We review currently available Canadian and international lithostratigraphic and lithodemic schemes and find most of them inadequate for classifying intrusive and strongly metamorphosed rocks of Canada and beyond. A new system is proposed, one that unifies, complements, and extends components of the revised North American Stratigraphic Code, the British Geological Survey Rock Unit Classification System of 2021, and the International Stratigraphic Guide of 1999. This new Cooperative Lithodemic and Stratigraphic System (CLASS) is intended to serve as a practical guide to geoscientists who need to classify and report on lithodemic units in North America and has broad applicability to other jurisdictions. It is built with database management practices in mind and employs the concept of inheritance of root characteristics between seven formal rock unit ranks, which will allow incorporation of the scheme into compact object-oriented and relational databases designed for purpose. Broad application of CLASS, especially to historically problematic lithodemic units, should help to foster jurisdictional interoperability, data sharing, global compilations, and thematic studies. At the heart of this proposed system is a subdivision and accompanying nomenclature that allows classification of rocks into seven formal ranks. Following the well-established lithostratigraphic supergroup, group, subgroup, formation, member, submember, and bed approach, CLASS proposes three classes of lithodemic subdivisions for formally naming lithodemic rock units.

The Beaverlodge district in northern Saskatchewan is known for "vein-type" uranium mineralization. Most of the uranium deposits are spatially related to major structures, and hosted by ca. 3.2-1.9 Ga granitic rocks (and albitite derived from them) and by ca. 233 Ga Murmac Bay Group amphibolite, all of which are unconformably overlain locally by deformed but unmetamorphosed redbeds of the ca. 1.82 Ga Martin Group, and by the flat-lying ca. 1.75-1.5 Ga Athabasca Group. The uranium mineralization is mainly hosted in fault rocks (breccias) and carbonate +/- quartz +/- albite veins, referred to as breccia-style and vein-style mineralization, respectively, with the latter being the focus of this study. Most of the mineralized veins occur in the basement rocks, although some crosscut the Martin Group. This study examines the field, petrographic, fluid inclusion and C-O isotope characteristics of mineralized and non-mineralized veins from 19 deposits/occurrences as well as from the Martin Group, with an aim to better understand the mineralizing environment and processes.The coexistence of liquid-dominated (L + V), vapour -dominated (V + L) and vapour-only (V) fluid inclusions within individual fluid inclusion assemblages (FlAs) in the veins suggests fluid immiscibility and heterogeneous trapping. The L + V inclusions with the lowest homogenization temperatures (T-h) within individual FIAs are interpreted to represent homogeneous trapping of the liquid phase, which yield Th values from 78 degrees to 330 degrees C (mainly 100 degrees to 250 degrees C), and salinities from 0.2 to 30.8 wt.% NaCI equivalent. Mass spectrometric analysis of bulk fluid inclusions shows that the volatiles are dominated by H2O (average 97.2 mol%), with minor amounts of CO2, CH4, H-2, O-2, N-2, Ar and He. Fluid pressures were estimated to be <200 bars based on the inference of fluid immiscibility, fluid temperatures of 100 degrees to 250 degrees C, and low concentrations of non-aqueous volatiles (<3 mol%). The delta O-18(vpDB) and delta C-13(vpDB) of carbonate minerals associated with mineralization range from -20.5 to -8.9%0 and -10.1 to - 0.9%., respectively. The delta O-18(vsmow) values of the parent fluids calculated using the Th values range from -9.6 to +17.0%, with the majority from 0 to + 5.0% O isotopes of paired equilibrium quartz and calcite, analyzed by secondary ion mass spectrometry (SIMS), yield temperatures from 161 degrees to 248 degrees C, which are consistent with the fluid inclusion data.The new fluid inclusion and stable isotope data are inconsistent with a metamorphic or magmatic-hydrothermal model as proposed in some previous studies (for breccia-style and vein-style mineralization), but rather support a model in which the vein-type uranium mineralization took place at relatively low temperature (100 degrees to 250 degrees C) and shallow (<2 km) conditions, with fluid pressure fluctuating between hydrostatic and sub-hydrostatic regimes, possibly related to episodic faulting. The mineralizing fluids were mainly sourced from the Martin Lake Basin, and uraninite was precipitated as a result of mixing between this basin-derived fluid and fluids carrying reducing agents (Fe2+, CH4) derived from the basement, although fluid-rock reactions and fluid immiscibility may have also played a role. (C) 2016 Elsevier B.V. All rights reserved.

