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Ecozones are described by the basal physical features of the environment: geological structure and chemistry, the landforms which have developed on the geological underpinnings over time, and climate. These are major geographical units with a characteristic macro climate, whose constituent physiographic forms, faunal and floral realms, hydrological systems and soils are inter-related. This paper examines the 33 earthworm species in three families recorded in the 15 Canadian ecozones. There is a discussion on the effect of climate change may have on earthworm's northern migration. [ABSTRACT FROM AUTHOR]

In this paper, the stratigraphic occurrence of n -alkanes (C n) is investigated in three peat cores (Mildred, JPH4 and McMurray) from the ombrotrophic peatlands in northeastern Alberta, Canada, to determine their origin, biomass input, and paleoclimatic significance. The molecular composition of n -alkanes is dominated by the >C 21 medium- to long-chain homologues, with a strong odd over even predominance. A number of n -alkane-based indices (e.g. predominant n -alkane, C 23 /C 29 , C 23 /(C 27 + C 31), P aq , ACL, and CPI), show changing conditions in the organic matter (OM) input from Sphagnum species or terrestrial vascular plants, which increasingly contributed upwards in the peat profiles, and through time. P aq and C 23 /(C 27 + C 31) proxies are similar in the three cores, and allow us to infer vegetation variations that coincide with the climate alternations of the Medieval Warm Period (MWP), Little Ice Age (LIA), and modern Recent Warming (RW). The utilization of ACL-ket and (C 23 + C 25)/(C 27 + C 29 + C 31)-ket proxies, performed in comparison with n -alkane proxies, further support the biomarker-based reconstructions of paleoclimate variations over recent centuries. This study suggests that n -alkane homologues are sensitive to vegetation and climate changes and thus are reliable biomarkers for tracking past shifts in vegetation and climate variations in peat archives. • Determine organic matter source of peat sediments from n -alkane biomarkers. • C 23 /(C 27 +C 31) n -alkane proxy is proposed and can effectively characterize climate changes. • P aq proxy indication could be misleading when the contribution of Sphagnum fuscum to the peat is large. • n -Alkan-2-one proxy is studied to further confirm the biomarker-based reconstruction of paleoclimatic changes. [ABSTRACT FROM AUTHOR]

The Taltson magmatic and Thelon tectonic zones have historically been considered parts of a single orogen recording collision between the Slave craton and Buffalo Head terrane to the Rae craton between 2.0 and 1.9 Ga. The Taltson–Thelon connection stemmed from recognition that the Taltson magmatic zone coincides with the Taltson aeromagnetic high that extends northward and merges with the Thelon aeromagnetic high. Analysis of geophysical data in this study, however, coupled with recent mapping, indicates that this magnetic high is underlain in large part by rocks of Taltson basement complex. In addition, both basement rocks and Taltson-age plutons can be traced eastward into northern Saskatchewan, below Athabasca Basin cover, and reappear/re-emerge to the south where they are truncated by the Virgin River shear zone (Snowbird tectonic zone). This paper presents new field, geochronological and geochemical data for the Lloyd domain of Saskatchewan bearing on the extent and nature of the Taltson orogen. The Lloyd domain is underlain mainly by magnetic dioritic–granodioritic orthogneisses and subordinate supracrustal rocks. It also hosts the Clearwater anorthosite complex, a ∼300 km 2 , northeast-elongate gabbro-anorthosite intrusion about 15 km northwest of the Virgin River shear zone. While previous geochronology established that some Lloyd domain orthogneisses are of Taltson (i.e., 1.98 Ga) age, geochronology presented herein has identified an appreciably older (ca. 2460 Ma) component. Geochemical study indicates that these older metaplutonic gneisses are distinguishable from younger (Taltson-age) ones based on trace element characteristics, but the true extent of basement rocks is impossible to evaluate. U–Pb geochronological data from the Clearwater anorthosite complex are complicated but allow interpretation that it was emplaced into this older basement complex at ca. 2.1 Ga and was subsequently metamorphosed during Snowbird orogenesis at ca. 1.9 Ga. Geochemical study also indicates that the Taltson-age quartz dioritic to granodiorite suite in Lloyd domain is chemically related but less evolved than the younger dominantly granitic, Taltson magmatic zone plutons of Alberta and N.W.T. The two are interpreted to be related and reflect gradual evolution of a subduction-related continental magmatic arc, challenging previous models invoking intra-plate magmatism. Collectively, these data, along with regional geological relationships, indicate that the Taltson orogen originally trended northwest–southeast and is a unique tectonic entity, distinct from the Thelon tectonic zone. Two alternative models are provided for Taltson orogeny. In the first, the Thelon orogeny develops along the margin of the Slave craton due to accretion of the Buffalo Head terrane between 2.0 and 1.95 Ga. In the meantime, the Taltson arc was built on the southwest margin of the Rae province as the now combined Slave craton and Buffalo Head terrane approached. Terminal collision of the Rae and Slave culminated with high-grade metamorphism between 1.94 and 1.93 Ga. In the second, the Slave craton was attached to the Rae craton far in advance of the Taltson orogeny, perhaps during the ca. 2.5–2.3 Ga Arrowsmith orogeny. In this model, the Taltson orogeny developed on the southwest margin of the amalgamated Rae-Slave craton due to accretion of the Buffalo Head terrane and the Thelon tectonic zone represents an intracontinental zone of reworking. [ABSTRACT FROM AUTHOR]

