|Subdivisions of the Quaternary period|
|In Europe and North America, the Holocene is subdivided into Preboreal, Boreal, Atlantic, Subboreal and Subatlantic stages of the Blytt-Sernander time scale. There are many regional subdivisions for the Upper or Late Pleistocene, usually these represent locally recognized cold (glacial) and warm (interglacial) periods. The last glacial period ends with the cold Younger Dryas substage.|
Although experts are not yet in agreement on how to subdivide the stages of The Pleistocene Epoch, there is an international consensus on one subdivision of The Pleistocene Epoch called the Ionian Stage. The Ionian stage includes all of the European Sicilian Stage and the first part of the Tyrrhenian Stage.
The base of the Ionian Stage is located near the top of the Calabrian Stage (the beginning of the Brunhes-Matuyama reversal). The top of the Ionian stage coincides with the base of the Upper Pleistocene, which in turn spans from the beginning of the last interglacial (Marine isotopic stage 5) to the base of the Holocene (~10.5 ka).
Suitable sections for defining the base of the Ionian Stage are located in southern Italy. During Lower and Middle Pleistocene the Adriatic-Ionian margin was characterized by high sedimentation rates, in response to intense differential tectonic subsidence and massive sedimentary yield. Specifically, candidate sections are the “Montalbano Jonico” Section (Bradanic Trough, Basilicata Region) and the “Valle di Manche Nord” Section (San Mauro Marchesato, Crotone Basin, Calabria Region). In the former, a spectacular succession of marls laid in the Apennine foredeep is exposed which, however, are unfortunately unsuitable for magnetostratigraphic analyses. The latter, which is represented by a shallowing-upward succession that developed in an outer-shelf environment, has the bonus of a sharp biomagnetostratigraphic record, which provides tighter age control.
Besides these exposures, a number of ODP cores drilled either in the Ionian Sea (Site 964) and in the Sicily Channel-Capo Rossello area (Site 963) are available, which correlate well with the on-land sections mentioned above based on a significant number of criteria (magnetostratigraphy, biostratigraphy, sapropel stratigraphy, stable isotopes, Tephrochronology). The interval corresponding to the Ionian Stage is especially well represented in Site 963, where no turbidites and/or hiatuses are recognized. Presently, the Montalbano Ionico section is possibly the main candidate for defining the Lower - Middle Pleistocene boundary, when a reliable magnetostratigraphic record is found.
|Early | Middle | Late||
Preboreal | Boreal |
Atlantic | Subboreal | Subatlantic