Single detrital zircon grains from various parts of the Wollaston Group, a Paleoproterozoic metasedimentary succession deposited along the southeastern margin of the Hearne Province, northern Saskatchewan, Canada, were analyzed by SHRIMP U–Pb geochronological techniques. Zircon analyses are mostly concordant and yield ages ranging from ca. 2800 to 1780Ma, although distinct age populations were detected in all samples. The stratigraphically oldest sample (Geoch 4) is dominated by a bimodal distribution of zircon ages (ca. 1.90 and 2.4–2.6Ga), which is similar to that preserved in the sample (Geoch 2) from the middle portion of the Wollaston Group. The stratigraphically youngest sample (Geoch 9) contains ca. 2.1Ga zircons, as well as zircons with the same ages as observed in Geoch 4 and Geoch 2. Zircon ages older than 2450Ma appear to be consistent with the age of the Hearne Province basement, suggesting that part of the sedimentary detritus was locally derived. Zircons with ages in the 2430–2350Ma range, found in all samples, may have been derived from a more distant source, such as Rae Province rocks that were affected by the recently identified Arrowsmith orogeny. Significant amounts of 1920–1880Ma zircon grains are found in all samples; these are interpreted to represent sedimentary detritus derived from juvenile volcanic terranes. Zircons younger than 1860Ma are interpreted to be the product of post-Wollaston Group thermal overprinting. Our data, together with field relationships and geochemical data, suggest that most of the preserved Wollaston Group was deposited in a back-arc to foreland basin environment. It received detritus from both Archean continental crust to the west and a juvenile continental magmatic arc, likely located to the east, as the youngest zircon ages are not consistent with the age of Taltson Orogen rocks to the west.

The Cree Lake Zone in the southwestern part of the Hearne craton, reworked during the Paleoproterozoic Trans-Hudson orogeny, includes the Wollaston Group, a sequence of Paleoproterozoic metasedimentary rocks. As these rocks have been multiply deformed and metamorphosed to high-grade, a geochemical and isotopic study was initiated to see through the overprinting events to better constrain the provenance and evolution of the Wollaston Group.The Wollaston Group consists of thick sedimentary successions representing different depositional and tectonic environments that can be subdivided into two subgroups. The Lower subgroup is represented by deep-water turbidite to shallow-water marine deposits. The Upper subgroup, separated from the Lower one by a regional unconformity, comprises molasse-type assemblages ranging from talus to shallow-marine/lacustrine, with subordinate volcanogenic rocks. Major and trace element data obtained from 31 psammopelitic rocks indicate that the clastic material was derived from sources consisting of both felsic and malic material, although felsic sources are more important in the samples from the Lower subgroup. Sedimentary tectonic discrimination diagrams demonstrate that most of the Wollaston Group was deposited on an active continental margin rather than a passive margin. The epsilon(Nd) values for the Wollaston Group psammopelites, calculated at 1.92 Ga, the approximate age of the boundary between the Lower and Upper subgroups, vary from -3.4 to -6.8, which yields an approximate 70:30 mixture between juvenile Paleoproterozoic detritus and Archean detritus from the Hearne craton. A secondary source of detritus may be 1.95-2.0 Ga rocks of the Taltson Orogen, which is exposed to the west of the Archean Rae-Hearne craton.The Wollaston Group records the complete evolution of the western margin of the Trans-Hudson Orogen during the Paleoproterozoic. The rifting of an Archean continent at ca. 2.1 Ga led to the deposition of the passive margin siliciclastic sediments comprising the lowermost, but poorly preserved part of Wollaston Group. The formation of a continental arc (Rottenstone) along the Hearne margin at ca. 1.92 Ga resulted in a change in tectonic environment from a passive margin to a back-arc basin, and detritus in most of the Lower subgroup was then derived from both basement and newly formed magmatic arc. Collision with the juvenile La Ronge arc led to uplift along the Hearne margin which transformed the back-arc basin into a retroarc foreland basin at ca. 1.88 Ga. Sedimentary starvation and shallowing of the basin led to widespread accumulation of carbonate and evaporite deposits in the west, whereas rapidly uplifted orogenic belts in the east provided sources of coarse-grained elastic detritus, forming the Wollaston Upper subgroup. Closure and inversion of the sedimentary basin occurred by ca. 1.86 Ga, coincident with the emplacement of mafic to felsic intrusive rocks in the Cree Lake Zone and the emplacement of the voluminous ca. 1860 Ma Andean-type Wathaman batholith into the continental margin. Closure was manifested by the onset of foreland-directed thrusting of the Wollaston Group. (C) 2003 Elsevier Science B.V. All rights reserved.