yield tuffs, and agglomerates, and thin metasedimentary porphyry and granite masses. In view of this bands (mainly calcareous). mob:lisation, the Townsend Quartzites are prefer- ably grouped with the Lower Proterozoic sequence. Metamorphism has produced massive and schistose rocks of amphibolitic grade, but relic Lower Proterozoic Mobilisations and Igneous In- volcanic and sedimentary textures are frequently trusives. recognised in the relatively unaltered zones. The Miller Volcanics are conformably overlain Mobilisations and igneous intrusives distinguished on both flanks by the Elder Dolomites, and in the within the area are:- axial sector are also intraded by two concordant Warburton Porphyry.-This name is tentatively porphyry sills (Warburton Porphyry). Basal beds Proposed for the massive or foliated fine-grained, of the Miller Volcanics are not exposed. dark grey, brown, or black, quartz-albite porphy- Elder Dolomites (after Elder Creek) .-Thinly ries which intrude the Miller Volcaiiics in the axial bedded dolomitic limestones, associated with rib- zone of the flexure and is also extensively deve- boned, argillaceous and cherty beds, are exposed loped along the eastern limb. on either side of the structure to form the im- Twin concordant porphyry intrusions appearing mediate lower slopes and foothills of the Warbur- on either side of the axis, form prominent ridges, ton Ranges. and are suggestive of two bedded horizons injected This dolomitic sequence is approximately 1,500 along axial crests in sill form. feet thick and is conformably overlain on both flanks by the Hughes Volcanics. The porphyry dykes contain prominent pheno- crysts of quartz, albite, and microline (rare), and Hughes Vokanics (after Hughes Creek).-A are locally pyritic. Felspars are pink or white, sequence of predominantly fine grained doleritic whilst quartz of similar dimension is pale blue and basaltic lava2 and flows which overlie the (ofter, opalescent) or clear. Elder Dolomites are tentatively grouped as the Hughes Volcanics. This sequence is approximately Along the eastern flank, the porphyry develop- ments are identical with the sill forms but often 3,000 feet thick and locally contains thin pyroclastic show relic bedding and contain remnant horizons and calcareous members. of “porphyritised” but undigested country rocks. A discontinuous thin chert breccia horizon ap- Further east, the porphyry passes transitionally pears towards the upper part of the sequence along into granitic rocks and is presumably a form of the western foothills, and forms two topographic rock mobilisation (analagous to grantitisation) r;dges. which may represent a “front” or pre-granitisation The Hughes Volcanics are conformably overlain stage. by the Ainslie Volcanics. Granitic Rocks.-Pink and grey, medium to Ainslie Volcanics (after Ainslie Hill) .-This name coarse grained granitic rocks developed in the is tentatively proposed for the sequence of fine to north-east sector are considered to represent a medium grained doleritic and basaltic lavas and further mobilisation from the “porphyritised’ flows which overlie the Hughes Volcanics. stage. Such rocks appear as composite, fine to The sequence is approximately 4,000 to 5,000 feet coarse grained, foliated, or gneissic varieties, often thick and locally contains thia pyroclastic and porphyritic in albite, microline, and blue quartz. sedimentary members. Amygdaloidal lava varieties The granite terrains also contain remnant meta- predominate throughout the sequence and appear morphics and younger dyke intrusives. as fine grained greenish rocks containing calcite and quartz amygdales, locally rimmed or replaced Absence of ferromagnesian minerals in some of by secondary epidote, and more rarely by copper the granitic terrains suggests a widespread mobili- carbonates or sulphides. sation of psammitic rocks. Prominent jojnting sets Copper mineralisation occurs within the Ainslie are developed in the granitic rocks but the general Volcanics on the western limb of the structure and rozk grain which can be observed, conforms to the forms the potentially cupriferous belt of the area. trend of the adjacent metamorphic belts. Epidote mineralisation in the form of stainings. Minor Intrusives.