The paleoecological significance of new species of Limbicysta (Acritarcha) from the upper Albian of the Canadian Arctic Islands

Abstract

Umbicysta octopedifomis and Limbicysta quadriformis are new acritarch species from the upper Aibian Bastion Ridge and Strand Fiord formations of the Sverdrup Basin, Canadian Arctic Islands. They are similar to the type species, Limbicysta pediformis Marshall, but have eight asymmetric or four symmetric process tips versus the four asymmetric and one symmetric process tips of L, pediformis. They are distinguished from other species of Limbicysta by their single wall layer, lack of longitudinal folds, and degree of compression. Like other species of Limbicysta, both new species are found associated with indicators of brackish-water paleoenvironments-in this example, assemblages dominated by terrestrial palynomorphs and with a low diversity of dinoflagellate cysts dominated by Nyktericysta spp, and acritarchs.

Sedimentary successions and palynoevent stratigraphy from the non-marine Lower Cretaceous to the marine Upper Cretaceous of the Nuussuaq Basin, West Greenland

“…The Kingittoq Member, dated as Cenomanian is characterised by common to abundant Rugubivesiculites rugosus pollen. MacRae et al (1996) reported a similar assemblage from the suggested upper Albian or younger, uppermost Bastion Ridge and Strand Fiord formations in Arctic Canada. The brackish water interval is characterised by the presence of Limbicysta octopediformis, Luxadinium spp., Nyktericysta arachnion, Quantouendinium sp., Wuroia sp., and the alga Tetraporina.…”

“…The dinocyst assemblage is only represented by the brackish water genera Balmula, Nyktericysta, Pseudoceratium, and Vesperopsis, originally described from fluvial to estuarine deposits of early late Albian age of the Western Interior, USA (Bint, 1986) and later reported from brackish water deposits of Albian age from eastern Canada (Zippi, 1998) and late Albian age from Arctic Canada (MacRae et al, 1996). Nøhr-Hansen and McIntyre (1998) recorded few Nyktericysta davisii and Psedoceratium interiorense, together with marine dinocysts of late middle Albian age, from Axel Heiberg Island, Arctic Canada.…”

“…The lower terrestrial assemblage is dominated by spores and pollen. Their dating was based on the presence of a diverse, normal marine dinocyst assemblage with the upper Albian marker species Chichaouadinium vestitum, Pseudoceratium expolitum, and Wigginsiella grandstandica in the underlying lower part of the Bastion Ridge Formation (MacRae et al, 1996). Nyktericysta arachnion becomes common upward.…”

“…The positions of the Cretaceous shorelines are poorly known due to uplift and erosion (Green et al, 2013). Stressed late Albian nearshore marine environments, probably brackish, are indicated by common occurrences of the acritarch Limbicysta together with dinocysts belonging to the genus Nyktericysta, common in the Sverdrup Basin, Canadian Arctic Islands (MacRae et al, 1996). A large influx of fluvial water into the Labrador Sea-Davis Strait-Baffin Bay seaway may thus have reduced the salinity.…”

Multistage Cretaceous magmatism in the northern coastal region of Ellesmere Island and its relation to the formation of Alpha Ridge – evidence from aeromagnetic, geochemical and geochronological data

“…The outline of Fig. 3 MPFZ -Mitchell Point Fault Zone, PBF -Petersen Bay Fault, PI -Phillips Inlet, WIC -Wootton Intrusive Complex, YB -Yelverton Bay. and sanidine data, MacRae et al, 1996), of 102.5 ± 2.6 Ma (whole-rock age, Estrada & Henjes-Kunst, 2013) and of 95.3 ± 0.4 Ma (whole-rock age, Tarduno et al, 1998) were reported for the Strand Fiord Formation. Basalts within the stratigraphically equivalent Hassel Formation are exposed on northern Amund Ringnes Island (Balkwill, 1983), Ellef Ringnes Island (Evenchick et al, 2015), and northeast Ellesmere Island (Embry & Osadetz, 1988;Osadetz & Moore 1988).…”