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TitleArchean and Paleoproterozoic gabbros in the Peter Lake Domain, northern Saskatchewan
AuthorRayner, NORCID logo; Maxeiner, R O; Corrigan, DORCID logo
SourceGAC-MAC-CSPG-CSSS Halifax 2005, building bridges - across science, through time, around the world: abstracts/AGC-AMC-SCGP-SCSS Halifax 2005, Jeter des ponts entre les disciplines scientifiques, les époques, et unifier le monde : recueil des résumés; GAC-MAC-CSPG-CSSS Joint Meeting, Abstracts vol. 30, 2005 p. 164
Alt SeriesEarth Sciences Sector, Contribution Series 2004337
MeetingHalifax 2005: GAC-MAC-CSPG-CSSS - AGC-AMC-SCGP-SCSS; Halifax, NS; CA; May 15-18, 2005
File formatpdf
AreaPeter Lake
Lat/Long WENS-104.0000 -103.5000 57.5000 57.2500
Subjectsgeochronology; general geology; tectonics; mafic rocks; platinum; lead lead dates; zircon dates; gabbroic composition; Hearne Province; Archean Swan River Complex; Love Lake Leucogabbro; Porter Bay Complex; Patterson Island pluton
AbstractThe Peter Lake Domain in northern Saskatchewan represents a southeastern component of the Hearne Province and is dominated by
Archean granitic and gabbroic rocks. It contains one of the largest concentrations of mafic rocks in North America and is highly prospective for platinum group elements. These mafic rocks have been, until recently, grouped together as the Archean Swan River Complex. Recent geochronological studies from the north end of eindeer Lake have identified a second episode of mafic plutonism in
the Paleoproterozoic. A gabbronorite from the homogneous Love Lake Leucogabbro suite provided three overlapping, concordant zircon fractions, which yield a crystallization age of 2562 ± 1 Ma (weighted mean 207Pb/206Pb age). Ninety kilometres to the northeast, a similar gabbro was sampled; the Wiley Bay leucogabbro has well preserved rhythmic igneous layering and breccia pipes with abundant autoliths. A regression through 3 zircon fractions (1 concordant, 2 discordant) gives an upper intercept age of 2560 ± 1 Ma, interpreted as the time of crystallization of the pluton. Both of these samples are part of the previously identified Archean Swan River Complex, which intrudes the granitoids of the Hearne Province. A spectacularly layered gabbroic to anorthositic body was sampled in a bay north of Patterson Island. A regression line through 3 discordant, co-linear zircon fractions gives an upper intercept age of 1917 +4/-3 Ma, which is interpreted as the time of igneous crystallization. A fourth discordant fraction does not lie on the regression line and gives aslightly younger 207Pb/206Pb age. Eight kilometres south of this gabbro, the Patterson Island pluton forms a large circular intrusion of monzonite and monzodiorite. A megacrystic hornblende-augite monzonite, collected from a small island southeast of Patterson Island, provided four tightly clustered slightly discordant zircon fractions that yield a weighted mean 207Pb/206Pb age of 1913 ± 1 Ma, which is interpreted as the time of crystallization. This newly identified suite of 1.9 Ga gabbros and diorites is referred to as the Porter Bay Complex.
The tectonic setting for these two suites of layered igneous rocks is still subject for debate. One option would view the 1.9 Ga gabbros as
having formed in a subduction-related continental arc setting along the southeast margin of the Hearne craton. Possible linkages between these 2.56 Ga and 1.9 Ga gabbros and granulites of similar age in the northern and western Hearne Province also need to be examined.

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