petrographic examination rpt - ontario...summary eleven drill core sections were received on may 1...

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Petrographie Examination of Eleven

Drill Core Samples

Report TR-05-02 Min Scan Consultants, Toronto, June, 2005

Summary

Eleven drill core sections were received on May 1 ill., 2005 for petrographic identification and description. Polished thin section were prepared and examined; petrographic observations are recorded below and typical textural features illustrated in the accompanying plates.

In an attempt to locate the source of the reported radioactivity in these samples, microprobe scanning was carried on selected grains; by Mati Raudsepp in the Geology Dept. at the University of British Columbia. Fine grains of possible interest were checked from samples B265163, B265164, B265166 and B265171. The only radioactive source located was in B265166, a pebble conglomerate, in which a rutile grain containing fine inclusions of oxides rich in Ti, U, Th, Ca and Pb was located. This probe work was preliminary in nature examination of a larger group 0 grains would be required to obtain systematic infonnation regarding the distribution of radioactive elements in these rocks.

X-Ray spectra generated during this analytical work are on file; copies can be supplied on request.

Most of the rocks are arenites containing abundant quartz and lesser amounts of alkali feldspar set in a sparse sericitic matrix; there are also some intercalated intennediate pyroclastic rocks and two examples of probable minor intrusions: aplite and diorite. Samples numbers and proposed identifications are as follows:

B-265163 B-265164 B-265165 B-265166 B-265167 B-265168 B-265169 B-265170 B-265171 B-265172 B-265173

Quartz Feldspar Arenite Quartz Feldspar Arenite Quartz Feldspar Arenite Quartz Pebble Conglomerate Intennediate Lapilli Tuff Diorite Quartz Feldspar Arenite Quartz Feldspar Arenite Aplite Intennediate Lapilli Tuff Intermediate Lapilli Tuff

These rocks appear to have been subjected to only low grade regional metamorphism. The fine matrix in the arenites is completely sericitised and the ferro magnesian components of the tuffs are chloritised. However the feldspar grains in the arenites, the diorite and the aplite are, generally, remarkable fresh.

There are no indications that the rocks have been subjected any systematic metasomatic alteration, such as silicification or carbonatization.

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Petrography

8-265163 Quartz Feldspar Arenite. This is a poorly sorted quartz sandstone which, because of the relatively small amount of matrix material present, can be classed as an Arenite. It is composed of abundant subangular to occasionally subrounded quartz grains set in a very fine grained sericitic matrix. Feldspar is subordinate component and sulphides are present in trace amounts ..

The quartz grains are mainly in the 0.5 to 2mm size range but there are many smaller and occasional coarser, grains. They generally display strained extinction and are occasionally aggregated together in irregular clusters. Also present are occasional/ subangular feldspar grains, up to 1 m in diameter. The feldspar grains are generally fresh and display twinning which indicates that both plagioclase and alkali feldspar are present (plate 1).

The matrix is made up of irregular aggregations of cryptocrystalline to very finely crystalline sericite.

Pyrite and marcasite are present as very occasional fine inclusions within quartz and feldspar grains.

There are a few fine anhedral rutile grains in the matrix anhedral grains. Probe scanning of one of these grains showed that it contains traces ofNb but no U or Th.

Estimated Modal Composition

Quartz Alkali Feldspar Plagioclase Sericitic Matrix Pyrite Marcasite Rutile

73 10 1

15 <0.5 <0.5 Trace

8-265164: Quartz Feldspar Arenite: This rock is generally similar to the previous sample but is somewhat coarser in grain.

The principal constituent, quartz, occurs as poorly sorted, subangular to occasionally subrounded grains which are generally less than 4mm in diameter.

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Feldspar grains are present in minor amounts and are generally smaller than those of quartz. They are subangular to subrounded in outline and have been subjected to minor sericitic alteration. Most are composed of alkali feldspar. (Plate 2)

The matrix is made of cryptocrystalline to finely crystalline sericite

Irregular, discontinuous bands of fine «0.25mm) subhedral, fresh pyrite grains traverse some areas within the section. The pyrite grains are generally associated with the sericitic matrix, but a few appear to be included within quartz grains. Associated with, and sometime intergrown, with the pyrite, are occasional fine rutile grains (Plate 3). There are also rare fine zircon grains.

Probe scanning of the rutile shows that it contain traces of Niobium but no uranium or thorium


Quartz 75 Alkali Feldspar 12 Sericitic Matrix 10 Pyrite 2 Rutile <0.5 Zircon Trace

8-265165: Quartz Feldspar Arenite: This rock similar in general appearance to the previous two samples.

