Bathymetry grids and maps of Mozambique Ridge compiled from cruises 64PE305, 64PE306, SO-87, SO-182, SO-183, ME-33/2, ME-63/1 bathymetry

Based on data from R.V. Pelagia, R.V. Sonne and R.V. Meteor multibeam sonar surveys, a high resolution bathymetry was generated for the Mozambique Ridge. The mapping area is divided into five sheets, one overview and four sub-sheets. The boundaries are (west/east/south/north): Sheet 1: 28°30' E/37°00' E/36°20' S/24°50' S; Sheet 2: 32°45' E/36°45' E/28°20' S/25°20' S; Sheet 3: 31°30' E/36°45' E/30°20' S/28°10' S; Sheet 4: 30°30' E/36°30' E/33°15' S/30°15' S; Sheet 5: 28°30' E/36°10' E/36°20' S/33°10' S. Each sheet was generated twice: one from swath sonar bathymetry only, the other one is completed with depths from ETOPO2 predicted bathymetry. Basic outcome of the investigation are Digital Terrain Models (DTM), one for each sheet with 0.05 arcmin (~91 meter) grid spacing and one for the entire area (sheet 1) with 0.1 arcmin grid spacing. The DTM's were utilized for contouring and generating maps. The grid formats are NetCDF (Network Common Data Form) and ASCII (ESRI ArcGIS exchange format). The Maps are formatted as jpg-images and as small sized PNG (Portable Network Graphics) preview images. The provided maps have a paper size of DIN A0 (1189 x 841 mm).

Bathymetry grids and maps of Mozambique Basin compiled from cruise SO183 bathymetry

Based on data from R/V Sonne multibeam sonar surveys in 2005 a high resolution bathymetry was generated for the Mozambique Basin. The area covers approx. 466,475 sqkm. The mapping area is divided into four sheets with boundaries (west/east/south/north): Sheet I (north-west), 37:00/39:45/-24:00/-20:20; Sheet II (north-east), 39:45/42:30/-24:00/-20:20; Sheet III (south-west), 37:00/39:45/-27:40/-24:00; Sheet IV (south-east), 39:45/42:30/-27:40/-24:00. Basic outcome of the investigation are Digital Terrain Models (DTM), one for each sheet with 0.05 arcmin (~91 meter) grid spacing and one for the entire area with 0.1 arcmin grid spacing. The DTM's were utilized for contouring and generating maps. Moreover the measured bathymetry was combined and compared with GEBCO bathymetry and predicted bathymetry, derived from altimeter satellites. The provided maps have a paper size of DIN A0 (1188.9 x 841 mm).

Biomarker records of DSDP Hole 24-231 and terrestrial sediments

ntegrated terrestrial and marine records of northeast African vegetation are needed to provide long high resolution records of environmental variability with established links to specific terrestrial environments. In this study, we compare records of terrestrial vegetation preserved in marine sediments in the Gulf of Aden [Deep Sea Drilling Project (DSDP) Site 231] and an outcrop of lacustrine sediments in the Turkana Basin, Kenya, part of the East African Rift System. We analyzed higher plant biomarkers in sediments from both deposits of known equivalent age, corresponding to a ca. 50-100 ka humid interval prior to the b-Tulu Bor eruption ca. 3.40 Ma, when the Lokochot Lake occupied part of the Turkana Basin. Molecular abundance distributions indicate that long chain n-alkanoic acids in marine sediments are the most reliable proxy for terrestrial vegetation (Carbon Preference Index, CPI = 4.5), with more cautious interpretation needed for n-alkanes and lacustrine archives. Marine sediments record carbon isotopic variability in terrestrial biomarkers of 2-3 per mil, roughly equivalent to 20% variability in the C3/C4 vegetation contribution. The proportion of C4 vegetation apparently increased at times of low terrigenous dust input. Terrestrial sediments reveal much larger (2-10 per mil) shifts in n-alkanoic acid delta13C values. However, molecular abundance and isotopic composition suggest that microbial sources may also contribute fatty acids, contaminating the lacustrine sedimentary record of terrestrial vegetation.

Late Miocene carbon isotope and paleoproductivity record

We examine whether or not a relationship exists between the late Miocene carbon isotope shift (~7.6-6.6 Ma) and marine productivity at four sites from the Indian and Pacific Oceans (Ocean Drilling Program Sites 721, 1146, 1172, and 846). We use a multiproxy approach based on benthic foraminiferal accumulation rates, elemental ratios, and dissolution indices, and we compare these data to benthic foraminiferal d13C values measured on the same samples. Although some of these sites have been targeted previously in studies of either the late Miocene/early Pliocene "biogenic bloom" (Sites 721 and 846) or the late Miocene carbon isotope shift (Site 1172), our records are the first to establish paired proxy records of carbon isotopes and paleoproductivity allowing a direct assessment of a potential link. Our results indicate that at all sites, productivity increased sometime during the d13C shift; at three sites (721, 1146, and 846), productivity increased at the beginning of the shift. The correlation coefficients derived from linear regression between micropaleontologically derived productivity and foraminiferal d13C values are relatively high during the time interval containing the late Miocene d13C shift (and statistically significant at three of the sites). Carbon flux and isotope mass balance considerations illustrate that transfer of organic matter between the terrestrial and marine reservoirs together with enhanced oceanic upwelling best approximates observed changes in carbon isotope records and paleoproductivity. We note that long-term trend in the Site 846 paleoproductivity record can be correlated to the long-term trend in the Site 848 eolian flux reconstructions of Hovan (1995, doi:10.2973/odp.proc.sr.138.132.1995) hinting at a link between strengthened wind regime and productivity during the late Miocene.

Median grain size in ODP Sites 184-1143 and 184-1144

Monsoon climate is an important component of the global climatic system. A comprehensive understanding of its variability over glacial-interglacial time scales as well as of its effects on the continent and in the ocean is required to decipher links between climate, continental weathering and productivity. A detailed multiproxy study, including bulk and clay mineralogy, grain-size analysis, phosphorus geochemistry (SEDEX extraction), organic matter characterization, and nitrogen stable isotopes, was carried out on samples from ODP Sites 1143 and 1144 (Leg 184, South China Sea), covering the past 140 000 years. We tentatively reconstruct the complex sedimentation and climatic history of the region during the last glacial-interglacial cycle, when sea-level variations, linked to the growth and melting of ice caps, interact with monsoon variability. During interglacial periods of high sea level, summer monsoon was strong, and humid and warm climate characterized the adjacent continent and islands. Clay minerals bear signals of chemical weathering during these intervals. High calcite and reactive phosphorus mass accumulation rates (MARs) indicate high productivity, especially in the southern region of the basin. During glacial intervals, strong winter monsoon provided enhanced detrital input from the continent, as indicated by high detrital MAR. Glacial low sea level resulted in erosion of sediments from the exposed Sunda shelf to the south, and clay mineral variations indicate that warm and humid conditions still prevailed in the southern tropical areas. Enhanced supply of nutrients from the continent, both by river and eolian input, maintained high primary productivity. Reduced circulation during these periods possibly induced active remobilization of nutrients, such as phosphorus, from the sediments. Intense and short cold periods recorded during glacial and interglacial stages correlate with loess records in China and marine climatic records in the North Atlantic, confirming a teleconnection between low- and high-latitude climate variability.