Late Ordovician brachiopods from eastern North Greenland:equatorial offshore migration of the Red River fauna

• Published in: Palaeontology
• Main Author: Mac Ørum Rasmussen, Christian
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2013
• Subjects: Kronprins Christian Land; Washington Land; Katian; Hiscobeccus fauna; BOrglum River Formation; Cape Calhoun Formation; Greenland; Kap; Kap Jackson; Peary; Peary Land; Kronprins Christian land; North Greenland; Washington land
• Online Access: https://curis.ku.dk/portal/da/publications/late-ordovician-brachiopods-from-eastern-north-greenland(ceff521d-514c-43ba-9529-9e63f8312071).html; https://doi.org/10.1111/j.1475-4983.2012.01205.x

Late Ordovician rhynchonelliformean brachiopods, typical of the North American Red River fauna, are found sporadically in the BOrglum River Formation of the Centrum SO area, Kronprins Christian Land, eastern North Greenland. The geographical distribution of this characteristic brachiopod fauna is thus extended to the easternmost extremity of the Laurentian craton. The assemblage compares specifically with the Hiscobeccus brachiopod fauna, based on key taxa such as notably Hiscobeccus gigas (Wang, 1949), and indicates a late Katian age for this part of the succession. For the first time, this typically inland, shallow-water fauna is found associated with genera like Bimuria, suggesting a transitional marginal facies with outer shelf benthos. The current study describes a Hiscobeccus fauna that lived at the seaward edge of its preferred habitat. Furthermore, an unpublished Hiscobeccus fauna, from the BOrglum River Formation of Peary Land, central North Greenland, as well as several occurrences from the Kap Jackson and Cape Calhoun formations in various parts of Washington Land, western North Greenland, are described here. These show a distinct shift from older strata containing H.capax (Conrad, 1842) to younger strata exclusively yielding specimens of H.gigas. As H.gigas occurs in the upper part of the Cape Calhoun Formation in Washington Land, it indicates that the upper boundary of the Cape Calhoun Formation is considerably younger than previous estimates, reaching into the uppermost Katian (middle CautleyanRawtheyan). The Cape Calhoun Formation correlates with the upper member of the BOrglum River Formation and further demonstrates that the Hiscobeccus fauna was widespread in Laurentian marginal settings of North Greenland. Even though the Hiscobeccus fauna was pan-continental during the late Katian (Richmondian), it possesses a strong provincial signal during the later Ordovician. The new occurrences indicate that this fauna extended to the north-eastern margin of the Laurentian Craton. It lived in close ...