Ontario Mineral Inventory

Ontario Geological Survey
Permanent Link to this Record: MDI31M05NW00019

Record: MDI31M05NW00019

General

Commodities

Primary Commodities: Kimberlite

Location

Township or Area: Firstbrook

Latitude: 47° 27' 15.01"    Longitude: -79° 45' 44.58"

UTM Zone: 17    Easting: 593289.629   Northing: 5256378.614    UTM Datum: NAD83

Resident Geologist District: Kirkland Lake

NTS Grid: 31M05NW

Point Location Description: Pit from GSC OF4492

Location Method: Field Visit with GPS

Access Description: On the west side of natural gas pipeline, north od South Wabi Creek on J. Seed's farm.

Exploration History

2001: Trenching of inferred shallow magnetic targets by the Geological Survey of Canada discovered the pipe.

Geology

Province: Southern

Subprovince: Cobalt Basin

Supergroup: Huronian Supergroup

Formation Group: Cobalt Group

Geological Age: Mesozoic  

Geology Comments

Dec 07, 2005 (D Guidon) - The Triple B kimberlite pipe intrudes Gowganda Formation sedimentary rocks of the Huronian Supergroup, within the Southern Subprovince of Superior Province. It is 2.8 km southwest of the Cross Lake Fault, a northwest-trending fault of the Timiskaming Structural Zone.

Dec 07, 2005 (G Grabowski) - Globular segregationary to segregationary phlogopite and monticellite-bearing Group 1 kimberlite of the hypabyssal facies.

Lithology

Lithology Comments

Dec 07, 2005 (D Guidon) - The following description is from McClenaghan and Kjarsgaard (2003). The Triple B kimberlite is intrusive into argillites of the Firstbrook Member. Host rock intrusive relationships for the Seed kimberlite were not observed in the excavations, but it is also inferred to intrude rocks of the Firstbrook Member. However, a backhoe pit at site SD-025 just southwest of the uncovered kimberlite (SD-013), encountered dia- base, suggesting the Seed kimberlite may be, in part, intrusive into Nippising diabase. The geology of the Triple B kimberlite is quite variable. At the northern contact of the main kimberlite body with the Firstbrook argillite, there is aphanitic hypabyssal kimberlite (about 20 to 30 cm in width), which contains small (< 1mm) olivine phenocrysts, and is almost completely devoid of olivine macrocrysts. Over 5 m, there is a transition (with increasing olivine macrocryst content) fromaphanitic kimberlite to 'normal' looking (i.e. macrocrystic) olivine-rich hypabyssal kimberlite (Fig. llb). Approximately 13m from the north contact, there is a significant increase in country rock clasts (limestone and argillite), pelletal lapilli are observed and the matrix is serpentine-rich. Ilmenite and garnet macrocrysts are noticeably abundant in hand samples. This rock is termed a diatreme kimberlite microbreccia. Approximately 16m south of the northern contact there is a sharp break, south of which the kimberlite is completely altered. The southern contact of the main Triple B body was not determined, although ground geophysics and trenching suggest the subcropping kimberlite is 30 m in width. A narrow kimberlite dyke trending approximately 310x subcrops and was uncovered in two backhoe pits. This dyke is a hypabyssal phlogopite spinel calcite kimberlite, based on petrographic observations. Ilmenite and garnet macrocrysts are noticeably abundant in hand samples of the dyke. The Triple B kimberlite has a strong negative magnetic response.

Mineralization

Mineralization Comments

Dec 07, 2005 (D Guidon) - The following is from McClenaghan and Kjarsgaard (2003). Similar to the Seed kimberlite, Mg-ilmenite is the most abundant indicator mineral in the Triple B kimberlite. It is most abundant in the smallest (0.25 to 0.5 mm) fraction, but is also abundant in the 0.5 to 1.0 mm and 1.0 to 2.0 nun fractions. Cr-diopside is the second most abundant indicator mineral in the Triple B kimberlite, although it is much less abundant than Mg-ilmenite. It is most abundant in the 0.25 to 0.5 mm fraction of the kimberlite. (Cr-) pyrope garnet is less abundant than Cr-diopside in the Triple B kimberlite, with its highest concentrations in the 0.25 to 0.5 mm fraction. Triple B diatreme kimberlite samples contain moderate to low amounts of olivine in the 0.25 to 0.5 and 0.5 to 1.0 mm fractions. These low contents are expected of diatreme kimberlite. The Triple B kimberlite contains few chromite grains.

Assay Samples

Mineral Record Details

Mineral Zones - Size and Shape

Site Visit Information

Date: May 05, 2004

Geologist: D Guidon

Notes: The propety was visited on July 3, 2003 as part of the International Kimberlite Conference field trip. The pipe was exposed in trenches dug for the field trip. Photos: 730365 - contact within blow showing increase in alteration (light green); 730366 - contact within blow showing increase in alteration (light green); 730367 - trench; 730368 - trench showing till composed also entirely of kimberlite; 730369 - trench to bedrock - Beth McClenaghan at bottom. Samples: 03305 - kimberlite - no analytical data; 03306 - green altered argillite.

References

Publication - The Seed and Triple B kimberlites and associated glacial sediments, Lake Timiskaming, Ontario; Geological Survey of Canada, Open File 4492

Publication Number: GSC OF 4492 Date: 2003

Author: McClenaghan, M.B. and Kjarsgaard, B.A.

Publisher Name: Geological Survey of Canada

Location: https://doi.org/10.4095/214645

Book - KIMBERLITE AND ULTRABASIC ROCKS..., IN 8TH INT. KIM. CONF. FIELD TRIP GB P.1-38

Publication Number: 8 IKC Date: 2003

Author: Kjarsgaard, B.A. et al.

Publisher Name:

Location: KIRKLAND LAKE RGP

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Ministry Contact Information

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