GSSP Zancleum / Piacenzium

Coordinates: 37 ° 17 ′ 20 ″  N , 13 ° 29 ′ 36 ″  E

GSSP Zancleum / Piacenzium​

Italy

The GSSP Zancleum / Piacenzium , which is integrated in a stratigraphic reference profile, defines the boundary between the geological levels Zancleum and Piacenzium . The profile is located on the Punta Piccola west of Porto Empedocle in Sicily . The level limit was dated to 3.596 million years BP .

history

The GSSP ( Engl. Global Boundary Stratotype Section and Point or Global Standard Stratotype-section and Point - global reference profile for determining stage boundaries) Zanclean / Piacenzian (often just GSSP Piacenzian or GSSP Lower / upper Pliocene) was in December 1996 by the Subcommission of Neogene Stratigraphy (SNS) of the International Commission on Stratigraphy (ICS) has been proposed. It was then ratified by the ICS in January 1997. The GSSP was scientifically described by Castradori et al. In 1998.

Description and definition

The cliff of Punta Piccola is located on the Sicilian south coast west-southwest of Agrigento , on the road between Realmonte and Porto Empedocle , about 4 kilometers east of Capo Rossello and 3 kilometers west-southwest of Porto Empedocle. The exposed sequence forms the final hanging wall of a composite profile along the coast (the approximately 100 meters thick Rossello Composite Section , consisting of the profiles at Punta di Maiata , Punta Grande and Punta Piccola ), which has become a standard for the Pliocene . The first 20 meters of the lying at the Punta Piccola are formed from cyclic limestone- marl alternating arcs of the Trubi formation , in the hanging wall then follow the marls of the Monte Narbone Formation with their sapropel horizons switched on . The sedimentation of the Trubi formation took place in 800 to 1000 meters water depth on the basin-facing continental slope and corresponds to open marine conditions. Structurally, the sediments belong to the Caltanisetta Basin of the Gela Nappe .

The basis of the piacenzium was defined as follows:

It lies (in the Trubi formation) at the lower edge of the beige marl layer of the carbonate cycle 77 . This corresponds to meters 2 in the Punta Piccola profile, 17 meters below the Monte Narbone formation.

Dating and Correlations

Megantereon disappeared in North America at the GSSP Zancleum / Piacenzium.

The carbonate cycle 77 correlates with the precession excursion 347, to which the astronomical age of 3.600 million years BP can be assigned.

The boundary also correlates with other stratigraphic schemes as follows:

• Magnetostratigraphy : The Gilbert- Gauss polarity reversal of the earth's magnetic field (Chron 2 Ar - Chron 2 An ) is located immediately above the GSSP. It belongs to the same precession cycle and can be dated astrochronologically to 3.596 million years BP.
• Oxygen isotope stratigraphy (δ O ¹⁸ ): The limit corresponds to the marine isotope stage (MIS) MG8 . or O-176 (Stadial).
• Biostratigraphy :
  • Foraminifera : First appearance in the Mediterranean area (FAD) sensu stricto of Globorotalia crassaformis 3.60 million years ago BP and temporary disappearance of Globorotalia puncticulata before 3.57 million years BP. In the North Sea area , Neogloboquadrina atlantica and Neogloboquadrina humerosa are disappearing at the GSSP . The last occurrence (LO) of Pulleniatina primalis (3.65 million years ago BP) can also be used to determine the limit in low and medium latitudes outside the Mediterranean region . Furthermore, BP Menardella pertenuis (or Globorotalia pertenuis ) appeared for the first time 3.51 million years ago .
    The GSSP is located at the lower limit of N 20 or in the lower section of PI 3 or in MPL 4 a .
  • Calcareous nannoplankton : Last appearance of Sphenolithus spp. 3.70 or 3.73 million years ago BP. Also Reticulofenestra pseudoumbilicus appeared for the last time before the GSSP. Discoaster pentaradiatus' main distribution period ended 3.61 or 3.56 million years ago BP. The GSSP is just above the lower limit of NN 16 (NN 16 a) or CN 12 a .
  • Radiolarians : The GSSP coincides with the disappearance of Lychnodictyum audax and falls in the middle of the radiolarian zone RN 11 a .
  • Dinoflagellates : The GSSP coincides with the last appearance of Melitasphaeridium choanophorum and is in the lower third of the dinoflagellate zone D 21 a .
  • Diatoms : a little below the GSSP, with the beginning of the diatom zone NPD 8, Neodenticula koizumii appears for the first time .
  • Land mammals :
    • In North America ( NALMMZ ): Last appearance of Megantereon and first appearance of Borophagus diversidens , Glyptotherium and Megalonyx leptostomus in the middle of Blancums Bl 3 .
    • In Europe ( ELMMZ ): The GSSP corresponds to the upper end of the land mammal zone MN 15 or the Upper Ruscinium .

