Aspects of problematic acid-resistant, organic-walled microfossils (acritarchs) in the upper proterozoic of the north atlantic region

1981 ◽  
Vol 15 (1) ◽  
pp. 9-23 ◽  
Author(s):  
G. Vidal
1993 ◽  
Vol 167 ◽  
pp. 1-38
Author(s):  
M Sønderholm ◽  
H Tirsgaard

In the region between Canning Land (71° 30’N) and Bessel Fjord (76°N) the Eleonore Bay Supergroup is up to 16 km thick and comprises both metasediments and sediments. It is divided into five new groups. In the eastern outcrops four groups are found; these are from base to top: the Nathorst Land Group (up to c. II 000 m thick), the Lyell Land Group (2000-2800 m thick), the Ymer Ø Group (900-1300 m thick) and the Andrée Land Group (900-1500 m thick). The lower two of these groups consist of altemating sandstones and mudstones (and their metamorphic equivalents). Information on the depositional environment of the Nathorst Land Group is scarce, but both fluvial and marine settings have been tentatively proposed. The Lyell Land Group mainly represents marine shelf environments. The Ymer Ø and Andrée Land Groups are dominated by carbonates deposited in a platform, slope and basinal environment. Furthest west, in the nunatak region, a succession of sandstones and mudstones more than 6300 m thick is included in the Petermann Bjerg Group. The stratigraphic relationship between the Petermann Bjerg Group and the rest of the Eleonore Bay Supergroup is uncertain but possibly correlates with parts of the Nathorst Land and Lyell Land Groups. The Eleonore Bay Supergroup is finally compared with other Upper Proterozoic successions in the North Atlantic region.


1998 ◽  
Vol 1 (1) ◽  
pp. 41-54 ◽  
Author(s):  
Tom Amorosi ◽  
Paul C. Buckland ◽  
Kevin J. Edwards ◽  
Ingrid Mainland ◽  
Tom H. McGovern ◽  
...  

2021 ◽  
Vol 3 (3) ◽  
Author(s):  
John Crossley ◽  
Christopher A. Skilbeck

This article describes a study of Tripleurospermum maritimum (L.) W.D.J. Koch and T. inodorum (L.) Sch. Bip. (Asteraceae) in the Orkney Islands (v.c.111), the results of which suggest that intermediates between these taxa may be rather common, and that T. maritimum subsp. nigriceps and subsp. maritimum are both involved, the former more frequently. Obviously this results in a complex taxonomic situation, evidently not confined to Orkney in the far north. Key identifying characters of the taxa are systematically examined and guidance offered on determining hybrids using a population level approach. The taxonomic complexities of these northern populations are discussed, with regard in particular to the identity of T. inodorum occurring there and the place of T. maritimum subsp. nigrescens in the forms and subspecies of T. maritimum found in the north Atlantic region.


Sign in / Sign up

Export Citation Format

Share Document