31 ground-penetrating radar lines of Area 3 - Beach ridge plain (high wave energy) from Maxwell Bay, King George Island, Antarctic Peninsula

During a field campaign in the Austral spring 2012 the sedimentary architecture of a polar gravel-beach system at the southern coast of Potter Peninsula (Area 3) was revealed using ground-penetrating radar (GPR, Geophysical Survey Systems, Inc. SIR-3000). 31 profiles were collected using a mono-static 200 MHz antenna operated in common offset mode. Trace increment was set to 0.05 m. A differential global-positioning system (dGPS, Leica GS09) was used to obtain topographical information along the GPR lines. GPR data are provided in RADAN-Format, dGPS coordinates are provided in ascii format; projection is UTM (WGS 84, zone 21S).

21 ground-penetrating radar lines of Area 1 - Beach ridge plain (low wave energy) from Potter Cove, King George Island, Antarctic Peninsula

During two field campaigns (Austral springs 2011 and 2012) the sedimentary architecture of a polar gravel-beach system at the western coast of Potter Peninsula (Area 1) was revealed using ground-penetrating radar (GPR, Geophysical Survey Systems, Inc. SIR-3000). 21 profiles were collected using a mono-static 200 MHz antenna operated in common offset mode. Trace increment was set to 0.05 m. A differential global-positioning system (dGPS, Leica GS09) was used to obtain topographical information along the GPR lines. GPR data are provided in RADAN-Format, dGPS coordinates are provided in ascii format; projection is UTM (WGS 84, zone 21S).

Experimental data from column and batch samples

The presented thesis was written in the frame of a project called 'seepage water prognosis'. It was funded by the Federal Ministry for Education and Science (BMBF). 41 German institutions among them research institutes of universities, public authorities and engineering companies were financed for three years respectively. The aim was to work out the scientific basis that is needed to carry out a seepage water prognosis (Oberacker und Eberle, 2002). According to the Federal German Soil Protection Act (Federal Bulletin, 1998) a seepage water prognosis is required in order to avoid future soil impacts from the application of recycling products. The participants focused on the development of either methods to determine the source strength of the materials investigated, which is defined as the total mass flow caused by natural leaching or on models to predict the contaminants transport through the underlying soil. Annual meetings of all participants as well as separate meetings of the two subprojects were held. The department of Geosciences in Bremen participated with two subprojects. The aim of the subproject that resulted in this thesis was the development of easily applicable, valid, and generally accepted laboratory methods for the determination of the source strength. In the scope of the second subproject my colleague Veith Becker developed a computer model for the transport prognosis with the source strength as the main input parameter.

Table 1 Microorganisms, identified with DOGE analysis. 16S rDNA sequences, obtained from sequencing of DOGE bands, were assigned to the corresponding microorganisms

Microorganisms play an important role in the transformation of material within the earth's crust. The storage of CO2 could affect the composition of inorganic and organic components in the reservoir, consequently influencing microbial activities. To study the microbial induced processes together with geochemical, petrophysical and mineralogical changes, occurring during CO2 storage, long-term laboratory experiments under simulated reservoir P-T conditions were carried out. Clean inner core sections, obtained from the reservoir region at the CO2 storage site in Ketzin (Germany) from a depth of about 650 m, were incubated in high pressure vessels together with sterile synthetic formation brine under in situ P-T conditions of 5.5 MPa and 40°C. A 16S rDNA based fingerprinting method was used to identify the dominant species in DNA extracts of pristine sandstone samples. Members of the alpha- and beta-subdivisions of Proteobacteria and the Actinobacteria were identified. So far sequences belonging to facultative anaerobic, chemoheterotrophic bacteria (Burkholderia fungorum, Agrobacterium tumefaciens) gaining their energy from the oxidation of organic molecules and a genus also capable of chemolithoautotrophic growth (Hydrogenophaga) was identified. During CO2 incubation minor changes in the microbial community composition were observed. The majority of microbes were able to adapt to the changed conditions. During CO2 exposure increased concentrations of Ca**2+, K**+, Mg**2+ and SO4**2- were observed. Partially, concentration rises are (i) due to equilibration between rock pore water and synthetic brine, and (ii) between rock and brine, and are thus independent on CO2 exposure. However, observed concentrations of Ca**2+, K**+, Mg**2+ are even higher than in the original reservoir fluid and therefore indicate mineral dissolution due to CO2 exposure.

