GSSP for Aquitanian Stage
Definition:
The Base of the Neogene System, Miocene Series and Aquitanian Stage is defined in the Lemme-Carrosio Section (35m from the top of the section) in the village of Carrosio, south of the town of Gavi and north of Voltaggio (Allessandria Province), Italy.
Location:
The Lemme-Carrosio Section is located in the village of Carrosio. Longitude: 8°50'11" East; Latitude: 44°39'32" North. Carta Geologica d'Italia: Foglio Genova No. 82 (1:100 000); Tav. Voltaggio I NE (1:25 000).
The area of the Lemme-Carrosio Section is situated within the Piedmont Tertiary Basin, in southern Piedmont, Italy. In the Lemme Section, the Rigoroso Fomation is characterized by poorly to very poorly sorted sediments which can be classified as fine and medium grained silts with fine silts dominating.
Primary Markers:
An excellent lithological marker for the GSSP is provided by a distinct boundary between lithologic Unit A (the more massive part of the section) and the overlying lithologic Unit B-1 (the more stratified part of the section). At the 50m mark from the top there is a horizon with yellowish nodules. The GSSP is exactly 15m above this lithologic boundary. A layer with yellowish nodules lies in lithologic Subunit B2, exactly one meter below meter 35.
Secondary Markers:
Calcareous Nannofossils:
- FAD of Sphenolithus ciperoensis is 21m below meter 35
- FAD of Sphenlithus delphix 12m below meter 35
- FAD and LAD of Sphenolithus capricornutus within one meter above meter 35
- LAD of Sphenolithus delphix 4m above meter 35
Planktonic Foraminifera:
- FAD of Paragloborotalia kugleri two meters above meter 35
- LAD of Paragloborotalia kugleri 25m above meter 35
- FAD of Globoquadrina dehiscens 12m above meter 35
- FAD of Globigerinoides altiaperturus 22m above meter 35
Benthic Foraminifera:
- FAD of Uvigerina spinicostata one meter above meter 35
Dinoflagellate Cysts:
- FAD of Ectosphaeropsis burdigalensis at meter 38
- Highest abundance of Chiropteridium spp. at meter 39
- LAD of Chiropteridium spp. one meter above meter 35
- Bloom of Deflandrea spp. about 10m above meter 35
- Highest abundance of Deflandrea at meter 15
- FAD of Distatodinium apenninicum at meter 10
- FAD of Membranilarnacia ?picena at meter 3
- FAD of Stoverocysta conerae at meter 1
Correlation Events:
Magnetic -- base of Chron C6Cn.2n; planktonic foraminifer FAD of Paragloborotalia kugleri; calcareous nannofossil near LAD Reticulofenestra bisecta (base Zone NN1); Oxygen isotopic event Mi-1.
Other Locations around the World:
The GSSP is potentially correlatable worldwide by means of magnetostratigraphy, marine microfossil biostratigraphy, and/or stable isotope stratigraphy.
Notes on Derivation of Age:
Astronomical cycles in sediments
Additional Comments:
Magnetostratigraphy:
Biostratigraphic correlations allow the interpretation of the geomagnetic pattern of this section using the magnetobiochronologic scale of Berggren et al. (1995). Association of the distinct polarity reversals at meter 35 with biostratigraphic events cited above permit identifications of the magnetozones as Chron C6Cn.2r and Chron C6Cn.2n respectively. This unambiguous reversal pattern and the excellent biostratigraphic markers have been among the main reasons for defining the base of the Neogene at meter 35 of the Lemme-Carrosio section.