Accumulation rates for western Dronning Maud Land from firn cores and snow pits

As a result of intensive field activities carried out by several nations over the past 15 years, a set of accumulation measurements for western Dronning Maud Land, Antarctica, was collected, based on firn-core drilling and snow-pit sampling. This new information was supplemented by earlier data taken from the literature, resulting in 111 accumulation values. Using Geographical Information Systems software, a first region-wide mean annual snow-accumulation field was derived. In order to define suitable interpolation criteria, the accumulation records were analyzed with respect to their spatial autocorrelation and statistical properties. The resulting accumulation pattern resembles well known characteristics such as a relatively wet coastal area with a sharp transition to the dry interior, but also reveals complex topographic effects. Furthermore, this work identifies new high-return shallow drilling sites by uncovering areas of insufficient sampling density.

Calcareous nannofossil bioevents of early-middle Pleistocene sediments from the Mediterranean Sea and the Noth Atlantic

Quantitative distributions of calcareous nannofossils are analysed in the early-middle Pleistocene at the small Gephyrocapsa and Pseudoemiliania lacunosa zone transition in deep-sea cores from the Mediterranean Sea and North Atlantic Ocean (Ocean Drilling Program [ODP] Sites 977, 964 and 967, Deep Sea Drilling Project [DSDP] Site 607). The temporal and spatial mode of occurrence of medium-sized gephyrocapsids and reticulofenestrids has been examined to refine biostratigraphic constraints and evaluate possible relationships of stratigraphic patterns to environmental changes during a period of global climatic deterioration. The timing of bioevents has been calibrated using high-resolution sampling and correlation to the delta18O record in chronologically well-constrained sections. Newly identified events and ecostratigraphical signals enhance the stratigraphic resolution at the early-middle Pleistocene. The first occurrence (FO) of intermediate morphotypes between Pseudoemiliania and Reticulofenestra (Reticulofenestra sp.) is proposed as a reliable event within marine isotope stage (MIS) 35 or at the MIS 35/34 transition. The distribution of Reticulofenestra asanoi is characterized by rare and scattered occurrences in its lowest range, but the first common occurrence (FCO) is consistently identified at MIS 32 or 32/31; the last common occurrence (LCO) of the species is a distinctive event at MIS 23. In the studied interval, Gephyrocapsa omega dominates among medium-sized Gephyrocapsa. The FO of G. omega and contemporaneous re-entry of medium-sized gephyrocapsids at the lower-middle Pleistocene transition are diachronous between the Atlantic Ocean and Mediterranean Sea and from the western to eastern Mediterranean. In the Mediterranean, the LO of G. omega falls at MIS 15, insolation cycle 54 and is isochronous among the sites. Abundance fluctuations of G. omega show notable relations to early-middle Pleistocene climate changes; they considerably increase in abundance at the interglacial stages, suggesting warm water preferences. Gephyrocapsa omega temporarily disappears during the glacial MIS 22 and MIS 20. Above MIS 20, an impoverishment in G. omega and in the total abundance of medium-sized gephyrocapsids occurs. A decrease in abundance of G. omega is observed between the western Site 977 and the easternmost Site 967 in the Mediterranean Sea, as a possible response to high salinity and/or low nutrient content. Possible environmental influences on the distribution of R. asanoi and of Reticulofenestra sp. are discussed.

Age determination and Heinrich Events in sediment cores SU90-08 and KET80-03

The Mediterranean Sea hydrology at the time of the Heinrich formation in the North Atlantic Ocean was analyzed by comparing sea surface temperatures (SSTs) and oxygen isotope composition of seawater (dw) changes during the past 75 kyr in two marine cores. These were compared to the palynological variations derived in the Mediterranean Sea core. During the last glacial the two oceanic SST records show similar and synchronous patterns, with several long-term cooling periods, ending by abrupt SST increases. At the time of the Heinrich events, cold SSTs and low salinity prevailed in the Mediterranean Sea. The freshwater budget was similar to the modern one, permitting the presence of a mixed forest on the Mediterranean borderlands. The post-Heinrich periods are marked by a freshwater budget decrease, limiting oak and fir tree growth in the Mediterranean region. Increase of precipitation or reduction of evaporation is observed before the Heinrich episode, and is associated with a well-developed mixed Mediterranean forest.

(Supporting Information) Collection date and location of the analysed herbarium Corallina officinalis samples of the Natural History Museum (BM)

Suporting Information 1; Herbarium Corallina officinalis samples of the Natural History Museum (BM) analysed for the present study. Where the same NHM barcodes are provided for more than one sample, multiple samples were present under the same barcode in the herbarium. (-) indicates samples were not barcoded in the NHM (BM) system.

