Microlite transfer by disaggregation of mafic inclusions following magma mixing at Soufrière Hills volcano,Montserrat

The Soufrière Hills volcano on Montserrat has for the past 12 years been erupting andesite with basaltic to basaltic–andesite inclusions. The andesite contains a wide variety of phenocryst textures and strongly zoned microlites. Analysis of minor elements in both phenocrysts and microlites allows us to put detailed constraints on their origins. Compositions of clinopyroxene, from overgrowth rims on quartz and orthopyroxene and coarse-grained breakdown rims on hornblende, are identical to those from the mafic inclusions, indicating that these rims form during interaction with mafic magma. In contrast, resorbed quartz and reversely zoned orthopyroxenes form during heating. Microlites of plagioclase and orthopyroxene are chemically distinct from the phenocrysts, being enriched in Fe and Mg, and Al and Ca respectively. However, microlites of plagioclase, orthopyroxene and clinopyroxene are indistinguishable from the compositions of these phases in the mafic inclusions. We infer that the inclusions disaggregated under conditions of high shear stress during ascent in the conduit, transferring mafic material into the andesite groundmass. The mafic component of the system is therefore greater than previously thought. The presence of mafic-derived microlites in the andesite groundmass also means that care must be taken when using this as a starting material for phase equilibrium experiments.     

A risk assessment approach to contaminants in Port Curtis, Queensland, Australia

Port Curtis is one of Australia's leading ports for which substantial industrial expansion is proposed over the next decade. However, there has been little attempt to date to assess the extent of contamination in waters, sediments and biota or to characterize the potential impacts of contaminants on aquatic biota. Contaminants of potential concern to biota and human health were investigated in the Port Curtis estuary using a screening-level risk assessment approach. Dissolved metal concentrations in waters were below [ANZECC/ARMCANZ, 2000. Australian and New Zealand Guidelines for Fresh and Marine Water Quality, Vol. 1. The Guidelines, Australian and New Zealand Environment and Conservation Council and Agriculture and Resource Management Council of Australia and New Zealand] trigger values, suggesting low risk of these contaminants. In sediments, arsenic, nickel and chromium concentrations exceeded interim sediment quality guidelines-low (ISQG-low), but were also high in the reference zone suggesting a natural origin. Historical data on naphthalene in Harbour sediments showed that it was also of potential concern. Bioaccumulation of contaminants in a range of biota was also used as an indicator of contaminant exposure. Biota were generally enriched in metals and tributyltin, which was also elevated in water and sediments. Although not unique to Port Curtis, mercury in barramundi was identified as a potential risk to human health.     

Revisiting the palaeoenvironmental and climatic history of the Cherangani Hills using fungal spores

Fungi are highly sensitive to environmental and climatic changes. Palaeoecological reconstructions utilising tropical African fungal spores, however, are rare and patchy. Here, we show that fossil fungal spores preserved in core KAP-01 from the Cherangani Hills in Kenya tracks critical environmental changes in the African tropics since the Last Glacial Maximum (LGM), largely synchronous with observations in the pollen record from the same site. Consistent with the pollen record, the presence of fungal taxa in the record, albeit meagre, during the LGM point to an intermittent wetter Cherangani that allowed for the presence of the observed taxa and the prevalence of cool, dry conditions during the last deglaciation. The elevated fungal spore activity during the Late Holocene is evidence for warm, moist environmental conditions and broadly consistent with the pollen record. These different fungal spore taxa, which can be employed to track distinct environmental conditions and processes, provide a dimension that can be overlooked if the reconstruction of the palaeoenvironment were to rely solely on pollen. Thus the fungal spore record enables us to affirm the interpretation of the prevalence of warm, moist conditions evident from such as the Holocene pollen record.     

The 6dF Galaxy Survey: final redshift release (DR3) and southern large-scale structures

We report the final redshift release of the 6dF Galaxy Survey (6dFGS), a combined redshift and peculiar velocity survey over the southern sky  (| b | > 10°)  . Its 136 304 spectra have yielded 110 256 new extragalactic redshifts and a new catalogue of 125 071 galaxies making near-complete samples with  ( K , H , J , r _F, b _J) ≤ (12.65, 12.95, 13.75, 15.60, 16.75)  . The median redshift of the survey is 0.053. Survey data, including images, spectra, photometry and redshifts, are available through an online data base. We describe changes to the information in the data base since earlier interim data releases. Future releases will include velocity dispersions, distances and peculiar velocities for the brightest early-type galaxies, comprising about 10 per cent of the sample. Here we provide redshift maps of the southern local Universe with   z ≤ 0.1  , showing nearby large-scale structures in hitherto unseen detail. A number of regions known previously to have a paucity of galaxies are confirmed as significantly underdense regions. The URL of the 6dFGS data base is http://www-wfau.roe.ac.uk/6dFGS .     

A technique for the molecular genetic analysis of Daphnia resting eggs from sub-recent lake sediments

The Polymerase Chain Reaction (PCR) was employed to facilitategenetic analyses of Daphnia ephippial egg banks fromsediment sequences from lakes Windermere and Esthwaite in the English LakeDistrict, UK. We present a robust DNA extraction technique for resting eggs andan account of genetic characterisation of dated resting eggs from sedimentcores using both mitochondrial and nuclear DNA markers. We also providepreliminary results from genetic analysis of egg banks preserved in shortsediment cores. PCR was employed to facilitategenetic analyses of Daphnia ephippial egg banks collected from both lakes. Thelong-term environmental data available from lake records can provide a backdropagainst which molecular genetic-environmental interactions over time can beexamined, providing a technique for direct assessments of population responseto environmental change in paleolimnological studies of biodiversityhistory.