(Appendix) Oxygen isotope record and carbonate mineralogy of the top part of ODP Hole 101-633A

Hole 633A was drilled in the southern part of Exuma Sound on the toe-of-slope of the southeastern part of Great Bahama Bank during ODP Leg 101. The top 55 m, collected as a suite of six approximately 9.5-m-long hydraulic piston cores, represents a Pliocene-Pleistocene sequence of periplatform carbonate ooze, a mixture of pelagic calcite (foraminifer and coccolith tests), some pelagic aragonite (pteropod tests), and bank-derived fine aragonite and magnesian calcite. A 1.6-m.y.-long hiatus was identified at 43.75 mbsf using calcareous nannofossil biostratigraphy and magnetostratigraphy. The 43.75-m-thick periplatform sequence above the hiatus is a complete late Pliocene-Quaternary record of the past 2.15 m.y. The d18O curve, primarily based on Globigerinoides sacculifera, clearly displays high-frequency/low-amplitude cycles during the early Pleistocene and low-frequency/high-amplitude cycles during the middle and late Pleistocene. Variations in aragonite content in the fine fraction of the periplatform ooze show a cyclic pattern throughout the Pleistocene, as previously observed in piston cores of the upper Pleistocene. These variations correlate well with the d18O record: high aragonite corresponds to light interglacial d18O values, and vice versa. Comparison of the d18O record and the aragonite curve helps to identify 23 interglacial and glacial oxygen-isotope stages, corresponding to 10.5 aragonite cycles (labeled A to K) commonly established during the middle and late Pleistocene (0.9 Ma-present). Strictly based on the aragonite curve, another 11 aragonite cycles, labeled L to V, were identified for the early Pleistocene (0.9 to 1.6 Ma). Mismatches between the d18O record and the aragonite curve occur mainly at some of the glacial-to-interglacial transitions, where aragonite increases usually lag behind d18O depletion. When one visually connects the minima on the Pleistocene aragonite curve, low-frequency (0.4 to 0.5 m.y.) supercycles seem to be superimposed on the high-frequency cycles. The timing of this supercycle roughly matches the timing of the Pleistocene carbonate preservation supercycles described in the Pacific, Indian, and Atlantic oceans. Mismatches between aragonite and d18O cycles are even more obvious for the late Pliocene (1.6 to 2.15 Ma). Irregular aragonite variations are observed for the late Pliocene, although after the onset of late Pleistocene-like glaciations in the North Atlantic Ocean 2.4 m.y. ago the d18O record has shown a mode of high-frequency/low-amplitude cycles. Initiation of climatically induced aragonite cycles occurs only at the Pliocene-Pleistocene transition, 1.6 m.y. ago. After that time, aragonite cycles are fully developed throughout the Quaternary. The 11-m-thick periplatform sequence below the hiatus represents a lower Pliocene interval between 3.75 and 4.45 Ma. The bottom half (4.25-4.45 Ma) has a fairly constant, high aragonite content (averaging 60%) and high sedimentation rates (28 m/m.y.) and corresponds to the end of the prolonged early Pliocene interglacial interval (4.1-5.0 Ma), established as a worldwide high sea-level stand. The second half (3.75-4.25 Ma), in which aragonite content decreases by successive steps, paralleled by a gradual 5180 enrichment in Globigerinoides sacculifera and low sedimentation rates (10 m/m.y), corresponds to the climatic deterioration established worldwide between 4.1 and 3.8 Ma, to a decrease of carbonate preservation observed in the equatorial Pacific Ocean, and to a global sea-level decline. Dolomite, a ubiquitous secondary component in the lower Pliocene, is interpreted as being authigenic and possibly related to diagenetic transformation of primary bank-derived fine magnesian calcite. Transformation of the primary mineralogical composition of the periplatform ooze was evidently minor, as the sediments have retained a detailed record of the Pliocene-Pleistocene climatic evolution. Clear evidence of diagenetic transformations in the periplatform ooze includes (1) the disappearance of magnesian calcite in the upper 20 m of Hole 633A, (2) the occurrence of calcite overgrowths on foraminiferal tests and microclasts at intermittent chalky core levels, and (3) the ubiquitous presence of authigenic dolomite in the lower Pliocene.

