The Wathaman Batholith in Saskatchewan is a stitching pluton emplaced at the boundary between accreted volcano-sedimentary rocks of the La Ronge Domain and the Archean Hearne Province margin. Along the northern shore of Reindeer Lake, megacrystic granitoid rocks
of the Wathaman suite intrude and host xenoliths of Archean gneiss of the Peter Lake Domain. The Swan River complex, which intrudes Archean gneiss of Peter Lake Domain, contains mafic-ultramafic sills including layered olivine gabbro and diorite. It locally mingles with megacrystic monzodiorite of
the Wathaman Batholith, suggesting a co-genetic relationship. Along its southern margin, the batholith intrudes metasedimentary rocks of the Park Island assemblage, interpreted as the remnant of a foreland basin. The Swan River complex, as well as voluminous granitic to granodioritic plutons
occurring in the La Ronge Domain, greatly increase the amount and compositional diversity of plutonic rocks believed to form part of the Wathaman suite.
Precambrian rocks exposed on Southampton Island, Nunavut, are dominated by plutonic units, consisting mainly of tonalite-granodiorite-monzogranite and minor mafic units. Based on geochemistry, 80 plutonic samples analyzed can be subdivided into 1) a mafic group,
2) a syenite to quartz monzonite group, and 3) a voluminous tonalite to syenogranite group. Compositional gaps and field relationships argue against either a consanguineous or a co-genetic relationship between mafic and felsic compositions. Most samples are metaluminous, magnesian, calcic to
calc-alkalic, and exhibit large variations in trace-element concentrations. Thirty regionally distributed Nd isotopic samples yielded TDM ages ranging from 2.79 to 3.65 Ga, indicating a Meso- to Paleoarchean crustal substrate. Strongly negative eNd (1.9 Ga) values (-4.91 to -19.81) argue against
significant material input from depleted mantle sources (e.g. MORB) during Paleoproterozoic granitoid petrogenesis. Regional Nd isotopic data sets plus U-Pb crystallization data sets from these Precambrian rocks support correlation with the diamond-hosting Repulse Bay block of the Rae
Province.
New U-Pb SHRIMP and ID-TIMS geochronological results have brought to light an extensive Archean history on Southampton Island, Nunavut. The oldest plutonic component documented is a ca. 3.0 Ga anorthositic complex whereas granulite facies tonalite-quartz diorite
from two widespread localities have ages of 2.77--2.76 Ga. This implies that a significant proportion of the Precambrian highland of Southampton Island comprises high-grade plutonic rocks dating back to the Mesoarchean. Mylonitic biotite monzogranite yields an age of 2.61 Ga. Gabbroic anorthosite
exposed west of the community of Coral Harbour is dated at 2.06 Ga, corresponding in age with rifting prior to the onset of the Trans-Hudson Orogen. Metamorphism related to the Trans-Hudson Orogen is recorded by zircon overgrowths dated between 1.88 Ga and 1.82 Ga in most rocks
analyzed.
We present 40Ar/39Ar hornblende and muscovite data from a 200 km transect across the northern flank of the Paleoproterozoic Trans-Hudson Orogen (THO) exposed along Reindeer Lake in Saskatchewan, Canada. The transect crosses a series of distinct lithotectonic domains that experienced pressuretemperature (PT) conditions of 600730 °C at 4.56.0 kbar (1 kbar = 100 MPa) during D2 peak metamorphism at 18201790 Ma. The distribution of 40Ar/39Ar hornblende ages shows that most of the transect cooled through approximately 500 °C by ca. 1765 Ma, with two significant exceptions. At the north end of the transect, older ages in the Peter Lake Domain (up to 2200 Ma) suggest that this region did not experience high-grade metamorphism that affected the rest of the transect and may indicate a structural break between these Archean rocks and the Cree Lake Zone to the north. In the south-central part of the transect, UPb (monazite, titanite) and 40Ar/39Ar (hornblende, muscovite) ages indicate that rocks in the vicinity of the Duck Lake Shear Zone, a ductile thrust zone separating the Kisseynew and La Ronge domains, cooled at a rate of 6 °C/Ma and that cooling was delayed by ca. 2025 million years relative to that of adjacent regions. Based on generic thermaltectonic models for large hot orogens, we suggest that delayed cooling in the vicinity of the shear zone reflects post-orogenic thermal relaxation of lower crustal isotherms that were perturbed by the effects of convergence.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.