Stop ELT-1

Outcrops are argillite/slate and grey sandstone of the Mckim Formation on the east side of the cul-de-sac. Note the deflection (dragging)) of the axial plane cleavage in the mudstone units. The movement of adjacent beds inferred from the deflection of the cleavage indicates the south limb of a syncline. A gabbroic dike is separated from the sedimentary rocks by a zone of sheared and fractured rocks. The McKim Formation is not present on the north limb of the syncline.

stop ELT-2

The low outcrops on north side of Spine Road are grey, buff and dark-grey arkose and radioactive, pyritic, quartz-pebble conglomerate of the Matinenda Formation. Pebble units are about 20-30 cm thick and dip about 10 degrees to the north. Pebbles in this outcrop are about 1-2 cm across which is much smaller than the typical pebbles in the ore zones of the Elliot Lake mines. Ruzicka and LeCheminant, (1984) report the radioactive conglomerate in the Elliot Lake mines contain rare-earth-element-bearing uranothorite, zircons, a Ti-U-Si-Fe phase (brannerite?), chalcopyrite and chromite. The distribution of radioactive minerals in the conglomerate displays layering thus indicating a detrital origin of these grains. The dark-grey areas in the radioactive beds are due to the presence of minor amounts radioactive carbon generally known in the Elliot Lake area as "thucolite" but also referred to a hydrocarbon kerogen. Ruzicka and LeCheminant, (1983) note that several generations of carbon occur in the conglomerates of the Matinenda Formation. The earliest generation occurs as layers concordant with the bedding or a component of the matrix and appears to have been deposited in areas of quiescent sedimentation during the last phase of an upward fining sedimentary cycle. Later generations are probably remobilized phases of the first generation of carbon. The carbonaceous matter in the Elliot Lake ores is comparable in occurrence and composition to similar hydrocarbon in the Witwatersrand gold reefs; interestingly Ruzicka and LeCheminant (1984) report elevated gold content (1000 - 2000 ppb) in the carbonaceous matter of the Elliot Lake ore beds.

In 1955 Rio Algom Mines Limited completed a diamond drill hole about 30 m south of this location. The logs of this hole indicate that the radioactive beds exposed here are about 35 meters above the Archean basement rocks. Diamond drilling has indicated that there are no ore-grade units in this area. Grab samples collected by the author in 1982 returned up to 0.80 lbs U3O8 /ton and 0.78 lbs ThO2/ton. A continuous chip sample returned 0.31 lbs U3O8/ton and 0.53 lbs ThO2/ton.

Stop ELT-3

at N46deg 24.302min; W42.140 - 17 - 371717E, 5140426N

One-meter thick beds of grey subarkose">subarkose of the Mississagi Formation on the west side of the highway display the rusty staining on the face of the outcrop reflecting the minor pyrite content along the foreset beds of trough cross-beds. The paleocurrent direction (from the west) can be best observed on the upper surface of the outcrop. – Please exercise caution when walking on smooth, wet rock surfaces - The grey colour of these sandstones and the presence of apparently detrital pyrite along bedding planes is held by most geoscientists to indicate of the very low partial pressure of free oxygen of the atmosphere during the deposition of the Mississagi Formation.

STOP ELT-4

A thick, sill-like body of Nipissing gabbro/diabase is exposed on the east side of Highway 108. Rhythmic, compositional layering is visible on the vertical face of the road-cut. Near the north end of the gabbro outcrop face the relatively planar, striated, surface is truncated by more irregular surface that has been interpreted as the result of erosion by high-pressure, waterborne sediment, presumably as a result of the load pressure of the adjacent melting Pleistocene ice sheet. North of gabbro sill, the upper portion of the Mississagi Formation is exposed along the east side of the highway. The distinctly pinkish hue of the sandstone is probably due to the formation of albite by hydrothermal fluids activated by the adjacent gabbro intrusion. Further evidence of hydrothermal activity is seen by dark-green to black chlorite deposited along fractures.

STOP ELT-5

Continue northward on foot for some tens of meters (a few hundred feet).

