Nitrogen and water bubbles, oxygen isotopes, shock effects: Deciphering the history of the Bencubbin meteorite breccia

We have observed vesicles filled with heavy nitrogen gas and water vapor in three settings in the Bencubbin CB chondrite: in the mesostasis of the silicate clasts, in the mesostasis of the chondrules of an ordinary chondrite (OC) xenolith, and in grains we refer to as bubble grains, and interpret as remelted OC chondrule mesostasis. In our view, these bubbles are a local phenomenon and formed as a consequence of the impact of the OC fragment onto the Bencubbin parent body. The heavy nitrogen in the bubbles came from one or several of its carrier phases in Bencubbin, and the water came from hydrous silicates. As formulated by Meibom et al. (Meibom A., Righter K., Chabot N., Dehn G., Antignano A., McCoy T. J., Krot A. N., Zolensky M. E., Petaev M. I. and Keil K. (2005) Shock melts in QUE 94411, Hammadah al Hamra 237, and Bencubbin: remains of the missing matrix? Meteorit. Planet. Sci.40, 1377-1391) these hydrous phases, similar to the hydrated clasts now found in CH and CB_b chondrites, were probably common in the Bencubbin parent body at that time. They were later almost totally destroyed by a large scale shock event, and contributed to form the impact melt that now fills space in between the large clasts of Bencubbin. Our observations indirectly confirm this hypothesis. From our composition measurements, we infer that the silicate part of the impact melt was made in roughly equal proportions of melted phyllosilicates and melted anhydrous silicates. The oxygen isotopic composition of the impact melt is much heavier than that of the silicate clasts, probably reflecting the composition of the water at the origin of the phyllosilicates. The O isotope measurements of the OC inclusion chondrules present some features that seem to be common in OCs: a composition of the chondrule crystals slightly lighter than that of whole chondrules, and one olivine crystal with a very light composition.     

Local Governance for Social Sustainability: equity as a strategic response to neoliberal constraints in food security initiatives

Scholarly literature recognises the importance of social sustainability as part of the wider sustainability agenda. A wide array of concepts such as equity, social justice, democratic government, social inclusion, social capital and quality of life are thought to constitute social sustainability. Local governments are charged with delivering social programs and services to their constituency, but market logics and performance-based institutional cultures, along with limited authority and funding, constrain their capacity to respond to new initiatives. We analyse two case studies in Victoria, Australia, to explore how elements of social sustainability are articulated and operationalised within local government. Each case study involved State-level and local government partnerships in health-promotion initiatives to improve food security. Analysis was conducted on 50 primary policy documents, 22 secondary data documents and 27 interviews. Findings reveal that a systems-based or integrated approach to social sustainability was not workable but not completely ineffective. Equity was prioritised by local government in both case studies, and well acknowledged as interconnected with other social goals. Although constrained in its capacity to deliver new initiatives, local government responded to neoliberalising ideologies, as well as its constituency, by strategically focusing on a particular goal, such as equity.     

Can Religion Account for Early Animal Domestications? A Critical Assessment of the Cultural Geographic Argument,Based on Near Eastern Archaeological Data*

Cultural geographers often ascribe early animal domestications to the spiritual propitiation practices of ancient peoples, an interpretation that is not widely shared. This paper evaluates the sacrifice theory against Near Eastern archaeological data and refutes the idea that ritual sacrifice could have induced the earliest animal domestications of the Near East. The earliest domestications were the outcome of essentially ecological and economic processes which later gave rise to the sacrificial practices referred to by cultural geographers.     

Impact of fish farming facilities on Posidonia oceanica meadows: a review

The impact of fish farming facilities on Posidonia oceanica meadows was assessed from studies of intensive facilities carried out over the last few years. The disturbances caused by these fish farms were measured by means of both abiotic (light, sediment, interstitial water) and biotic variables (meadow density, leaf biometry, lepidochronology, primary production, epiphytes, reserve carbohydrates in the rhizomes), in function of increasing distance from cages and/or inside a geographically close reference site. The results showed significant degradation of these seagrass meadows in all the sectors investigated. When fish farming cages were placed above a P. oceanica bed, the meadow was severely degraded or disappeared and the sediment showed a strong increase in organic matter that could lead to anoxia phenomena. The irreversible impact of fish farming projects on P. oceanica meadows requires the application of the precautionary principle. Several recommendations (site selection, preliminary studies and monitoring over time) are suggested in order to enable piscicultural activities to be incorporated in a global process of Integrated Coastal Zone Management.     

