Ontario Mineral Inventory

Ontario Geological Survey
Permanent Link to this Record: MDI42A10SW00059

Record: MDI42A10SW00059

General

Commodities

Primary Commodities: Gold

Location

Township or Area: Cody

Latitude: 48° 29' 48.26"    Longitude: -80° 58' 2.92"

UTM Zone: 17    Easting: 502402.52   Northing: 5371513.68    UTM Datum: NAD83

Resident Geologist District: Timmins

NTS Grid: 42A10SW

Point Location Description: GPS reading taken on top of the north wall of the Ramp Zone open pit

Location Method: Field Visit with GPS

Access Description: Access to the mine is via Hwy 575, a gravel road that begins at Highway 101 East, immediately east of the bridge over the Fredrickhouse River. From there one proceeds southwards approximately 5 km onto the North Penninsula. Proceed down the right fork approximately 500 metres to arrive at the mine.

Exploration History

The Nighthawk Mine was discovered in 1909 when the water level of Nighthawk Lake was artificially lowered in order to enable prospecting to be done on a nearby claim. The lowering of the water level exposed a gold-bearing quartz vein at the southern end of the North Peninsula, and subsequent work included sinking a shaft on the vein in 1917. Some underground lateral work followed and a 200 tpd mill was built on the property in 1923 (Leahy 1971). Royal Oak Mines Inc. acquired the property in 1990. Recent activity includes major exploration programs, an open pit mine which was in operation during 1994-1995, and an underground operation which started in 1995. Ore from the mine is trucked to the Pamour Mill for processing. The Nighthawk Mine (underground) contributed a mill adjusted 722 274 tons at a grade of 0.135 oz / ton (97 528 ounces) of high grade ore and 62 486 tons at 0.066 oz / ton (4126 ounces) of low grade material to the Timmins Division of Royal Oak from start-up in 1995 through to June 1998.

Geology

Province: Superior

Subprovince: Abitibi

Terrane: Wawa-Abitibi

Belt: Abitibi

Geological Age: Archean  

Metamorphism Type: Regional

Metamorphism Grade: Greenschist

Geology Comments

Dec 07, 2005 (R Pressacco) - The mine occurs within a +/- 1000 foot wide subvertical, south dipping, easterly oriented deformation zone localized along the Nighthawk Lake Break which is bounded to the north and south by mafic volcanic rocks. These tholeiitic volcanic rocks form massive, pillowed and variolitic flows. On a property scale, the stratigraphic units generally strike 070 degrees to 090 degrees and dip steeply to the south, however on a stope scale, abrupt changes in strike and dip by 45-60 degrees over a few feet are common. This suggests that the rocks have undergone a complex structural history. Post-ore block faulting has affected the entire mine. Kink folds, M-style minor folds, crenulations and asymmetric minor folds are common through the mine within the tuffs and carbonate rocks. These features are related to both complex faulting and folding events within the mine stratigraphy.

Lithology

Lithology Comments

Dec 07, 2005 (R Pressacco) - Rock types within the deformation zone include sediments (argillites and tuffs), unaltered to intensely altered mafic and ultramafic volcanic rocks, scattered relics of felsic intrusions and quartz veins. The sedimentary units generally mark the northern limit of most zones of mineralization within the mine. These units are composed of argillite (thinly laminated and often graphitic) and are commonly adjacent to and/or intercalated with grey volcanic tuffs and lapilli tuffs. The tuffs are banded on a 0.5 inch scale with alternating felsic and mafic layers, are often tightly contorted and vary in colour from pale grey to dark grey. The lapilli tuffs are similar to the grey volcanic tuffs but contain 10-50% felsic lapilli and the units are generally a pale brown colour. When mineralized with 5-10% pyrite, these units may contain gold values between 0.030 to 0.100 oz per ton. The sedimentary units range in thickness from a few feet to several tens of feet and are best developed at the Ramp Zone located at the east end of the mine. The largest zones of mineralization occur adjacent to, or several 10's to 100's of feet south of the sedimentary units and are hosted in highly deformed and altered mafic and ultramafic volcanic rocks. These rocks are differentiated on the basis of their alteration and are described under Section 4.2. Randomly scattered through the altered rocks and tuffs are 1-5 foot sized irregular-lensoidal relicts of felsic intrusive rocks of a syenitic or albitic composition. The relicts are generally pale orange-brown, highly fractured and silica flooded and are often well mineralized with 2-10% fine pyrite and may contain significant gold values. INSUFFICIENT ROOM LEFT TO CONTINUE. PLEASE SEE PRESSACCO (1999) FOR FURTHER DETAILS.

Mineralization

Mineralization Comments

Dec 07, 2005 (R Pressacco) - There are currently six gold-bearing zones known to exist in the mine. They are the No. 1 Zone, the Main Zone, the No. 4 Zone, the Ramp Zone, the A Zone, and the Deadman Island area. At present the Deadman Island area consists of two zones of mineralization that lie approximately 500 feet east of the Ramp Zone. The economically more important of the two zones is a narrow structure referred to as the South Zone that has an average width of 5.3 feet. This zone dips steeply to the south with dips ranging between 70 and 90 deg. The second zone (North Zone) lies approximately 100 feet to the north of the first structure. This North Zone outcrops on Deadman Island and extends to a vertical depth of 300 feet. This latte mineralization contains erratic gold values within a larger, 50 foot wide mineralized envelope of green and brown carbonate. The No. 1 Zone is located adjacent to and parallels the No. 1 Fault. It extends from surface to below the 750 Level and has a strike length of about 600 feet (Figure 4). An interval of weak mineralization divides the No. 1 Zone into Upper and Lower Zones. The economic mineralization is typically 10 to 20 feet wide. The zone plunges to the east at 70 degrees and dips to the south at 70 degrees to 80 degrees . Local blowouts along the footwall of the zone are up to 50 feet in width. The zone consists of varying degrees of primarily pyrite mineralization within a highly sheared and brecciated 100 foot wide sericite alteration zone (brown carbonate). The economic mineralization lies on the footwall of the alteration zone. The sulphide component is used as a guide in determining the location of the economic mineralization (3 to 8 % pyrite) within the alteration zone (1 to 3 % pyrite). PLEASE REFER TO THE VISITS FIELD UNDER THE DEPOSIT HEADING FOR DESCRIPTIONS OF THE MAIN, NO.4, RAMP, AND A ZONES.

