Trends of stable oxygen-isotope data through four European sections of Middle–Upper Turonian sediments show three phases of synchronous variations, each phase having a duration of about 250 ka. The isotopic variations are independent of local facies, sedimentary thickness and diagenetic history. Two positive δ18O shifts are associated with a southward spread of northern macrofaunas. This coincidence of geochemical and palaeontological data implies that the δ18O trends reflect a southward shift of cooler water masses. This southward extension of cooler waters was caused by changes in ocean circulation and was associated with a major regression in the early Late Turonian.

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