Present status of the astronomical (polarity) time-scale for the Mediterranean Late Neogene

Abstract

Sedimentary cycles may reflect orbitally induced climate oscillations and can then be used to construct astronomical time–scales. Following the initial tuning of the Late Pleistocene, the ‘anchored’ astronomical time–scale was extended to the base of the Pliocene, using palaeoclimatic records from Ocean Drilling Project (ODP) sites in the eastern equatorial Pacific and North Atlantic and sedimentary cycle patterns in marine successions exposed onland in the Mediterranean. In this paper we present a review of the progress subsequently made in establishing a Late Neogene astronomical (polarity) time–scale (A(P)TS) in the Mediterranean region. Major steps forward are (1) the evaluation of the initial time–scale, using high–resolution climatic proxy records, different astronomical solutions and the additional influence of obliquity on sedimentary cycle patterns, (2) the extension of the A(P)TS into the Middle Miocene, i.e. back to about 12 3Ma, (3) the closure of the Messinian gap in the A(P)TS, (4) the incorporation of the continental record, and (5) the intercalibration of astronomical and radioisotopic time.