-These include younger quartz coatings, joint and shear fillings, is also common bars and doleritic dykes. The quartz bars are ex- in the Ainslie rocks, particularly about the areas tensively developed in the metamorphic rocks, being of known copper mineralisation. generally concordant but on the west flank locally The Ainslie Volcanics are overlain on both flanks appear as transverse joint or fracture fillings. by the Townsend Quartzites and in the south-west sector are also transgressed by the Palaeozoic beds. A more or less conformable doleritic dyke in- On the west flank, outliers of overthrusted Town- trudes the Hughes Volcanics along the central send Quartzites are frequently repeated over the northern margin. Other minor forms are also Ainslie Volcanics, whilst on the east flank the present in the granitic terrains. upper Ainslie Volcanics and Townsend Quartzites Prefolding sill intrusives appear as dark green, are mobilised to yield porphyry. mottled and black, coarse grained, basic, gabbroic, Townsend Quartzites (after Townsend Range) .- amphibolitic rocks. These are difficult to distin- A sequence consisting of some 500 feet or more of guish from the hypabyssal phases associated with quartzites, form a prominent escarpment facing most of the volcanic belts. Some of the basic and north-east near the junction of Hughes and Elder ultrabasic gabbroic rocks could be related to the Creeks. These extend in an almost unbroken line broader developments of similar rocks known in for some 30 miles south-east to Lilian Creek, where the Blackstone Range area and forming part of they form the topographic prominence known as the Giles Complex of South Australia. the Townsend Range. The dominant lithology is a uniform white to Palaeodoic Glacial Beds. buff coloured, thinly laminated, current-bedded, The Proterozoic rocks are overlapped to the west medium grained, blocky quartzite which also con- and south-west by a flat-lying glacial sequence tains thin pebble horizons towards the base. considered to be of Palaeozoic age. The sequence Talbot and Clarke (1917) refer to these beds as is unfossiliferous but similar extensive develop- comprising part of their “Townsend Range Series” ments known in adjacent regions are generally re- of Ordovician age. garded as Permian.

(21-57786 17 For the most part, the sequence is overlain by Foliations and lineations noted in the granite extensive sand plains or secondary cappings of and porphyry terrains generally parallel the bedding ferruginous (lateritic) or siliceous (billy) cements. trends of the adjacent metamorphic belts. Other Geology in these areas is therefore restricted to lineations including those related to thrusting cliff edges, breakaways, or flat-topped mesas. movements, are mainly parallel to the axis of re- In the south-west sector (“Sisters” locality), folding and trend at 215”. approximately 60 feet of section is exposed. Here Small displacements noted in the metamorphic the beds consist of tillitic siltstones showing terrains and the presence of numerous quartz bars graduations into sandy varieties and are often indicated the widespread existence of minor trans- micaceous, ripple-marked or current-bedded. cordant and strike faults. Except for the thrust- Erratics generally occur within the siltstone flour ing recorded on the western flank, the existence matrix but can appear in any horizon. The of major faulting within the area was not estab- erratics are commonly faceted, and unsorted, and lished. show a great variation from pebble to boulder size. Flat-lying Palaeozoic glacial beds occur marginal A basal bed which transgresses the volcanic to, or transgress the Proterozoic rocks in the west rocks on the western flank is made up of a fine and south-west. From the extensive developments grained, brown, sandstone which is extensively known west of the area it is apparent that arched ripple-marked. This sandstone also contains a structures are extremely unlikely and if present heavy concentration of rounded pebbles and would only exist in the broadest form. Absence boulders to present a conglomeratic appearance. of major escarpments is sufficient evidence that the glacial beds have remained comparatively Upper beds of the sequence contain scattered undisturbed since deposition. erratics only, and these consist mainly of quartz- ite similar to the Townsend Quartzites which form Tertiary and Quaternary formations of this area the uppermost member of the Proterozoic sequence. are merely superficial and contain no structural elements. Cainozoic Formations. Ferruginous and siliceous cements are common CORRELATION WITH ADJACENT AREAS. in the interdune areas of the sand plain country Suggested correlations already referred to in the and represent portion of the lateritic profile as