Age determinations in Lena Delta

The age correlation between the three main geomorphological terraces in the Lena Delta, especially that of the second sandy terrace (Arga Island) and the third terrace (Ice Complex and underlying sands) is still being discussed, Knowledge about the age of the lee Complex and its underlying sands, and the Arga sands is necessary for understanding the past and modern structure of the delta. Geochronometrie data have been acguired for three sediment seguences from the Lena Delta by lumineseence dating using the potassium feldspar IR-OSL technique. Additionally, 14C dates are available for geochronological discussion. Typical sediments of the upper part of Arga Island as found in the area of Lake Nikolay are of Late Pleistoeene age (14.5-10.9 ka), Typical third terrace sediments from two seguenees located at the Olenyokskaya branch are older. At the profile "Nagym" sandy seguences were most probably deposited between about 65 ka and 50 ka before present. The lower part of the sandy seguence at "Kurungnakh Island" is possibly older than the sediments of the section at Nagym. However, methodological difficulties in luminescence dating (insufficient bleaching at the time of deposition) and younger 14C dates make the discussion of the results difficult.

Hydrochemical and microbiological properties of groundwater from pristine aquifer sampled at the Lower Rhine Embayment

The hydrochemistry and the microbial diversity of a pristine aquifer system near Garzweiler, Germany next to the open-pit lignite mine Garzweiler 1, were characterized. Hydrogeochemical and isotopic data indicate a recent activity of sulfate-reducing bacteria in the Tertiary marine sands. The community structure in the aquifer was studied by fluorescence in situ hybridization (FISH). Up to 7.3 x 10**5 cells/ml were detected by DAPIstaining. Bacteria (identified by the probe EUB338) were dominant, representing 51.9% of the total cell number (DAPI). Another 25.7% of total cell were affiliated with the domain Archaea as identified by the probe ARCH915. Within the domain Bacteria, the beta-Proteobacteria were most abundant (21.0% of total cell counts). Using genusspecific probes for sulfate-reducing bacteria (SRB), 2.5% of the total cells were identified as members of the genus Desulfotomaculum. This reflects the predominant role these microorganisms have been found to play in sulfatereducing zones of aquifers at other sites. Previously, all SRB cultured from this site were from the spore-forming genera Desulfotomaculum and Desulfosporosinus. Samples were taken after pumping for >= 40 min and after parameters such as temperature, pH, redox potential, oxygen and conductivity of the groundwater had remained stable for >= 15 min due to recharge of aquifer water. Hybridization and microscopy counts of hybridized and 4',6'-diamidino-2-phenylindole (DAPI)- stained cells were performed as described in Snaidr et al., (1997, http://aem.asm.org/content/63/7/2884.full.pdf). Means were calculated from 10 to 20 randomly chosen fields on each filter section, corresponding to 800-1000 DAPI stained cells. Counting results were always corrected by subtracting signals observed with the probe NON338. Formamide concentrations and oligonucleotide probes used please see further details.

Heavy mineral and bulk mineral compositions of cores from Kumano Basin

Coring during Integrated Ocean Drilling Program Expeditions 315, 316, and 333 recovered turbiditic sands from the forearc Kumano Basin (Site C0002), a Quaternary slope basin (Site C0018), and uplifted trench wedge (Site C0006) along the Kumano Transect of the Nankai Trough accretionary wedge offshore of southwest Japan. The compositions of the submarine turbiditic sands here are investigated in terms of bulk and heavy mineral modal compositions to identify their provenance and dispersal mechanisms, as they may reflect changes in regional tectonics during the past ca. 1.5 Myrs. The results show a marked change in the detrital signature and heavy mineral composition in the forearc and slope basin facies around 1 Ma. This sudden change is interpreted to reflect a major change in the sand provenance, rather than heavy mineral dissolution and/or diagenetic effects, in response to changing tectonics and sedimentation patterns. In the trench-slope basin, the sands older than 1 Ma were probably eroded from the exposed Cretaceous-Tertiary accretionary complex of the Shimanto Belt and transported via the former course of the Tenryu submarine canyon system, which today enters the Nankai Trough northeast of the study area. In contrast, the high abundance of volcanic lithics and volcanic heavy mineral suites of the sands younger than 1 Ma points to a strong volcanic component of sediment derived from the Izu-Honshu collision zones and probably funnelled to this site through the Suruga Canyon. However, sands in the forearc basin show persistent presence of blue sodic amphiboles across the 1 Ma boundary, indicating continuous flux of sediments from the Kumano/Kinokawa River. This implies that the sands in the older turbidites were transported by transverse flow down the slope. The slope basin facies then switched to reflect longitudinal flow around 1 Ma, when the turbiditic sand tapped a volcanic provenance in the Izu-Honshu collision zone, while the sediments transported transversely became confined in the Kumano Basin. Therefore, the change in the depositional systems around 1 Ma is a manifestation of the decoupling of the sediment routing pattern from transverse to long-distance axial flow in response to forearc high uplift along the megasplay fault.

