Synthesis of chronostratigraphic data and methods in the Georgia Basin, Canada, with implications for convergent-margin basin chronology

Improved Provenance Constraints for Nanaimo Group Sediments, British Columbia, Canada, Through Zircon LA‐ICP‐MS Depth‐Profiling

“…B. Miller et al, 2009) (Figure 1). Minor Paleozoic populations in some samples are interpreted to have been derived from rocks of the Sicker Group of the Wrangellia terrane (Coutts et al, 2020;Mahoney et al, 2021), consistent with interpreted local sediment sources for similar populations in Comox Formation samples from the base of the Nanaimo Group (Alberts et al, 2021;Huang et al, 2019Huang et al, , 2022Mahoney et al, 2021) (Figure 2).…”

“…Facies 1 zircon populations are characterized by modes at 150 and 90 Ma and are interpreted to have been derived from the adjacent Coast Mountains Batholith and Cascade Crystalline Core (Alberts et al., 2021; Cecil et al., 2018; Coutts et al., 2020; Englert et al., 2018; Huang et al., 2019; Mahoney et al., 1999, 2021; Matthews, Guest, Coutts, et al., 2017; Mustard et al., 1995) where plutonic rocks of these ages are common (Cecil et al., 2018; Friedman & Armstrong, 1995; R. B. Miller et al., 2009) (Figure 1). Minor Paleozoic populations in some samples are interpreted to have been derived from rocks of the Sicker Group of the Wrangellia terrane (Coutts et al., 2020; Mahoney et al., 2021), consistent with interpreted local sediment sources for similar populations in Comox Formation samples from the base of the Nanaimo Group (Alberts et al., 2021; Huang et al., 2019, 2022; Mahoney et al., 2021) (Figure 2).…”

“…By the middle of the Campanian deep‐water depositional systems were established throughout the basin, and these are well studied in exceptional exposures of slope channel systems in the Gulf Islands (Bain & Hubbard, 2016; England & Hiscott, 1992; Englert et al., 2018; Katnick & Mustard, 2003). The chronology of the Nanaimo Group has largely been established through biostratigraphic and magnetostratigraphic techniques (e.g., Enkin et al., 2001; Haggart et al., 2005; Huang et al., 2022; McGugan, 1979, 1982; McLachlan & Haggart, 2018; Ward, 1978; Ward et al., 2012). Detrital zircon maximum depositional ages (MDAs) calculated using the youngest grain cluster that overlaps at 2 σ uncertainty (e.g., Coutts et al., 2019; Dickinson & Gehrels, 2009) have been shown to agree with paleomagnetic and biostratigraphic age constraints (Englert et al., 2018, 2020) and suggest the youngest Nanaimo Group unit (i.e., Gabriola Formation) can be no older than earliest Paleocene in age (64.3–63.0 Ma; Englert et al., 2020).…”

“…The provenance of the Nanaimo Group has been the focus of considerable interest due to the basin's importance in constraining Late Cretaceous paleogeographic reconstructions (Cowan et al, 1997;Housen & Beck, 1999;Huang et al, 2019Huang et al, , 2022Isava et al, 2021;Mahoney et al, 1999Mahoney et al, , 2021Matthews, Guest, Coutts, et al, 2017;Mustard et al, 1995). A recent basin-wide compilation of detrital zircon dating of the Upper Nanaimo Group (N = 49) by Coutts et al (2020) defined two major and three minor detrital zircon facies.…”

Stratigraphy, palaeogeography and evolution of the lower Nanaimo Group (Cretaceous), Georgia Basin, Canada

“…Arc-parallel variations in the physical parameters that drive high sedimentation rates result in highly variable and complex stratigraphic architectures and depositional histories that are further complicated by both coeval and post-depositional deformation and erosion. Consequently, stratigraphic frameworks developed for forearc basins are typically lithostratigraphic and/or biostratigraphic (Aksoy et al, 2005;Huang et al, 2019Huang et al, , 2022Takashima et al, 2004), and rarely genetic or sequence stratigraphic. Lithostratigraphic frameworks enable regional-scale geologic mapping of structurally deformed strata that are lithologically similar but spatially and temporally disconnected.…”