The Jurassic of Argentina and its ammonites

Abstract

Ammonites have been fundamental for improving the knowledge of the Argentinean Jurassic. Since 1870 they have been fundamental to prove the existence, in marine facies, of all Jurassic stages, except the Kimmeridgian. Paleobiogeographic distinction provided the basis to establish a regional biostratigraphic framework of 45 biostratigraphic units for the Hettangian - Tithonian, which has helped to define, existence and scope of a number of stratigraphic discontinuities, space and time relationships among lithostratigraphic and dicontinuity-bounded units, and transgressive-regressive cycles and related environmental changes, and to locate within the global time scale, biozones based on other fossil groups as well as astronomically controlled sedimentary cycles, paleomagnetic reversals, changes in the apparent polar wander path of South America, and isotopic excursions. Anchorage of radimetric ages to regional ammonite biostratigraphy and linkage to the global time scale, provide a basis for dating Jurassic non-marine events, e.g. continental, igneous, metamophic.