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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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U-series dating of constructional cold-water corals is a powerful tool to reconstruct the evolution of corals on carbonate mounds. Here we have investigated the time framework of corals such as Lophelia pertusa and Madrepora oculata on five different mound settings of the eastern North Atlantic (on Rockall Bank and in Porcupine Seabight), sampled at variable depth and location (610-880 m water depth). We have found that the past 11 ka reflect a period generally favourable for coral development. We further determined local mound growth rates and identified mound surface erosion (framework collapse) during times of active coral framework construction. "Local" vertical mound growth rates vary between less than 5 cm ka − 1 and up to 220 cm ka − 1 . We interpret rates exceeding 15 cm ka − 1 as representative of densely populated coral reefs. During times of reduced or absent coral development, mound evolution rates are by far smaller (0 to < 5 cm ka − 1 ). The time resolution achieved here furthermore provides first evidence for reduced coral (ecosystem) activity at 1.8-2.0 ka, 4.2-4.8 ka and between 6 and 8.2 ka within the Holocene that may be related to climate driven changes of the coral growth environments. During Glacial periods coral growth in those areas seems apparently extremely reduced or is even absent on mounds.