Here N46deg 24.755; W 82deg 40.189min UTM (17T-371668, 5141245)

the Mississagi Formation is overlain by matrix-supported conglomerate of the Bruce Formation. The Bruce Formation forms the base of the Quirke Lake Group. The dispersed megaclasts of the Bruce Formation are predominantly grey, granitic rocks with smaller mafic clasts of what are prpbably fragments of Huronian mafic volcanic rocks. The abundant matrix of the conglomerate is dark-grey to black. Sand-sized quartz grains have a glassy, black appearance, a reflection of the dark, chloritic matrix behind the clear quartz. There is no evidence of significant disconformity at the base of the Bruce Formation.

Click here to see a table of Formations of the Huronian Supergroup.

STOP ELT-5

Continue northward on foot for some tens of meters (a few hundred feet).

Here N46deg 24.755; W 82deg 40.189min UTM (17T-371668, 5141245)

the Mississagi Formation is overlain by matrix-supported conglomerate of the Bruce Formation. The Bruce Formation forms the base of the Quirke Lake Group. The dispersed megaclasts of the Bruce Formation are predominantly grey, granitic rocks with smaller mafic clasts of what are prpbably fragments of Huronian mafic volcanic rocks. The abundant matrix of the conglomerate is dark-grey to black. Sand-sized quartz grains have a glassy, black appearance, a reflection of the dark, chloritic matrix behind the clear quartz. There is no evidence of significant disconformity at the base of the Bruce Formation.

Click here to see a table of Formations of the Huronian Supergroup.

STOP ELT-6

The base of the Espanola Formation is a green, laminated unit about a meter or so thick. Laminated silty metamorphosed limestone (marble) and minor thin, chert beds of the Bruce Limestone member of the Espanola Formation, overlie this unit. At this location the proximity of Nipissing gabbro intrusions has led to the development of calc-silicate minerals including: grossularite garnet, idocrase (vesuvianite), diopside, and wollastonite typical of a skarn (Robertson, 1968). Wollastonite (identified by X-ray diffraction) is found just below the north-dipping diabase sill near the north end of the exposure, where it occurs as sub-parallel groups of pale-grey to white prismatic crystals about one mm wide and up to a centimeter long. X-ray diffraction analysis has determined that the pink coating on joint surface is apophyllite (KFCa4[Si8O20]8H20) an uncommon mineral, sometimes found in amygdules in basalts, but is also associated with calc-silicates (Figure 1.23). Young (1991) states that the small scale thrust faults and folds in the limestone on the west side of the highway is probably the result of slumping during early tectonic activity.

The upper, ferruginous dolostone-bearing member of the Espanola Formation and the overlying Serpent Formation are not present at this location but are well represented on the north limb of the syncline. Since the Serpent Formation is missing we can infer that the ferruginous dolostone was removed during a period of pre-Gowganda uplift and erosion.

STOP ELT-7

2.0-2.5 km = 1.3-1.6 mile. Gowganda Formation diamictite. Megaclasts of pink granite, grey granite and granitic gneiss and mafic rocks are widely distributed in a dark green matrix. Most geologists now consider at least some of the diamictites in the Gowganda Formation to be tillites, although a debris-flow origin, either glaciogenic or as submarine debris flows is a more reasonable interpretation at specific localities. Roscoe, (1969) places the appearance of significant free oxygen in the Earth's atmosphere (“oxyatmoversion”) as coinciding with the appearance of the reddish hue of hematite just above the base of the Gowganda Formation a short distance north of STOP ELT-6.

3.8 km. = 2.4 mi. 17- 371841E, 5143180N

STOP ELT-8
Park just south of the rock-cut on east side of the highway. This is an impressive exposure though a stratified sequence of diamicites, clast-supported conglomerates and sandstones of the Gowganda Formation. The base of the sequence at the extreme southern end of the exposure on the west side of Highway 108 consists of massive diamictite overlain by a thin unit of laminated mudstone-siltstone with a few small dropstones. About a meter of stratified Gowganda overlies the siltstone. Distinct beds of diamictite, sandstone, pebbly sandstone and clast supported polymictic conglomerate are present. Some conglomerate units display normal and reverse grading suggestive of debris flows. The rocks displayed here may be interpreted to represent a depositional environment proximal to retreating glacial margin.

Note the predominance of red and pink granitic clasts, in marked contrast to the pale grey clasts of the Bruce and Livingstone Creek Formations seen earlier. There is also a significant proportion of black pebble to cobble-sized clasts (Figure 1.24). The mineral assemblage and metamorphic grade of the few of the mafic clasts examined by the writer many years ago indicated that the clasts were probably from Huronian basaltic flows.

