Original paper

The Hettangian-Sinemurian Boundary (Early Jurassic): Reply to Bloos 1983

Taylor, David G.

Newsletters on Stratigraphy Volume 16 Number 2 (1986), p. 57 - 67

32 references

published: May 27, 1986

DOI: 10.1127/nos/16/1986/57

BibTeX file

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This paper replies to Bloos' (1983) discussion rejecting our (Guex & Taylor 1976) allocation of the marmorea Zone, Alpine Europe. (We assigned the zone primarily to the Sinemurian Stage.) Bloos presented his arguments out of the context of our discussion, which was implicitly a phylogenetic one and involved a major revision of previous age assignments of the canadense Zone (North America). The problem has become one of correlation at the Hettangian-Sinemurian Stage boundary, making it useful to refer to the stratotype boundary in Dorset, southern England. The boundary is situated immediately above youngest Hettangian ammonites of the complanata Subzone. The depressa Horizon (southern Germany), canadense and B zones (North America) and most of the marmorea Zone may be allocated to the Sinemurian Stage (rather than Hettangian Stage) based on their post-complanata age and faunal composition.


SinemurianHettangianstratotypeammonitesphylogeneticDorsetsouthern England