Contusotruncana contusa abundances and morphotypes in the cretaceous mid-latitude South Atlantic

Spatial and temporal patterns in test size and shape (test conicity and spiral roundness) and absolute abundance (accumulation rate) of the planktonic foraminifer Contusotruncana contusa were studied in the South Atlantic Ocean (DSDP sites 356, 516, 525 and 527) during an interval corresponding to the last 800 kyr of the Cretaceous. The variation in absolute abundance of C. contusa was characterised by alternating periods of high and low abundance; some of these periods were traceable across the entire mid-latitude South Atlantic Ocean. While the mean spiral roundness did not show any interpretable patterns, a sudden increase of the mean test size and mean test conicity occurred between 65.3 and 65.2 Ma (based on linear interpolation within the Cretaceous part of Subchron C29R) at all sites studied, indicating a poleward migration followed by rapid withdrawal of the low-latitude C. contusa morphotypes from the mid-latitude South Atlantic Ocean. We suggest that this event was caused by a short period of surface-water warming in the southern mid-latitudes corresponding to the brief high-latitude warming event and associated faunal migrations in the Boreal and Austral realms.

CaCO3 content and bulk densitiy of east equatorial Pacific Ocean sediment cores

Nine piston cores and six triggerweight cores retrieved from the eastern equatorial Pacific Ocean during the Venture 1 expedition were analyzed for dry-bulk density (DBD) and CaCO3 content. Sites are located along a north-south transect at 110°W from 11°N to 3°S and along an east-west transect from 110° to 90°W, at approximately 3°S. The data reveal two DBD-CaCO3 relationships and four patterns of CaCO3 abundance.

Chiasmolithus species in middle Eocene and Oligocene sediments of ODP Holes 105-647A and 120-748B

In this preliminary biometric study of the calcareous nannofossil species Chiasmolithus expansus, Chiasmolithus oamaruensis, and Chiasmolithus altus from the upper middle Eocene to lower Oligocene of Sites 647 and 748, we document a complete gradation of forms among all three species. Chiasmolithus oamaruensis has significantly higher morphologic variance than the other species. The Chiasmolithus population at each site changes from C. expansus to C. oamaruensis and then to C. altus. This may not reflect a true evolutionary sequence because a major reversal in shape change of the central cross-bar structure accompanies this sequence, and because C. altus is morphologically closer to C. expansus than it is to C. oamaruensis. The change in the width of the cross-bar structure is primarily a result of changes in the alignment of the central connecting bar, rather than of changes in the cross-bar angle. At Site 748, two fluctuations in morphology produce sample populations intermediate between all three species. In addition, reported stratigraphic and paleogeographic occurrences of C. oamaruensis and C. altus show different latitudinal distributions. These morphological and distributional patterns may be explained by a continuous morphologic gradient between C. oamaruensis and C. altus, with C. oamaruensis occurring more commonly in cool-water paleoenvironments, and C. altus occurring more commonly in cold-water paleoenvironments. Thus, paleoenvironmental fluctuations at Site 748 may be the cause of the morphologic fluctuations in Chiasmolithus. This hypothesis can be tested against previously proposed evolutionary models by more detailed sampling of sections along a latitudinal transect.

Paleomagnetism and bedding orientations at DSDP Sites 87-582, 87-583 and 87-584

Paleomagnetic measurements of sediment samples provide the magnetostratigraphy at Deep Sea Drilling Sites 582, 583, and 584 in the Nankai Trough and the Japan Trench. Drastic changes in the rate of sediment accumulation are documented by the magnetostratigraphic and biostratigraphic correlations. The changes in the accumulation rate correspond to the supply of sediments and variations in the accretionary process, which are directly related to the tectonic cycles in the geologic evolution of the Japanese island arc. Faults and folds within the drilled sedimentary sequences are oriented by paleomagnetic declination. Their directions and stress patterns are related to the relative plate motion along the trough and trench. The original remanent magnetization of the sediment was modified and remagnetized in the tectonic process of accretion by physical deformation, faulting, and intrusion of dewatering veinlets.

Statistics on low cloud occurrence per month along the South-Western African coast at 7:00 and 14:00 UTC, 2004 to 2009

The spatial and temporal patterns of fog and low clouds along the South-Western African coast are characterized based on an evaluation of Meteosat SEVIRI satellite data. A technique for the detection of fog/low clouds in the region is introduced, and validated using 1 year of CALIOP cloud lidar products, showing reliable performance. The frequency of fog and low cloud in the study area is analyzed by systematic application of the technique to all available Meteosat SEVIRI scenes from 2004 to 2009, for 7:00 UTC and 14:00 UTC. The highest frequencies are encountered in the area around Walvis Bay, with a peak in the summer months. Fog and low clouds clear by 14:00 UTC almost everywhere over land.