Sea level

At the time of the GSSP the sea ​​level was in an interim regression phase between the high level Za 2 in the upper Zancleum (4.01 million years ago BP) and the low level Pia 1 in the lower Piacenzian (3.27 million years ago BP). In the long term, however, the sea level was slowly rising.

climate

During the GSSP Zancleum / Piacenzium there was a deterioration in the climate with decreasing average temperatures and increasing aridification.

Other equivalents

The GSSP Zancleum / Piacenzium corresponds in Europe to the pollen level of the Upper Brunssumium (Brunssumium C), in California to the Upper Delmontium and in Australia to the Upper Kalimnum .

meaning

The GSSP Zancleum / Piacenzium shows a very good correspondence with the Gilbert-Gauss polarity reversal, which can thus be used for its relatively precise, stratigraphic localization.

literature

• J. Hardenbol, inter alia: Cenozoic-Mesozoic Biochronostratigraphy . 1998.
• F. Gradstein, among others: A Geologic Time Scale 2004 . Cambridge University Press, 2004, ISBN 0-521-78673-8 .
• JG Ogg, among others: The Concise Geologic Time Scale . 2008.

Individual evidence

1. ↑ Castradori, D. et al .: The Global Standard Stratotype-section and Point (GSSP) of the Piacenzian Stage (Middle Pliocene) . In: Episodes, Volume 21, 2 . 1998, p. 88-93 .
2. ↑ ^{a b c d} L. J. Lourens, among others: Evaluation of the Plio-Pleistocene astronomical timescale . In: Paleoceanography . tape 11 , 1996, pp. 391-413 .
3. ^ R. Sprovieri, G. Barone: I foraminiferi bentonici della sezione pliocenica di Punta Piccola (Agrigento) . In: Geologica Romana . tape 1 , 1982, pp. 677-686 .
4. ^ FJ Hilgen,: Extension of the astronomically calibrated (polarity) time scale to the Miocene / Pliocene boundary . In: Earth and Planet. Sci. Lett. tape 107 , 1991, pp. 349-368 .
5. ↑ NJ Shackleton, MA Hall, D. Pate: Pliocene stable isotope stratigraphy of ODP site 846 . In: Proc. Ocean Drilling Program, Sci. Results . tape 138 , 1995, pp. 337-353 ( odp.tamu.edu [PDF]).
6. ^ LJ Lourens, inter alia: Correction to “Evaluation of the Plio-Pleistocene astronomical timescale” . In: Paleoceanography . tape 12 , 1997, p. 527 .
7. ^ ^{A b} R. Sprovieri: Pliocene-early Pleistocene Astronomically forced planktonic foraminifera abundance fluctuations and chronology of Mediterranean calcareous plankton bio-events . In: Riv. It. Paleont. Strat. Band 99 , 1993, pp. 371-414 .
8. ↑ WA Berggren, among others: Late Neogene (Pliocene-Pleistocene) Chronology: New Perspectives in High Resolution Stratigraphy . In: Geol. Soc. At the. Bull. Band 107 , 1995, pp. 1272-1287 .