| The Ferryland Head Formation of Ediacaran age is exposed along the southeastern coast of the Avalon Peninsula, Newfoundland and Labrador. A detailed sedimentological study was undertaken at Ferryland, its type locality, 72 km south of St. John's, where approximately 500 m of the formation are exposed. The objectives of this study are to establish a stratigraphic and sedimentological framework in order to determine depositional environments and the stratigraphic evolution of the succession and to document the diversity of synsedimentary structures. Three detailed stratigraphic sections, covering approximately 600 m were constructed.; The Ferryland Head Formation consists of interbedded tabular reddish-to-purplish-brown siltstones and buff-to-greenish-grey arenites with minor occurrences of lithic arenites and lithofeldspathic arenites. Grain size varies from silt to medium sand; the mode being fine sand. Five lithofacies including 22 subfacies are defined at Ferryland. Facies 1 comprises siltstone and finer grained sandstones. Facies 2 encompasses silty sandstone. Facies 3 is composed of clean sandstone. Facies 4 and 5 comprise intraformational conglomerates and ash-rich beds respectively. Three facies associations are recognised in the Ferryland Head Formation. Facies association I is interpreted as mouth-bar deposits, facies association II is interpreted as channelised sediments and facies association III is interpreted as overbank deposits. Palaeoflow in the study area is unimodal and south-directed. The depositional environment for the Ferryland Head Formation is interpreted to be a humid fan delta. The abundance of synsedimentary structures in the study area is attributed to rapid deposition, a high water table and probable seismic activity in a tectonically active pull-apart basin. |
