The late MIS 5 Mediterranean tephra markers: a reappraisal from peninsular Italy terrestrial records

We present new tephrostratigraphic records from the late MIS 5 (ca 110–80 ka) terrestrial sediments from southern and central Italy. On the one hand, the central Italy record consists of an outcropping lacustrine sequence from the Sulmona intermountain basin that contains four trachytic–phonolitic tephra layers (POP3, POP2a, POP2b, POP1), all of which show a K-alkaline affinity that is typical for the Roman co-magmatic Province. The POP3 and POP1 layers were dated by 40Ar/39Ar method at 106.2 ± 1.3 ka (2σ) and 92.4 ± 4.6 ka (2σ), respectively. The sequence in southern Italy, on the other hand, is represented by post-Tyrrhenian coastal deposits of the Cilento area, Campania, which contain two trachytic layers (CIL2, CIL1) that show the same K-alkaline affinity. Based on their chemical compositions and radiometric ages, POP3 and POP1 are firmly correlated with the marine tephra layers X-5 (105 ± 2 ka) and C-22 (ca 90 ka), which, in turn, match tephras TM-25 and TM-23-11, respectively, in the lacustrine sequence of Lago Grande di Monticchio (southern Italy). Of note, the POP1 layer also matches the Adriatic Sea tephra PRAD 2517 that was previously correlated with the older X-5 layer. The tephra couplet POP2a and POP2b (ca 103 and 103.5 ka, extrapolated ages) are compatible with the TM-24b and TM-24-3 tephras in Monticchio, which match both the stratigraphic positions and the chemical compositions. In the Cilento area, as well as the already described X-6 layer (ca 108 ka) (CIL2), we recognise a new stratigraphic superimposed layer (CIL1) that matches the POP3/TM-25/C-27/X-5 Mediterranean marker(s). In summary, the data presented here provide new chemical and 40Ar/39Ar chronological constraints towards a robust late MIS 5 tephrostratigraphy of the central Mediterranean, although at the same time, they also reveal how the tephrostratigraphy itself might be flawed when dealing with tephra markers that are not adequately constrained and characterised.

► Geochemical fingerprint of the Mediterranean late MIS 5 (110–80 ka) tephra markers. ► Large EMP geochemical dataset of the marine X-5 and C-22 correlative tephras. ► First high-precision 40Ar/39Ar dating of the terrestrial counterpart of the X-5 marker. ► First recognition and 40Ar/39Ar dating of the C-22 tephra in continental setting. ► Discriminating the X-5 marker from other miscorrelated late MIS 5 tephras.