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GSSP for Chattian Stage

Definition:

The base of the Chattian Stage of the Oligocene Series is defined in the Monte Cagnero Section a few kilometers southwest of Urbania, Italy. The GSSP is at meter level 197 in the Monte Cagnero Section (MCA Section) and coincides with the highest common occurrence (HCO) of planktonic foraminifer Chiloguembelina cubensis at the base of planktonic foraminifer zone O5. This level falls in the upper part of nannofossil zone NP24 and lower part of dinocyst zone Dbi and the lower Chron C9n. Depending on which astronomical tuning option is preferred the GSSP has an astronomical age of 27.82 Ma or 27.41 Ma.

Location:

The Monte Cagnero Section (MCA) is located a few kilometers southwest of Urbania, Italy on the southeastern slope of Monte Cagnero. The section is located at a latitude of 43°38'47.81"N and a longitude of 12°28'03.83"E 		GSSP for Chattian Stage


Sedimentology:

The Monte Cagnero Section (MCA) consists of rhythmic alternations of gray- bluish, pelagic marls, calcareous marls and marly limestones of the Scaglia Cinera Formation. Rare biotite-rich horizons allow for radioisotopic dating. The section is characterized by cyclic hard limestone layers alternating with softer marls. The GSSP is located at meter level 197 thirty centimeters below the base of a prominent calcareous bed within an otherwise relatively thick marly interval.


Primary Markers:

Foraminifera:
The GSSP coincides with the highest common occurrence (HCO) of planktonic foraminifer Chiloguembelina cubensis at meter level 197 at the base of foraminifer zone O5 and in the upper part of nannofossil zone NP24.

Secondary Markers:

from youngest to oldest:
  • 201-208m level, abundance interval of Arctic dinocyst Svalbardella cooksoniae
  • 201-202m level, highest common occurrence (HCO) of calcareous nannofossil Sphenolithus distentus (base of NP25 zone)
  • 197m level, highest common occurrence (HCO) of planktonic foraminifer Chiloguembelina cubensis (GSSP)
  • 196m level, highest occurrence of calcareous nannofossil Sphenolithus predistentus
  • 195.1m level, base of Chron C9n
  • 193m level, oxygen isotope excursion possibly related to Oi2a glaciation event in the middle of Chron C9r
  • 190.2 meter level, top of Chron C10n


Correlation Events:

HCO (highest common occurrence) of planktonic foraminifer Chiloguembelina cubensis

Additional Comments:

The age of the Rupelian/Chattian boundary found in the lower part of Chron C9n at 197 m is 27.82 Ma according to Astronomical Tuning 1, and 27.41 Ma according to Astronomical Tuning 2 (See Episodes 41/1, p. 26).

References:

Coccini, R., Montanari, A., Bice, D., Brinkhuis, H., Deino, A., Frontalini, F., Lirer, F.,Maiorano, P., Monechi, S.,Pross, J., Rochette, P., Sagnotti, L., Sideri, M., Sprovieri, M., Tateo, F., Touchard, Y., Simaeys, S., and Williams, G., 2018. The Global Stratotype Section and Point (GSSP) for the base of the Chattian Stage (Paleogene System, Oligocene Series) at Monte Cagnero, Italy. Episodes 41/1, p.17 - 32.

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