Oxygen isotopes from two snow trenches from Kohnen Station, Dronning Maud Land, Antarctica from the 2012/13 field season

In low-accumulation regions, the reliability of d18O-derived temperature signals from ice cores within the Holocene is unclear, primarily due to the small climate changes relative to the intrinsic noise of the isotopic signal. In order to learn about the representativity of single ice cores and to optimise future ice-core-based climate reconstructions, we studied the stable-water isotope composition of firn at Kohnen station, Dronning Maud Land, Antarctica. Analysing d18O in two 50 m long snow trenches allowed us to create an unprecedented, two-dimensional image characterising the isotopic variations from the centimetre to the hundred-metre scale. This data set includes the complete trench oxygen isotope record together with the meta data used in the study.

Seafloor to Summit: The Birth of Everest

This lecture, delivered at Montana Tech, documents the 2012 expedition to Mt. Everest in Nepal by Conard Anker and Dave Lageson from Bozeman, Montana. The trip commemorated the 50th anniversary of the first American assent in 1963. The climbers gathered rock samples on and near the summit and created a new educational outreach model to elementary school children.

Th-234 and Po-210 as POC flux proxies during the ARK-XXVII/3 expedition (August-October 2012)

The Arctic sea-ice extent reached a record minimum in September 2012. Sea-ice decline increases the absorption of solar energy in the Arctic Ocean, affecting primary production and the plankton community. How this will modulate the sinking of particulate organic carbon (POC) from the ocean surface remains a key question. We use the 234Th/238U and 210Po/210Pb radionuclide pairs to estimate the magnitude of the POC export fluxes in the upper ocean of the central Arctic in summer 2012, covering time scales from weeks to months. The 234Th/238U proxy reveals that POC fluxes at the base of the euphotic zone were very low (2 ± 2 mmol C/m**2/d) in late summer. Relationships obtained between the 234Th export fluxes and the phytoplankton community suggest that prasinophytes contributed significantly to the downward fluxes, likely via incorporation into sea-ice algal aggregates and zooplankton-derived material. The magnitude of the depletion of 210Po in the upper water column over the entire study area indicates that particle export fluxes were higher before July/August than later in the season. 210Po fluxes and 210Po-derived POC fluxes correlated positively with sea-ice concentration, showing that particle sinking was greater under heavy sea-ice conditions than under partially ice-covered regions. Although the POC fluxes were low, a large fraction of primary production (>30%) was exported at the base of the euphotic zone in most of the study area during summer 2012, indicating a high export efficiency of the biological pump in the central Arctic. This article is protected by copyright. All rights reserved.

IODP Expedition 339 in the Gulf of Cadiz and off West Iberia : decoding the environmental significance of the Mediterranean outflow water and its global influence

IODP Expedition 339 drilled five sites in the Gulf of Cadiz and two off the west Iberian margin (November 2011 to January 2012), and recovered 5.5 km of sediment cores with an average recovery of 86.4%. The Gulf of Cadiz was targeted for drilling as a key location for the investigation of Mediterranean outflow water (MOW) through the Gibraltar Gateway and its influence on global circulation and climate. It is also a prime area for understanding the effects of tectonic activity on evolution of the Gibraltar Gateway and on margin sedimentation. We penetrated into the Miocene at two different sites and established a strong signal of MOW in the sedimentary record of the Gulf of Cadiz, following the opening of the Gibraltar Gateway. Preliminary results show the initiation of contourite deposition at 4.2–4.5 Ma, although subsequent research will establish whether this dates the onset of MOW. The Pliocene succession, penetrated at four sites, shows low bottom current activity linked with a weak MOW. Significant widespread unconformities, present in all sites but with hiatuses of variable duration, are interpreted as a signal of intensified MOW, coupled with flow confinement. The Quaternary succession shows a much more pronounced phase of contourite drift development, with two periods of MOW intensification separated by a widespread unconformity. Following this, the final phase of drift evolution established the contourite depositional system (CDS) architecture we see today. There is a significant climate control on this evolution of MOW and bottom-current activity. However, from the closure of the Atlantic–Mediterranean gateways in Spain and Morocco just over 6 Ma and the opening of the Gibraltar Gateway at 5.3 Ma, there has been an even stronger tectonic control on margin development, downslope sediment transport and contourite drift evolution. The Gulf of Cadiz is the world's premier contourite laboratory and thus presents an ideal testing ground for the contourite paradigm. Further study of these contourites will allow us to resolve outstanding issues related to depositional processes, drift budgets, and recognition of fossil contourites in the ancient record on shore. The expedition also verified an enormous quantity and extensive distribution of contourite sands that are clean and well sorted. These represent a relatively untapped and important exploration target for potential oil and gas reservoirs.

