Late Quaternary geochemical record of sediment core GeoB3375-1

Analyses of terrigenous sediments from the Chilean continental slope off the southern border of the Atacama desert (27.5°S), focusing on illite crystallinity and the Fe:Al ratio of the sediments, reveal a high-frequency variability of the position of the Southern Westerlies, which is very similar to the coeval short-term climatic events known from Greenland ice cores and from North Atlantic sediments. Besides showing dominantly precession-driven variability in precipitation over the Andes, these analyses also reveal rapid changes in weathering intensity along the Chilean Coastal Range during the last 80,000 years. These rapid changes occur at much shorter timescales than the 19-100 kyr orbital forcing of the Milankovitch cycles.

Magnesium/Calcium ratios and sea surface temperature estimation for sediments of the Timor Sea

We use a multiproxy approach to monitor changes in the vertical profile of the Indonesian Throughflow as well as monsoonal wind and precipitation patterns in the Timor Sea on glacial-interglacial, precessional, and suborbital timescales. We focus on an interval of extreme climate change and sea level variation: marine isotope (MIS) 6 to MIS 5e. Paleoproductivity fluctuations in the Timor Sea follow a precessional beat related to the intensity of the Australian (NW) monsoon. Paired Mg/Ca and d18O measurements of surface- and thermocline-dwelling planktonic foraminifers (G. ruber and P. obliquiloculata) indicate an increase of >4°C in both surface and thermocline water temperatures during Termination II. Tropical sea surface temperature changed synchronously with ice volume (benthic d18O) during deglaciation, implying a direct coupling of high- and low-latitude climate via atmospheric and/or upper ocean circulation. Substantial cooling and freshening of thermocline waters occurred toward the end of Termination II and during MIS 5e, indicating a change in the vertical profile of the Indonesian Throughflow from surface- to thermocline-dominated flow.

Composition of soil samples from injection location

CO2 leakage from subsurface storage sites is one of the main concerns connected with the CCS technology. As CO2 leakages into near surface formations appear to be very unlikely within pilot CCS projects, the aim of this work is to emulate a leakage by injecting CO2 into a near surface aquifer. The two main questions pursued by the injection test are (1) to investigate the impact of CO2 on the hydrogeochemistry of the groundwater as a base for groundwater risk assessment and (2) to develop and apply monitoring methods and monitoring concepts for detecting CO2 leakages in shallow aquifers. The presented injection test is planned within the second half of 2010, as a joint project of the University of Kiel (Germany), the Helmholtz-Centre for Environmental Research (Leipzig, Germany) and the Engineering Company GICON (Dresden, Germany). The test site has been investigated in detail using geophysical methods as well as direct-push soundings, groundwater well installation and soil and groundwater analyses. The present paper presents briefly the geological and hydrogeological conditions at the test site as well as the planned injection test design and monitoring concept.

Interstitial water chemistry of ODP Leg 103 sites

Interstitial waters were squeezed from strata recovered at Sites 637-641 of ODP Leg 103 on the Galicia margin, along the northwestern Iberian continental margin in the northeast Atlantic. Chemical profiles of Site 638 show the most complexity, which appears to be related to an unconformity in the strata between Cretaceous and Neogene sediments and to rapid deposition of Cretaceous syn-rift sediments upon pre-rift strata. Analyses of waters from all of the Leg 103 sites show generally antithetical trends for calcium and magnesium; calcium increases with depth as magnesium decreases. No calcium-magnesium 'crossover' profiles are observed in these data. Data from Site 637 show an unusual pattern; calcium increases with increasing depth, but magnesium remains relatively constant. Sulfate is either stable or shows an overall decrease with depth, and boron profiles show some structure. At all but one site (Site 638), strontium profiles do not show marked depth structure. The structure of alkalinity and silica profiles is highly site dependent. Bromide profiles are, in general, constant. In nearly every case, observed bromide concentrations are near average seawater values. Relatively low concentrations of iron and manganese are common within the upper 10 m of the sediment sequence and typically are near detection limits at deeper depths

