Geochronologic Studies in the La Ronge and Glennie Domains 1

T.K. Kyser2, M. Fayek2, and T.1.1. Sibbald

Kyser, T.K., Fayek, M., and Sibbald, T.1.1. (1992): Geochronologic studies in the la Range and Glennie domains; in Summary of Investigations 1992, Saskatchewan Geological Survey, Sask. Energy Mines, Misc. Rep. 92-4.

This paper presents the results of new U-Pb and Pb-Pb studies of zircons from a diversity of rock types in the La Ronge and Glennie domains. Previously published U­Pb ages of volcanic and intrusive rocks from these domains are summarized as are Ar-Ar ages of minerals associated with gold mineralization in the La Range Domain.

Zircons from the following samples of rocks from the La Ronge Domain were selected for U-Pb and Pb-Pb analysis (Table 1 ): the granitic phase of the Little Deer Lake composite pluton, which hosts the Contact Lake lode gold deposit; a rhyolite from the nearby Pap­Preview area; a meta-arkose hosting the Greywacke gold showing; and the diorite phase of the Kruger Lake Pluton associated with the Bay Zone gold showing. In the Glennie Domain, zircons from a quartz-feldspar por­phyry, one of the rocks hosting mineralization at the Seabee gold deposit in the Glennie Domain, were also analyzed (Table 2).

The techniques used for determining the age of the zir­cons were Pb-evaporation, for single zircons described by Ansdell and Kyser (1991, in prep. a) and U-Pb, described by Krogh (1973, 1982). The Pb-Pb technique is a simple and relatively fast method of analyzing the age of a single zircon. Laboratories that use the U-Pb technique also measure Pb-Pb ages, but these are usually younger than the concordia ages of the zircons. However, the Pb-Pb ages obtained from digestion of zir­cons are rarely as reliable as the Pb-Pb ages obtained from the evaporation technique because the former con­tains Pb from extraneous sources that are difficult to remove. Ages obtained from the analysis of single zir­cons using the Pb-evaporation technique are similar to those obtained from either precise U-Pb single zircon dissolution techniques or from more conventional U-Pb dissolution techniques including fractions of different zir­cons (Table 3).

1. La Range Domain The Little Deer Lake Pluton, which is crosscut by the structures that host the Contact Lake gold deposit, yields a Pb-Pb age of 1837 ±5 Ma. This is among the youngest intrusives in the La Ronge Domain, along with the Waddy Lake stock and the Numabin Bay tonalite (Table 1 ). The Star Lake Pluton and Island Lake Pluton, which respectively host the structurally-controlled Star

Lake and Jasper lode gold deposits, yield U-Pb and Pb­Pb zircon ages of ca. 1855 Ma {Bickford et al., 1986). The Kruger Lake Pluton, which hosts the Bay Zone gold showing, is among the oldest of the intrusions in the La Ronge Domain, with a Pb-Pb age of 1867 ±7 Ma (Table 1). Thus, structurally-controlled lode gold deposits in the La Range Domain are hosted by plutons that have ages spanning the entire range of intrusive events, from 1834 to 1867 Ma.

The Pap-Preview rhyolite yielded an imprecise U-Pb age of 1833 ±33 Ma (Table 1). The zircons from this unit were euhedral but very small (i.e. <20 µm). The large uncertainty associated with the U-Pb age may be due to the presence of inherited zircons because one fraction of zircons, that was not used to determine the age, yielded an aberrantly old age. The rhyolite appears to be significantly younger than falsie volcanics of the Central Metavolcanic Belt, although there is large uncer­tainty in the determination (Table 1 ). The indicated age is ca. 10 Ma younger than the U-Pb age of 1843 ±2 Ma (Heaman, per. comm., 1992) determined for the North Lake 'felsite' within the Mclennan Group. This age relationship is apparently inconsistent as the Mclennan Group unconformably overlies the Pap-Preview rhyolite sequence of rocks, suggesting that the true age of the rhyolite is significantly younger, but still within error, or that the North Lake felsite is a sediment rather than a primary volcanic rock. In the latter case its contained zir­cons are detrital and are likely derived from plutons of Contact Lake age.

The Greywacke gold showing is hosted by meta-arkosic rocks of the Maclean Lake Belt near their boundary with the Mclennan Group. Although zircons from this unit were sparse, four zircons of presumably detrital origin, yielded Pb-Pb ages ranging from 1827 to 1886 Ma. Maximum host rock age is constrained by the youngest zircon, that is, 1827 ±6 Ma. Volcanic and in­trusive rocks in either the La Range or Glennie domains could have been the major source of the zircons in the meta-arkose (Table 1).

In that the Mclennan Group overlies the Maclean Lake Belt rocks, the occurrence of ca. 1830 Ma zircons in the latter provides a maximum age for the former lending weight to the suggestion that the zircons from the North Lake felsite are detrital.

