GSSP for Calabrian Stage
Definition:
The base of the Calabrian Stage is defined as the base of the marine claystones conformably overlying the sapropelic Marker Bed "e" in the Vrica Section, Italy.
Location:
The Vrica Section is located 4km south of the town of Crotone in the Marchesato Peninsula, Calabria, Italy. Latitude: 39°02'18.61" north, longitude: 17°08'05.79" east.
Sedimentology:
The Vrica section consists of open sea deposits preserved in the emergent portion of a late Cenozoic sedimentary basin. The rocks are bathyal, marly and silty claystones (dark grey or blue-gray in color) with interbedded, fairly conspicuous, pale grey-pink sapropelic marker beds. Some very thin sandy horizons and a volcanic ash layer also occur within the section. Sedimentation rates through the section range from 310mm to more than 750mm per thousand years.
Primary Markers:
The base of the Calabrian Stage is defined as the base of the marine claystones conformably overlying the sapropelic Marker Bed "e" in the Vrica Section
Secondary Markers:
Foraminifera and Nannoplankton :
The following taxa are distinctive foraminifera and nannoplankton of widespread distribution.
- LAD of Discoaster brouweri below GSSP
- LAD of Globigerinoides obliquus extremus and Cyclococcolithus macintyrei above GSSP
- FAD of Geophyrocapsa oceanica and Globigerinoides tenellus above GSSP
Paleomagnetics:
The boundary is some 3 - 6m (representing a period of 10,000 - 20,000 years) above the top of the Olduvai normal polarity subchron.
Correlation Events:
Magnetic -- ~15 kyr after end of Olduvai (C2n) normal polarity chron
Notes on Derivation of Age:
The accepted age is 1.80 Ma as published in Cita et al. (2012), and derives from the orbitally-tuned age of 1.806 Ma for the midpoint of sapropel "c" at the Vrica type section (Lourens et al., 1996, 2005). The GSSP is placed immediately above this sapropel and is therefore slightly younger than the sapropel's midpoint (Cita et al., 2012). The age of the GSSP is rounded to 3 significant figures, reflecting uncertainties in tuning and sedimentation rates (Cita et al., 2012, p. 395).
Additional Comments:
The base of the Quaternary System/Period, and thus the Neogene-Quaternary boundary, is formally defined by the Monte San Nicola GSSP and thus is coincident with the bases of the Pleistocene and Gelasian. The Gelasian Stage/Age was transferred from the Pliocene Series/Epoch to the Pleistocene. Ratified by IUGS on 29 June 2009.
References:
Aguirre, E. and Pasini, G., 1985. The Pliocene - Pleistocene Boundary. Episodes, 8/2, p. 116 - 120.