Geochemistry of recent sediments from the Indian Ocean

During the International Indian Ocean Expedition (1964/65) sediment cores were taken on six profiles off the western coast of the Indian Subcontinent. These profiles run approximately perpendicular to the coast, from the deep-sea over the continental slope to the continental shelf. Additional samples and cores were taken in a dense pattern in front of the delta of the Indus River. This pattern of sampling covered not only marine sediments, but also river and beach sediments in Pakistan. The marine samples were obtained with piston, gravity and box corers and by a Van Veen grab sampler. The longest piston core is about 5 meters long. 1. Distribution of the elements on the sediment surface The area of maximal carbonate values (aprox. 80-100% CaCO3) essentially coincides with the continental shelf. The highest Sr values were observed largely within this area, but only in the vicinity of the Gulf of Cambay. Mainly the aragonitic coprolites are responsible for those high Sr contents. The Mg contents of the carbonates are comparatively low; surprisingly enough the highest Mg concentrations were also measured in the coprolites. The maximum contents of organic matter (Core) were found along the upper part of the continental slope. They coincide with the highest porosity and water content of the sediments. Frequently the decomposition of organic matter by oxydation is responsible for the measured Corg contents. On the other side the quantity of originally deposited organic material is less important in most cases. The enrichment of the "bauxitophile" elements Fe, Ti, Cr and V in the carbonate- and quartz-free portions of the sediments is essentially due to the influence of coarse terrigenous detritus. For the elements Mn, Ni and Cu (in per cent of the carbonateand quartz-free sediment) a strong enrichment was observed in the deep-sea realm. The strong increase in Mn toward the deep-sea is explained by authigenesis of Mn-Fe-concretions. Mn-nodules form only under oxydizing conditions which obviously are possible only at very low rates of deposition. The Mg, B and, probably also Mn contents in the clay minerals increase with increasing distance from the continent. This can be explained by the higher adsorption of those elements from sea water because of increasing duration of the clay mineral transport. The comparison of median contents of some elements in our deep-sea samples with deep-sea sediments described by TUREKIAN & WEDEPOHL (1961) shows that clear differences in concentration exist only in the case of "bauxitophile" elements Cr and Be. The Cr and Be contents show a clear increase in the Indian Ocean deep-sea samples compared to those described by TUREKIAn & WEDEPOHL (1961) which can obviously be attributed to the enrichment in the lateritic and bauxitic parent rocks. The different behaviour of the elements Fe, Ti and Mn during decomposition of the source rocks, transport to the sea and during oxydizing and reducing conditions in the marine environment can be illustrated by Ti02/Fe and MnO/Fe ratios. The different compositions of the sediments off the Indus Delta and those of the remaining part of the area investigated are characterized by a different distribution of the elements Mn and Ti. 2. Chemical inhomogenities in the sediments Most longer cores show 3 intervals defined by chemical and sedimentological differences. The top-most interval is coarse-grained, the intermedial interval is fine grained and the lower one again somewhat coarser. At the same time it is possible to observe differences from interval to interval in the organogenic and detrital constituents. During the formation of the middle interval different conditions of sedimentation from those active during the previous and subsequent periods have obviously prevailed. Looking more closely at the organogenic constituents it is remarkable that during the formation of the finer interval conditions of a more intensive oxydation have prevailed that was the case before and after: Core decreases, whereas P shows a relative increase. This may be explained by slower sedimentation rate or by a vertical migration of the oxygen rich zone of the sea-water. The modifications of the elements from minerals in detrital portion of the sediments support an explanation ascribing this fact to modifications of the conditions of denudation and transportation which can come about through a climatic change or through tectonic causes. The paleontological investigations have shown (ZOBEL, in press) that in some of the cores the middle stratum of fine sedimentation represents optimal conditions for organic life. This fact suggests also oxydizing conditions during the sedimentation of this interval. In addition to the depositional stratification an oxydation zone characterized by Mn-enrichment can be recognized. The thickness of the oxidation zone decreases towards the coast and thins out along the middle part of the continental slope. At those places, where the oxydation zone is extremely thin, enrichment of Mn has its maximum. This phenomenon can probably be attributed to the migration of Mn taking place in its dissociated form within the sediment under reducing conditions. On the other side this Mn-migration in the sediment does not take place in the deep-sea, where oxydizing conditions prevail. 3. Interstitial waters in the sediments Already at very small core depths, the interstitial waters have undergone a distinct modification compared with the overlying sea water. This distinct modification applies both to total salinity and to the individual ions. As to the beginning of diagenesis the following conclusions can be drawn: a) A strong K-increase occurs already at an early stage. It may be attributable to a diffusion barrier or to an exchange of Mg-ions on the clays. Part of this increase may also originate from the decomposition of K-containing silicates (mica and feldspars). A K-decrease owing to the formation of illite (WEAVER 1967), however, occurs only at much greater sediment depth. b) Because of an organic protective coating, the dissolution of carbonate is delayed in recent organogenic carbonates. At the same time some Ca is probably being adsorbed on clay minerals. Consequently the Ca-content of the interstitial water drops below the Ca-content of the sea water. c) Already at an early stage the Mg adsorption on the clays is completed. The adsorbed Mg is later available for diagenetic mineral formations and transformations.

