Provenance and depositional environment of organic-rich calcareous black shale of the Late Ordovician Macasty Formation, western Anticosti Basin, eastern Canada

Research on the Late Ordovician Macasty Formation in Anticosti, Canada, reveals that its organic-rich black shale was deposited under anoxic conditions during the Taconic orogeny. Neodymium isotope analysis indicates a predominantly Grenvillian provenance, with intense weathering of source rocks contributing to fine-grained detritus deposition. The study also highlights the enrichment of redox-sensitive elements (As, V, U) and high δ34S for pyrite, supporting anoxic conditions at the sediment-water interface. Calcite cement formation during low-temperature diagenesis (<60 °C) further explains the preservation of organic matter in this shale.

Hattori, K., Desrochers, A., & Pedro, J. (2019). Provenance and depositional environment of organic-rich calcareous black shale of the Late Ordovician Macasty Formation, western Anticosti Basin, eastern Canada. Canadian Journal of Earth Sciences, 56(3), 321–334. https://doi.org/10.1139/cjes-2018-0095