Andean Jurassic Inoceramids as Potential Bioevent Markers for the Austral Realm

DAMBORENEA, S.E.

Advances in Jurassic Research

Trans Tech Publications

Lugar: Zurich; Año: 1996; p. 433 - 442

Present knowledge on first and last appearances of inoceramid species at key sections in the Neuquén Basin is reviewed in order to test these organisms as bioevent markers. Several potential biological event units are recognized from Pliensbachian to Bathonian. Species currently referred to Parainoceramus are known from Hettangian to uppermost lower Bajocian, but tend to be restricted geographically and are still poorly understood from a systematic point of view. Nevertheless, the first appearances of both P. apollo (Leanza) and P.? westermanni Damborenea seem to be good bioevent markers at local and/or regional level. On the other hand, species of Retroceramus have very wide geographical distributions and short time ranges which are consistent in different areas of the South Pacific. First appearances of R. marwicki (Speden) and R. patagonicus (Philippi) are regarded as bioevents for the Neuquén Basin. The results are compared with the distribution of the same species-groups in other South Pacific regions.