Acritarch biostratigraphy and taxonomy of the Winterhouse Formation (Upper Ordovician), Port au Port Peninsula, Newfoundland.

摘要

The Upper Ordovician Winterhouse Formation (Long Point Group) is exposed only along the northwestern coast of Long Point on the Port au Port Peninsula, southwest Newfoundland. Detailed acritarch study of this formation has identified 74 palynomorph species assigned to 31 genera. One new combination, Ammonidium parvipinnatum (Uutela and Tynni), is proposed here. Fossils are extremely well preserved. An average Acritarch Alteration Index of 1.6 {dollar}pm{dollar} 0.3 in transmitted light corresponding with clear and colourless to pale yellow and white to bright yellow in fluorescence, indicates that these acritarchs have undergone very little thermal maturation. These rocks sit at or above the oil window. Co-occurrence of Villosacapsula setosapellicula, Multiplicisphaeridium irregulare, Ordovicidium heteromorphicum, Petaloferidium stigii, Cheleutochroa diaphorasa, Dicommopalla macadamii, Actinotodissus crassus, Poikilofusa spinata, and Excultibrachium concinnum confirm the middle to late Caradoc age assignment of Quinn et al. (in prep.).; In distribution, a minimum of three acritarch assemblage zones are defined from palynomorph counts and statistical analysis. (Abstract shortened by UMI.)