Quartz is again the principal constituent; it occurs as poorly sorted subangular to subrounded grains .Most of these grains are less than 2.0mm in diameter but there are occasional examples with diameters up to 5.0mm.(Plate 4)

Present in lesser amounts are subrounded grains of alkali feldspar up to 2.0mm 111

diameter. The feldspar is fresh, except for minor sericitic alteration along cracks.

The matrix is composed of cryptocrystalline to very fine grained sericitic material. There are occasional very fine zircon grains in the matrix.

Some areas within the thin section contain irregular groups of fine, subhedral pyrite grains; the pyrite is accompanied by, and sometimes intergrown with, lesser amounts of rutile.

Zircon is present accessory amounts.

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Quartz Alkali Feldspar Sericitic Matrix Pyrite Rutile Zircon

70 10 15 4 0.5 Trace

B-265166: Quartz Pebble Conglomerate: This rock js made up of subangular to subrounded pebbles of quartz and of quartzite set in a fine grained sericitic matrix (Plate 5). Fine grained pyrite is abundant in some areas in the rock; associated with the pyrite are subordinate amounts of rutile and zircon.

The quartz pebbles range up to 50.mm in diameter. They are made up of intergrowths of medium to coarsely crystalline quartz and of lithic clasts of fine grained quartzite. Also present are lesser amounts of alkali feldspar - it occurs in fresh, subangular grains, generally less than 0.5mm in diameter.

The matrix is, for the most part, composed of cryptocrystalline to very finely crystalline sericite and lesser amounts of very fine grained quartz. Occasional fine zircon grains are present in the matrix.

In some areas within the section, the matrix contains aggregations of fine, fresh, subhedral pyrite grains. Associated with pyrite are minor amounts of irregular fine subhedral grains of a rutile.

Probe scanning of one of the rutile grains (Plate 6) showed that, although it is not itself uraniferous, it contains many very fine inclusions of oxides rich and U, Th and Pb.


Quartz Pebbles Alkali Feldspar Sericitic Matrix Pyrite Rutile Zircon

72 5 15 7 0.5 Trace

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8-265167: Intermediate LapiJIi Tuff: This rock has a very fine grained, intensely chloritised matrix.

Scattered within the chloritic matrix are many irregularly outlined clasts of heavily chloritised, very fine grained basic volcanic rocks and of very fine to fine grained quartzose sedimentary rock up 2mm in diameter. There are also occasional rounded clasts, up to 10mm in diameter made up of interlocking masses of coarsely crystalline quartz (Plate 7).

Minor amounts of fine subhedral pyrite accompanied in some cases by chalcopyrite, are present in some of the quartzose clasts. Sphene and rutile are present in trace amounts.


Fine Chloritic Matrix Clasts of fine grained Quartzose Rocks Clasts of coarsely crystalline Quartz Pyrite Chalcopyrite Sphene Rutile

54 25 20 0.5 Traces. Traces Traces.

8-265168: Diorite: This is a medium grained rock with a generally, equigranular texture. The principal con.<;tituent is plagioclase: it forms a mosaic of randomly orientated subhedral laths, mostly between Imm and 2mm in length (Plate 8). The plagioclase is generally fresh and displays optical properties indicating a composition in the calcic oligoclase range

Quartz is present in minor amounts; it forms anhedral, interstitial grains within the feldspar mosaic.

Irregular aggregations, up to I mm in diameter, of chlorite, sphene and fine grained magnetite are found throughout. These bodies likely represent the remnants of primary hornblende or biotite grains which have been completely replaced by secondary minerals

A O.5mm wide carbonate vein traverses the thin section.

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8-265169: Quartz Arenite:

Plagioclase Quartz Chlorite Magnetite Sphene Carbonate

82 2 4 S 3 4

The principal component is quartz. It occurs as poorly sorted subangular to subrounded grains ranging up to Smm. in diameter.

Feldspar is present in lesser amounts It occurs as subangular to subrounded in the same size range as those of quartz. Alkali feldspar is the most common type present; it frequently displays microperthitic textures (Plate 9).

The matrix is composed of cryptocrystalline to very fine grained sericite together with finely granular felsic materia1.

Opaques are generally absent but there are traces of rutile and of pyrite.


Quartz Alkali Feldspar Sericitic Matrix Pyrite Rutile

70 20 10

Traces Traces

8-265170: Quartz Feldspar Arenite: This rock is made up mainly of a closely packed, poorly sorted, mass of subangular to subrounded quartz grains ranging up to about 4mm in diameter. Alkali feldspar is present in lesser amounts; it forms subangular to subrounded grains, to 1.0mm in diameter, which frequently display perthitic textures (Plate 10).