Organic geochemistry of late Cenozoic sediments from the eastern subtropical Atlantic

Detailed organic geochemical investigations have been performed on sediment samples from upwelling Site 658 and nonupwelling Sites 657 and 659. The major objective of this study has been the relationship between organic carbon accumulation and paleoclimatic and paleoceanographic conditions in the upwelling area off northwest Africa during late Cenozoic times. The study is based on results from organic carbon, nitrogen, and hydrogen analyses, Rock-Eval pyrolysis, kerogen microscopy, gas chromatography, and gas chromatography/mass spectrometry. In general, nonupwelling Sites 657 and 659 are characterized by low organic carbon values of less than 0.5%. At Site 657, four events of high organic carbon deposition (total organic carbon of 1%-3%) occur and represent turbidites and a slump interval. The upper Pliocene to Pleistocene sediments of upwelling Site 658 display high organic carbon contents of 0.5%-4%, with higher contents concentrated in the upper Pliocene. Accumulation rates of organic carbon vary between 0.1 and 0.5 gC/cm-**2/1000 yr, with maximum values between 3.5 and 3.1 Ma. Short-term cyclic ("Milankovitch-type") variations in organic carbon accumulation suggest climate-controlled mechanisms causing these fluctuations. The quality of organic matter at Site 658 is a mixture of kerogen type II and HI, with a dominance of the marine type. This is indicated by high hydrogen-index values of 200-400 mgHC/gC, low C/N ratios of 5-15, atomic H/C ratios of 1.0-1.5, and high amounts of marine macerals (alginite and liptodetrinite). We have estimated paleoproductivity for Sites 658 and 659 based on the amount of marine organic carbon. At open-marine Site 659, mean paleoproductivity varies between 20 and 50 gC/m**2/yr. At Site 658, mean paleoproductivity reaches high values of 160 to 320 gC/m**2/yr, very similar to those recorded in modern upwelling areas. The changes in productivity off northwest Africa are linked to changes in nutrient supply caused by both upwelling and fluvial input. The change from a dominantly humid climate to one characterized by fluctuations between humid and fully arid climates in northwest Africa occurs between 3.1 and 2.45 Ma.

Organic matter from black shales collected in DSDP Holes 41-367 and 41-368

It is shown that microscopic algae dominate in source material of organic matter of black shales, and admixture of residues of organisms and terrestrial humic material is contained. The main direction of source material transformation during syngenesis and sedimentogenesis is associated with jellofication resulting to formation of organic matter of significantly sapropelic type. Low reflectance of vitrinite and alginite from organic matter refer to the primary and secondary lignite stages of its carbonification. Significantly sapropel type of organic matter and low stage of carbonification are reliable criteria for assigning black shales to the category of potential oil source strata.

Hydrocarbon contents and carbon isotope composition of organic matter from holes of DSDP Legs 50 and 64

The book is devoted to fundamental problems of organic geochemistry of ocean sediments. It is based on materials of organic matter and gas studies in cores from DSDP Legs 50 and 64. Experimental results obtained in the Laboratory of Carbon Geochemistry (V.I. Vernadsky Institute of Geochemistry and Analytical Chemistry, Moscow) take the main part of the book. Evolution of organic matter in specific environment of deep ocean sediments, sources of organic matter in the ocean and methods of their identification based on isotopic analysis and other methods are under discussion. Gas geochemistry in normal conditions of diagenesis, and in conditions under intense heating is studied.

Organic matter C and N composition and N. pachyderma stable isotope ratios of ODP Hole 188-1166A sediments

We report the results of downhole stable isotopic (d13Corg [organic carbon] and d15N) and elemental measurements (total organic carbon [TOC], total nitrogen [TN], and carbon/nitrogen [C/N]) of sedimentary organic matter (SOM) along with stable isotopic measurements (d18O and d13C) of left-coiling Neogloboquadrina pachyderma planktonic foraminifers from Ocean Drilling Program Site 1166. TOC and TN measurements indicate a large change from organic-rich preglacial sediments with primary organic matter to organic-poor early glacial and glacial sediments, with mainly recycled organic matter. Results of the stable isotopic measurements of SOM show a range of values that are typical of both marine and terrestrial organic matter, probably reflecting a mixture of the two. However, C/N values are mostly high (>15), suggesting greater input and/or preservation of terrestrial organic matter. Foraminifers are only present in glacial/glaciomarine sediments of latest Pliocene to Pleistocene age at Site 1166 (lithostratigraphic Unit I). The majority of this unit has d13Corg and TOC values that are similar to those of glacial sediments recovered at Site 1167 (lithostratigraphic Unit II) on the slope and may have the same source(s). Although the low resolution of the N. pachyderma (s.) d18O and d13C data set precludes any specific paleoclimatic interpretation, downcore variations in foraminifer d18O and d13C values of 0.5 per mil to 1 per mil amplitude may indicate glacial-interglacial changes in ice volume/temperature in the Prydz Bay region.

