Isotope Signature of calcareous Organisms from upper and Lower carbonate mound sediments 2

、冷水珊瑚丘或碳酸盐丘是已知的在豪猪海滨广泛存在的。来自重力岩心的沉积岩心，特别是ICDP在Challenger Mound勘探的307号钻探岩心，显示了碳酸盐岩丘生长的周期性和突发性变化。浮游有孔虫和底栖有孔虫以及冷水珊瑚骨骼中的地球化学信号将使我们能够了解这些变化的机制。从丘陵开始的海底有孔虫(δ18O，δ13O)的稳定同位素特征表明，来自地中海(地中海外流)的水团的特征值发生了显著变化。根据珊瑚骨骼的锶/钙比值得出的古温度表明了这些生物群的最佳生长条件。我们推测，σө=27.35-27.65 kg/m~3的密度包络对于现今冷水珊瑚生长的环境海水特征在过去也起到了重要作用。为了重建和更好地理解土丘生长中“关闭”和“关闭”状态之间的变化，我们计划从lODP-Kem 1317C获得更多样品，以弥合现有的信息差距。由于传统的U/Th方法仅限于岩心上部(约350ka)，我们还将应用精确的234U/238U(234U超额衰变)和87Sr/86Sr(海洋中放射性成因锶的演化)，以更好地约束生长模式和重建遇到的间断。地质年代学方面是过去一年的中心部分，旨在重建与古环境、古气候和古地形条件有关的丘体形成机制。地球化学工作的重点将是分析有孔虫中的同位素和珊瑚中的元素配给，以重建古温度和古盐度，这些结合起来可能提供关于海水古密度的数据。

, Cold-water coral mounds or carbonate mounds are known to occur widespread within the Porcupine Seabight. Sediment cores from gravity corer and especially drill cores from ICDP Expedition 307 at Challenger Mound indicate the recurring and abrupt occurring changes of carbonate mound growth. Geochemical signals in biogenic tests of planctonic and benthic foraminifers, as well as in skeletons of cold-water corals will allow us to understand the mechanisms of these changes. Stable isotope signature of benthic foraminifera (δ18O, δ13O) from the mound initiation shows a significant change to values characteristic for the water masses derived from the Mediterranean Sea (Mediterranean Outflow). Paleotemperatures derived from Sr/Ca from coral skeletons indicate optimum conditions of growth fort these biota. We speculate that the density envelope of σө= 27.35 - 27.65 kg/m3 characteristic for the ambient seawater of present day cold water coral growth played also an important role in the past. To reconstruct and to better understand these changes between „shut on" and „shut off“ conditions in mound growth we aim to date more samples from lODP-Kem 1317C to close thc existing gap in information. Since conventional U/Th methods are limited to the upper portions of the core (about 350 ka), we shall also apply precise 234U/238U (234U excess decay) and 87Sr/86Sr (radiogenic Sr evolution in the ocean), to better constrain the growth modcl and to reconstmct the encountered hiatuses. The geochronological aspect is a central part for the last year, to reconstmct the mound shaping mechanisms in relation to paleoenvironmental, to paleoclimatotological and to palcoceanographical conditions. The geochemical work will focus on thc analysis of isotopes in foraminifera and element rations in corals to reconstruct paleotemperatures and paleosalinilies, which in combination may provide data on paleodensities of sea water.