Fossil manganese deposits buried within DSDP/ODP cores, Legs 1-126

Probable in-situ manganese deposits larger than 1 cm in diameter buried in ODP/DSDP cores were selected for study after examining previous descriptions of the manganese deposits in site reports and the ODP data base. Most of the selected samples from 11 cores occur at or just above sedimentary hiatuses or in slowly deposited sediments and are overlain by rapidly deposited sediments of biogenic, terrigenous or volcanogenic origin. The changes in sedimentation recorded in the lithostratigraphic sections around these deposits are closely related to changes in tectonic evolution, deep water circulation or biological productivity at the sites. The similarity in composition and structure of the buried deposits to those of the modern manganese nodules and crusts with no evidence of post-depositional change suggest that buried manganese deposits may be used as indicators of past sedimentary conditions during which they formed. Their major components are hydrogenetic and earlydiagenetic manganese minerals as well as detrital minerals. The characteristics of these manganese deposits suggests that similar processes of deposition have taken place since the Paleogene or older.

Composition of sedimentary rocks from the Mountainous Crimea and the Northwestern Caucasus

Detailed data obtained on chemistry of sedimentary rocks from the Mountainous Crimea and the Northwestern Caucasus that were dated at the Cenomanian/Turonian boundary and formed during Oceanic Anoxic Event 2 make it possible to calculate dissolved oxygen concentration in bottom waters of the sedimentation basin. Enrichment factors of trace elements in black shales are revised and an explanation is suggested for genesis of the rocks with regard for unusual climatic changes.

Chemical composition of bulk sediments from ODP Hole 199-1215A

Elemental concentrations were determined on 21 samples from Hole 1215A to evaluate the influence of hydrothermal sources on bulk sediment composition. Rare earth element (REE) concentrations were also determined on 10 of these samples. Concentration profiles and REE patterns are consistent with a strong hydrothermal influence on sediment composition at the base of Hole 1215A.

Element oxides in basaltic glass fragments from ODP Hole 203-1243B

Sand-sized basaltic glass fragments were recovered in the liner of Core 203-1243B-19R, the deepest recovery from Hole 1243B. Microprobe analysis of 582 glassy cuttings cluster into five compositionally distinct groups, most of which are unlike the lithologic units described on board ship. Drilling operations intended to sweep cuttings from the caving hole and differences between the cuttings and geochemically distinct lithologic units of the upper part of the basement indicate that the cuttings came mainly, if not entirely, from the lower part of the hole. They give information about the part of Hole 1243B that had poor core recovery. Enriched mid-ocean-ridge basalt (MORB) from the upper part of the hole and transitional MORB from two groups of cuttings from sources low in the hole may be a trace of the Galápagos plume on the Pacific plate or may be a normal consequence of eruptions from two distinct magmas on fast-spreading crust.

Petrographic description and geochemistry of basalts and altered volcanic rocks from ODP Leg 183 sites

The basalts recovered during Legs 183 and 120 from the southern, central, and northernmost parts of the Kerguelen Plateau (Holes 1136A, 1138A, 1140A, and 747C, respectively), as well as those recovered from the eastern part of the crest of Elan Bank (Hole 1137A), represent derivates from tholeiitic melts. In the northern part of the Kerguelen Plateau (Hole 1140A), basalts may have formed from two sources located at different depths. This is reflected in the presence of both low- and high-titanium basalts. The basalts are variably altered by low-temperature hydrothermal processes (at temperatures up to 120°C), and some are affected by subaerial weathering. The hydrothermal alteration led mainly to the formation of smectites, chlorite minerals, mixed-layer hydromica-smectite and smectite-chlorite minerals, hydromica, serpentine(?), clinoptilolite, heulandite, stilbite, analcime, mordenite, thomsonite, natrolite(?), calcite, quartz, and dickite(?). Alteration of extrusive basalts is mainly related to horizontal fluid flow within permeable contact zones between lava flows. Under a nonoxidizing environment of alteration, the tendency to lose most of elements, including rare earth elements, from basalts dominates. Under on oxidizing environment, basalts accumulate many elements.