(1) Saskalchewan Project A 141 was funded in 1991-92 under the Canada-Saskatchewan Partnership Agreement on Mineral Development 1990· 95 with additional funding from NSERC Operating and Equipment Grants to T.K. Kyser.

(2) Department o f Geological Sciences, University of Saskatchewan, Saskatoon, Saskatchewan, S7N OWO.

130 Summary of Investigations 1992

Table 1- Summary of U-Pb and 207Pb/06Pb ages from the La Ronge Domain.

Sample Name

Little Deer Lake Pluton

Pap-Preview Rhyolite

Greywacke

Kruger Lake Pluton

Laroque Lake Rhyolite

McLennan Lake Rhyolite

Island Lake Pluton

Star Lake Pluton

Brindson Lake Pluton

Waddy Lake Rhyolite

Upper Waddy Lake Stock

Kenwood Lake Pluton

Nistoassini-Nayelles Pluton

Contact Lake Pluton

Macoun Lake Pluton

Numabin Bay Tonalite

Notes:

Description

composite, calc-alkaline (central granitic phase hosting the Contact Lake gold deposit)*

metavolcanic hosting the Pap-Sulphide gold showings

metasediment hosting the Greywacke gold showing

diorite /monzodiorite hosting the Bay Zone gold showing

metavolcanic

metavolcanic

zoned, calc-alkaline (central granitic phase hosting the Jasper gold deposit)*

:i:oned, calc-alkaline (central granitic phase hosting the Star Lake gold deposit)*

quartz diorite to granodiorite

metavolcanic

medium- to fine-grained hornblende granite

medium- to coarse-grained monzodiorite

medium- to coarse-grained granite

strongly foliated biotite granite

granodiorite

strongly foliated medium­grained granodiorite

* parentheses indicate the phase which has been dated ** detrital zircons 1 = this study 2 = Bickford et al. (1986) 3 = Hrdy et al. (1991)

Zircon Dating Method

single zircon Pb-Pb (3 zircons)

U-Pb

single zircon Pb-Pb

single zircon Pb-Pb (3 zircons)

U-Pb

U-Pb

U-Pb single zircon Pb-Pb (3 zircons)

U·Pb

U-Pb

U-Pb

U-Pb

U-Pb

U-Pb

U-Pb

U-Pb

U-Pb

Age (Ma) Reference

1837 ±5

1833 ±33

1827 ±6** 1828 ±11** 1844 ±6** 1886 ±7**

1867 ±7

1876 ±33 2

1882 ±9 2

1855 ±22 2 1855 ±8 3

1848 ±14 2

1866 ±12 2

1880 ±7 2

1834 ±13 2

1855 ±9 2

1853 ±10 2

1853 ±16 2

1849 ±10 2

1837 ±8 2

a) Age of Gold Mineralization in the La Ronge Domain

very late in the evolution of the La Range Domain. The gold was deposited concurrently with hydrous phases such as biotite (Star Lake area) or muscovite (Jasper and Contact Lake deposits) and sulphides such as galena and chalcopyrite. Ar-Ar spectra of muscovite,

Geologic and petrographic relations indicate that struc­turally-hosted lode gold deposits within intrusions are

Saskatchewan Geological SuNey 131

Table 2 - Summary of U-Pb and 207Pbj206Pb ages from the Glennie Domain.

Sample Name

Parr Lake Rhyolite

Deschambault Narrows Tonalite

Wykes Lake Pluton

Eyahpaise Pluton

Stevens Lake Pluton

Dirks Lake Gneiss

Laonil Lake Intrusive

Seabee Porphyry

Brownell Lake Pluton

Maynard Lake Intrusive

Maynard Lake Pluton

Gee Lake Rhyolite

Porky Lake Rhyolite

Carroll Lake Gneiss

Wood Lake Batholith

McGillivray Bay Gneiss

Drinking Lake Gneiss

Mountain Lake Gneiss

Drope Lake Gneiss

Thomas Lake Gneiss

Lac La Ronge Gneiss

lskwatikan Lake Gneiss

Notes: 1 = this study 3 = Bickford et al. (1986) 5 = Chiarenzelli (1989) 6 = Delaney et al. (1991) 7 = Heaman eta/. (1991)

Description

metavolcanic with quartz and feldspar phenocrysts

tonalite

granodiorite

tonalite

granodio rite

biotite-hornblende-quartz-feldspar gneiss

quartz diorite

quartz-feldspar porphyritic lens

granite

feldspar porphyry

g ranod iorite

metavolcanic

metavolcanic

gneiss

leucocratjc granodiorite to mesocratic granodiorite to tonalite

dioritic gneiss

granodiorite gneiss

granodiorite gneiss

quartz diorite gneiss

quartz diorite gneiss

granodiorite gneiss

granodiorite gneiss

8 = Van Schmus and Bickford (1984) 9 = Delaney et al. (1988)