text and those given below, are purely tentative developed during the Tertiary period. Thicker proposals which could assist in providing a better cappings (up to 10 feet) were recorded in dissected understanding of the Precambrian Stratigraphy Palaeozoic areas. both in this State and those adjoining. Calcrete limestone formations, also of Tertiary age, are recorded along the trunk drainages of the Lower Proterozoic Rocks. area. These form the principal sources of shallow The Lower Proterozoic rocks are unfossiliferous water, and are further discussed in a separate but are classified as Proterozoic purely on struc- report. tural and lithlogical similarities to rocks of the Quaternary aeolean sand plains and other out- “Nullagine System” which overlie the undoubted wash plain formations which mask a large propor- Archean in other sectors of this State (Pilbara, tion of the area have already been discussed under Murchison). A similar correlation has been sug- Physiography. gested by Forman (1932, 1933). In the Warburton area (and also in the East STRUCTURE. Pilbara) , these Proterozoic rocks are considered to have undergone geosynclinal deformation and From the repetition of strata and recorded dips mobilisation to yield granite and porphyry masses. it is apparent that the Lower Proterozoic rocks of For this reason they are tentatively grouped as the Warburton Area form part of a major anti- Lower Proterozoic. clinal flexure. The anticline is itself refolded along south-west lines to present a distribution which Comparing descriptions given by Commonwealth arcuates from a north-west trend in the north-west geologists (Wells, Forman and Ranford) in Bureau sector to an east trend in the south-east. Local of Mineral Resources Records 1959-61 entitled dip reversals noted across the structure indicate “Geological Reconnaissance of the Rawlinson- the existence of minor crenulations. Macdonald Area, Western Australia,” the meta- morphic rocks of the Warburton area are tenta- No closure is evident in the mapped area but tively suggested as being equivalent to the “Dean fro% the structural widening in the south-east, a Metamorphics” (also classified by Commonwealth closure to the north is suspected. As evidenced geologists as Lower Proterozoic). by the relationship between the Townsend Quartz- ites and Ainslie Volcanics, the folding gives way Further, the “Rawlinson Prophyry” which in- to low angle thrusting on the west flank. trudes the “Dean Metamorphics” in the northern areas is similar in composition, characater, and On the eastern limb, upper members of the rock relationshps to the Warburton Porphyry. Lower Proterozoic sequence have been mobilised Similar porphyries are also known in the East to yield porphyry bodies which are locally intrusive Pilbarian and South Australian extensions. into the metamorphic rocks and also pass tran- s:tionally into granitic rocks further east. Upper Proterozoic Rocks. As mentioned earlier, the “porphyritisation” is Upper Proterozoic tillites and associated beds regarded as a form of rock mobilisation (analagous recorded by the Commonwealth geologists in the to granitisation) and probably represents a “front” Rawlinson-Macdonald area suggest affinities with or pregranitisation stage. (Similar transitions from the tillites of the Upper Proterozoic “Adelaide identical porphyries to granite have also been re- System” of South Australia. They are not repre- corded by Noldart and Wyatt (unpublished) on sented in the Warburton area. what could represent a strike extension of the same group of rocks, east of the Gregory Range in the East Pilbara) . Palaeozoic Rocks. The mobilisation is probably contemporaneous Ordovician rocks as recorded in the Rawlinson- with the period of major folding and has been re- Macdonald area have no equivalents in the War- sponsible for the introduction of minor forms of burton region. mineralisation into the associated metamorphic The glacial beds fxm part of Talbot and rocks. Clarke’s “Wilkinson Range Beds”, and in the War- Both granite and porphyry are strongly factured burton locality, form the northern margins of the with master jointing developed along north-east “Officer Basin”. and north-west lines. Quartz bars, copper bearing They are tentatively regarded as Permian and shears, younger doleritic dykes, and minor faults are probably correlative with the “Buck Forma- follow similar directions but also appear as con- tion” as recorded in the adjacent Rawlinson- formable strike features. Macdonald area.