Major ion concentrations and chlorine isotope composition of water-soluble chloride and structurally bound chloride in DSDP/ODP serpentinized ultramafic rocks

Eight DSDP/ODP cores were analyzed for major ion concentrations and d37Cl values of water-soluble chloride (d37Clwsc) and structurally bound chloride (d37Clsbc) in serpentinized ultramafic rocks. This diverse set of cores spans a wide range in age, temperature of serpentinization, tectonic setting, and geographic location of drilled serpentinized oceanic crust. Three of the cores were sampled at closely spaced intervals to investigate downhole variation in Cl concentration and chlorine isotope composition. The average total Cl content of all 86 samples is 0.26±0.16 wt.% (0.19±0.10 wt.% as water-soluble Cl (Xwsc) and 0.09±0.09 wt.% as structurally bound Cl (Xsbc)). Structurally bound Cl concentration nearly doubles with depth in all cores; there is no consistent trend in water-soluble Cl content among the cores. Chlorine isotope fractionation between the structurally bound Cl**- site and the water-soluble Cl**- site varies from -1.08? to +1.16?, averaging to +0.21?. Samples with negative fractionations may be related to reequilibration of the water-soluble chloride with seawater post-serpentinite formation. Six of the cores have positive bulk d37Cl values (+0.05? to +0.36?); the other two cores (173-1068A (Leg-Hole) and 84-570) have negative bulk d37Cl values (-1.26? and -0.54?). The cores with negative d37Cl values also have variable Cl**-/SO4**2- ratios, in contrast to all other cores. The isotopically positive cores (153-920D and 147-895E) show no isotopic variation with depth; the isotopically negative core (173-1068A) decreases by ~1? with depth for both the water-soluble and structurally bound Cl fractions. Non-zero bulk d37Cl values indicate Cl in serpentinites was incorporated during original hydration and is not an artifact of seawater infiltration during drilling. Cores with positive d37Cl values are most likely explained by open system fractionation during hydrothermal alteration, with preferential incorporation of 37Cl from seawater into the serpentinite and loss of residual light Cl back to the ocean. Fluid / rock ratios were probably low as evidenced by the presence of water-soluble salts. The two isotopically negative cores are characterized by a thick overlying sedimentary package that was in place prior to serpentinization. We believe the low d37Cl values of these cores are a result of hydration of ultramafic rock by infiltrating aqueous pore fluids from the overlying sediments. The resulting serpentinites inherit the characteristic negative d37Cl values of the pore waters. Chlorine stable isotopes can be used to identify the source of the serpentinizing fluid and ultimately discern chemical and tectonic processes involved in serpentinization.

(Table 2) Chemical composition of ice-rafted brecciated crystalline schist and biotite-garnet crystalline schist from the Kara Sea

Composition and distribution.of ice-rafted coarse debris from the Kara Sea bottom were investigated. This material was obtained on 42 stations in Cruise 49 of R/V Dmitry Mendeleev by Sigsby trawls, box corers, grabs, and gravity corers. Existence of two main petrographic provinces is suggested: (1) West Kara and (2) East Kara. They differ in composition and sources of debris material. It is supposed that debris was transported mainly by floating ice. In Upper Pleistocene time rafting by glaciers and icebergs was also very possible.

Climatic impact on Al, K, Sc and Ti in marine sediments: Evidence from ODP Site 1144, South China Sea

Al, K, Sc and Ti concentrations of the terrestrial material-dominant sediments from ODP site 1144 were reported. Comparison between the bulk and the acid-leached sediments indicates that about 20~30% of the Al, K and Sc in the bulk sediments are not hosted in terrestrial detritus, rather they are of authigenic origin. However, authigenic Ti is negligible. The results indicate that Ti rather than Al is the best proxy for terrestrial materials. Significant climate controls are displayed in the Al/Ti, K/Ti and Sc/Ti variation patterns both for the bulk and the acid leached sediments. Such variation patterns can be mainly accounted for in terms of climate change in their provenance areas in South China. Elevated Al/Ti, K/Ti and Sc/Ti ratios during interglacial periods indicate that chemical weathering then was stronger than during glacial periods, which might be related to a more humid climate in interglacial periods.

Terrigenous proxy record from ODP Site 202-1237 and sediment core RRV9702a-69PC

ODP Site 1237 and sediment core RRV9702a-69PC were investigated for siliciclastic grain-size distributions and changes in geochemical composition to reconstruct southeast trade-wind variability during the past 5 Ma. Because both, working and archive halves of all ODP Site 1237 cores were completely depleted between 3.3 and 8.1 meters composite depths, (mcd), the corresponding sections of pre-site survey core RRV9702A-69PC were sampled and investigated to fill the gap.