Pliocene-Plistocene deposition of carbonate and organic carbon in ODP Hole 159-959C

During Ocean Drilling Program (ODP) Leg 159, four sites (Sites 959-962) were drilled along a depth transect on the Côte d'Ivoire/Ghana Transform Margin. In this study, the Pliocene-Pleistocene history of carbonate and organic carbon accumulation at Hole 959C is reconstructed for the eastern equatorial Atlantic off the Ivory Coast/Ghana based on bulk carbonate, sand fraction, organic carbon, and other organic geochemical records (d13Corg, marine organic matter percentages derived from organic petrology, hydrogen index, C/N). Pliocene-Pleistocene sedimentation off the Ivory Coast/Ghana was strongly affected by low mean sedimentation rates, which are attributed to persistently enhanced bottom-water velocities related to the steep topography of the transform margin. Sand fraction and bulk carbonate records reveal typical glacial/interglacial cycles, preserved, however, with low time resolution. Intermediate carbonate accumulation rates observed throughout the Pliocene-Pleistocene suggest intense winnowing and sediment redistribution superimposed by terrigenous dilution. 'Atlantic-type' sand and carbonate cycles, consistent with records from pelagic areas of the eastern equatorial Atlantic, are encountered at Hole 959C prior to about 0.9 Ma. Total organic carbon (TOC) records are frequently inversely correlated to carbonate contents, indicating mainly productivity-driven carbonate dissolution related to changes in paleoproductivity. During Stages 22-24, 20, 16, 12, 8, and 4, sand and carbonate records reveal a 'Pacific-type' pattern, showing elevated contents during glacials commonly in conjunction with enhanced TOC records. Formation of 'Pacific-type' patterns off the Ivory Coast/Ghana is attributed to drastically increased bottom-water intensities along the transform margin in accordance with results reported from the Walvis Ridge area. Short-term glacial/interglacial changes in paleoproductivity off the Ivory Coast/Ghana are to some extend recognizable during glacials prior to 1.7 Ma and interglacial Stages 21, 19, 13, 9, and 1. Enhanced coastal upwelling during interglacials is attributed to local paleoclimatic and oceanographic conditions off the Ivory Coast/Ghana. Quantitative estimates of marine organic carbon based on organic petrologic and d13Corg records reveal an offset in concentration ranging from 15% to 60%. Highest variabilities of both records are recorded since ~0.9 Ma. Discrepancies between the isotopic and microscopic records are attributed to an admixture of C4 plant debris approaching the eastern equatorial Atlantic via atmospheric dust. Terrestrial organic material likely originated from the grass-savannah-covered Sahel zone in central Africa. Estimated C4 plant concentrations and accumulation rates range from 10% to 37% and from almost zero to 0.006 g/cm**2/k.y., respectively. The strongest eolian supply to the northern Gulf of Guinea is indicated between 1.9 and 1.68 Ma and during glacial isotopic Stages 22-24, 20, 14, and 12. The presence of grass-type plant debris is further supported by organic petrologic studies, which reveal well-preserved cell tissues of vascular plants or tube-shaped, elongated terrestrial macerals showing different levels of oxidation.

Quantity, provenance, and thermal maturity of organic matter at DSDP Holes 95-612 and 95-613

Using methods of analysis from organic geochemistry and organic petrography, we investigated six Pliocene to Maestrichtian samples from DSDP Site 612 and five Pliocene to Eocene samples from DSDP Site 613 for the quantity, type, and thermal maturity of organic matter. At both sites, organic carbon content is low in the Eocene samples (0.10 to 0.20%) and relatively high in the Pliocene/Miocene samples (0.87 to 1.15%). The Maestrichtian samples from Site 612 contain about 0.6% organic carbon. The organic matter is predominantly terrigenous, as indicated by low hydrogen index values from Rock-Eval pyrolysis and the dominance of long-chain wax alkanes in the extractable hydrocarbons. The organic matter is at a low level of thermal maturity; measured vitrinite reflectance values were between 0.27 and 0.44%.