(Table 1) Strontium isotopic ratios of interstitial waters from ODP Leg 125 holes

The strontium isotopic data presented here are from interstitial waters squeezed from unconsolidated serpentine, an unusual type of substrate that was recovered from Mariana and Bonin forearc seamounts and has not been previously drilled by the Deep Sea Drilling Project or Ocean Drilling Program. The texture and composition of some of these serpentine deposits from Conical Seamount, located on the Mariana forearc, indicate emplacement as low- or high-viscosity, cold gravitational flows, which are therefore neither sediment nor igneous rock. The strontium isotopic ratios of the interstitial waters from the unconsolidated serpentine range from 0.70912 to 0.70525 and trend toward a relatively less radiogenic composition with increasing sub-bottom depth. These strontium isotopic ratios are derived from at least two strontium sources: seawater and igneous. The strontium isotopic gradients from the interstitial waters from the Leg 125 sites are probably the result of diffusive transport of strontium from an igneous source deep within the lithosphere that may be contaminated with subducted or underplated sediment.

Carbon14 ages of surface sediment samples from ther Persian Gulf

A simplified classification of the Holocene sediments based on textures and grain type results in fourteen major units, twelve of which are essentially carbonate in composition. A brief description and photographic illustration of these units, together with the sedimentary and diagenetic processes which have contributed to their formation, is designed to give the reader a broad but valid impression of Persian Gulf sediments. The distribution of the fourteen sediment units throughout the Arabian parts of the basin, although complicated by numerous local bathymetric highs and depressions, is relatively simple. Because the Arabian sea floor slopes progressively from a windward shoreline to the basin center there is increasing protection from wave action towards the center of the basin. As a result sediments grade from skeletal, oolitic and pelletoidal sands (and muds in coastal lagoons) and fringing reefs, through an irregular zone of compound grain sands,into widespread skeletal muddy sands, and finally into basin center muds. These simple relationships vary laterally around the Arabian side of the gulf. Lateral variation is dependant upon orientation of the regional slope with respect to the prevailing NW wind-driven waves, angle of slope, and presence or absence of regional, structurally based barriers.

Results of the pollen analysis of the Dyanushka peat sediments K7/P2

A 415cm thick permafrost peat section from the Verkhoyansk Mountains was radiocarbon-dated and studied using palaeobotanical and sedimentological approaches. Accumulation of organic-rich sediment commenced in a former oxbow lake, detached from a Dyanushka River meander during the Younger Dryas stadial, at ~12.5 kyr BP. Pollen data indicate that larch trees, shrub alder and dwarf birch were abundant in the vegetation at that time. Local presence of larch during the Younger Dryas is documented by well-preserved and radiocarbon-dated needles and cones. The early Holocene pollen assemblages reveal high percentages of Artemisia pollen, suggesting the presence of steppe-like communities around the site, possibly in response to a relatively warm and dry climate ~11.4-11.2 kyr BP. Both pollen and plant macrofossil data demonstrate that larch woods were common in the river valley. Remains of charcoal and pollen of Epilobium indicate fire events and mark a hiatus ~11.0-8.7 kyr BP. Changes in peat properties, C31/C27 alkane ratios and radiocarbon dates suggest that two other hiatuses occurred ~8.2-6.9 and ~6.7-0.6 kyr BP. Prior to 0.6 kyr BP, a major fire destroyed the mire surface. The upper 60 cm of the studied section is composed of aeolian sands modified in the uppermost part by the modern soil formation. For the first time, local growth of larch during the Younger Dryas has been verified in the western foreland of the Verkhoyansk Mountains (~170km south of the Arctic Circle), thus increasing our understanding of the quick reforestation of northern Eurasia by the early Holocene.