Alteration Comments

Dec 07, 2005 (R Pressacco) - Underground mapping by Royal Oak geologists is confined to within the mine area and has resulted in identification of the unaltered rock types described in Section 4.1. The Highly Altered Rocks are differentiated on the basis of their colour as described below. When mineralized with 3-10% pyrite, each of these rock types generally contain gold values in the 0.100-0.500 ounce per ton range. Grey Carbonate (GCRB): This is the most common rock type in the mine. Ankerite is the dominant alteration mineral and this unit varies from dark grey to pale grey in colour, and is banded and/or contorted in appearance due to abundant chlorite which has developed on foliation surfaces. Irregular and tabular centimetre-scale quartz veining of multiple ages dissect the carbonate rock and may form 50% or more of individual samples. Locally this unit contains leucoxene flakes which suggests a high Fe-tholeiite protolith. Brown Carbonate (BCRB): This unit is texturally similar to Grey Carbonate, however sericite is the dominant alteration mineral, giving the rock a pale brown to yellow-brown colour. Chloritic Carbonate (CCRB): The Chloritic Carbonate unit is very similar to the Grey Carbonate, but chlorite is the dominant mineral which gives the unit a dark green colour. Fuchsitic Carbonate (FCRB): This rock is texturally similar to Grey Carbonate, however the presence of emerald green fuchsite suggests an ultramafic protolith. Additionally, a second type of FCRB, which is massive and cut by barren stockwork type quartz veins, is common in the area of the Ramp Zone located at the east end of the mine.

Mineral Record Details

Mineral Zones - Size and Shape

Rank: 1       Structure Type: Vein

Rank: 1       Structure Type: Vein

Rank: 1       Structure Type: Vein

Rank: 1       Structure Type: Vein

Site Visit Information

Date: Jan 28, 1999

Geologist: R Pressacco

Notes: The Main Zone extends from roughly the 230 Level to the 525 Level, and forms an inverted J-shaped structure with the No. 4 Zone when viewed in Cross Section (Fig.5). It has an elliptical shape formed by N dipping faults and is 150 ft wide at its widest point. It strikes about N70 degrees E, plunges 65 degrees to the E, and is located S of the No.1 Zone. The upper and lower limits of the Main Zone appear to be truncated by N dipping faults. The zone is comprised of well mineralized (3-15 % pyrite) grey coloured ankerite alteration (grey carbonate). The No. 4 Zone extends from the 180 Level to below the 750 Level. It strikes at N90 degrees E, dips at 50 degrees S, and has an average width of about 25 ft, however in the area of the 425 Level the zone widens to 50-70 ft. The zone is comprised of a gold-bearing 1-2 ft wide crack-seal hanging wall quartz vein and a well mineralized (5-15 % pyrite) grey coloured ankerite alteration (grey carbonate) ftwall. The Ramp Zone lies about 500 ft E of the zones described above. It consists of a series of 3-15 ft wide, steeply S dipping zones of mineralization which occur over a strike length of about 1000 ft (Fig.6). The strike of the zones changes from an azimuth of 090 degrees at the western and central portion to an azimuth of about 130 degrees at the eastern end. Mineralization within these zones is variable, and consists of well mineralized sericite alteration (brown carbonate) within a highly siliceous envelope of lapilli and grey volcanic tuffs, relics of felsic intrusions, and gold-bearing quartz veining. The A Zone strikes to the N and dips 70 degrees E. It is one of the N-S structures that lie in the 500 ft long interval between the Ramp Zone and three other zones mentioned previously. The A Zone is located approximately 50 ft E of the Main Zone and extends from the 300 Level to the 525 Level. The zone consists of an albite alteration zone enclosed by fuchsitic alteration of the

References

Map - Geological Compilation of the Timmins Area, Abitibi Greenstone Belt

Publication Number: P3379 Scale: 1:100,000    Date: 1998

Author: Ayer J.A., Trowell N.F.

Publisher Name:

Location:

Mono - Special Project: Timmins Ore Deposit Descriptions

Publication Number: OFR5985 Page: 155-168  Date: 1999

Author: Pressacco R.E.

Publisher Name: Ontario Geological Survey

Location:

Map - Night Hawk Lake area, Cochrane District

Publication Number: M2222 Scale: 1:31,680    Date: 1971

Author: Leahy E.J.

Publisher Name: Ontario Dept. of Mines and Northern Affairs

Location:

MonoMap - Geology of the Night Hawk Lake area, District of Cochrane

Publication Number: R096 Date: 1971

Author: Leahy E.J.

Publisher Name: Ontario Dept. of Mines and Northern Affairs

Location:

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For detailed information regarding this mineral record please contact the Timmins Resident Geologist District Office