Zircon Dating Method

U-Pb

U-Pb

U-Pb

U-Pb

U-Pb

U-Pb

U-Pb

single zircon Pb-Pb (3 zircons)

U-Pb

U-Pb

U-Pb

U-Pb

U-Pb

U-Pb

U-Pb

U-Pb

U-Pb

U-Pb

U-Pb

U-Pb

U-Pb

U-Pb

Age (Ma)

1881 ±6

1850 ±4

1850 ±9

1859 ±5

1836 ±7

1852 ±12

1889 ±9

1877 ±10

1831 ±7

1834 ±4

1831 +6/·5

1866 ±3

1838 ±2

1893 ±35

1850 ±1

1837 ±7

1846 ±5

1859 ±10

1850 ±13

1851 ±2

2482 ±13

2464 ±28

Reference

3

3

3

3

3

3

5

6

7

6

7

7

8

9

5

5

5

5

5

5

5

from the Jasper gold deposit, and biotite, from deposits within the Star lake Pluton, yield ages of 1719 Ma (Table 4). These ages are similar to the 1742 Ma Rb-Sr age obtained from coexisting tourmaline and feldspar gangue minerals from veins within the Star Lake area (Ibrahim and Kyser, 1991). These results indicate that structurally-controlled gold mineralization may have oc­curred up to 100 Ma after the youngest igneous events

within the la Ronge Domain. Similar results were ob­tained for the relative age of intrusive events and lode gold mineralization in the Flin Flon Domain by Ansdell and Kyser (in prep. b) and Fedorowich et al. (1991).

132 Summary of Investigations 1992

2. The Glennie Domain

The Glennie Domain comprises Early Proterozoic rocks spanning the spectrum of ages from ca. 1830 to 1890 Ma (Table 2). The Seabee deposit is partly hosted by a quartz-feldspar porphyritic lens that yields zircon Pb-Pb ages of 1877 ±10 Ma. This is among the oldest intrusive bodies in the Glennie Domain. Petrographic relations indicate that the gold and associated minerals of the Seabee deposit are relatively undeformed and late and probably much younger than the maximum age constraint provided by the dating of the porphyry. Work is presently under way to determine the age of the gold mineralization more precisely.

Table 3 - Comparison of 207 Pb/06Pb and U-Pb ages of zircons.

Sample

Duluth Anorthosite. Minnesota

Otto Stock granitoid, Kirkland Lake, Ont.

Phantom Lake granodiorite, Flin Flon Domain, Sask.

Boot Lake monzodiorite, Flin Flon Domain, Sask.

Island Lake Pluton, La Range Domain, Sask.

Notes: References in parentheses 1 = this study 2 = Heaman et al., this volume 3 = Bickford et al. (1986) 4 = Hrdy et al. (1991)

207Pbj2°6Pb age (Ma)

1098 ±16 (10) 1108 ±12 (10)

2675 ±4 (12) 2685 ±4 (12)

1840 ±7 (12)

1842 ± 13 (12)

1855 ±8 (4)

10 = Ansdell and Kyser (in prep. a) 11 = Corfu et al. (1989) 12 = Ansdell and Kyser (1991) 13 = J. Paces (pers. comm.)

3. Acknowledgments We would like to thank Karla Richard and Michele Innes for their diligence in picking the appropriate samples, and Dale Schultz for his input. We gratefully acknow­ledge April Vuletich for donating her time in obtaining some of the analytical results.

4. References Ansdell, K.M. and Kyser, T.K. (1991): Plutonism, deformation,

and metamorphism in the Proterozoic Flin-Flon greenstone belt, Canada: Limits on timing provided by the single-zircon Pb-evaporation technique, Gear., v19, p518-521.

U-Pb age (Ma)

1099 ±1 (1) 1099 ±1 (13)

2680 ±1 (11)

1838 ±2 (2)

1838 ±2 (2)

1855 ±22 (3)

--,c"'h-=-e.,,m.,..1c-};h~~e:~t~:n~:~~~~~ ~nyd zircon during the Pb-evaporation technique; Submitted to American Mineralogist.

--...,..,.__,.(in prep. b): Mesothermal gold mineralization in a Proterozoic greenstone belt: Western Flin Flan Domain, Sas­katchewan, Canada; Submitted to Economic Geology.

Bickford, M.E., Van Schmus, W.R., Macdonald, R., Lewry, J.F., and Pearson, J.G. (1986): U-Pb zircon geochronology project from the Trans-Hudson Orogen: Current sampling and recent results; in Summary of Investigations 1986, Saskatchewan Geological Survey, Sask. Energy Mines, Misc. Rep. 86-4, p101-107.

