226 resultados para Caledonian orogeny


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The stratigraphies of foreland basins have been related to orogeny, where continent–continent collision causes the construction of topography and the downwarping of the foreland plate. These mechanisms have been inferred for the Molasse basin, stretching along the northern margin of the European Alps. Continuous flexural bending of the subducting European lithosphere as a consequence of topographic loads alone would imply that the Alpine topography would have increased at least between 30 Ma and ca. 5–10 Ma when the basin accumulated the erosional detritus. This, however, is neither consistent with observations nor with isostatic mass balancing models because paleoaltimetry estimates suggest that the topography has not increased since 20 Ma. Here we show that a rollback mechanism for the European plate is capable of explaining the construction of thick sedimentary successions in the Molasse foreland basin where the extra slab load has maintained the Alpine surface at low, but constant, elevations.

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Based on Ann Radcliffe's The castles of Athlin and Dunbayne.

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Purports to be translations from Gaelic but may be original, cf. Dictionary of National Biography.

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Two new species of hemiurine hemiurid are described from Spratelloides robustus off Woodman Point in southern Western Australia. Hemiurus lignator n. sp. differs from its congeners by a combination of similar-sized suckers, long sinus-sac, tandem testes, relatively elongate shape and unthickened seminal vesicle wall. Parahemiurus xylokopos n. sp. differs from its congeners in a combination of its squat form, its distinctly lobed vitellarium and the proximity of the gonads to the ventral sucker. P. merus (Linton, 1910) is reported from Acanthopagrus australis, Pomatomus saltatrix and Trachinotus coppingeri off northern New South Wales, Caranx sexfasciatus, Scorpis lineolata, Siganus nebulosus, Thunnus tonggol and T. coppingeri off southern Queensland, Cephalopholis boenak and Euthynnus affinis off Heron Island, southern Great Barrier Reef, P. saltatrix off southern Western Australia and Priacanthus hamrur off New Caledonia.

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The Priestlaw and Cockburn Law intrusions are zoned granitoid plutons intruded into Lower Palaeozoic sediments at the margin of, and prior to closure of, the Iapetus Ocean. They vary from marginal basic rocks to more acid rocks towards their centres. The parental magmas to the plutons were derived from an isotopically depleted mantle modified by melts/fluids during subduction. Zonation in the plutons was caused by combined assimilation and fractional crystallisation (AFC), and rates of assimilation were low relative to rates of fractionation. A series of pyroxene-mica diorites in Priestlaw are however hybrids formed by simple mixing. Porphyrite-acid porphyrite dykes, associated with the plutons, represent chilled portions of the pluton magmas; more evolved quartz porphyry dykes represent crustal melts. Lamprophyre dykes have high LILE and LREE abundances and relative depletions of HFS elements, typical of subduction related ultra-potassic magmas. High Mg numbers, Ni and Cr contents and experimental constraints, imply near primary status for the least evolved lamprophyres. Their enrichments in incompatible elements, high La/Nb, La/Yb, Sr and low Nd indicate derivation from a previously metasomatised mantle source. Granitoid plutons and lavas in the northern Southern Uplands have high Nd and low Sr, whereas the younger plutons of the southern Southern Uplands have higher Sr, La/Yb and lower Nd, consistent with derivation from a more enriched source. No plutons however have remained as closed systems. Three magmatic suites are present in southern Scotland: (1) Midland Valley Suite (2) Northern Southern Uplands Suite and (3) Southern Southern Uplands Suite, consistent with previous models indicating northward underthrusting of English lithosphere below the southern Southern Uplands. Further underthrusting of decoupled lithospheric mantle is indicated by the presence of lamorophyres in the eastern Southern Uplands, and took place between 410 Ma and 400 Ma.

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The Criffell-Dalbeattie pluton from SW Scotland is one of a suite of late Caledonian granitoids which are associated with extensive, contemporaneous and compositionally diverse suits of minor intrusions. The minor intrusive suite associated with the Criffell-Dalbeattie pluton is dominantly composed of a series of porphyritic microdiorites, microgranodiorites and microgranites known collectively as the porphyrite-porphyry series. This series can be divided into two groups, the porphyrites and the quartz porphyries, on the basis of petrography and geochemistry although there is some compositional overlap between the two. Compositionally, the porphyrites and quartz porphyries appear to correspond to the granodiorites and granites, respectively, which comprise the Criffell-Dalbeattie pluton, suggesting that the porphyrite-porphyry series of dykes represent magmas which were tapped from the evolving granitic magma chamber. The most mafic component of the minor intrusive suite is represented by calc-alkaline hornblende- and mica bearing lamprophyres. Geochemical studies, including fractional crystallisation, combine assimilation-fractional crystallisation (AFC) show that these are mafic, LILE and LREE enriched melts derived by low degrees of partial melting of a subduction-modified mantle source. It is suggested that the source of the lamprophyres is "Lake District" lithosphere, metasomatised by Lower Palaeozoic subduction, and thrust under the southern part of the Southern Uplands. AFC modelling using chemical and isotopic data further suggest that there is a close genetic link between the lamprophyres and the Criffell-Dalbeattie granitoids and that lamprophyres represent the mantle derived precursors of the Criffell-Dalbeattie granitoids.

