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In the nineties, cold-water coral mounds were discovered in the Porcupine Seabight (NE Atlantic, west of Ireland). A decade later, this discovery led to the drilling of the entire Challenger cold-water coral mound (Eastern slope, Porcupine Seabight) during IODP Expedition 307. As more than 50% of the sediment within Challenger Mound consists of terrigenous material, the terrigenous component is equally important for the build-up of the mound as the framework-building corals. Moreover, the terrigenous fraction contains important information on the dynamics and the conditions of the depositional environment during mound development. In this study, the first in-depth investigation of the terrigenous sediment fraction of a cold-water coral mound is performed, combining clay mineralogy, sedimentology, petrography and Sr-Nd-isotopic analysis on a gravity core (MD01-2451G) collected at the top of Challenger Mound. Sr- and Nd-isotopic fingerprinting identifies Ireland as the main contributor of terrigenous material in Challenger Mound. Besides this, a variable input of volcanic material from the northern volcanic provinces (Iceland and/or the NW British Isles) is recognized in most of the samples. This volcanic material was most likely transported to Challenger Mound during cold climatic stages. In three samples, the isotopic ratios indicate a minor contribution of sediment deriving from the old cratons on Greenland, Scandinavia or Canada. The grain-size distributions of glacial sediments demonstrate that ice-rafted debris was deposited with little or no sorting, indicating a slow bottom-current regime. In contrast, interglacial intervals contain strongly current-sorted sediments, including reworked glacio-marine grains. The micro textures of the quartz-sand grains confirm the presence of grains transported by icebergs in interglacial intervals. These observations highlight the role of ice-rafting as an important transport mechanism of terrigenous material towards the mound during the Late Quaternary. Furthermore, elevated smectite content in the siliciclastic, glaciomarine sediment intervals is linked to the deglaciation history of the British-Irish Ice Sheet (BIIS). The increase of smectite is attributed to the initial stage of chemical weathering processes, which became activated following glacial retreat and the onset of warmer climatic conditions. During these deglaciations a significant change in the signature of the detrital fraction and a lack of coral growth is observed. Therefore, we postulate that the deglaciation of the BIIS has an important effect on mound growth. It can seriously alter the hydrography, nutrient supply and sedimentation processes, thereby affecting both sediment input and coral growth and hence, coral mound development.

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Encore pieces: An old man's soliloquy / Roswell Field -- A n old sweetheart of mine / James Whitcomb Riley -- And the band played / Maurice E. McLaoughlin -- The ballad of the colors ; Ben Bolt / Thomas Dunn English -- A brave little girl ; Casey at the bat / Anon -- The cataract of Lodore / Robert Southey -- The countersign was Mary / Margaret Eytinge -- Dinnis Kilboo's sanatarium / Chas. T. Catlin -- A dude in a horse-car / G.W. Kyle -- Elsinore / Lucy H. Hooper -- Entertaining sister's beau / Bret Harte -- Family financiering ; Farmer John ; Father's voice ; A fly's cogitations / Anon -- Foreign views of the statue / Fred. Emerson Brooks -- Going to school / Anon -- Grandma -- The granger and the gambler / W.H. -- A great tune / John Habberton -- Hail fellow, well met / Albert Hardy -- Hans and Fritz -- How girls study / Belle McDonald -- Jack the evangelist / N.Y. Evangelist -- The kitchen clock / J.V. Cheney -- Life's magnet / Ella Wheeler Wilcox -- The little boy's prayer / S.M. Talbot -- Little Nan -- Little orphant Annie / James Whitcomb Riley -- A little woman / Eugene Field -- Maud Rosihue's choice / T. Edwin Leary -- The mischievous misses / James G. Small -- Miss Maloney on the Chinese question / Mary M. Dodge -- Mrs. Stuart learns how to skate / Clara Augusta -- My lover / Emma Mortimer White -- My garden / Anon -- Nancy / Arty Brace -- Now and then / Anon -- O captain, my captain / Walt Whitman -- The old man in a palace car / John H. Yates -- The orthod-ox team / Fred Emerson Brooks -- The porter's story / Maurice Edmunds -- The proposal -- Romeo and Juliet / The Poet-Scout -- Room enough for all / Anon -- The saint and the sinner / Madeline Bridges -- Sam / Albert Hardy -- A schoolroom idyl / Charles B. Going -- A telephone message -- The countersign / J. Hooker Hamersley -- Uncle Ned's defense / Anon -- Unforgiven / Frank McHale -- The valentine / Mary D. Brine -- Wash dolly up like that / Eleanor Kirk Ames -- What is a gentleman / N.L. O'D -- The witness / Anon -- Yellow roses / J. Hooker Hamersley.