The Henson Gletscher Formation, North Greenland, and its bearing on the global Cambrian Series 2–Series 3 boundary

Abstract

The Henson Gletscher Formation of North Greenland yields moderately diverse trilobite faunas which bracket the Cambrian Series 2-Series 3 boundary interval. A number of the trilobite taxa permit correlation into other parts of Laurentia and to other Cambrian continents, thus enhancing correlation within this stratigraphical interval of the traditional Lower-Middle Cambrian boundary. In particular, the occurrence of Ovatoryctocara granulata and O. yaxiensis substantially improves the intercontinental recognition of the O. granulata level, a prime GSSP candidate. In contrast, the level with Oryctocephalus indicus cannot be located in a number of Cambrian continents with sufficient precision, making this level unsuitable for the definition of a GSSP for the base of the Cambrian Series 3 and Stage 5. Further support for the correlation potential of the base of the range of Ovatoryctocara granulata comes from recent carbon isotope studies that indicate a striking negative excursion in sections of South China (ROECE event) that probably coincides with similar excursions in Laurentia. Four new trilobite species are described: Zacanthopsis blakeri sp. nov., Protoryctocephalus arcticus sp. nov., Eoptychoparia pearylandica sp. nov. and Onchocephalus? freucheni sp. nov.

The Cambrian trilobites of Jordan – taxonomy, systematic and stratigraphic significance

“…Bathynotus is a trilobite genus known from Laurentia, South China, Australia and Siberia, and therefore suitable to enhance the resolution of intercontinental correlation in the traditional Lower−Middle Cambrian boundary interval. Such stratigraphical considerations have been described in detail by Geyer and Peel (2011).…”

“…Therefore, the Morocconus Zone of the Moroccan Atlas ranges and equivalent strata in western Avalonia correlate at least in part with the Ovatoryctocara granulata Zone in Siberia and northern Greenland and the Ovatoryctocara granulata-Bathynotus holopygus Zone of the Duyunian in South China. A detailed discussion is provided by Geyer and Peel (2011) Rushton and Powell (1998), the traditional systematic position of the endemic monotypic genus Redlichops within the Subfamily Pararedlichiinae (Zhang 1966;Zhang et al 1980) cannot be maintained. Clearly distinguishing characters are the moderately wide (rather than distinctly slender) interocular area, the shape of the palpebral lobes, and primarily, the character of the glabella.…”

“…Kingaspis campbelli was identified from the easternmost Anti-Atlas close to the Moroccan-Algerian border, but unfortunately in rocks which cannot be placed unequivocally into one distinct zone. According to the existing zonation for the Atlas ranges (Geyer 1990a), the species occurs either in the upper part of the Morocconus Zone (formerly the Cephalopyge Zone 1 ) or in the overlying Ornamentaspis frequens Zone (Geyer 1990b), which are coeval with part of the lower (but not lowest) range of Paradoxides s. l. and thus the base of the traditional 'Acadobaltic' Middle Cambrian (compare Geyer 2005;Geyer and Peel 2011).…”

“…Yuan et al (2009) used the taxonomic lumping of Schistocephalus with Palaeolenus and a supposed similarity of Enixus antiquus with Megapalaeolenus deprati (Mansuy, 1912) Geyer and Peel 2011). Ovatoryctocara granulata, a candidate GSSP marker for the base of the proposed Cambrian Series 3 (to replace the traditional Middle Cambrian), is a fairly common trilobite in the lower Amgan of the Yudoma-Olenek facies region, where it defines the lowermost Amgan biozone and thus the base of the Middle Cambrian series in Siberia (e.g., Korovnikov 2001;Shabanov et al 2008;Naimark et al 2011).…”

Trilobites, their traces and associated sedimentary structures as indicators of palaeoenvironment of Cambrian of the Ociesęki Range (Holy Cross Mountains, Poland)

“…Well-pre served trilobites, bur ied in life po si tion in heterolithic muddy-silty-sandy rocks in South China were noted by Degan et al (1995). Com pletely pre served and en rolled trilobites were re corded from the Cam brian of Green land (Geyer and Peel, 2011) and Can ada (Ortega-Hernández et al, 2013). Other oc cur rences of trilobites pre served in situ with their burrows, such as Thalassinoides nets with Asaphus raniceps, are known from car bon ate fa cies of the Swed ish Or do vi cian (Cherns et al, 2006).…”