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Habitat fragmentation is a major threat to biodiversity, as it can alter ecological processes at various spatial and trophic scales. At the species level, fragmentation leading to the isolation of populations can trigger reductions in genetic diversity, potentially having detrimental effects on population fitness, adaptability and ultimately population persistence. Leptomyrmex pallens is a widespread rainforest ant endemic to New Caledonia but now confined to habitat patches that have been fragmented by anthropogenic fire regimes over the last 200 years. We investigated the social structure of L. pallens in the Aoupinié region (c.a. 4900 ha), and assessed the impacts of habitat fragmentation on its population genetic structure. Allele frequencies at 13 polymorphic microsatellite loci were compared among 411 worker ants from 21 nests distributed across the region. High within-nest relatedness (r = 0.70 ± 0.02), and a single queen found in 38 % of the nests by pedigree analysis indicate that the species is monogynous to weakly polygynous. Estimates of gene flow and genetic structure across the region were subsequently determined using a combined dataset of single workers per nest and of unrelated foraging workers. These estimates coupled with a comprehensive landscape genetic analysis revealed no evidence of significant population structure or habitat effects, suggesting that the Aoupinié region harbours a single panmictic population. In contrast, analyses of mitochondrial DNA sequence data revealed a high degree of genetic structuring, indicating limited maternal gene flow and suggesting that gene flow among nests is driven primarily by winged males. Overall these findings suggest that fire-induced habitat fragmentation has had little impact on the population dynamics of L. pallens. Additional studies of less mobile species should therefore be conducted to gain further insights into fire related disturbances on the unique biodiversity and function of New Caledonian ecosystems.

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The complete mitochondrial genome and a set of polymorphic microsatellite markers were identified by 454 pyrosequencing (1/16th of a plate) for the New Caledonian rainforest spider-ant Leptomyrmex pallens. De novo genome assembly recovered the entire mitochondrial genome with mean coverage of 8.9-fold (range 1-27). The mitogenome consists of 15,591 base pairs including 13 protein-coding genes, 2 ribosomal subunit genes, 22 transfer RNAs, and a non-coding AT-rich region. The genome arrangement is typical of insect taxa and very similar to the only other published ant mitogenome from the Solenopsis genus, with the main differences consisting of translocations and inversions of tRNAs. A total of 13 polymorphic loci were also characterized using 41 individuals from a single population in the Aoupinié region, corresponding to workers from 21 nests and 16 foraging workers. We observed moderate genetic variation across most loci (mean number of alleles per locus = 4.50; mean expected heterozygosity = 0.53) with evidence of only two loci deviating significantly from Hardy-Weinberg equilibrium due to null alleles. Marker independence was confirmed with tests for linkage disequilibrium. Most loci cross amplified for three additional Leptomyrmex species. The annotation of the mitogenome and characterization of microsatellite markers will provide useful tools for assessing the colony structure, population genetic patterns, and dispersal strategy of L. pallens in the context of rainforest fragmentation in New Caledonia. Furthermore, this paper confirms a recent line of evidence that comprehensive mitochondrial data can be obtained relatively easily from small next-generation sequencing analyses. Greater synthesis of next-generation sequencing data will play a significant role in expanding the taxonomic representation of mitochondrial genome sequences.

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The construction industry demands priority from all governments because it impacts economically and socially on all citizens. A number of recent studies have identified inefficiencies in the Australian construction industry by modelling the building process. A culture of reform supported by industry and government is now emerging in the industry – one in which alternate forms of project delivery are being trialed. The Australian Building and Construction Industry Action Agenda brought together industry and government to identify actions necessary to lift Australia’s innovative and knowledge creating capacity at the sector level. A central activity under this Action Agenda was dissemination of information relating to industry best practice initiatives in innovation, project delivery and the use of information technology. Government and industry identified project alliance contracting and more advanced information technology as means to increase efficiency in construction as part of a new innovative procurement environment.

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This paper examines the working pathways of young full-time university students in Australia. It draws on some of the data from a three year research project funded by the Australian Research Council. The project was called ‘Changing the way that Australian enter the workforce: Part-time working careers of young full-time school and tertiary students’. The project had three industry partners: Service Skills Australia (the Industry Skills Council for the service industries), McDonalds Australia (a fast food company) and The Reject Shop (a discount chain). Much of the research took place inside companies, in schools and with national stakeholders (eg Smith & Patton, 2011; Smith & Patton, 2013), but this paper reports on the research that took place with students in universities. In the project we were keen to explore the notion of part-time working while studying as a medium-term career, especially in the context of the need for career flexibility and adaptability (Poehnell & Amundson, 2002).