PETROLOGICAL AND GEOCHEMICAL COMPARISON OF THE EISLER INTRUSIVE SUITE AND THE LAONIL LAKE INTRUSIVE COMPLEX, GLENNIE DOMAIN, NORTHERN SASKATCHEWAN
Date
2023-03-15
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
ORCID
Type
Thesis
Degree Level
Masters
Abstract
The Paleoproterozoic Pine Lake greenstone belt of northern Saskatchewan, which is part of the Glennie domain of the Reindeer zone of the Trans-Hudson orogen, contains orogenic gold deposits that are hosted in shear zones. The Seabee Gold Operation exploits these deposits and includes the historical Seabee mine and the active Santoy mines. The Pine Lake greenstone belt is divided into the ca. 1.88 Ga Assemblage A, comprising various metamorphosed mafic-intermediate volcanic and volcaniclastic rocks as well as minor siliciclastic rocks, the younger Assemblage B, comprising a polymictic conglomerate at its base overlain by metamorphosed volcaniclastic and sedimentary rocks, and the Porky Lake siliciclastic rocks. Of particular relevance to this study, a variety of intrusive intermediate to mafic igneous rocks ranging in age from ca. 1.89 Ga to 1.83 Ga occur within the belt; several of which are associated with gold mineralization, including the Laonil Lake intrusive complex at Seabee and the Eisler intrusive suite at the prospective Fisher property. These two plutonic suites show similar rock types but are separated by a younger pluton (the ca. 1.86 Ga Eyahpaise pluton) making it unclear if they were originally part of the same intrusive complex or if they were intruded at different times from different magma sources. To test the geological relationships between these intrusive complexes, a study that included zircon U-Pb geochronology, Sm-Nd isotopic analysis, whole rock major and trace element geochemistry, and petrographic analysis was conducted on samples from the Laonil and Eisler intrusive suites. Whole rock major and trace element geochemistry and petrographic data were obtained from additional samples from the Fisher property, including the Footprint and Mac North targets, as well as northeast of George Lake. In this study, rock types from Laonil Lake intrusive complex include gabbro and diorite, from Eisler include gabbro, pegmatitic quartz gabbro, pyroxenite, and hornblende gabbro, a granodiorite from Mac North, and gabbro from the Footprint gabbro. Concordant U-Pb zircon geochronology data yielded a crystallization age of 1878.7 ± 1.3 Ma for the Laonil Lake intrusive complex and 1883.8 ± 0.9 Ma for the Eisler intrusive suite. The new crystallization age for the Laonil Lake intrusive complex is ca. 10 million years younger than a previous U-Pb zircon age determination and refines the emplacement time with a smaller analytical error. The Eisler intrusive suite was not previously dated. Both the Laonil Lake and Eisler ages indicate two temporally separate plutons that both fall within the local Assemblage A rock package. Regionally, they correspond to the ca. 1890-1870 Ma early plutonic intrusions. All samples have positive ƐNd values and plot on, or near, the depleted mantle line indicating that these samples were mantle-derived and lack crustal input. The ƐNd values and the trace element profiles, with negative Nb anomalies, are suggestive of a subduction-related magmatic signature. In addition, an I-type plutonic classification and metaluminous alumina saturation support that these samples (and therefore plutonic bodies) likely formed in a juvenile oceanic arc tectonic setting.
Description
Keywords
geochronology, U-Pb geochronology, Seabee Gold Operation, Pine Lake greenstone belt, igneous petrology, geochemistry
Citation
Degree
Master of Science (M.Sc.)
Department
Geological Sciences
Program
Geology