Description: Water column stratification increased at climatic transitions from cold to warm periods during the late Quaternary and led to anoxic conditions and sapropel formation in the deep eastern Mediterranean basins. High-resolution data sets on sea-surface temperatures (SST) (estimated from UK'37 indices) and d18O of planktonic foraminifer calcite (d18Ofc) across late Pleistocene sapropel intervals show that d18Ofc decreased (between 1 and 4.6 per mil) and SST increased (between 0.7° and 6.7°C). Maximal d18Oseawater depletion of eastern Mediterranean surface waters at the transition is between 0.5 and 3.0 per mil, and in all but one case exceeded the depletion seen in a western Mediterranean core. The depletion in d18Oseawater is most pronounced at sapropel bases, in agreement with an initial sudden input of monsoon-derived freshwater. Most sapropels coincide with warming trends of SST. The density decrease by initial freshwater input and continued warming of the sea surface pooled fresh water in the surface layer and prohibited deep convection down to ageing deep water emplaced during cold and arid glacial conditions. An exception to this pattern is "glacial" sapropel S6; its largest d18Oseawater depletion (3 per mil) is almost matched by the depletion in the western Mediterranean Sea, and it is accompanied by surface water cooling following an initially rapid warming phase. A second period of significant isotopic depletion is in isotope stage 6 at the 150 kyr insolation maximum. While not expressed as a sapropel due to cold SST, it is in accord with a strengthened monsoon in the southern catchment.

Description: The 1.4-m.y.-long stable oxygen isotope record of Site 1006 in the low-latitude North Atlantic Ocean shows large glacial/interglacial amplitude changes caused by a combination of temperature and salinity fluctuations. A trend of increased sea-surface temperatures during the interglacial periods is present in the record beginning at isotopic Stage 11 and ultimately leading to the lightest d18O values in isotopic Stages 9, 5, and 1. Maximum d18O values are recorded during glacial isotopic Stages 6 and 8. Stable isotopic variability increased during the Brunhes Chron at the 100-ka time scale. The large amplitude changes can best be explained by global and regional ocean circulation changes. Increased strengthened return flow of warm salty water from the Pacific may have occurred during interglacial periods since isotopic Stage 11, which was largely reduced during glacial periods. The large climate fluctuations had a profound effect on the shallow-water carbonate production of the Great Bahama Bank. The aragonite content of the sediments shows fluctuations that follow the d18O record. The leeward side of the Great Bahama Bank received increased input of platform material during sea-level highstands when the sea-surface waters were warm.

Description: The Late Cretaceous-Early Paleogene is the most recent period of Earth history that experienced sustained global greenhouse warmth and was characterised by a dynamic carbon cycle. Yet, knowledge of ambient climate conditions and the evolution of atmospheric pCO2 at this time, along with their relation to forcing mechanisms, are still poorly constrained. Here we present an unprecedented 14.75 million year long high-resolution orbitally-tuned record of paired climate change and carbon-cycling (based on the oxygen and carbon isotope composition of benthic foraminiferal tests) compiled to date for the enigmatic Late Cretaceous to Early Eocene, and compare these records to the most up-to-date compilation of atmospheric pCO2 records for this time. We identify eccentricity as the dominant pacemaker of the observed climate and carbon cycle changes, through the modulation of precession. The carbon cycle (e.g., d13C) lagged changes in climate by ~22,800 years within the long eccentricity (405,000 year) band and ~3,000-4,500 years within the short eccentricity (100,000 year) band, suggesting that light carbon was released as a positive feedback to warming induced by small changes in orbital forcing. The majority of the hyperthermals of this time period occur during maxima in the long eccentricity cycle, with the exception of the Paleocene-Eocene Thermal Maximum and Late Maastrichtian warming event, which are likely to have been triggered by Large Igneous Province volcanism.

Description: This preliminary report does not present the distribution of selected key planktonic species in each Leg 133 hole, but rather, extracts the best chronodatum levels in two sets of holes, which comprise the Queensland Trough and Townsville Trough transects. In general, the sampling interval was 1.5 m, but sometimes was larger. To convert the datum levels into time, the absolute ages of Berggren et al. (1985, doi:10.1144/GSL.MEM.1985.010.01.18) were used. Extinction levels were employed in the main, because they are the most easily recognized, the order of events seems to be consistent from hole to hole, and they correlate reasonably well with chronodatum levels obtained from nannofossil biostratigraphy (see Gartner et al., 1993, doi:10.2973/odp.proc.sr.133.213.1993).

Description: To reveal changes in the oceanic environment on the continental slope adjacent to the Great Barrier Reef, east of Cairns (NE Australia), planktonic and benthic foraminiferal abundances were counted and planktonic percentages (P/B ratios) were determined in sediments from two sites. Counts of planktonic and benthic specimens per gram of sediment over the last glacial/interglacial cycle at the shallowest Site 821, located in a water depth of 212 m just below the core of Subtropical Lower Water, show high abundances in the last glacial compared with the Holocene interglacial. We interpret the apparent increase in abundances during the last glacial as mainly a consequence of fluctuations in the intensity of flow of Subtropical Lower Water along the outer shelf edge and upper slope. During the lowstand in sea level, the increased flow winnowed the sediments, concentrating the foraminiferal skeletons. The P/B ratios are low throughout, with the highest values occurring during the Holocene interglacial and glacial stage 2. This suggests that some upwelling might have occurred during glacial stage 2. The relatively deeper water Site 819 is located in 565.2 m of water in a zone of mixing between Subtropical Lower Water and Antarctic Intermediate Water. The studied record at this site represents middle to upper Quaternary sediments, but it was interrupted by a hiatus just above stage 15 (Alexander et al., this volume); stages 7 through 13 are missing. Below the hiatus (isotopic stages 15 through 21), the foraminiferal abundances are low, while above the hiatus, the highest abundances occur in isotopic stage 6. In addition, a major change in the P/B ratio occurs across the unconformity. Below the hiatus, the ratios are low and resemble the values of the top of Site 821; but above it, ratios rapidly fluctuate, with a tendency for high values during glacial periods. We interpret the changes across the hiatus as having been caused by a shift in the position of the mixing zone between subsurface Subtropical Lower Water and Antarctic Intermediate Water. The mixing zone of these watermasses was farther down the slope in isotopic stages 15 through 21. This is indicated by the low P/B ratios, similar to the values found in the top of Site 821, which presently is bathed in subtropical waters. Above the hiatus, the influence of Antarctic Intermediate Water increased, as inferred from the high P/B ratios.