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The sericitic matrix observed in previous samples is absent in this case; intergranular spaces are filled with very finely granular quartz and feldspathic material.

Pyrite occurs in occasional groups of fine subhedral grains; it is accompanied by trace amounts of rutile, galena and zircon.


Quartz 90 Alkali Feldspar 10 Pyrite <0.5 Rutile Traces Galena Traces Zircon Traces

8-265171: Aplite: This a fine grained rock made up of an interlocking mass of quartz and feldspar (Plate 11).

The quartz forms very irregularly outlined grains up to I mm in width.

Two varieties of feldspar are present: a perthitic alkali feldspar which forms irregularly outlined grains to 1 mm in diameter; and albitic plagioclase which occurs as randomly orientated, subhedrallaths generally less than O.5mm in length.

There are occassional subhedral grains, to 0.5mm in diameter of rutile. Probe scanning of the grain in Plate 12 showed that it contains no U or Th ..


Quartz Alkali Feldspar Plagioclase Rutile

30 30 40 <0.5

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8-265172: Intermediate Lapilli Tuff: This rock is somewhat similar to B-265167. It has a fine grained, completely chloritised matrix. Set in this matrix are abundant crystalline clasts of feldspar, mainly in the O.5mm to 1.5mm size range (Plate 13).

The chlorite in the matrix is a pale green, weakly pleochroic variety. It occurs as masses of randomly orientated, fine flakes.

The feldspar clasts are sub rounded to subhedral in outline. Most are composed of microperthitic intergrowths of alkaline feldspars and there are a few laths of albite. The feldspar all has a completely fresh appearance.

There are only rare traces of opaque minerals.


Chloritic Matrix Feldspar Clasts Opaques

65 35

Trace

8-265173: Intermediate Lapilli Tuff: This rock has a very fine grained matrix composed of abundant chlorite and lesser amounts pf quartz, feldspar, biotite and sphene. Parallel elongation of the constituent grains is fairly well developed.

Enclosed in the fine matrix are many elongated lapilli up to 30mm in length There are several different types of lapilli present, including clasts of fine grained quartzose sediments and of fine grained basic volcanic rocks (Plate 14) ..

Fine specks of iron oxide are scattered throughout in trace amounts.


Chloritic Matrix 40 Clasts of Basic Volcanics 40 Quartz-rich Clasts 20 Iron Oxides Trace

I \'

\.G.Llinciair, P.Eng .. -.~-~~

Plate I: 8·265163: Quartz and Alkali Feldspar grains in sericitic matrix. Crossed Polariser.; Scale 1-----------------1400 Microns

Plale 2 8·265164: Quartz and Alkali Feldspar grains in sparse sericitic matrix. Crossed Polarisers Scale 1-·---------------1200 Microns

Plate 3 8-265164: Pyrile-ru tile intergrowth. A single fi ne zircon grain is present. Reflected Light Scale 1-----------------1200 Microns

Plate 4 8-265165.Quartz. K-Feldspar and Sericite. A single bi refringen t z ircon is present. Crossed Polarisers ScaJe 1-------------1400 Microns

matrix. Crossed Polarisers Scale 1------------------1 400 Microns

Plale 6: 8 -265166: U and Th Oxides form very fine inclusions in this rutile grain. Reflec.ed Ligh. Scale 1------------------1200 Microns

Plate 7: 8·265167 Quartzose lapilli are set in a fine chloritic matrix. Crossed Polarisers Scale 1---···············1400 Microns

Plate 8: 8·265168: This rock contains abundant. subhedral plagioclase laths. Crossed Polarisers Scale 1-----.------------1400 Microns

Plate 9: 8-265169: Quartz and Alkali Feldspar in Sericitic Matrix. Crossed Polarise,,; Scale 1-----------1200 Micron

Plate 10: 8-265170: Quartz and Alkali Feldspar in finely granular matrix. Crossed Polarisers Scale 1-----------1200 Microns

Plate II: 8 -265171; Mass of interlocking quartz, plagioclase and alkaJi feldspar. Crossed Polarisers Scale 1-----------1400 Microns

Plate 12 8 -26517 J; Subhedral rutile grains are present in minor amounts .. ReOected Light Scale 1-----------1400 Microns

Plate 13: 8 -265 t 72 Crystalline Feldspar clasts in Chlorilic matrix. Crossed Polari sers Scale 1-----------1200 Microns

Plate 14: 8 -265173: Quartzose clast in Chloritic matrix. Crossed Polari sers Scale 1-----------1400 Microns

petrographic examination rpt - ontario...summary eleven drill core sections were received on may 1...

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