Mineralogical and isotopic compositions of ODP Hole 107-650A

Red-brown dolomitic claystones overlay the Marsili Basin basaltic basement at ODP Site 650. Sequential leaching experiments reveal that most of the elements considered to have a hydrothermal or hydrogenous origin in a marine environment, such as Fe, Cu, Zn, Pb, Co, Ni, are present mainly in the aluminosilicate fraction of the dolomitic claystones. Their vertical distribution, content and partitioning chemistry of trace elements, and REE patterns suggest enhanced terrigenous input during dolomite formation, but no significant hydrothermal influence from the underlying basaltic basement. Positive correlations in the C and O isotopes in the dolomites reflect complex conditions during the dolomitization. The stable isotopes can be controlled in part by temperature variations during the dolomitization. Majority of the samples, however, form a trend that is steeper than expected for only temperature control on the C and O isotopes. The latter indicates possible isotopic heterogeneity in the proto-carbonate that can be related to arid climatic conditions during the formation of the basal dolomitic claystones. In addition, the dolostones stable isotopic characteristics can be influenced by diagenetic release of heavier delta18O from clay dehydration and/or alteration of siliciclastic material. Strontium and Pb isotopic data reveal that the non-carbonate fraction, the "dye" of the dolomitic claystones, is controlled by Saharan dust (75%-80%) and by material with isotopic characteristics similar to the Aeolian Arc volcanoes (20%-25%). The non-carbonate fraction of the calcareous ooze overlying the dolomitic claystones has a Sr and Pb isotopic composition identical to that of the dolomitic claystones, indicating that no change in the input sources to the sedimentary basin occurred during and after the dolomitization event. Combination of climato-tectonic factors most probably resulted in suitable conditions for dolomitization in the Marsili and the nearby Vavilov Basins. The basal dolomitic claystone sequence was formed at the initiation of the opening of the Marsili Basin (~2 Ma), which coincided with the consecutive glacial stage. The glaciation caused arid climate and enhanced evaporation that possibly contributed to the stable isotope variations in the proto-carbonate. The conductive cooling of the young lithosphere produced high heat flow in the region, causing low-temperature passive convection of pore waters in the basal calcareous sediment. We suggest that this pumping process was the major dolomitization mechanism since it is capable of driving large volumes of seawater (the source of Mg2+) through the sediment. The red-brown hue of the dolomitic claystones is terrigenous contribution of the glacially induced high eolian influx and was not hydrothermally derived from the underlying basaltic basement. The detailed geochemical investigation of the basal dolomitic sequence indicates that the dolomitization was most probably related to complex tectono-climatic conditions set by the initial opening stages of the Marsili Basin and glaciation.

Physical properties and elastic constants of ODP Holes 137-504B and 140-504B upper crustal rocks

Seismic velocities have been measured at confining pressures of 100 MPa and 600 MPa for sheeted dike samples recovered during Ocean Drilling Program Legs 137 and 140. The compressional- and shear-wave velocities show an increase with depth at Hole 504B, which is in sharp contrast to the atmospheric pressure velocity measurements performed as part of the shipboard analyses. Rocks exposed to different types of alteration and fracture patterns show distinct changes in their physical properties. The seismic reflectors observed on the vertical seismic profile (VSP) experiment performed during Leg 111 may have been caused by low velocity zones resulting from alteration. The amount of fracturing and hydrothermal alteration in several zones also may have contributed to the acoustic impedance contrast necessary to produce the E5 reflector. Poisson's ratios calculated from laboratory velocity measurements show several low values at depths ranging from 1600 mbsf to 2000 mbsf, which tends to follow similar trends obtained from previous oceanic refraction experiments. A comparison of physical properties between samples recovered from Hole 504B and ophiolite studies in the Bay of Islands and Oman shows a good correlation with the Bay of Islands but significant differences from the measurements performed in the Oman complex.

Decade Wind and Wave Data for NW Iberia, Cabo Sillerio

Seafloor sediment mobilization on the inner Northwest Iberian continental shelf is caused largely by ocean surface waves. The temporal and spatial variability in the wave height, wave period, and wave direction has a profound effect on local sediment mobilization, leading to distinct sediment mobilization scenarios. Six grain-size specific sediment mobilization scenarios, representing seasonal average and storm conditions, were simulated with a physics-based numerical model. Model inputs included meteorological and oceanographic data in conjunction with seafloor grain-size and the shelf bathymetric data. The results show distinct seasonal variations, most importantly in wave height, leading to sediment mobilization, specifically on the inner shelf shallower than 30 m water depth where up to 49% of the shelf area is mobilized. Medium to severe storm events are modeled to mobilize up to 89% of the shelf area above 150 m water depth. The frequency of each of these seasonal and storm-related sediment mobilization scenarios is addressed using a decade of meteorological and oceanographic data. The temporal and spatial patterns of the modeled sediment mobilization scenarios are discussed in the context of existing geological and environmental processes and conditions to assist scientific, industrial and environmental efforts that are directly affected by sediment mobilization. Examples, where sediment mobilization plays a vital role, include seafloor nutrient advection, recurrent arrival of oil from oil-spill-laden seafloor sediment, and bottom trawling impacts.

