Ontario Mineral Inventory

Ontario Geological Survey
Permanent Link to this Record: MDI52B11NE00001

Record: MDI52B11NE00001

General

Mineral Record Identification
Record Name(s) Eva Lake Stock - 1996
Related Record Type Simple
Record Status Occurrence
Date Created 1996-Dec-14
Date Last Modified 2022-Jan-05
Created By W Bellinger
Revised By W Bellinger

Commodities

Primary Commodities: Granite



Location

Township or Area: Eva Lake Area

Latitude: 48° 41' 29.7"    Longitude: -91° 13' .3"

UTM Zone: 15    Easting: 631232.06   Northing: 5394705.63    UTM Datum: NAD83

Resident Geologist District: Thunder Bay South

NTS Grid: 52B11NE

Point Location Description: Outcrop

Location Method: Data Compilation

Access Description: GENERAL LOCATION: The pluton lies on Hwy. 11 approximately 55 km west of Kashabowie. This area is just southwest of Gateway Bay, Eva Lake. ACCESS: Highway 11 transects the northeast and southwest parts of the pluton. The southwest half of the intrusive is accessible by two bush roads off the TransCanada Hwy. Limited access to the northeast half of the area is available via the Eva Lake Resort Road.



Exploration History

No claims staked on ground; only activity in area is cottage lots on Marion and Eva Lakes and Hwy. construction 1994 The majority of the pluton is open.


Geology

Province: Superior

Subprovince: Quetico

Geological Age: Archean  



Geology Comments

Dec 07, 2005 (W Bellinger) - GENERAL GEOLOGY AND STRUCTURE: The Eva Lake Stock has intruded Archean gneissic-migmatite rocks of the Quetico Subprovince. The stock is oval and measures 1.6 km by 1.3 km. Outcrop exposure is poor due to the Eagle-Finlayson end moraine. The Eva Lake Stock has been identified as a diatextite with a composition that classifies it as a quartz monzonite. The rock exhibits weak foliation and ghost-like structures, termed nebulites, both of which are recognized by the concentrations of mafic minerals.




Lithology

Lithology Data
Rock Type Rank Composition Texture Relationship
Quartz Monzonite 1 Uniform Host
Diatexite Migmatite 2 Gneissic-Migmatite Rocks Gneissic Adjacent

Lithology Comments

Dec 07, 2005 (W Bellinger) - MINERALOGY: Staining of a sample showed the rock to be composed of 40 to 50% potassium feldspar, 30 to 50% plagioclase, 15 to 20% quartz, and 5% hornblende and muscovite together. JOINTING: The jointing in the examined outcrops was well developed and regular. The best developed set has an orientation of 140 degrees with a near vertical dip, and a spacing of 2.5 to 3 m. A weaker developed joint set was noted trending 40 to 50, but it is irregular in its occurrence. Little or no fracturing was observed in the outcrops examined. Even the road outcrops that had been blasted show very little fracturing. Where outcrops allowed the measuring of sheeting, it was noted to be horizontal and 2 to 3 m thick. COLOUR: Near the centre of the intrusive the colour is a consistent light grey. Upon close examination, one can see the ghost structures defined by the concentration of mafic minerals. These structures sometimes outline assimilated xenoliths or are seen as streaks with irregular orientations. Close to the edge, the colour varies from pink to grey, and the ghost structures are still recognizable. TEXTURE: The texture of the rock is very uniform. The stone is a medium grained (1 to 5 mm) with rare phenocrysts up to 1 cm in length. OTHER FEATURES: In the outcrops examined, two small (2.5 to 5 cm wide) pegmatitic dikes that parallel joint sets, were noted. Other than the nebulites, no inclusions or xenoliths were identified. At one outcrop a small horizontal shear zone was observed.




Mineralization

Mineralization and Alteration
Rank Mineral Name Class Economic Mineral Type Alteration Mineral Type Alteration Ranking Alteration Intensity Alteration Style
1MicroclineEconomicOre
2QuartzEconomicOre
3PlagioclaseEconomicOre
1HornblendeEconomicGangue
2MuscoviteEconomicGangue

Mineralization Comments

Dec 07, 2005 (W Bellinger) - MINERALOGY: Staining of a sample showed the rock to be composed of 40 to 50% potassium feldspar, 30 to 50% plagioclase, 15 to 20% quartz, and 5% hornblende and muscovite together. COLOUR: Near the centre of the intrusive the colour is a consistent light grey. Upon close examination, one can see the ghost structures defined by the concentration of mafic minerals. These structures sometimes outline assimilated xenoliths or are seen as streaks with irregular orientations. Close to the edge, the colour varies from pink to grey, and the ghost structures are still recognizable. TEXTURE: The texture of the rock is very uniform. The stone is a medium grained (1 to 5 mm) with rare phenocrysts up to 1 cm in length. OTHER FEATURES: In the outcrops examined, two small (2.5 to 5 cm wide) pegmatitic dikes that parallel joint sets, were noted. Other than the nebulites, no inclusions or xenoliths were identified. At one outcrop a small horizontal shear zone was observed.



Mineral Record Details

References

Mono - Dimensional Stone Occurrences and Deposits in Northwest Ontario

Publication Number: OFR5890 Scale:     Date: 1994

Author: Hinz P., Landry R.M., Gerow M.C.

Publisher Name: Ontario Geological Survey


MonoMap - Geology of the Crooked Pine Lake area, District of Rainy River

Publication Number: R179 Scale:     Date: 1978

Author: Pirie J.

Publisher Name: Ontario Geological Survey


Book - GRANITIC PLUTONS OF THE SUPERIOR TRAVERSE,IN GEOTRAVERSE CONF 1977

Publication Number: CONF Scale:     Date: 1977

Author: Goodwin, A.M. et al

Publisher Name:


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For detailed information regarding this mineral record please contact the Thunder Bay South Resident Geologist District Office