GSSP for Piacenzian Stage

 

Definition:

The base of the Piacenzian Stage is defined as the base of the beige marl bed of the small-scale carbonate cycle 77. It corresponds to precessional excursion 347 as numbered from the present, with an astrochronological age estimate of 3.600 Ma. The GSSP is located in the Punta Piccola section, Italy.

Location:

The Punta Piccola section is located on the southern coast of Sicily (Italy). The section is represented on the Carta Topografica d'Italia in the 1:25,000 series, Foglio 271, Quadrante IV, NO (Porto Empedocle) at a latitude of 37°17'20" N and a longitude of 13°29'36" E of Greenwich. The section is located along the road from Porto Empedocle to Realmonte, 4km to the east of Capo Rossello and about 3km to the W-NW of Porto Empedocle.

 

Sedimentology:

The Punta Piccola section is the upper part of the Rossello Composite Section, which is made up by about 100m of alternating marls and limestones of the Trubi Formation, transitionally grading upward into the more marly Monte Narbonne Formation. The Monte Narbonne Formation is characterized by the cyclical occurrence of laminated (sapropelic) layers. The transition from the Trubi Formation to the Monte Narbonne Formation occurs in the Punta Piccola section at about 20m from its base. The depositional environment for the boundary is inferred to be a slope-basin setting with water depth ranging from 800 to 1000m.

 

Primary Markers:

Astrocyclostratigraphy:
The base of the Piacenzian Stage is defined as the base of the beige marl bed of the small-scale carbonate cycle 77. It corresponds to precessional excursion 347 as numbered from the present, with an astrochronological age estimate of 3.600Ma.
Paleomagnetics:
The section spans the interval from the upper part of the Gilbert Chron (C2Ar) through the entire Gauss Chron and to the lowermost part of the Matuyama Chron. The Gilbert-Gauss magnetic reversal is recorded immediately above the GSSP within the same precessional cycle, having an astrochronological age of 3.596Ma.

Secondary Markers:

Foraminifera:
In the Mediterranean the base of the Piacenzian can be recognized by the first influx of Globorotalia crassaformis (3.60 Ma) and by the temporary disappearance of Globorotalia puncticulata (3.57 Ma). In low and mid-latitude areas outside of the Mediterranean the last occurrence of Globorotalia margeritae (3.58 Ma) and Pulleniatina primalis (3.65) are close to the boundary.

Correlation Events:

Magnetic -- Gauss/Gilbert (C2An/C2Ar) magnetic reversal is recorded immediately above the GSSP

Notes on Derivation of Age:

Astronomical cycles in sediments

References:

Castradori, D., Rio, D., Hilgen, F. J., and Lourens, L. J., 1998. The Global Standard Stratotype-section and Point (GSSP) of the Piacenzian Stage (Middle Pliocene).. Episodes 21/2, p. 88-93.



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