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Pliocene cyclostratygraphy of Scala dei Turchi

Italy

Panoramic view of Punta di Maiata. Deposition of the distinct lithological cycles of calcareous and marly imestones of the Trubi Formation was astronomically controlled. Layers richer in carbonate correspond to eccentricity minima.

Panoramic view of Punta di Maiata. Deposition of the distinct lithological cycles of calcareous and marly imestones of the Trubi Formation was astronomically controlled. Layers richer in carbonate correspond to eccentricity minima.

Geological Period

Miocene to Pliocene

Main geological interest

Stratigraphy and sedimentology
Paleontology

Location

Sicily – Realmonte, Italy
37°17’23”N, 013°28’21”E

Panoramic view of Punta di Maiata. Deposition of the distinct lithological cycles of calcareous and marly imestones of the Trubi Formation was astronomically controlled. Layers richer in carbonate correspond to eccentricity minima.

A beautiful natural cliff where Zanclean calcareous and marly limestones reflect depositional control by Milankovitch cycles

The Punta di Majata (Scala dei Turchi) and Eraclea Minoa sections represent the reference sequences of the entire Pliocene and contain the Messinian-Zanclean boundary at the Arenazzolo-Trubi contact. The boundary represents the return to normal marine condition after the Messinian Salinity Crisis. The beautiful exposure and the clear signal of the Milankovitch cycles make these sections a clear scientific example recognized worldwide. Punta di Majata was previously chosen for the Messinian-Zanclean GSSP, but due to the weak paleomagnetic signal was then replaced by the Eraclea Minoa section that outcrops only 25 kilometers away.

Key planktonic foraminiferal species from the Scala dei Turchi section, providing a Zanclean-Piacenzian age for the Trubi Formation.

Key planktonic foraminiferal species from the Scala dei Turchi section, providing a Zanclean-Piacenzian age for the Trubi Formation.

  • Geological description

The Punta di Majata sequence is a beautiful sedimentary succession from Messinian to Pleistocene constituted by 93 m of calcareous marls and marly limestones, known as Trubi Formation and represent the return to normal marine conditions after the Messinian Salinity Crisis. The outcrop is known as “Scala dei Turchi” and includes the Messinian-Zanclean boundary. The section is constituted by 96 lithological cycles made by a quadriplet (grey-white-beige-white) that reflects astronomical controlled. The colour variations are due to precessional cycles that induced climatic and oceanographic variations in the Mediterranean Sea. Here was proposed the astronomical tuning for the whole Pliocene sequence. Grey layers are richer in warmer planktonic foraminifers, lower oxygen isotope values and higher content of illite and chlorite. The clays minerals formed in warmer and humid conditions during insolation maxima. On the contrary, beige layers are richer in temperate species and in palygorskite that is a clay mineral typical of arid conditions, transported as dust from north African during insolation minima. The thickness of some beige layers is due to the obliquity of earth’s axis. The richer carbonate layers, clearly visible in the profile of the cliff, formed by an increase of calcareous planktonic microfossils deposited during eccentricity minima (100-400 kyr).

  • Scientific research and tradition

The succession was studied in the 1970’s when it was proposed as the stratotype for the Zanclean Stage (Cita and Gartner, 1973). In 1991 it became the reference section for the Pliocene Astronomical Time Scale (Hilgen, 1991; Lourens et al., 1996). Numerous teams published data on foraminifera, paleomagnetism, mineralogy, stable isotopes and alkenones.

A) Geological map of Realmonte-Scala dei Turchi; B) particular view of the quadriplet precessionally controlled at Scala dei Turchi; to the left of the Messinian-Zanclean boundary.

A) Geological map of Realmonte-Scala dei Turchi; B) particular view of the quadriplet precessionally controlled at Scala dei Turchi; to the left of the Messinian-Zanclean boundary.

  • Reference

Beltran, C. et al. (2011) ‘Long chain alkenones in the Early Pliocene Sicilian sediments (Trubi Formation — Punta di Maiata section): Implications for the alkenone paleothermometry’, Palaeogeography, Palaeoclimatology, Palaeoecology, 308(3–4), pp. 253–263. Available at: https://doi.org/10.1016/j.palaeo.2011.03.017.

Cita, M.B. and Gartner, S. (1973) ‘The stratotype Zanclean foraminiferal and nannofossil biostratigraphy’, Rivista Italiana Paleontologia e Stratigrafia, 79, pp. 503–558.

Foucault, A. and Mélières, F. (2000) ‘Palaeoclimatic cyclicity in central Mediterranean Pliocene sediments: the mineralogical signal’, Palaeogeography, Palaeoclimatology, Palaeoecology, 158(3), pp. 311–323. Available at: https://doi.org/10.1016/S0031-0182(00)00056-0.

Hilgen, F.J. (1991a) ‘Astronomical calibration of Gauss to Matuyama sapropels in the Mediterranean and implication for the Geomagnetic Polarity Time Scale’, Earth and Planetary Science Letters, 104(2), pp. 226–244. Available at: https://doi.org/10.1016/0012-821X(91)90206-W.

Hilgen, F.J. (1991b) ‘Extension of the astronomically calibrated (polarity) time scale to the Miocene/Pliocene boundary’, Earth and Planetary Science Letters, 107(2), pp. 349–368. Available at: https://doi.org/10.1016/0012-821X(91)90082-S.

Lourens, L.J. et al. (1996) ‘Evaluation of the Plio-Pleistocene astronomical timescale’, Paleoceanography, 11(4), pp. 391–413. Available at: https://doi.org/10.1029/96PA01125.

Sgarrella, F. et al. (1997) ‘Paleoceanographic conditions at tha base of the Pliocene in the Southern Mediterranean Basin’, Rivista Italiana di Paleontologia e Stratigrafia, 103. Available at: https://doi.org/10.13130/2039-4942/5291.

  • Author(s)

Antonio Caruso.
Università degli studi di Palermo – Dipartimento di Scienze e Tecnologie Biologiche Chimiche e Farmaceutiche. Italy.

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