Analyzing spatial patterns of thermal alteration in the Stikine and Wrangell terranes of the Canadian Cordillera using the conodont color alteration index (CAI) to identify hot spots and cold spots

Abstract

Spatial analysis has been conducted on CAI data from archival conodont collections across the Canadian Cordillera of British Columbia and Yukon, creating thermal alteration maps with Kriging interpolation surfaces and Getis-Ord Gi* statistical hot spots. Major hot spots include the southeast corner of British Columbia, the central coast of British Columbia, southern Vancouver Island, and most of the British Columbia - Yukon border. Major cold spots include the northeast quadrant of British Columbia, the northern tip of Vancouver Island, and central Haida Gwaii. Hot spots on Vancouver Island generally correlate with the prevalence of intrusive units nearby; however, the largest hot spot coincides with a southern region unique on the island for having significant outcroppings of Permian limestone, which is more heavily altered than the Triassic limestones commonly sampled for conodonts further north on the island. Comparison of locations where paleoenvironmental studies have utilized delta-13C, both near the British Columbia - Yukon border, as well as at the far north of Vancouver Island, demonstrates that stratigraphic sections which preserves a primary delta-13C signal tends to be situated closer to the center of a thermal alteration cold spot than sections that do not. Beyond the select examples discussed in this study, the broader analysis has potential applications in a wide variety of research, from Cordilleran tectonics to preliminary hydrocarbon exploration.