Abstract

The Cambrian Anse Maranda Formation is a glauconite-bearing clastic succession within the Quebec Reentrant. It is part of the Appalachians Humber Zone, particularly of the shale – feldspathic sandstone assemblage, which represents the rift-to-drift deposits of the Laurentian margin. The massive sandstones of the Anse Maranda were originally interpreted as the proximal turbidites of a deep-sea fan. The occurrence of glauconite and the high degree of bioturbation, which give the sandstones a massive aspect, suggest a different depositional environment. Detailed ichnology and lithofacies descriptions indicate that the Anse Maranda predominantly represents shelf sediments deposited in storm-influenced environment and that intense bioturbation destroyed most of the sedimentary structures. The paleogeographic reconstruction suggests that the Anse Maranda was deposited seaward of a headland identified as the Montmorency Promontory, along a narrow shelf with an irregular topography. Some coeval turbidites of similar composition were deposited in the deeper sub-basins. This reconstruction allows for sustained sediment-starved conditions to be maintained for more than 10 Ma and to produce anomalously thick glauconite-bearing succession. The bioturbation has influenced the diagenetic evolution of the Anse Maranda Formation. The laminated sandstones and burrows were cemented by early calcite, while the microporosity of the bioturbated sandstones lasted longer and permitted the formation of a muddy pseudomatrix.

You do not currently have access to this article.