Submarine record of volcanic island construction and collapse in the Lesser Antilles arc: First scientific drilling of submarine volcanic island landslides by IODP Expedition 340

IODP Expedition 340 successfully drilled a series of sites offshore Montserrat, Martinique and Dominica in the Lesser Antilles from March to April 2012. These are among the few drill sites gathered around volcanic islands, and the first scientific drilling of large and likely tsunamigenic volcanic island-arc landslide deposits. These cores provide evidence and tests of previous hypotheses for the composition and origin of those deposits. Sites U1394, U1399, and U1400 that penetrated landslide deposits recovered exclusively seafloor sediment, comprising mainly turbidites and hemipelagic deposits, and lacked debris avalanche deposits. This supports the concepts that i/ volcanic debris avalanches tend to stop at the slope break, and ii/ widespread and voluminous failures of preexisting low-gradient seafloor sediment can be triggered by initial emplacement of material from the volcano. Offshore Martinique (U1399 and 1400), the landslide deposits comprised blocks of parallel strata that were tilted or microfaulted, sometimes separated by intervals of homogenized sediment (intense shearing), while Site U1394 offshore Montserrat penetrated a flat-lying block of intact strata. The most likely mechanism for generating these large-scale seafloor sediment failures appears to be propagation of a decollement from proximal areas loaded and incised by a volcanic debris avalanche. These results have implications for the magnitude of tsunami generation. Under some conditions, volcanic island landslide deposits composed of mainly seafloor sediment will tend to form smaller magnitude tsunamis than equivalent volumes of subaerial block-rich mass flows rapidly entering water. Expedition 340 also successfully drilled sites to access the undisturbed record of eruption fallout layers intercalated with marine sediment which provide an outstanding high-resolution data set to analyze eruption and landslides cycles, improve understanding of magmatic evolution as well as offshore sedimentation processes.

Letter and Recollections of Alexander Agassiz: The 1891 Albatross Expedition

Presented here is another in the list of historic accounts of iconic research cruises of the USFC Steamer Albatross, this a reminiscence of the renowned scientist Alexander Agassiz edited by his son G. R. Agassiz, a chapter from the volume “Letters and Recollections of Alexander Agassiz,” published in 1913. Agassiz made three major cruises in the Albatross in 1891, 1899–1900, and 1904–05, adding greatly to the world’s store of specimens and knowledge of thalasography, his favored term for oceangraphy, and specifically of the Pacific Ocean. Having made important cruises and studies with the Blake in the Caribbean, he sought to do comparable research in the Pacific. His opportunity came in 1890, and with the consent of President Benjamin Harrison, he took charge of this Albatross research cruise, paying much of the expense himself. In contrast with the other ships he had been on, he found the laboratories, equipment, and furnishings to be comparatively luxurious and extremely well appointed for his work. Further, the Albatross was then captained by Lieutenant Commander Zera Luther Tanner who seemed to take as much interest in the oceanographic research as did the scientists, and Agassiz appreciated working with him, too. Little of the original text has been altered, and readers are cautioned that some of the views expressed may reflect unfortunate prejudices of that era toward individuals, nationalities, etc.

A national security strategy for England: Matthew Sutcliffe, the Earl of Essex, and the Cadiz Expedition of 1596

The English cleric Matthew Sutcliffe arguably produced the first comprehensive security concept in history. It had at its centre the war between England and Spain (1585-1604), and Sutcliffe advocated taking the war to the Iberian Peninsula to seize Philip II's main Atlantic ports, rather than remaining satisfied with the indirect combat of Spain in Flanders, defensive action against naval attacks on England and the guerre de course on Spanish shipping at sea. This approach seems to be at the heart of Essex's 1596 naval campaing against Spanish ports, which foundered on the bureaucratic politics of the Elizabethan government.

The objectives of the US Exploring Expedition's circumnavigation (1838-1842): longitude, nautical charting and the establishment of modern geographic coordinates

This article analyzes the main objectives of the scientific voyage to circumnavigate the earth, undertaken by the United States from 1838 to 1842. Charting was one of the most important of the scientific and strategic goals of the exploratory voyage. The initiative for the undertaking was the search for exact positioning on the high seas after the establishment of the longitude system, when nautical charts and maps from various countries were compared, and other, new ones were drawn. The United States participated in this international effort, leading to the creation of its own cartographic system.

Taxonomic study on the molluscs collected in Marion-Dufresne expedition (MD55) to SE Brazil: Xenophoridae, Cypraeoidea, mitriforms and Terebridae (Caenogastropoda)