STOP ELT-10 Diamictites of the Ramsay Lake Formation contain cobbles of grey granitic rocks, mafic clasts of Huronian volcanic rocks and Archean felsic volcanic clasts in an abundant dark-grey to black sandy matrix. The Ramsay Lake Formation is overlain by dark laminated siltstone and mudstone (argillite) of the Pecors Formation. The latter contains a few dropstones (Figure 1.25). Note: the Matinenda Formation of the Elliot Lake Group, expected between the basement and the Ramsay Lake Formation, is truncated by the Ramsay Lake Formation in this area. The Matinenda Formation does occur in the mine workings down-dip from this location.

STOP ELT-11

Continue east to the end of the Panel Mine road. This is the rehabilitated area of the former Panel Mine. There is little evidence of the uranium mine and mill complex that was on this site until 1993. Return to Highway 108. Reset Odometer. Continue north on Highway 108. Tailings dam of the Quirke Mine is visible west of the Highway.

STOP ELT-12

A gated road leads west from Highway 639 leads to one of the Quirke Mine tailings dams. Park near the gate and walk a short distance along a rough road from the gate to the base of the tailings dam. Note the very dark-green to black, flattened, chlorite amygdules characteristic of the Huronian mafic volcanic rocks between the crest to the low hill. The Huronian volcanics at this location (17 – 371428E, 5152342N) include transitional alkalic types, hawaiite and mugearite (unpublished analyses in the authors files). The eastward trending, south dipping unconformity between the Archean granitic basement rocks and Huronian volcanic is visible near the crest of the hill. There appears to be no visible paleosol development at this location. Near the west end of the outcrop, a thin, quartz-pebble conglomerate/breccia unit, comprised mainly of angular, quartz-clasts, overlies the granitic rocks at the base of the volcanic unit. Scattered, isolated, mainly cobble-sized clasts of quartz can also be found along the unconformity. Some visitors to this site have proposed that the contact between the Archean and Huronian volcanics is not an unconformity, but a fault contact. However, during a visit to the Stanleigh Mine in 1990, the writer along with Rob Henderson, Mine Geologist and Dr. Larry Jensen of the Ontario Geological Survey observed identical scattered, quartz pebbles were found along the contact of he Huronian volcanic rocks where they overlie Archean mafic volcanic rocks in the haulage drift of the Stanleigh Mine on the south limb of the Quirke Lake Syncline. The writer proposes that these quartz cobbles are lag deposits left behind while the finer grained sediment was washed from the surface.

A few kilometers west of this location, occurrences of this conglomerate unit contain more rounded quartz, and are commonly are overlain by a thin arkosic unit. Quartz-pebble conglomerate, which locally contain significant pyrite as well as uranium, occur sporadically at or near the base of the Huronian volcanic sequence of the Quirke Lake Syncline and westward to the Sault Ste. Marie area. The conglomerate at this location occupies the same stratigraphic position as the radioactive, quartz-pebble conglomerate at the base of the Huronian volcanic rocks in the Thessalon and Sault Ste Marie areas.

STOP ELT-13
Archean mafic metavolcanics displaying well-developed pillow structures are exposed, on north sloping outcrop, the east side of highway (Figure 1.25). Pillows are deformed, but facing directions can easily be determined. Small amygdules are concentrated near the upper surface of many pillows. Click herefor my more detailed explanation of the origin of pillow lava.

STOP 14
9.1 km = 5.7 mi. Pale grey sandstone of the Bar River Formation with herringbone cross-bedding. 9.8 km = 6.2 mi. Christman Lake.

STOP ELT-15

Sandstones of the Bar River Formation display ripple marks, mud cracks and sinuous structures, which have been described as possible worm casts. Comparison with desiccation structures in the Gordon Lake Formation led Young (1969) to suggest that these features are the result of the transportation of consolidated desiccation fracture fillings.

STOPELT 16

Laminated, maroon buff siltstone and chert with reduction spots in the upper part of the Gordon Lake Formation. This is another red-bed occurrence within the Cobalt Group.

STOP ELT 17

Siltstones and sandstones of the Gordon Lake Formation display ripple marks, desiccation cracks, cross bedding and a late cleavage . Note: the presence of pyrite in contrast to hematitic nature of the Gordon Lake Formation near the top of the formation.