Ammonite stratigraphy of the Bajocian in Northern Chile

von Hillebrandt, Axel (2001) Ammonite stratigraphy of the Bajocian in Northern Chile. Hantkeniana, 3. pp. 49-87. ISSN 1219-3933

Preview

Text 49-87_Hantkeniana_3_2001.pdf Download (15MB) | Preview

Abstract

Ammonites of Bajocian age are found in Northern Chile at many localities, but sections with ammonite beds of different age of this stage are rare. The Bajocian is subdivided in ammonite horizons. The distinguishable number of horizons is much smaller than that in Europe and corresponds to the quantity of zones or subzones occuring there. Faunal diversity is much lower than in Europe and many of the South American species are likely to have a longer biostratigraphic range. The lower diversity is probably caused by the special paleogeographic and biogeographic back arc basin situation. The entrance to this basin was restricted and its dimensions was much smaller than the huge area of the European shelf with a high potential of ecologic possibilties. Proof of the European Discites Zone is difficult. The Ovalis Zone is represented only by one horizon. The Laeviuscula to Subfurcatum Zones can each be subdivided into two horizons. It is not easy to ascertain the middle and upper part of the Upper Bajocian because ammonites of this age are very rare, endemic or unsuitable for an exact age determination. Two new species are described being important for the biostratigraphy of the lowest Upper Bajocian.

Actions (login required)

Edit Item