Major element and mineral composition of gabbroic xenoliths and megacrysts from Jeju Island, South Korea

Gabbroic xenoliths and diverse megacrysts (e.g., clinopyroxenes, amphiboles and plagioclases), which correspond to the lithology ranging from gabbro-norite to gabbro, occur in the Pleisto-Holocene alkali basalts from Jeju Island, South Korea. The gabbroic xenoliths consist primarily of moderate-K2O plagioclase, Ti-Al-rich clinopyroxene and CaO-rich orthopyroxene; additionally, TiO2-rich amphibole (kaersutite) and Ti-Fe oxides might or might not be present. The plagioclase is the most dominant phase (approx. 60-70 vol.%). The xenoliths and megacrysts provide evidence for the modal metasomatism of the lower continental crust by the mafic magmas during the Pleistocene. The coarse grain size (up to 5 mm), moderate Mg# [=100xMg/(Mg+Fe(total)) atomic ratio] of pyroxenes (70-77) and textural features (e.g., poikilitic) indicate that the gabbroic xenoliths are consistent with a cumulus origin. The clinopyroxenes from these xenoliths are enriched in REE with smooth convex-upward MREE patterns, which are expected for cumulus minerals formed from a melt enriched in incompatible trace elements. The strikingly similar major and trace element variations and the patterns of constituent minerals clearly indicate a genetic link between the gabbroic xenoliths (plus megacrysts) and the host basalt, indicating that the xenoliths belong to the Jeju Pleisto-Holocene magma system. On the basis of the textural features, the mineral equilibria and the major and trace element variations, the xenoliths appear to have crystallized from basaltic melts at the reservoir-roof environment within the lower crust (4-7 kbars) above the present Moho estimates beneath Jeju Island, where the xenoliths represent wall rocks. Following the consolidation of the xenolith lithologies, volatile- and incompatible element-enriched melt/fluid, as metasomatic agents, infiltrated through the grain boundaries and/or cracks and reacted with the preexisting anhydrous phases, which produced the metasomatic amphiboles. This volatile-enriched melt/fluid could have evolved from the initially anhydrous compositions to the volatile-saturated compositions by the active fractional crystallization in the Jeju Pleisto-Holocene magma system. This process was significant in that it was a relatively young event and played an important role in the formation of the hydrous minerals and the metasomatization of the lower continental crust, which is a plume-impacted area along the Asian continental margin. The major and trace element analyses of the mineral phases from the xenoliths were performed to define the principal geochemical characteristics of the crustal lithosphere segment represented by the studied xenoliths.

Analysis of the iron oxide assemblages in the ANDRILL AND-1B drill core, Ross Sea, Antarctica

The AND-1B drill core recovered a 13.57 million year Miocene through Pleistocene record from beneath the McMurdo Ice Shelf in Antarctica (77.9°S, 167.1°E). Varying sedimentary facies in the 1285 m core indicate glacial-interglacial cyclicity with the proximity of ice at the site ranging from grounding of ice in 917 m of water to ice free marine conditions. Broader interpretation of climatic conditions of the wider Ross Sea Embayment is deduced from provenance studies. Here we present an analysis of the iron oxide assemblages in the AND-1B core and interpret their variability with respect to wider paleoclimatic conditions. The core is naturally divided into an upper and lower succession by an expanded 170 m thick volcanic interval between 590 and 760 m. Above 590 m the Plio-Pleistocene glacial cycles are diatom rich and below 760 m late Miocene glacial cycles are terrigenous. Electron microscopy and rock magnetic parameters confirm the subdivision with biogenic silica diluting the terrigenous input (fine pseudo-single domain and stable single domain titanomagnetite from the McMurdo Volcanic Group with a variety of textures and compositions) above 590 m. Below 760 m, the Miocene section consists of coarse-grained ilmenite and multidomain magnetite derived from Transantarctic Mountain lithologies. This may reflect ice flow patterns and the absence of McMurdo Volcanic Group volcanic centers or indicate that volcanic centers had not yet grown to a significant size. The combined rock magnetic and electron microscopy signatures of magnetic minerals serve as provenance tracers in both ice proximal and distal sedimentary units, aiding in the study of ice sheet extent and dynamics, and the identification of ice rafted debris sources and dispersal patterns in the Ross Sea sector of Antarctica.