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

，冷水珊瑚土丘或碳酸盐土丘是众所周知的，广泛出现在豪猪海湾。来自重力取芯器的沉积物岩心，特别是来自挑战者丘ICDP远征307的钻孔岩心，表明碳酸盐丘生长的反复和突然发生的变化。浮游有孔虫和底栖有孔虫的生物成因测试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。丘体形成时底栖有孔虫的稳定同位素特征（δ 18 O、δ 13 O）显示，地中海（地中海外流）水团的特征值发生了重大变化。由珊瑚骨骼Sr/Ca的古温度值推断出这些生物群的最佳生长条件。我们推测，现今冷水珊瑚生长的环境海水的密度包线σ_（max）= 27.35 - 27.65 kg/m3在过去也起了重要作用。为了重建和更好地理解土丘生长中的”关闭”和“关闭”条件之间的这些变化，我们的目标是对来自IODP-Kem 1317 C的更多样本进行定年，以弥补现有的信息差距。由于常规的U/Th方法仅限于岩芯上部（约350 ka），我们还将应用精确的~（234）U/~（238）U（~（234）U过量衰变）和~（87）Sr/~（86）Sr（海洋放射成因Sr演化），以更好地约束生长模式和重建所遇到的间断。地质年代学方面是去年的核心部分，以重建与古环境，古气候和古海洋条件有关的丘形成机制。地球化学工作的重点将是有孔虫同位素和珊瑚元素比值的分析，以重建古温度和古盐度，这两者结合起来可能提供古海水密度的数据。

, 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.