(Table S1) Qualitative and semi-quantitative abundance of magnetic particles in Paleocene-Eocene sediments

On the mid-Atlantic Coastal Plain of the United States, Paleocene sands and silts are replaced during the Paleocene-Eocene Thermal Maximum (PETM) by the kaolinite-rich Marlboro Clay. The clay preserves abundant magnetite produced by magnetotactic bacteria and novel, presumptively eukaryotic, iron-biomineralizing microorganisms. Using ferromagnetic resonance spectroscopy and electron microscopy, we map the magnetofossil distribution in the context of stratigraphy and carbon isotope data and identify three magnetic facies in the clay: one characterized by a mix of detrital particles and magnetofossils, a second with a higher magnetofossil-to-detrital ratio, and a third with only transient magnetofossils. The distribution of these facies suggests that suboxic conditions promoting magnetofossil production and preservation occurred throughout inner middle neritic sediments of the Salisbury Embayment but extended only transiently to outer neritic sediments and the flanks of the embayment. Such a distribution is consistent with the development of a system resembling a modern tropical river-dominated shelf.

Quartz grain microtextures of sediments from ODP Hole 188-1166A (Table 1)

This paper presents the results of the scanning electron microscopic (SEM) analysis of quartz grains from a selection of samples at Site 1166. Ocean Drilling Program Leg 188 drilled Site 1166 on the Prydz Bay continental shelf, Antarctica, to document onset and fluctuations of East-Antarctic glaciation. This site recovered Upper Pliocene-Holocene glacial sediments directly above Cretaceous through Lower Oligocene sediments recording the transition from preglacial to early glacial conditions. SEM analysis of quartz grains at Site 1166 was used to characterize the glacial and preglacial sediments by their diagnostic textures. Angular edges, edge abrasion as well as arcuate to straight steps, are the most frequent features in glacial deposits. The highest frequency of grains with round edges is present in Middle-Late Eocene fluvio-deltaic sands. However, angular outlines, fractured plates with subparallel linear fractures and edge abrasion indicating glacier influence are also present. Preglacial carbonaceous mudstone and laminated gray claystone show distinctive high relief quartz grains and some chemical weathering on grain surfaces. The results of the microtextural analysis of quartz grains are used to verify some critical periods of ice sheet evolution, such as the transition from the East Antarctic preglacial to glacial conditions on the continental shelf from Middle/Late Eocene to Late Eocene/Early Oligocene time.

Enviromagnetic, major element, and grain-size analyses of surface sediment samples along the continental margin between East Brazil and Patagonia

Continental margin sediments of SE South America originate from various terrestrial sources, each conveying specific magnetic and element signatures. Here, we aim to identify the sources and transport characteristics of shelf and slope sediments deposited between East Brazil and Patagonia (20°-48°S) using enviromagnetic, major element, and grain-size data. A set of five source-indicative parameters (i.e., chi-fd%, ARM/IRM, S0.3T, SIRM/Fe and Fe/K) of 25 surface samples (16-1805 m water depth) was analyzed by fuzzy c-means clustering and non-linear mapping to depict and unmix sediment-province characteristics. This multivariate approach yields three regionally coherent sediment provinces with petrologically and climatically distinct source regions. The southernmost province is entirely restricted to the slope off the Argentinean Pampas and has been identified as relict Andean-sourced sands with coarse unaltered magnetite. The direct transport to the slope was enabled by Rio Colorado and Rio Negro meltwaters during glacial and deglacial phases of low sea level. The adjacent shelf province consists of coastal loessoidal sands (highest hematite and goethite proportions) delivered from the Argentinean Pampas by wave erosion and westerly winds. The northernmost province includes the Plata mudbelt and Rio Grande Cone. It contains tropically weathered clayey silts from the La Plata Drainage Basin with pronounced proportions of fine magnetite, which were distributed up to ~24° S by the Brazilian Coastal Current and admixed to coarser relict sediments of Pampean loessoidal origin. Grain-size analyses of all samples showed that sediment fractionation during transport and deposition had little impact on magnetic and element source characteristics. This study corroborates the high potential of the chosen approach to access sediment origin in regions with contrasting sediment sources, complex transport dynamics, and large grain-size variability.