Organic geochemistry on sediment profiles from the Arctic Ocean

During the ARCTIC '91-Expedition with RV 'Polarstern', several Multicorer and Kastenlot-cores were recovered along a profile crossing the eastern part of the Arctic Ocean. The investigated cores consist mainly of clayey-silty sediments, and some units with a higher sand content. In this thesis, detailed sedimentological and organic-geochemical investigations were performed. In part, the near surface sediments were AMS-14C dated making it possible to Interpret the results of the organic-geochemical investigations in terms of climatic changes (isotopic stage 2 to the Holocene). The more or less absence of foraminifers within the long cores prevented the development of an oxygen isotope stratigraphy. Only the results of core PS2174-5 from the Amundsen-Basin could be discussed in terms of the climatic change that could be dated back to oxygen isotope stage 7. Detailed organic-geochemical investigations in the central Arctic Ocean are rare. Therefore, several different organic-geochemical methods were used to obtain a wide range of data for the Interpretation of the organic matter. The high organic carbon content of the surface sediments is derived from a high input of terrigenous organic matter. The terrigenous organic material is most likely entrained within the sea-ice On the Siberian shelves and released during ice-drift over the Arctic Ocean. Other factors such as iceberg-transport and turbidites are also responsible for the high input of terrigenous organic matter. Due to the more or less closed sea-ice Cover, the Arctic Ocean is known as a low productivity system. A model shows, that only 2 % of the organic matter in central Arctic Ocean sediments is of a marine origin. The influence of the West-Spitsbergen current increases the marine organic matter content to 16 %. Short chain n-alkanes (C17 and C19) can be used as a marker of marine productivity in the Arctic Ocean. Higher contents of short chain n-alkanes exist in surface sediments of the Lomonosov-Ridge and the Makarov-Basin, indicating a higher marine productivity caused by a reduced sea-ice Cover. The Beaufort-Gyre and Transpolar-Drift drift Patterns could be responsible for the lower sea-ice distribution in this region. The sediments of Stage 2 and Stage 3 in this region are also dominated by a higher content of short chain-nalkanes indicating a comparable ice-drift Pattern during that time. The content and composition of organic carbon in the sediments of core PS2174-5 reflect glaciallinterglacial changes. Interglacial stages 7 and 5e show a low organic carbon content (C 0,5 %) and, as indicated by high hydrogen-indices, low CIN-ratios, higher content of n-alkanes (C17 and C19) and a higher opal content, a higher marine productivity. In the Holocene, a high content of foraminifers, coccoliths, ostracodes, and sponge spicules indicate higher surface-water productivity. Nevertheless, the low hydrogenindices reveal a high content of terrigenous organic matter. Therefore, the Holocene seems to be different from interglacials 7 and 5e. During the glacial periods (stages 6, upper 5, and 4), TOC-values are significantly higher (0.7 to 1.3 %). In addition, low hydrogen-indices, high CIN-ratios, low short chain n-alkanes and opal contents provide evidence for a higher input of terrigenous organic matter and reduced marine productivity. The high lignin content in core sections with high TOC-contents, substantiates the high input of terrigenous organic matter. Changes in the content and composition of the organic carbon is believed to vary with the fluctuations in sea-level and sea-ice coverage.

(Table 2) Fauna Harpacticoida and its distribution in the Kandalaksha Bay (White Sea) in July 1998 and 1999

Dependence of the faunal composition and species structure of the White Sea littoral Harpacticoida on sediment properties was studied. Three groups of species could be distinguished according to their relationship with sediment properties: (1) species typical of silty sediments, (2) species preferring sediments with high gravel content, and (3) species inhabiting well-sorted washed sands. Vertical distribution of crustaceans within sediments of different types was studied. Vertical migrations of harpacticoids (3) during the tidal cycle were described. Data on interannual variability of harpacticoid fauna are presented.