Migration of C1 to C8 volatile organic compounds in sediments at DSDP Hole 75-530A

The distribution of C1 to C8 hydrocarbons in sediment samples from DSDP Leg 75, Hole 530A, indicates that significant amounts of methane and ethane have migrated from organic-rich to organic-lean shales in close proximity. Most compounds larger than ethane are not migrating out of black shales, where they occur in high concentrations. These results lead to a general model for assessing migration. In addition, three shale types are identified on the basis of organic carbon and pyrolysis products and patterns.

Geochemistry of sediment cores from METEOR cruise M76/1b

Marine sediments are the main sink in the oceanic phosphorus (P) cycle. The activity of benthic microorganisms is decisive for regeneration, reflux, or burial of inorganic phosphate (Pi), which has a strong impact on marine productivity. Recent formation of phosphorites on the continental shelf and a succession of different sedimentary environments make the Benguela upwelling system a prime region for studying the role of microbes in P biogeochemistry. The oxygen isotope signature of pore water phosphate (d18OP) carries characteristic information of microbial P cycling: Intracellular turnover of phosphorylated biomolecules results in isotopic equilibrium with ambient water, while enzymatic regeneration of Pi from organic matter produces distinct offsets from equilibrium. The balance of these two processes is the major control for d18OP. Our study assesses the importance of microbial P cycling relative to regeneration of Pi from organic matter from a transect across the Namibian continental shelf and slope by combining pore water chemistry (sulfate, sulfide, ferrous iron, Pi), steady-state turnover rate modeling, and oxygen isotope geochemistry of Pi. We found d18OP values in a range from 12.8 per mill to 26.6 per mill, both in equilibrium as well as pronounced disequilibrium with water. Our data show a trend towards regeneration signatures (disequilibrium) under low mineralization activity and low Pi concentrations, and microbial turnover signatures (equilibrium) under high mineralization activity and high Pi concentrations. These findings are opposite to observations from water column studies where regeneration signatures were found to coincide with high mineralization activity and high Pi concentrations. It appears that preferential Pi regeneration in marine sediments does not necessarily coincide with a disequilibrium d18OP signature. We propose that microbial Pi uptake strategies, which are controlled by Pi availability, are decisive for the alteration of the isotope signature. This hypothesis is supported by the observation of efficient microbial Pi turnover (equilibrium signatures) in the phosphogenic sediments of the Benguela upwelling system.

Organic matter composition and sulfate reduction intensity in Oman Margin sediments

Petrographical and geochemical studies of Neogene marine sediments from the Oman Sea (Leg 117, Sites 720, 724, 726 and 730), show a close relationship between the nature and amount of the organic matter, and the degree of degradation of organic matter by sulfate reduction, i.e. pyritization. Petrographically, three major pyritization types were observed: (1) Finely dispersed pyrite framboids in sediments from Oman Margin and Indus Fan, enriched in autochthonous marine organic matter. (2) Infilling of pores by massive pyrite crystals in Oman Margin sediments with a low TOC and a high microfossil content. (3) Pyrite mineralization of lignaceous fragments in organic-depleted sediments from the Indus Fan leading to more massive pyrite. Geochemically, we can define a sulfate reduction index (SRI) as the percentage of initial organic carbon versus that of residual organic carbon. Finely laminated Pliocene-Pleistocene sediments from the Oman Margin exclusively contain organic matter deriving from organic phytoplankton, for which the quantity (TOC) positively correlates with the geochemical quality (Hydrogen Index). We think that the occurrence of this residual organic matter is linked mainly to a high primary paleo-productivity. The intensity of sulfate reduction is constant for sediments with TOC up to 2% and becomes more important when organic input decreases. This degradation process can destroy up to 50% of the initial organic matter, but is not sufficient to explain some of the encountered very low TOC values. It can be seen that sharp increases of certain plankton species (with mineral skeletons) are responsible for a pronounced degradation of organic matter, due to increased sulfate reduction. In that case, the organic matter may be strongly degraded (high SRI), although deposited in an oxygen-depleted environment. Conversely, Miocene-Pliocene sediments contain an autochthonous organic matter that is typical of both low productivity and oxic processes; their very low sulfate reduction index indicates that very little metabolizable organic matter was initially present.