Lithic grain and mineral composition of sand and sandstones from the North Pacific Ocean and the Bering Sea (Table 3)

Sand and sandstone compositions from different types of basins reflect provenance terranes governed by plate tectonics. One hundred and one thin sections of Upper Miocene to Holocene sand-sized material were examined from DSDP/IPOD Sites in the North Pacific Ocean and the Bering Sea. The Gazzi-Dickinson point-counting method was used to establish compositional characteristics of sands from different tectonic settings. Continental margin forearc sands from the western North America continental margin arc system are clearly different from backarc/marginal-sea sands from the Aleutian intraoceanic arc system. The forearc sands have average QFL percentages of 29-42-29, LmLvLst percentages of 32-34-34, 3 Fmwk%M and 0.82 P/F. Aleutian backarc sands have average QFL percentages of 8-22-69. LmLvLst percentages of 9-85-6, 0.5 Fmwk%M and 0.96 P/F. A trend of increasing QFL%Q and decreasing LmLvLst%Lv westward in the backarc region of the Aleutian Ridge reflects the influence of the Asiatic continental margin. Aleutian backarc sands without continental influence have average QFL percentages of 1-20-79, LmLvLst percentages of 1-98-1, 0 Fmwk%M and 0.99 P/F. Of the continental margin forearc samples, sands on the Astoria Fan (west of the Oregon-Washington trench) contain the highest LmLvLst%Lv and lowest P/F; sands from mixed transform-fault and trench settings (Delgada Fan and Gulf of Alaska samples) have slightly higher Qp/Q (0.03); and sands from the Pacific-Juan de Fuca-North America triple junction have the highest Fmwk%M. Delgada Fan and Gulf of Alaska sands have average QFL percentages of 27-38-35, LmLvLst percentages of 37-26-37, 2 Fmwk%M and 0.86 P/F. Astoria Fan sands have average QFL percentages of 35-41-24, LmLvLst percentages of 30-47-23, 3 Fmwk%M and 0.74 P/F. The triple-junction sands have average QFL percentages of 28-59-13, LmLvLst percentages of 25-26-49, 9 Fmwk%M and 0.87 P/F. The petrologic data from the modern ocean basins examined in this study can provide useful analogs for interpretation of ancient oceanic sequences. Our data suggest some refinements of, but generally substantiate, existing petrologic models relating sandstone composition to tectonic setting.

(Table 1) Sediment properties at DSDP Leg 67 Holes

The plasticity characteristics of the Quaternary sediments of the Guatemalan continental margin were determined from five sites drilled during Leg 67 of the Deep Sea Drilling Project. The 64 samples analyzed are from various marine environments, including the Cocos Plate, Middle America Trench, and the trench lower slope to midslope of the Guatemalan continental slope. The sediments are primarily hemipelagic muds and trench-fill turbidites and include quantities of siliceous and calcareous biogenic components. The sediments are generally classified as organic clays of medium to high plasticity, containing micaceous sands and silts, with 14% classed as inorganic clays of medium to high plasticity. High sedimentation rates in Quaternary sediments are the result, in part, of sediment gravity flows that depend upon rheological properties, i.e., sediment plasticity. Mudflows and cohesive debris flows appear to be significant downslope transport mechanisms in these highly plastic sediments.

(Table T4) Final depth vs. velocity and two-way traveltime data, ODP Site 178-1103

Site 1103 was one of a transect of three sites drilled across the Antarctic Peninsula continental shelf during Leg 178. The aim of drilling on the shelf was to determine the age of the sedimentary sequences and to ground truth previous interpretations of the depositional environment (i.e., topsets and foresets) of progradational seismostratigraphic sequences S1, S2, S3, and S4. The ultimate objective was to obtain a better understanding of the history of glacial advances and retreats in this west Antarctic margin. Drilling the topsets of the progradational wedge (0-247 m below seafloor [mbsf]), which consist of unsorted and unconsolidated materials of seismic Unit S1, was very unfavorable, resulting in very low (2.3%) core recovery. Recovery improved (34%) below 247 mbsf, corresponding to sediments of seismic Unit S3, which have a consolidated matrix. Logs were only obtained from the interval between 75 and 244 mbsf, and inconsistencies on the automatic analog picking of the signals received from the sonic log at the array and at the two other receivers prevented accurate shipboard time-depth conversions. This, in turn, limited the capacity for making seismic stratigraphic interpretations at this site and regionally. This study is an attempt to compile all available data sources, perform quality checks, and introduce nonstandard processing techniques for the logging data obtained to arrive at a reliable and continuous depth vs. velocity profile. We defined 13 data categories using differential traveltime information. Polynomial exclusion techniques with various orders and low-pass filtering reduced the noise of the initial data pool and produced a definite velocity depth profile that is synchronous with the resistivity logging data. A comparison of the velocity profile produced with various other logs of Site 1103 further validates the presented data. All major logging units are expressed within the new velocity data. A depth-migrated section with the new velocity data is presented together with the original time section and initial depth estimates published within the Leg 178 Initial Reports volume. The presented data confirms the location of the shelf unconformity at 222 ms two-way traveltime (TWT), or 243 mbsf, and allows its seismic identification as a strong negative and subsequent positive reflection.

