The geological timescale was developed during the 19th century and is based mainly on invertebrate fossils. The problem is that this type of fossil is rarely encountered in subsurface boreholes. Fortunately, many thousands of microfossils can be in a single subsurface sample, and they are precise markers of the age of the geological strata in which they are found. Without microfossils, we would only have a hazy notion of the evolution over time of oil-rich sedimentary basins such as the Jeanne d’Arc Basin, located on Newfoundland’s Grand Banks, that is home to Hibernia and other major oil fields.
The Geological Survey of Canada has become an international leader in using microfossils to date the strata of sedimentary basins and to assess past environments. Inorganic-walled microfossil groups include conodonts (tiny tooth-like structures of early chordates), foraminifera, and ostracods.
The study of organic-walled microfossils is called palynology and encompasses fossil spores, pollen, dinoflagellates and other groups. The photograph shows Palaeoperidinium pyrophorum, a dinoflagellate that became extinct some 58 million years ago. When a palynologist encounters this microfossil in drill-core samples, he or she can assign an accurate age range to the sample.
Category: Science Advances
Williams, G.L., Fensome, R.A., and Dehler, S.A., 2014. Rocks of the deep: the subsurface geology of offshore eastern Canada; in Voyage of Discovery: Fifty years of Marine Research at Canada’s Bedford Institute of Oceanography, (ed.) D.N. Nettleship, D.C. Gordon, C.F.M. Lewis, and M.P. Latremouille; Bedford Institute of Oceanography-Oceans Association, Dartmouth, Nova Scotia, p. 215–223.