Tithonian Stage

▪ geology

      uppermost of the three divisions of the Upper Jurassic Series, representing all rocks formed worldwide during the Tithonian Age, which occurred between 150.8 million and 145.5 million years ago during the Jurassic Period. The Tithonian Stage overlies the Kimmeridgian Stage and underlies the Berriasian (Berriasian Stage), the lowest stage of the Cretaceous Period.

      The name of this stage is derived not from a geographic source but from the Greek mythological figure Tithonus, who was the consort of Eos (Aurora), goddess of the dawn. The Tithonian Stage has replaced the Volgian and Purbeckian Stages, which were previously locally recognized in Russia and England, respectively.

      In Europe the Tithonian is divided into the Lower, Middle, and Upper Tithonian. Each of these intervals is further divided into numerous standard European ammonite (ammonoid) biozones (biozone): the Lower Tithonian includes the Hybonotum and Darwini zones; the Middle Tithonian includes the Semiforme, Fallauxi, and Ponti zones; and the Upper Tithonian includes the Micracanthum and Durangites zones.

      In other parts of the world, Mexico is one of the few regions where an extensive, detailed ammonite stratigraphic zonation has been developed. Elsewhere only a few zones have been recognized, and in some areas the exact timing and correlations of these zones have not been finalized. As with the other Upper Jurassic stages, the lack of well-developed global correlations is due to patchy distribution of ammonites and tightly constrained geographic distributions for individual species.

Carol Marie Tang

 

* * *