Correlation of late Miocene to early Pliocene sequences between the Mediterranean and North Atlantic

Ocean Drilling Program (ODP) Site 982 in the North Atlantic contains a comp lete latest Miocene to early Pliocene section that was tuned to the astrono mical timescale by correlating the record of gamma ray attenuation (GRA) bu lk density to summer insolation at 65 degreesN and the benthic delta O-18 s ignal to orbital obliquity for the interval from 4.6 to 7.5 Ma. The astrono mical tuning of the Site 982 record permits a direct bed-to-bed correlation to the cyclostratigraphy of Messinian sections in the Mediterranean [Krijg sman et al., 1999a, 2001]. The benthic delta O-18 signal at Site 982 record s a latest Miocene glacial period that lasted from similar to6.26 to 5.50 M a and consisted of 18 glacial-to-interglacial oscillations that were contro lled by the 41-kyr cycle of obliquity. Although the intensification of glac iation at 6.26 Ma may have contributed to the restriction of the Mediterran ean, it preceded the depositional onset of the lower evaporite unit at 5.96 Ma by some 300 kyr. The transition from Stage TG12 to TG11 at 5.5 Ma marks the end of the latest Miocene glacial period and precedes the Miocene/Plio cene boundary by 170 kyr. Although benthic delta O-18 values are relatively low and delta O-18 of bulk carbonate reaches a minimum at the Miocene/Plio cene boundary at 5.33 Ma, there is no single "event" that would indicate de glaciation and sea level rise as the cause of the reflooding of the Mediter ranean. We conclude that glacioeustatic changes alone were not responsible for either the start or end of evaporite deposition during the Messinian, s uggesting that tectonic or local climate changes in the Mediterranean regio n were the dominant cause(s).