The deep-water molluscs collected during the expedition MD55 off SE Brazil have been gradually studied in some previous papers. The present one is focused on samples belonging to caenogastropod taxa Xenophoridae Troschel, 1852, Cypraeoidea Rafinesque, 1815, mitriforms and Terebridae Morch, 1852. Regarding the Xenophoridae, Onustus aquitanus n. sp. is a new species, collected off the littoral of Espirito Santo and Rio de Janeiro, Brazil, 430-637 m depth (continental slope). The main characters of the species include the small size (c. 20 mm), the proportionally wide shell, the white colour, the short peripheral flange, the oblique riblets weakly developed and a brown multispiral protoconch. This appears to be the smallest living species of the family, resembling in this aspect fossil species. In respect to the Cypraeoidea, the following results were obtained: family Cypraeidae Rafinesque, 1815: Erosaria acicularis (Gmelin, 1791) and Luria cinerea (Gmelin, 1791) had the deepest record, respectively 607-620 m and 295-940 m, although the samples were all dead, eroded shells. Family Lamellariidae d'Orbigny, 1841: a total of three lots were collected, provisionally identified as Lamellaria spp. as the samples consist of only vestigial shells; possibly each lot represents a different species. Family Pediculariidae Gray, 1853: a sample of Pedicularia tibia Simone, 2005 was found, expanding the range c. 1000 km southwards, from Ceara to Espirito Santo. Family Ovulidae Fleming, 1822: Pseudosimnia lacrima n. sp., collected off Espirito Santo, 607-620 m depth, is described here and is mainly characterised by its strong biconic outline, small size (c. 7 mm), and a thick peripheral callus. Family Triviidae Troschel, 1863: Cleotrivia antillarum (Schilder, 1922) is recorded for the first time as deep as 620 m, and its distribution expanded from Rio Grande do Norte to Espirito Santo; Dolichupis akangus n. sp. with rounded outline and c. 15 transverse ribs; D. pingius n. sp. with the outer lip expanded posteriorly and c. 10 ribs. In respect to the mitriform neogastropods, the following species are emphasised: family Costellariidae MacDonald, 1860: Vexillum sp., 607-620 m depth; Turricostellaria amphissa n. sp., 295 m depth; T. jukyry n. sp.; T. apyrahi n. sp., both 790-1575 m depth; T. ovir n. sp., 1200 m depth; Nodicostellaria crassa (Simone, 1995), 240-600 m depth, with extension northwards of the range up to Espirito Santo; Austromitra decresca n. sp., 60-105 m depth. Family Mitridae Swainson, 1829: Subcancilla joapyra n. sp., 295 m depth; S. cf. straminea (Adams, 1853), 607-620 m depth. Family Volutomitridae Gray, 1854: Microvoluta corona n. sp., 1500-1575 m depth. Family Mitromorphidae Casey, 1904: Mitromorpha sama n. sp., 607-940 m depth; M. mirim n. sp., 60105 m depth. Regarding the conoidean Terebridae, this paper is a complement of a previous study. It deals with a new species Terebra assu Simone n. sp., from the Abrolhos Bank, 295 m depth, characterised by its narrow outline, yellowish colour, weak sculpture on the last whorls, and a proportionally broad, paucispiral protoconch. A second finding of Terebra alagoensis Lima, Tenorio & Barros, 2007 expands the geographic range from Alagoas to north Espirito Santo. A discussion on the systematics of the "complex Terebra doellojuradoi" in South American coast is also provided, highlighting the improbability of synonymy between T. leptapsis Simone, 1999 and T doellojuradoi Carcelles, 1953. Differences in size, sculpture, spire angulation, aperture, and mainly in protoconch, indicate specific separations. The presently studied terebrids belong to the "complex Terebra doellojuradoi", which encompasses closely related, deep-water, small species, possessing a relatively high degree of endemicity.

Os objetivos da circunavegação da U.S. Exploring Expedition (1838-1842): longitude, mapeamento náutico e instituição das coordenadas geográficas modernas

Analisa o principal objetivo da viagem científica de circunavegação realizada pelos EUA entre 1838 e 1842. A tarefa de mapeamento destaca-se entre outras metas científico-estratégicas da viagem exploratória. A iniciativa da empreitada foi movida pela busca da exata localização em alto-mar após a instituição do sistema de longitudes, quando cartas náuticas e mapas de vários países foram conferidos, e outros, novos, desenhados. Os EUA participaram desse esforço internacional, dando início à constituição de um sistema cartográfico próprio.

Solar radiation over and under sea ice and photographic quantification of Ice algal aggregates during the POLARSTERN cruise ARK-XXVII/3 (IceArc) in summer 2012

The ice cover of the Arctic Ocean has been changing dramatically in the last decades and the consequences for the sea-ice associated ecosystem remain difficult to assess. Algal aggregates underneath sea ice have been described sporadically but the frequency and distribution of their occurrence is not well quantified. We used upward looking images obtained by a remotely operated vehicle (ROV) to derive estimates of ice algal aggregate biomass and to investigate their spatial distribution. During the IceArc expedition (ARK-XXVII/3) of RV Polarstern in late summer 2012, different types of algal aggregates were observed floating underneath various ice types in the Central Arctic basins. Our results show that the floe scale distribution of algal aggregates in late summer is very patchy and determined by the topography of the ice underside, with aggregates collecting in dome shaped structures and at the edges of pressure ridges. The buoyancy of the aggregates was also evident from analysis of the aggregate size distribution. Different approaches used to estimate aggregate biomass yield a wide range of results. This highlights that special care must be taken when upscaling observations and comparing results from surveys conducted using different methods or on different spatial scales.