Conodonts and corals in kimberlite xenoliths confirm a Devonian seaway in central Ontario and Quebec

Eighteen samples containing sedimentary rock xenoliths were obtained from c ores drilled into eight Mesozoic kimberlite pipes in the Kirkland Lake area , Ontario, and in Ontario and Quebec near Lake Timiskaming. Nine samples fr om five pipes contained fossils that were used for age determinations. Thes e fossils are Middle or Late Ordovician graptolites, inarticulate brachiopo ds, and conodonts; Silurian and (or) Devonian conodonts; Early Devonian col onial corals; a Devonian stromatoporoid; and Early to Middle Devonian conod onts. Regionally, conodonts are unaltered (conodont colour alteration index , CAI 1). Conodont CAI values from the xenoliths are elevated (CAI 2), and a few conodonts have surface colour changes, suggesting hydrothermal altera tion. Age determinations allow stratigraphic correlation between xenoliths and Paleozoic outcrops. For the Ordovician and Silurian samples, correlatio ns are made to exposures in the nearby Lake Timiskaming outlier. For the De vonian samples, the closest possible correlative outcrops are about 300 km away. These fossils provide the first physical evidence of a connection bet ween a Lake Timiskaming "basin" and other Ontario basins during at least pa rt of the Devonian. These strata persisted at least until the Mesozoic befo re they were removed by erosion.