Cenozoic ichthyolith biostratigraphy: Tofino Basin, British Columbia

Abstract

Five new late Eocene -Pliocene ichthyolith zones are defined based on indigenous faunal occurrences in strata that outcrop along western Vancouver Island and samples from six offshore Tofino Basin wells. Five new interval zones are each defined based on distinct transported ichthyolith assemblages. Results are correlated within the framework of established Cenozoic west coast and Arctic foraminifer zones and ichthyolith occurrences in deep-sea core samples and Cretaceous Queen Charlotte Group and Nanaimo Group strata of coastal British Columbia. The use of multiple data sets was important to interpret complex active tectonic margin sedimentation and structures. The integrated ichthyolith and foraminifer biostratigraphy allowed an interpretation of well log data and lithology reports. Also, we reassessed previous offshore seismic data, evaluated fossil preservation and thermal alteration, and distinguished transported from indigenous ichthyolith occurrences. These data allowed a reinterpretation of tectonic segments and associated strata of the Pacific Rim and Crescent terranes and the Cascadia Accretionary Complex onshore and offshore Vancouver Island.

Two pulses of morphological diversification in Pacific pelagic fishes following the Cretaceous–Palaeogene mass extinction

“…Fish teeth have distinct morphological shapes that are likely a combination of taxonomic history and ecological role, and which exhibit distinct stratigraphic ranges (figure 1). To quantify morphological variation in these microfossils, we developed and employed a character-based coded system to create a non-hierarchical, 'taxon-free' morphological classification based on prior ichthyolith work [22,23,[48][49][50][51][52], updated to include additional morphological diversity, and to use reflected, rather than transmitted light microscopy (see electronic supplementary material for details of the full coding scheme and electronic supplementary material, figure S1 for a visual summary of the characters considered). For this study, we defined any tooth that had a unique set of character-states as a distinct morphotype: 136 unique tooth morphotypes were identified and given descriptive inhouse names to facilitate analysis.…”

Optical thermal maturity parameters and organic geochemical alteration at low grade diagenesis to anchimetamorphism: A review

“…3) successfully applied these microfossils to decipher complex tectonic structures, basin evolution (Johns et al, 2006(Johns et al, , 2012, thermal anomalies (Johns et al, 2000(Johns et al, , 2012 and regional maturation patterns for hydrocarbon exploration (Johns et al, 1999a(Johns et al, , 1999b(Johns et al, , 2000. In these publications the ichthyolith alteration index (IAI) was introduced which closely follows CAI values.…”

“…Johns et al, 2006). As they are composed of biogenic apatite, the primary oxygen isotope signal may be preserved provided that diagenetic recrystallization did not alter the original isotope composition.…”

Barkley Canyon Gas Hydrates: A Synthesis Based on Two Decades of Seafloor Observation and Remote Sensing

“…The occurrence of the gas hydrate mounds and associated leakage of thermogenic hydrocarbons at Barkley Canyon is rather unique. No location with similar gas composition has been identified to date along the northern Cascadia margin, despite the wide spatial extent of the oil-bearing Tofino Basin (e.g., Johns et al, 2006;Hayward and Calvert, 2007;Johns et al, 2012), the presumed source region for the thermogenic hydrocarbons leaking at Barkley Canyon (Pohlman et al, 2005). Compositional and carbon isotope ratio data from gases extracted from oil samples collected in 2011 (Figure 12) further strengthen this link.…”