(Table 1, page 168) Iron, manganese, and phosphorus concentrations in Fe-Mn-concretions from the Gulf of Bothnia, northern Baltic Sea

Fe-Mn-concretions of a spheroidal type were found according to electron probe determinations to consist of alternating iron- and manganese-rich layers. This pattern was ascribed to seasonal variations in the physico-chemical conditions governing the precipitation of the hydrous oxides of iron and manganese. Calculations based on the rhythmic growth of the concretions investigated gave a mean accumulation rate of 0.15-0.20 mm/yr. The rather high phosphorus content (average 3.5 % P2O5) of the concretions was found to be concentrated in the iron-rich layers, probably as a result of the scavenging effect of ferric hydroxide.

Description of recent sediments of Nile Delta, Red Sea and Gulf of Aden (Table 1-3)

The study of textural, structural, chemical, and physical properties of fine-grained recent marine sediments leads to the conclusion that only a few compositional factors are responsible for significant changes in mass physical characteristics in the upper meters below sea bottom. Fossil-induced porosity increases water content and liquid limit. It also seems to have partially influenced the plastic limit and plasticity index of calcareous sandy silts from the Red Sea and the western Gulf of Aden so that they become similar to the montmorillonite rich prodelta clays from the Nile Delta. Diagrams based on liquid limit and plasticity loose their original meaning in these cases. Activity of sediments rich in microorganisms can be higher than that of montmorillonitic clay. The shear strength-depth relationship of normally consolidated sediments is surprisingly little influenced by changes in sand or clay content and clay mineralogy. Only high lime content, submarine erosion and beginning cementation increase the strength considerably. Erosional disconformities near the present surface can be deduced from the strength-depth curve when as little as 1 or 2 m sediment have been removed. Flat or irregular strength-depth curves indicate beginning cementation and probably discontinuous sedimentation, provided the composition of the material remains in some degree constant. In our samples diagenetic pyrite, but no recristallisation of carbonates could be detected under the microscope. Underconsolidation and excess pore-water pressure, factors which tend to foster submarine slides, mud lumps, and diapiric folding, seem to be restricted Varito areas with mainly rapidly deposited, homogeneous or layered sediments. But where an abundance of burrowing organisms increases the vertical permeability of the sediment, normal consolidation and stable deposits are to be expected, at least in the upper meters below the present surface. According to 14C-determinations on calcareous microorganisms the rate of deposition of the investigated sediments seems to range from 26 to 167 cm per 1000 years.

Analysis of radioactive manganiferous nodules from Tanokami, Japan

Characteristic black nodules have been retrieved in 1922 from the bed of the Kichijo River, that runs along the Tanakamiyama mountain in the Oni Province and ends into Lake Biwa in Japan. Their radiocativity has been studied along with that of crusts of similar nature found covering rock formations in the vicinity overlooking the stream. The high content in radium observed may be due to the high uranium content of the granite host rock typical of the Tanakamiyama formation.

(Table T1) Geochemical composition of ODP Site 177-1089 sediments

A primary objective of Ocean Drilling Program Leg 177 was to document changes in circulation and biogeochemical cycling on glacial/interglacial time scales across a wide latitudinal range of the south Atlantic Ocean. One of the more northerly sites drilled, Site 1089 (41°S, 10°E), is located within the present-day Subantarctic Zone, south of the Subtropical Front. The drilling site itself is located in the southern Cape Basin at a water depth of 4620 m. Pleistocene sediments at this site are dominated by interbedded carbonate and opal oozes. Initial shipboard stratigraphy identified the opal-rich sediments as deposited during glacial intervals and the carbonate-rich sediments as deposited during interglacial intervals (Gersonde, Hodell, Blum, et al., 1999, doi:10.2973/odp.proc.ir.177.1999). Postcruise isotopic stratigraphy, however, verified that this site displayed a Pacific Pleistocene sedimentation pattern with glacial intervals marked by high carbonate content (Hodell and Charles, 1999). To assess changes in biological productivity and terrigenous inputs at this site, a number of geochemical indicators were determined. Phosphorus concentrations and P/metal ratios were determined to assess changes in export production on glacial/interglacial time scales. Metal concentrations, along with elemental ratios, were used to assess terrigenous inputs. Sediment geochemistry allows us to identify changes in the lithologic component using elemental data based on Fe, Al, and Ti concentrations. Records of concentrations and ratios of biologically related elements identify changes in export production. The P and metal results are important to assess the glacial/interglacial changes in P burial and the relationships between a major nutrient such as P with metals (and possibly trace nutrients) like Fe.