A sea bottom multichannel hydrophone array

The PUMA (Pull-Up Multichannel Array) is a sea-bottom instrument for remotely recording data from a 12 channel hydrophone array. Its purpose is to achieve (i) denser data coverage, leading to (ii) improved velocity analysis and (iii) multichannel processing of wide angle seismic data collected on the continental shelf. The instrument consists of a 1.2 km array terminating with a pressure case in which 8 FM cassette recorders, a power supply, microprocessor controller and internal clock are housed. It can be pre-programmed to switch on during shot windows for a total of four hours recording time.The PUMA was successfully used in an experiment west of Lewis, Outer Hebrides, U.K. in August–September 1984. We show an example of PUMA data from this experiment. Indications are that the instrument will provide improved constraints on seismic velocities in the lower continental crust and uppermost mantle.     

Substrate Effects on the Bioeroding Demosponge Cliona orientalis.1. Bioerosion Rates

Abstract. Bioeroding sponges are highly specialised to live in and to erode various natural and man-made calcareous substrates. They encounter very different substrate features. Previous field observations suggest that damage caused by sponge bioerosion may vary with substrate density and architecture. This study aims to experimentally investigate influences of structurally different calcareous substrates on bioerosion activities of Cliona orientalis Thiele, 1900 , an important eroder of inshore Great Barrier Reef calcium carbonate. Blocks were made of the corals Goniopora tenuidens , massive Porites sp., Astreopora listeri, Favites halicora, Favia pallida, Goniastrea retiformis and Cyphastrea serailia , and of the clam Tridacna squamosa . They were grafted with C. orientalis tissue and re-examined after 9 months. Block weight loss, increase of pore volume and differences in breaking stability were measured as indicators of sponge erosion.Erosion caused by C. orientalis differed between substrates and was significantly more pronounced in denser materials with lower pore volume and in coral blocks with more structural barriers. Coral substrates with imperforate thecae and thicker dissepiment walls were more strongly eroded than those with perforate thecae and thinner dissepiments. At similar growth rates, more material has to be removed in denser material with more barriers compared to more porous substrates. Existing pores will be occupied, resulting in lower erosion rates. Erosion capabilities of the sponge could best be detected by the blocks' loss in dry weight, but the sponges also significantly reduced block breaking stability. Change in pore volume was not found to be a reliable parameter to investigate sponge erosion.     

Microsomal estrogen metabolism in channel catfish

Our goal was to study the involvement of cytochrome P450 genes in estrogen metabolism and the extent to which the potentially carcinogenic 4-hydroxyestradiol metabolite is formed by channel catfish (Ictalurus punctatus; CC). Estradiol metabolism and ethoxyresorufin-O-deethylase (EROD) activity were assessed in several tissues from fish collected from three variably contaminated sites in the Mississippi River Delta, from laboratory control fish, and from fish exposed to 20 mg/kg benzo(a)pyrene (BaP) i.p. for 4 days. Liver EROD activity was induced by BaP, but Delta fish EROD activities were not statistically higher than activities in control fish. Gill microsomal EROD activity was also induced by BaP, but activities were 8- to 77-fold lower than those from liver. The predominant estrogen metabolites formed by CC liver, gill and gonad microsomes were 2-hydroxyestradiol and estrone as detected by GC/MS. Liver and gill 2-hydroxyestradiol formation was induced in BaP-dosed fish. The trends in hydroxyestradiol formation in field collected fish were more variable. In all fish liver microsomes there was more 2- compared to 4-hydroxyestradiol formed. However, BaP-treatment increased the 4:2 hydroxyestradiol ratio from 0.04 in control fish to 0.2 in BaP-exposed fish, suggesting that BaP induces the formation of the potentially genotoxic estrogen metabolite. No detectable 4-hydroxyestradiol was produced by gill and gonad microsomes. These results will ultimately help in determining which fish P450 genes are susceptible to environmental contamination and may be involved in estrogen genotoxicity.     

Résultats préliminaires sur la sédimentation pélagique de l'Atlantique tropical au Crétacé et au Tertiaire (plateau de Demerara,Leg ODP 207)

Five sites located on a bathymetric transect of the distal Demerara Rise were studied by ODP Leg 207. Albian sediments of essentially terrigenous nature (clay, siltstone, sandstone) are the oldest drilled stratigraphic levels and form apparently the top of the synrift sequence. They are overlain by Cenomanian to Santonian finely laminated black shales, rich in organic matter of marine origin, which accumulated on a thermally subsiding ramp. Early Campanian hiatuses are thought to be the result of final disjunction of Demerara Rise (South America) from Africa and the onset of deep water communication between the two Atlantic basins (south and central). The overlying Uppermost Cretaceous–Oligocene chalk includes rich and diversified calcareous plankton assemblages, as well as two radiolarian-rich intervals (Late Campanian and Middle Eocene). A complex erosional surface developed during the Late Oligocene–Early Miocene. Sedimentation was impeded since then on the intermediate and deep sites of Demerara Rise, possibly due to the action of deep submarine currents. To cite this article: T. Danelian et al., C. R. Geoscience 337 (2005).