Age determination of sediments from Kilkeel and sediment core Y69-71P

Evidence from the Irish Sea basin supports the existence of an abrupt rise in sea level (meltwater pulse) at 19,000 years before the present (B.P.). Climate records indicate a large reduction in the strength of North Atlantic Deep Water formation and attendant cooling of the North Atlantic at this time, indicating a source of the meltwater pulse from one or more Northern Hemisphere ice sheets.Warming of the tropical Atlantic and Pacific oceans and the Southern Hemisphere also began at 19,000 years B.P. These responses identify mechanisms responsible for the propagation of deglacial climate signals to the Southern Hemisphere and tropics while maintaining a cold climate in the Northern Hemisphere.

Oxygen isotope and Mg/Ca record of planktonic foraminifera of sediment core MD01-2390

Changes in the local freshwater budget over the last 22,000 years have been estimated from a sediment core located in the southern South China Sea (SCS) using a combined approach of Mg/Ca and oxygen isotopes on the planktonic foraminifera Globigerinoides ruber (white) sensu stricto (s.s.). Core MD01-2390 (06°28,12N, 113°24,56E; water depth 1591 m) is located near the glacial paleo-river mouths of the Baram, Rajang and North Sunda/Molengraaff Rivers that drained the exposed Sunda Shelf. The delta18Oseawater record reveals lower average values (-0.96±0.18 per mil) during the Last Glacial Maximum (LGM) when compared with modern values (-0.54±0.18 per mil). Low salinity during the LGM is interpreted to reflect a higher freshwater contribution due to a greater proximity of the core site to the mouths of the Baram, Rajang and North Sunda/Molengraaff Rivers at that time. A general deglacial increasing trend in salinity due to the progressive landward displacement of the coastline during deglacial shelf flooding is punctuated by several short-term shifts towards higher and lower salinity that are likely related to abrupt changes in the intensity of the East Asian summer monsoon. Thus, the deglacial delta18Oseawater changes reflect the combined effects of sea-level-induced environmental changes on the shelf (e.g. phases of retreat and breakdown of the shelf drainage systems) and East Asian monsoon climate change. Lower salinity than at present during the Early Holocene may be attributed to an increase in summer monsoonal precipitation that is corroborated by previous marine and terrestrial studies that report a Preboreal-Early Holocene monsoon optimum in the Asian monsoon region.

Geochemical data from the USGS #1 Portland core, Canon City, Colorado

During the Cretaceous, widespread black shale deposition occurred during a series of Oceanic Anoxic Events (OAEs). Multiple processes are known to control the deposition of marine black shales, including changes in primary productivity, organic matter preservation, and dilution. OAEs offer an opportunity to evaluate the relative roles of these forcing factors. The youngest of these events-the Coniacian to Santonian OAE 3-resulted in a prolonged organic carbon burial event in shallow and restricted marine environments including the Western Interior Seaway. New high-resolution isotope, organic, and trace metal records from the latest Turonian to early Santonian Niobrara Formation are used to characterize the amount and composition of organic matter preserved, as well as the geochemical conditions under which it accumulated. Redox sensitive metals (Mo, Mn, and Re) indicate a gradual drawdown of oxygen leading into the abrupt onset of organic carbon-rich (up to 8%) deposition. High Hydrogen Indices (HI) and organic carbon to total nitrogen ratios (C:N) demonstrate that the elemental composition of preserved marine organic matter is distinct under different redox conditions. Local changes in d13C indicate that redox-controlled early diagenesis can also significantly alter d13Corg records. These results demonstrate that the development of anoxia is of primary importance in triggering the prolonged carbon burial in the Niobrara Formation. Sea level reconstructions, d18O results, and Mo/total organic carbon ratios suggest that stratification and enhanced bottom water restriction caused the drawdown of bottom water oxygen. Increased nutrients from benthic regeneration and/or continental runoff may have sustained primary productivity.

Table 1: Parameters of 21 samples from core III of Vernagtferner

The purpose of this study was: (1) To make an attempt at finding a stratification of the snowpack in order to help remove ambiguities in dating the snowlayers by standard methods. (2) To verify the depth at which the transition between firn and ice occurs. Clearly the first goal was missed, the structural information in a temperate firn being strongly smoothed out in time. Interesting details like horizontal ice lenses and layers of "cold snow" however, were revealed. In spite of strong variations of density, gravimetric density PG and ice density PI, computed from point density, are identical for the firn pack between Z = 2.0 m and 6.0 m. p(ice) = 0.522 ± 0.034 x 10**3 kg/m**3. The ice density of 0.8 x 10**3 kg/m**3, the assumed transition between firn and ice, was found to occur at a depth of Z= 19 m. Even at this level, rather important variations in density may be localized. Between Z= 19 m and 21 m, the ice density varies from 0.774 x 10**3 to 0.860 x 10**3 kg/m**3.