Calcium carbonate conctent and stable isotope ratios of glacial-holocene sediments from the South China Sea

A bathymetric transect of cores in the South China Sea extending from 4200-m to less than 1000-m water depth has been examined for glacial-interglacial changes in carbonate and organic carbon sedimentation. Typical 'Pacific carbonate cycles' (high carbonate content during glacials and low carbonate content during interglacials) characterize cores from water depths deeper than 3500 m. In contrast, 'Atlantic carbonate cycles' (low carbonate during glacials and high carbonate during interglacials) are observed in cores from depths shallower than 3000 m as a result of increased dilution of carbonate by terrigenous material during glacial low stands of sea level. Glacial-interglacial changes in the carbonate chemistry of South China Sea intermediate and deep waters resulted in significant changes in the positions of the carbonate compensation depth (CCD) and the aragonite compensation depth (ACD). During the last glacial the CCD and ACD were at least 400 and 1200 m deeper, respectively, than at present. Organic carbon accumulation rates in the South China Sea were approximately 2 times higher during the last glacial than the Holocene. Carbon isotopic analyses and C/N ratios of the organic matter indicate that only a small fraction of the increase in glacial organic carbon accumulation can be attributed to input of terrestrial carbon. On the basis of this we conclude that surface water productivity in the South China Sea was approximately 2 times higher during the last glacial maximum. This is consistent with previous studies which have demonstrated that glacial productivity was higher in low- to mid-latitude regions of the Atlantic and eastern Pacific. The deglacial decrease in organic carbon accumulation is accompanied by a decrease in delta13Corg. Using the relationship between delta13Corg and [CO2](aq) developed by Popp et al. [1989], we estimate that surface water pCO2 values in the South China Sea during the last 25,000 years were very similar to atmospheric CO2 concentrations.

Geochemical and stable isotope composition of Middle Campanian marl-limestone rhythmites of the Lehrte West Syncline near Hannover (Lower Saxony, northern Germany)

A cyclic marl-limestone succession of Middle-Late Campanian age has been investigated with respect to a Milankovitch-controlled origin of geochemical data. In general, the major element geochemistry of the marl-limestone rhythmites can be explained by a simple two-component mixing model with the end-members calcium carbonate and 'average shale'-like material. Carbonate content varies from 55 to 90%. Non-carbonate components are clay minerals (illite, smectite) and biogenic silica from sponge spicules, as well as authigenically formed zeolites (strontian heulandite) and quartz. The redox potential suggests oxidizing conditions throughout the section. Trace element and stable isotopic data as well as SEM investigations show that the carbonate mud is mostly composed of low-magnesium calcitic tests of planktic coccolithophorids and calcareous dinoflagellate cysts (calcispheres). Diagenetic overprint results in a decrease of 2% d18O and an increase in Mn of up to 250 ppm. However, the sediment seems to preserve most of its high Sr content compared to the primary low-magnesium calcite of co-occurring belemnite rostra. The periodicity of geochemical cycles is dominated by 413 ka and weak signals between 51 and 22.5 ka, attributable to orbital forcing. Accumulation rates within these cycles vary between 40 and 50 m/Ma. The resulting cyclic sedimentary sequence is the product of (a) changes in primary production of low-magnesium calcitic biogenic material in surface waters within the long eccentricity and the precession, demonstrated by the CaCO3 content and the Mg/Al, Mn/Al and Sr/Al ratios, and (b) fluctuations in climate and continental weathering, which changed the quality of supplied clay minerals (the illite/smectite ratio), demonstrated by the K/Al ratio. High carbonate productivity correlates with smectite-favouring weathering (semi-arid conditions, conspicuously dry and moist seasonal changes in warmer climates). Ti as the proxy indicator for the detrital terrigenous influx, as well as Rb, Si, Zr and Na, shows only low frequency signals, indicating nearly constant rates of supply throughout the more or less pure pelagic carbonate deposition of the long-lasting third-order Middle-Upper Campanian sedimentary cycle.