• The 1853 ± 11 Ma Fröderyd Group represents a rifted volcanic arc in SE Sweden. • The volcanic arc activity was simultaneous with 1.86–1.85 Ga granitoid emplacement. • The Fröderyd Group is comparable with the Flin Flon rifted arc in Canada. • The Vetlanda and Västervik metasedimentary rocks formed at two separate events. The Fröderyd Group forms part of the Vetlanda-Oskarshamn belt (also known as the Oskarshamn-Jönköping Belt), which is a piece of Palaeoproterozoic crust that is completely encapsulated by 1.81–1.77 Ga granitoids of the Transscandinavian Igneous Belt in the southern part of the Fennoscandian Shield. New U-Pb zircon data from a felsic metavolcanic rock in the Fröderyd Group have been acquired using LA-ICP-MS single collector. The age is determined to 1853 ± 11 Ma. The Fröderyd Group is interpreted to represent a volcanic arc that was located southwest of the margin to the proto-continent Fennoscandia. Tonalitic magma, identified in the Eksjö-Bäckaby regions, formed the middle crust in this arc complex and intruded the volcanic arc rocks at ca. 1.83–1.82 Ga. When this arc complex gradually approached the margin to the proto-continent Fennoscandia, parts of it were uplifted above sea level and initiated lacustrine sedimentation in restricted basins, which now are found in the Vetlanda region. Parallel with the development of this arc complex, 1.86–1.85 Ga granitoids intruded the margin to the proto-continent Fennoscandia and 1.87–1.86 Ga clastic metasedimentary rocks in the Västervik area in an Andean-type active continental margin. It can be concluded that the Vetlanda and Västervik sedimentary basins formed in two completely different geological environments during two separate events. The Västervik sediments formed along the margin to the proto-continent Fennoscandia before the Fröderyd arc system had developed while the Vetlanda sediments formed in a post-arc environment outboard to the southwest of the margin to the proto-continent Fennoscandia. It is suggested that the mafic volcanic rocks close to the lake Nömmen should be excluded from the Vetlanda supergroup and instead be related in time to the Fröderyd Group. This paper presents an interpretation of the tectonic evolution including volcanic arc and rifted volcanic arc during the 1.87 to 1.77 Ga time span with relevance to the evolution of the active southwestern margin of the proto-continent Fennoscandia depicted as a sequence of schematic profiles. [ABSTRACT FROM AUTHOR]

This Special volume published by the Canadian Journal of Earth Sciences consists of a collection of six papers on the petrology, geochemistry, and metallogeny of igneous rocks emplaced in large igneous provinces (LIPs). The papers provide a snapshot of results presented at a Special Session of the 2017 Geological Association of Canada – Mineral Association of Canada Joint Annual Meeting held in Kingston, Ontario, by members of the vibrant geoscience community dedicated to the study of LIPs. Participants applauded the idea of a joint session on these topics and as a result, the session fostered animated discussions and new collaborations. The scope of magmatic and metallogenic studies of LIPs often precludes the type of brainstorming that took place during the meeting. This Special volume demonstrates that a robust understanding of magmatic processes represents the essential first step towards the search for mineral deposits in LIPs worldwide. [ABSTRACT FROM AUTHOR]