18 Discussion on Precambrian Correlations. consist of a ferruginised silica-calcite matrix con- On regional trends, lithology, and folding, the taining varying amounts of copper carbonates, metamorphic belts of the Warburton area are silicates, oxides (local) and sulphides (rare). suggested as forming an extension of the “Nulla- The copper lodes are usually vertically disposed gine System” of the Pilbara area, and developed and can appear as thin copper bearing veinlets, within a major north-west to south-east trending or tabular, lenticular bodies from several inches geosynclinal belt, marginal to the more primitive up to 3 to 4 feet thick. Local developments up to Archean (Pdbarian-Yilgarnian) nucleus. The 8 feet thick are also known. The principal lodes same belt is also suggested as extending through generally have well defined walls and are recognised the Blackstone-Musgrave areas and thence to as occupying minor shears or fractures in the Spencer’s Gulf in South Australia. volcanic rocks. These are transcordant to the Mobilisations recognised within these terrains enclosing country rocks (similar to the mapped have apparently been confined to the main quartz bars) and would correspond to the fracture geosynclinal trough, and are not evident where pattern recognised in the adjacent porphyry, filling shallow basins on the more stable Archean granite and metamorphic belts. block. Within the geosyncline, a comparable pat- Epidote veins are commonly associated with the tern of folding, acd generation of similar suites copper lodes and epidotisation of country rocks of microcline, blue quartz (often opalescent), and adjacent to copper lodes is also a prominent albite bearing granite and porphyry (often tran- feature. sitional) has resulted. Future of the Industry.-There are no deposits of Epidotisation, minor copper mineralisation and major economic importance known within the area. the generation of charnockitic and younger ad- Deposits 1, 3, and 5 are considered to be suitable amellitic granites are also characteristic and hrve for small scale mining by native working parties. been recognised throughout the belt. Mr. Timoney estimates that deposit No. 1 could A.ge deterxiinations on the more primitive “Pil- supply some 400 to 500 tons of 10 per cent. to 12 barian Yilgarnian” block show the oldest metam- per cent. copper ore which at current prices and orphism to be 2400 to 2800 m.y. (Wilson et al. cartage costs is estimated to give a net return of 1960). This is considerably older than the oldest E10 to E12 per ton. Deposits Nos. 3 and 5 show metamorphisms recordeci on other Pre-Cambrian possibilities of smaller tonnages of higher grade areas of this and adjoining States (1100, 1500- ores if selectively mined. Other deposits of the 1800 m.y.). area are ccjnsidered insignificant. From the above it is further suggested that the Under normal circumstances, the exploitation of rocks forming the undoubted Archean in the these deposits would be out of the question as the “Pilbarian-Yilgarnian” block are not represented full valuz of most of the ores capable of being in these eastern areas. Also, the Archean of produced would be taken up in transportation to South Australia would be equivalent to the Lower the nearest rail head (Leonora, 440 miles). Proterozoic as recognised by the present author in The present development by native working the Warburton area and to the Lower Proter-zoic parties is probably the only method of exploitation mapped by Commonwealth geologists in the ad- and the success of this venture is wholly dependent jacent West Australian and Central Australian on the cheap cartage rates offered by the Mission regions. Station. Scope of these operations is fixed at 20 tons per month which is the back-loading capacity ECONOMIC GEOLOGY of the mission truck. Underground water and copper form the princi- Mr. Timoney considers that if worked as a co- pal m nerals of economic interest known within operative, a balanced production of 20 tons per the area. The former is discussed in a separate month from Nos. 1 and 3 deposits should yield a report entitled “Water Supplies, Warburton Range wage of E10 per week for eleven men. and Adjoining Areas” (Sofoulis, this publication). Despite the primitive methods of working, the Copper, other minerals, and the oil potentialities continuation of this industry would make a sub- of the sedimentary rocks are discussed below. stantial contribution to the local native economy, as well as provide a useful form of emplo!,ment in Copper Mining. what would otherwise be an idle native community. The presence of copper mineralisation from this remote region mas first reported by explorer F. Other Minerals. Hann in 1903, but it was not until recently that Minor forms of gold and silver mineralisation any development had been undertaken. There have been recorded about the area but as yet no Pre no registered tenements as the area forms part economic deposits have been located. of a large native reserve and the mining itself is Restricted occurrences of coarse grained basic carried out exclusively by native working parties. and ultrabasic sills which may be related to the To date, a total production of 68.68 tons of “Giles Complex” of South Australia, could contain approximate 11 per cent. ore and valued at E1,526 minor amounts of nickel, chromite, and allied has been reported to the Mines Statistical Branch segregations. as bnving been s Id for use in the trace mineral The area has not been fully prospected for fertilising industry. minerals but from similar occurrences recorded from the easterly extensions of this province, their Workings.