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Canada is one of the most important diamonds producers in the world despite the first diamond mine opening relatively recently in 1998 in the Slave craton. Given the increasing economic and scientific interest towards Canadian diamonds, an investigation of their geochemical and petrological properties was needed to better understand their genesis. A detailed review is given of all available petrological and geochemical data from >3000 Canadian diamonds and their silicate, oxide and sulfide inclusions from published literature and unpublished datasets, compared with data from worldwide datasets. Based on the available published data, different abundances of peridotites and eclogites in the lithosphere of the Canadian cratons are indicated by mineral inclusions, with the Slave craton exhibiting a high amount of eclogitic diamonds, and the Superior craton exhibiting a strong prevalence of peridotitic diamonds. Diamond formation from extremely 13C-depleted subducted organic matter is necessary to explain the extremely low δ13C observed in some samples from the Canadian lithosphere, which, as of today, are the lowest values ever recorded in mantle diamonds. Core-to-rim δ13C analyses revealed progressive rimward enrichment in 13C for some of the samples, a behavior which is associated to the crystallization of diamonds from oxidized C species (e.g., CO 2). Using the available data geothermobarometric calculations were performed on both single inclusions and inclusion pairs and provide a formation window for Canadian lithospheric diamonds from ∼140 to ∼210 km, with temperatures ranging from 900 to 1400 °C, which are generally higher than mantle residence temperature given by N aggregation geothermometry. Sub-lithospheric diamonds are sampled from ∼240 km to >660 km based on geobarometry on majoritic garnets and observations of inclusion assemblages. The age range of Canadian diamonds suggest numerous diamond-forming events that took place from the Paleo-Archean to the Neoproterozoic. • Petrological and geochemical differences exist among Canadian cratons. • Diamonds formed in different pulses from the Paleo-Archean to the Neoproterozoic. • Oxidizing fluids are involved in the formation of Canadian diamonds. • Lithospheric diamond stability field extends from ∼5 to ∼7 GPa. [ABSTRACT FROM AUTHOR]

Highlights: [•] We investigated the molecular and isotopic compositions of biodegraded oils from the Alberta Basin. [•] Alberta heavy oils show increasing biodegradation from top to bottom of the oil columns. [•] The level of oil biodegradation varies regionally in the basin, ranging from PM2 to PM10+. [•] S and N isotopic compositions of the heavy oils are not affected by severe biodegradation. [•] The S and N isotopic compositions of biodegraded oils are indicative of the primary oil charge. [Copyright &y& Elsevier]

The South Mountain Batholith (SMB) of southwestern Nova Scotia is a large, highly differentiated, peraluminous, granitic batholith in which the average A/CNK (mol Al2O3/mol(CaO + Na2O + K2O)) increases from 1.16 to 1.23 with chemical evolution. We use vector analysis of variations solely in Al2O3–(CaO + Na2O + K2O) space to assess the fractionation, assimilation, fluid, and source controls on the peraluminosity of the SMB. With increasing chemical evolution, Al2O3 decreases, CaO decreases sharply, Na2O is approximately constant, and K2O increases in the early and middle stages but decreases in the most evolved stage. Initial 87Sr/86Sr and 143Nd/144Nd isotopic ratios for granites and average Meguma Supergroup country rocks suggest an upper limit of ~33% of wall-rock contamination for the most evolved rocks, if the most primitive rocks are uncontaminated. The trend of chemical evolution of the SMB through Al2O3–(CaO + Na2O + K2O) space is the resultant of all input vectors (processes). In the early stages, those processes are fractional crystallization of plagioclase ± K-feldspar ± cordierite ± biotite and contamination by country rocks. In the later stages, those processes are fractionation of plagioclase ± K-feldspar ± andalusite ± muscovite, further contamination by country rocks, and selective partitioning of Ca–Na–K into aqueous fluid phases. Clear geochemical evidence for variation in the source composition is lacking. [ABSTRACT FROM AUTHOR]

Presents a study that examined neodymium isotope geochemistry of felsic volcanic and intrusive rocks from the Yukon-Tanana terrane (YTT) in the Finlayson Lake region, Yukon, Canada. Geological setting of the YTT in the Finlayson Lake region; Geochemical attributes of the intrusive rocks; Systematics of the neodymium isotopes.

• Geochemistry, geochronology and zircon Hf isotopic compositions of the Eoarchean to Neoarchean crust from the Saglek-Hebron Complex (SHC). • The SHC felsic crust formed over one billion years through six distinct magmatic events. • Newly identified Paleoarchean Iluilik magmatic event. • Hadean to Eoarchean mafic crustal source for the SHC TTG. • Reworking of Eoarchean TTG producing granite over one billion years. • Distinct shift to more juvenile Hf isotopic composition at ∼3.2 Ga. • Implications for Earth's early crust evolution. The Saglek-Hebron Complex (SHC) located in Northern Labrador, Canada, includes some of the oldest crustal rocks on Earth. This granite-greenstone terrain is dominated by trondhjemite, Mg-rich tonalite, granite, with subordinate granodiorite, and recorded over one billion years of early magmatic history between ∼3900 Ma and ∼2700 Ma. New in-situ U-Pb analyses on zircons from eighteen rock samples, suggest that six distinct magmatic events formed the felsic crust of the SHC, during the Archean Eon. Age deconvolution analysis constrains these magmatic episodes at ca. 3857 Ma, 3744 Ma, 3575 Ma, 3330 Ma, 3224 Ma and 2750 Ma, respectively defined as the Iqaluk, the Uivak I, the Uivak II, the Iluilik, the Lister and the late granite events. The 3330 Ma Iluilik represents a newly defined magmatic event, distinct from the Lister event previously recognized at ∼3200 Ma. Uranium-Pb geochronology, combined with in-situ Hf isotopic data on zircons and geochemistry of the host rocks, reveal a complex and protracted crustal history of the SHC marked by the reworking of mafic and felsic crust over one billion years. Zircons from the oldest Iqaluk and Uivak I samples yield slightly suprachondritic initial εHf values (up to ∼+4), consistent with the involvement of a long-term depleted source in the Eoarchean. The 3330 Ma Iluilik granodiorite exhibits a low initial εHf value of −6, clearly diverging from the near-chondritic Hf isotopic composition of the 3224 Ma Lister tonalites. Considering a mafic crustal precursor (with a 176Lu/177Hf ratio of ∼0.02) for trondhjemite-tonalite-granodiorite (TTG) samples, the initial Hf isotopic compositions of the SHC Eoarchean to Paleoarchean zircons would be consistent with the reworking of Hadean mafic crust. The zircon εHf vs. time trend for granite samples corresponds to a 176Lu/177Hf ratio of ∼0.01, suggesting that the granitic crust was mainly produced by crustal reworking of the oldest TTG. Similarly to the felsic crust of the Itsaq Gneiss Complex of SW Greenland, the SHC granitoids appear to record a shift to more juvenile compositions at the end of the Paleoarchean. However, contrary to what is observed in SW Greenland, almost no input of juvenile material has been recorded by the SHC Neoarchean felsic crust. [ABSTRACT FROM AUTHOR]