Chiarenzelli, J.R. (1989): The Nis­towiak and Guncoat gneisses: Im­plications for the tectonics of the Glennie and La Range Domains, northern Saskatchewan, Canada; unpubl. Ph.D. thesis, Univ. Kan­sas, 229p.

Table 4 - Summary of 40Ar/39Ar ages from the Star Lake area, La Ronge Domain.

Sample Name and Description Mineral Closure Spectra Age (Ma) Spectra Temperature Type

Jasper Gold Deposit (a) vein muscovite 350 ±50* disturbed - 1700

Star Lake Pluton (b) biotite from Rush Lake vein near vein-wall rock

300 ±50** plateau 1719 ±5

contact

Star Lake Pluton (c) biotite from wall rock 300 ±50** plateau 1719 ±5 near Rush Lake vein-wall rock contact

Star Lake Pluton (d) biotite a few metres 300 ±50** plateau 1719 ±5 away from Rush Lake vein

Notes: * Hanes (1991) ** Harrison et al. (1985)

Saskatchewan Geological SuNey 133

Corfu, F., Krogh, T.E., Kwok, Y.Y., and Jensen, LS. (1989): U· Pb zircon geochronology in the southwestern Abitibi greenstone belt, Superior Province; Can. J. Earth Sci., v26, p1747-1763.

Delaney, G.D., Carr, S.D., and Parrish, R.R. (1988}: Two U-Pb zircon ages from eastern Glennie Lake Domain, Trans­Hudson Orogen, Saskatchewan; in Radiogenic Age and Isotopic Studies, Report 2, Geel. Surv. Can., Misc. Pap. 188-2, p51·58.

Delaney, G.D., Heaman, L.M., Kama, S., Parrish, R.R., Slim­mon, W.L., and Reilly, B.A. (1990): U-Pb sphene/zircon geochronological investigations; in Summary of Investiga­tions 1990, Saskatchewan Geological Survey, Sask. Ener­gy Mines, Misc. Rep. 90-4, p54·57.

Fedorowich J., Stauffer, M. R., and Kerri ch, R. ( 1991 ) : Stru C· tural setting and fluid characteristics of the Proterozoic Tartan Lake gold deposit, Trans-Hudson Orogen, northern Manitoba; Econ. Geol., v86, p1434-1467.

Hanes, T.A. (1991): K·Ar and 40Ar;39Ar geochronology: Methods and applications; in Heaman, L.H. and Ludden, J.N. (eds.), Short Course Handbook on Applications of Radiogenic Isotope Systems to problems in Geology, Mineral. Assoc. Can., v19, p27-57.

Harrison, T.M., Duncan, I., and McDougall, I. (1985): Diffusion of 40Ar in biotite: Temperature, pressure, and composition­al effects; Geochim. Cosmochim. Acta, 1149, p2461-2468.

134

Heaman, L.M., Kame, S.L., Delaney, G.D., Harper, C.T., Reilly, 8.A., Slimmon, W.L., and Thomas, D.J. (1991): U-Pb geochronological investigations in the Trans-Hudson Orogen, Saskatchewan: Preliminary results by the ROM Laboratory in 1990-91; in Summary of Investigations 1991, Saskatchewan Geological Survey, Sask. Energy Mines, Misc. Rep. 91-4, p74-75.

Hrdy, F., Kyser, T.K., and Kusmirski, R.T. (1991): Mineral paragenesis, fluid characteristics, and radiogenic isotopic data from the Proterozoic Jasper gold zone, La Ronge Domain; in Summary of Investigations 1991, Sas­katchewan Geological Survey, Sask. Energy Mines, Misc. Rep. 91-4, p178-180.

Ibrahim, M.S. and Kyser, T.K. (1991): Fluid inclusion and isotope systematics of the high-temperature Proterozoic Star Lake lode gold deposit, northern Saskatchewan, Canada; Econ. Geel., 1186, p1468-1490.

Krogh, T.E. (1973}: A low-contamination method for hydrother­mal decomposition of zircon and extraction of U and Pb for isotopic age determinations; Geochim. Cosmochim. Acta, v37, p485-494.

____ (1982): Improved accuracy of U-Pb zircon ages by the creation of more concordant systems using an air abrasion technique; Geochim. Cosmochim. Acta, v46, p637-649.

Van Schmus, W.R. and Bickford, M.E. (1984): Preliminary U­Pb age data from the Trans-Hudson Orogen in northern Saskatchewan; in Summary of Investigations 1984, Sas­katchewan Geological Survey, Sask. Energy Mines, Misc. Rep. 84·4, p81-85.

Summary of Investigations 1992