-Examination of the known copper concentrations into major economic deposits seem occurrences were made in conjunction with Mr. unlikely. E Timoney of the Mines Inspectors’ Branch, and the relative plans, sampling, and assay data for Remoteness of the locality wot:ld preclude any each deposit are given in Mr. Timoney’s report but higher grade ores being exploited. entitled “Copper Deposits, Warburton Range Area”, (W.A. Mines Department, unpublished). Oil Potentialities. Development of the eight known occurrenccs are The Paleozoic glacial beds which flank and trans- still in the prospect-ng stages and the workings are gress the Proterozoic rocks to the west and south- mainly in the form of scattered costeans and west form the northerly margin of the Officer shallow trenches, confined to the “Ainslie Volcan- Basin at present being investigated for oil along ics” at the localities shown on the accompanying its south-easterly extension in South Australia. plate. These deposits are numbered one to e ght Westerly these glacials are known to extend as in keepag with Mr. Timoney’s classifications. far as the western edge of Lake Throssell where Deepest workings (13 ft. V.D.) are at the “Wind- they unconforinably overlie Proterozoic rocks and lass Shaft” on No. 3 deposit, located approximately Archean granites. Little is known of the strati- graphic sequence across this 200 miles width and ore n-ile north-west of the Mission Station. the possibility of older Palaeozoic or Proterozoic Copper Lodes.-Some of the lodes are dis- souse? beds occusring in deeper portions of the continuously traceable over the surface for long basin should not be overlooked. distances but show considerable variation in copper On present indications, these beds appear as content and can grade into barren quartz-calcite flat, structureless, thin aqueoglacial or fluvioglacial or quartz bars. Where copper bearing, the lodes deposits which have negligible oil prospects. REFERENCES. The main r$ef which is about 380 feet long, Forman, F. G., 1932: Preliminary report on a striking N. 85 E. and dipping to the north at geological reconnaissance between Laver- 45” (hanging wall), forms the southern edge of ton and the Warburton Ranges. W.A. Geol. a plateau 50 feet above the lower creek flats. A Surv. Ann. Rept., 1931. cutting made along the hanging wall from the eastern end of the reef is 75 feet long, 3 feet to -, 1933: Conclusions of report on reconnais- 1@ feet wide and up to 10 feet deep. sance survey of the country lying between The pegmatite has a lensing quartz core with Lavertcn and the Warburton Ranges, with a maximum width of 27 feet. The coarse-grained appendix. Geol. Surv. Ann. Rept. 1932. felspar outcrops in a band about 10 feet wide on Noldart, A. J. and Wyatt, J. D.: The Geology the hanging wall of the quartz but on the southern of that portion of the Pilbara Goldfield in- side the felspar occurs in veins intruding the cluded between the Limits Lat. 20’ 45’5. granitic country rock. The band of felspar on the and Lat. 22” 0’s. and between Long. 118” hanging wall is zoned and the mineral associations 30’E. and Long. 121’ 30’E. Geol. Surv. W.A. with each zone are quite distinct. Bull. No. 115 (in press). The adjacent country rock is a black, highly Sofoulis, J.: Water Supplies, Warburton Range micaceous gneiss while the outer shell of the peg- and Adjoining Areas, Eastern Division, matite consists of felspar with onion-shaped mus- Western Australia (this publication). covite and some quartz. The shell is three feet Talbot, H.W.B., and Clarke, E. de C. 1917: A thick and the “onions” OP muscovite which are Geological Reconnaissance of the Country two to three inches in diameter form in clusters. between Laverton and the South Australian This same onion-shape was noticed in the mica Border. Geol. Surv. of W.A. Bull. No. 75. occurrence in pegmatite to the north. Timoney, E. G.: Copper Occurrence, Warbur- The second zone on the hanging wall, about 18 ton Range Mission Station. W.A. Dept. inches to two feet thick, contains felspar and beryl Mines (unpublished). with some topaz. The beryl is white with occa- Wells, A. T., Forman, D. J., and Ranford, L. C.: sional light colouring. Between this zone and the Geological