Sr isotope stratigraphy provides a new age model for the fi rst complete section drilled through a deep-water coral mound. The 155-m-long section from Challenger Mound in the Porcupine Seabight, southwest of Ireland, is on Miocene siliciclastics and consists entirely of sediments bearing well-preserved cold-water coral Lophelia pertusa. The 87 Sr/ 86 Sr values of 28 coral specimens from the mound show an upward-increasing trend, correspond to ages from 2.6 to 0.5 Ma, and identify a signifi cant hiatus from ca. 1.7 to 1.0 Ma at 23.6 m below seafl oor. The age of the basal mound sediments coincides with the intensifi cation of Northern Hemisphere glaciations that set up the modern stratifi cation of the northeast Atlantic and enabled coral growth. Mound growth persisted throughout glacial-interglacial fl uctuations, reached a maximum rate (24 cm/k.y.) ca. 2.0 Ma, and ceased at 1.7 Ma. Unlike other buried mounds in Porcupine Seabight, Challenger Mound was only partly covered during its growth interruption, and growth restarted ca. 1.0 Ma.

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