Biogenic opal and diatoms in surface sediments of the South Western Atlantic

Based on 66 surface sediment samples collected in the SW Atlantic Ocean between 27 and 50°S, this study presents an overview of the spatial distribution of biogenic opal and diatom concentrations, and diatom assemblages. Biogenic opal has highest values in the deepest, pelagic stations and decreases toward the slope. Diatoms closely follow the spatial trend of opal. Diatom assemblages reflect the present-day dominant hydrographical features. Antarctic diatoms are the main contributors to the preserved diatom community in core top sediments, with coastal planktonic and tropical/subtropical diatoms as secondary components. Dominance of Antarctic diatoms between 35 and 50°S in the pelagic realm mirrors the northward displacement of Antarctic-source water masses, characterized by high nutrient content and low salinity. Northward of ca. 35°S, the highest contribution of tropical/subtropical, pelagic diatoms, typical for nutrient-poor and high salinity waters, matches the main southward path of the Brazil Current. Mixing of Antarctic and tropical waters down up to 45°S is clearly illustrated by the diatom assemblage. Concentrations of biogenic opal and diatoms rather reflect the path of predominant water masses, but are less correlated with surface water productivity in the SW Atlantic.

Dinoflagellate cycst in Neogene sediments of ODP Leg 178 holes

Protoperidiniacean dinoflagellate cysts were identified in 19 of 28 samples from two sites on the Antarctic Peninsula continental rise. Cysts are most common in the lower Pliocene and upper Miocene and include species of Brigantedinium, Lejeunecysta, and Selenopemphix. Autotrophic gonyaulacacean dinoflagellate cysts are very rare in the samples. The dominance of taxa derived from assumed heterotrophic dinoflagellate motile forms may indicate high nutrient content in the surface waters, which sustained a considerable diatom population.

Age analysis, aragonite and high magnesium calcite content from different IODP Holes from Exp 310

The widespread occurrence of microbialites in the last deglacial reef frameworks (16-6 Ka BP) implies that the accurate study of their development patterns is of prime importance to unravel the evolution of reef architecture through time and to reconstruct the reef response to sea-level variations and environmental changes. The present study is based on the sedimentological and chronological analysis (14C AMS dating) of drill cores obtained during the IODP Expedition #310 "Tahiti Sea Level" on the successive terraces which typify the modern reef slopes from Tahiti. It provides a comprehensive data base to investigate the microbialite growth patterns (i.e. growth rates and habitats), to analyze their roles in reef frameworks and to reconstruct the evolution of the reef framework architecture during sea-level rise. The last deglacial reefs from Tahiti are composed of two distinctive biological communities: (1) the coralgal communities including seven assemblages characterized by various growth forms (branching, robust branching, massive, tabular and encrusting) that form the initial frameworks and (2) the microbial communities developed in the primary cavities of those frameworks, a few meters (1.5 to 6 m) below the living coral reef surface, where they heavily encrusted the coralgal assemblages to form microbialite crusts. The dating results demonstrate the occurrence of two distinctive generations of microbialites: the "reefal microbialites" which developed a few hundred years after coralgal communities in shallow-water environments, whereas the "slope microbialites" grew a few thousands of years later in significantly deeper water conditions after the demise of coralgal communities. The development of microbialites was controlled by the volume and the shape of the primary cavities of the initial reef frameworks determined by the morphology and the packing of coral colonies. The most widespread microbialite development occurred in frameworks dominated by branching, thin encrusting, tabular and robust branching coral colonies which built loose and open frameworks typified by a high porosity (> 50%). In contrast, their growth was minimal in compact coral frameworks formed by massive and thick encrusting corals where primary cavities yielded a low porosity (~ 30%) and could not host a significant microbialite expansion.