Reconnaissance of the Rawlin- quartz core is a layer sf quartz and felspar about son-Macdonald Area, Western Australia. five feet thick. Bur. Min. Resour. Aust. Rec. 1961/59 (un- The pegmatite bands on the footwall side of the published). quartz show a beryl content, and some fluorite was Wilson, A. F., Compston, W., Jeffrey, P. M., and identified at the western end of the body. Riley, G. H., 1960: Radioactive Ages from Some eluvial tantalite and tin was reported from the Precambrian Rocks in Australia. Jour. the lower ground dowr, the slope from the foot- Geol. SOC.Aust. Vol. 6, Pt. 2, PP. 179-196. wall but neither mineral has been found in the pegmatite so far. There appears to be a considerable amount of beryl in this pegmatite but the dip of the ore zone REPORT ON SOME PEGMATITES NORTH OF may cause some difficulty in mining. YALGOO. M.C. 27. By L. E. de la Hunty, B.Sc. Dan Todd pegged this 300 acre claim about 3.7 INTRODUCTION miles south-east of Dalgaranga outcamp and about 39 miles south-west of M.C. 26 (4.3 miles by track). On the 19th and 20th October, 1961, the writer Besides the main quartz-cored pegmatite there are inspected the pegmatites on Mineral Claims 26, 27 several small pegmatite veins on the claim acc! and P.A. 2571 on Dalgaranga Station also M.C.’s 34 these have yielded beryl in many places. A feature and 35 at Warda Warra (near the Kylie Group). of the quartz and felspar occurrences on this claim These claims were pegged earlirr this year, after is their grey colour. The grey felspar also shows the discovery by the Todd brothers of the preseme creamy patches in crystallographic continuity with of beryl, tantalite and tapiolite in and around some the grey material. The country rock is greenstone. pegmatites on Dalgaranga Station. In the north-east part of the claim there is a The homestead on Dalgaranga Station is about prominent reef of grey quartz about 120 yards long. 60 miles north-east of Yalgoo in the Yalgoo Gold- It strikes east-west, is about 30 feet wide and has field and Warda Warra is 15 miles north-north- a pegmatite envelope. About 25 yards south of east of the homestead on the other (north-west) the western end of the quartz is a pit (6 ft. x 6 ft. x side of the No. 2 Rabbit Proof Fence. 20 ft.) in pegmatite. The reported beryl produc- tion from this pit is six tons. GENERAL GEOLOGY. A shallow trench two feet deep and 40 feet long has been dug east along the northern edge of the All of the ore-bodies visited are in country of Quartz reef (in pegmatite) from a point 25 yards low relief with a large amount of soil cover. east of the western end. Some tantalite has been All of the rocks seen in the area are Archean in exposed in the partly decomposed pegmatite. age and these include greenstones, gneisj and A deep trench 50 feet long has been dug east granite, and the pegmatite bodies. The pegmatites along the north wall of the main pegmatite from have intruded both gneiss and greenstone. 60 feet east of the quartz outcrop. This trench, The pegmatites themselves have prominent quartz which varies in depth up to 15 feet, has an aver- cores with pegmatitic envelopes which are often age width of about three feet. The trench exposes obscured by soil and they have preferred strikes a vertical contact between decomposed greenstone of north-north-east or east. to the north and the decomposed pegmatite. The The main economic minerals are beryl, tantalite outer zone of the pegmatite is of felspar and onion- and tapiolite. shaped muscovite. This trench has yielded a parcel of tapiolite THE DEPOSITS. (about 14 cwt. at 71 per cent. TazOs) from a narrow M.C. 26. 70176) at, the outer edge of the pegmatite. The West Australim Government Chemical Laboratories This claim for 300 acres which was pegged by identified tapiolite, with some microlite and simp- Don Todd is now being worktd by Todd and Pal- sonite, (using X-ray methods) from samples sub- mer. It is 3 miles east of Dalgaranga outcamp mitted by the claim holder. The microlite (crl- which is about 16 miles north-east of Dalgaranga CiUm Pyrotantalate) and simposonite (calcium alu- Homestead (22 miles by track) and has about ths minium tantalate) are not highly desirable. same latitude as Mt. Palmer. Tapiolite is dimorphous with tantalite. It has There is one main pegmatite reef and several the same chemical composition (Fe Taz06) but smaller ones on the claim. The main reef was belongs to the tetragonal crystalline system while being mined at the time of inspection while several tantalite is orthorhombic. The isomorphous tapio- potholes have been dug in a smaller beryl-bearing lite-mossite series range from iron tantalate to pegmatite which runs north-east for about 200 iron niobate in the same way as the tantalite- yards from a point about 150 Yards north of the columbite series is isomorphous from iron tantalate centre of the main body. to iron niobate.

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