Late Triassic to early Jurassic microfossils and palaeoenvironments of the Waterloo Mudstone Formation

[摘要] Northern Ireland Waterloo Mudstone Formation has received relatively little attention due to the scarcity of exposures and poor availability of subsurface records. The recent recovery of latest Triassic to Early Jurassic strata from boreholes permits further study of biostratigraphical and palaeoenvironmental using foraminifera and ostracods. The samples are from boreholes (Ballinlea-1, Magilligan and Carnduff-1) and exposures (White Park Bay, Tircrevan Burn, Larne, Ballygalley, Ballintoy and Kinbane Head). The age of the sections, established using foraminiferal biozonation ranges from latest Triassic (Rhaetian) to earliest Pliensbachian (JF9a). The assemblages recovered broadly similar to those elsewhere in NW Europe; European Boreal Atlantic Realm. The latest Rhaetian to earliest Sinemurian low diverse microfossil assemblages dominant by metacopid ostracods with occasional influx of opportunist foraminifera but gradually, foraminiferal abundances exceed the ostracods in the Early Sinemurian onwards with their highest diversity in the Late Sinemurian. The foraminiferal assemblages are dominated by foraminifera of the Lagenida, other groups include the Miliolida, Buliminida and Robertinida.Based on the microfossils, the sediments are considered to represent confined inner shelf environment in latest Rhaetian to Hettangian then gradually recovered to well-oxgenated, open marine deposits of outermost inner shelf to middle shelf in Early Sinemurian to Early Pliensbachian.

[发布机构] University:University of Birmingham;Department:School of Geography, Earth and Environmental Sciences, Department of Earth and Environmental Sciences

[关键词] G Geography. Anthropology. Recreation;GB Physical geography