Provenance of Holocene Calcareous Aeolianites, Eastern South Australia

The southeastern coast of South Australia contains a spectacular and world-renown suite of Quaternary calcareous aeolianites. This study is focused on the provenance of components in the Holocene sector of this carbonate breach-dune succession. Research was carried out along seven transects from ~30 meters water depth offshore across the beach and into the dunes. Offshore sediments were acquired via grab sampling and SCUBA. Results indicate that dunes of the southern Lacepede and Otway coasts in particular are mostly composed of modern invertebrate and calcareous algal allochems. The most numerous grains are from molluscs, benthic foraminifera, coralline algae, echinoids, and bryozoans. These particles originate in carbonate factories such as macroalgal forests, rocky reefs, seagrass meadows, and low-relief seafloor rockgrounds. The incorporation of carbonate skeletons into coastal dunes, however, depends on a combination of; 1) the infauna within intertidal and nearshore environments, 2) the physical characteristics of different allochems and their ability to withstand fragmentation and abrasion, 3) the wave and swell climate, and 4) the nature of aeolian transport. Most aeolian dune sediment is derived from nearshore and intertidal carbonate factories. This is particularly well illustrated by the abundance of robust infaunal bivalves that inhabit the nearshore sands and virtual absence of bryozoans that are common as sediment particles in water depths > 10mwd. Thus, the calcareous aeolianites in this cool-water carbonate region are not a reflection of the offshore marine shelf factories, but more a product of shallow nearshore-intertidal biomes.

Revisiting the Late Jurassic-Early Cretaceous of the NW South Iberian Basin: new ages and sedimentary environments

The study of the Upper Jurassic-Lower Cretaceous deposits (Higueruelas, Villar del Arzobispo and Aldea de Cortés Formations) of the South Iberian Basin (NW Valencia, Spain) reveals new stratigraphic and sedimentological data, which have significant implications on the stratigraphic framework, depositional environments and age of these units. The Higueruelas Fm was deposited in a mid-inner carbonate platform where oncolitic bars migrated by the action of storms and where oncoid production progressively decreased towards the uppermost part of the unit. The overlying Villar del Arzobispo Fm has been traditionally interpreted as an inner platform-lagoon evolving into a tidal-flat. Here it is interpreted as an inner-carbonate platform affected by storms, where oolitic shoals protected a lagoon, which had siliciclastic inputs from the continent. The Aldea de Cortés Fm has been previously interpreted as a lagoon surrounded by tidal-flats and fluvial-deltaic plains. Here it is reinterpreted as a coastal wetland where siliciclastic muddy deposits interacted with shallow fresh to marine water bodies, aeolian dunes and continental siliciclastic inputs. The contact between the Higueruelas and Villar del Arzobispo Fms, classically defined as gradual, is also interpreted here as rapid. More importantly, the contact between the Villar del Arzobispo and Aldea de Cortés Fms, previously considered as unconformable, is here interpreted as gradual. The presence of Alveosepta in the Villar del Arzobispo Fm suggests that at least part of this unit is Kimmeridgian, unlike the previously assigned Late Tithonian-Middle Berriasian age. Consequently, the underlying Higueruelas Fm, previously considered Tithonian, should not be younger than Kimmeridgian. Accordingly, sedimentation of the Aldea de Cortés Fm, previously considered Valangian-Hauterivian, probably started during the Tithonian and it may be considered part of the regressive trend of the Late Jurassic-Early Cretaceous cycle. This is consistent with the dinosaur faunas, typically Jurassic, described in the Villar del Arzobispo and Aldea de Cortés Fms.