2,102 research outputs found
L'expédition Shackleton. Sauvetage du groupe de la mer de Ross
No full textZimmermann Maurice. L'expédition Shackleton. Sauvetage du groupe de la mer de Ross. In: Annales de Géographie, t. 26, n°141, 1917. pp. 239-240
Le problème de la Barrière de glasse de Ross d'après l'expédition Shackleton
No full textZimmermann Maurice. Le problème de la Barrière de glasse de Ross d'après l'expédition Shackleton. In: Annales de Géographie, t. 19, n°108, 1910. pp. 473-474
Geochronology, structural geology and petrology of the northwestern Lagrange Nunataks, Shackleton Range, Antarctica
No full textThe metamorphic rocks of the La Grange Nunataks, northwestern Shackleton Range, have a complex structural and metamorphic history, involving Mid-Proterozoic and Ross- (Cambro-Ordovician) aged events. The protolith of the Stratton Group Mathys Gneiss was emplaced at 2328 ± 47 Ma (U-Pb zircon), and underwent migmatization at 1715 ± 6 Ma. Migmatization took place at P-T conditions of > 640 ºC / > 4-6 kbar and was accompanied by the formation of multiple generations of ductile structures (D1) and the development of local shear zones (D2). Three distinct deformation events (D3 – D5) took place during the Ross Orogeny, affecting the supracrustal Schimper Group, and to a lesser extent, the Mathys Gneiss. The Ross events, which disturbed the U-Pb systems of zircons in the Proterozoic gneisses, are dated by an Sm-Nd garnet age of 535 ± 22 Ma for Schimper Group kyanite-staurolite-garnet-gneiss. The penetrative event D3, which is characterized by west-directed shearing, took place under Barrovian-type peak P-T conditions of 645 ºC / 7.05 kbar, reflecting crustal thickening during the Ross Orogeny. Subsequent polyphase folding (D4) formed the dominant E-W trending fold axes, and can be correlated with a NW-SE to N-S crustal shortening during initial exhumation. The final deformation episode (D5) is characterized by sinistral strike-slip displacement related to a final transpressional overprint. The D5 event took place under low grade metamorphic conditions, in the stability field of chlorite
An Ophiolitic complex in the northern Shackleton Range, Antarctica
No full textThree lithotectonic and metamorphic units are exposed in the Bernhardi Heights-Hogbom Outcrops area of the eastern Herberts Mountains (northern Shackleton Range). From N to S, and structurally from top to bottom, they include: i) a high-grade gneiss-migmatite complex containing garnet-bearing meta-intrusives of dioritic to tonalitic composition ('Upper High Grade Gneiss Complex'); ii) a metamorphic 'Ophiolitic Complex' consisting of medium-grade mafic-ultramafic rocks and metasedimentary cover rocks, and iii) a high-grade gneiss complex made up of migmatitic gneisses and rare amphibolites ('Lower High Grade Gneiss Complex'). Prominent rock types in the Ophiolitic Complex are amphibolites of N-type MORB to OIB geochemical and Nd isotope affinity, metagabbros interpreted as metacumulate rocks having been formed in a MORB-type setting and metaperidotites. Single-stage Nd-model ages for the OIB-type amphibolites of around 1.0 Ga constrain a maximum formation age for the igneous protoliths of the ophiolitic unit. The polyphase metamorphic evolution of this complex included an early Barrovian-type metamorphic stage (550°C, 7-8 kbar), followed by decompression with concomitant T increase (up to 650°C, 5-6 kbar) and a late retrogression under greenschist facies conditions. K-Ar amphibole dates for amphibolites which are in the range of 500-490 Ma provide evidence for a late-Pan-African (Ross-age) age of metamorphism. Relict felsic granulites from the Upper High Grade Gneiss Complex record an early high-P granulite facies event (675-750°C, 8.4-11.3 kbar), followed by migmatization under low-P upper amphibolite facies conditions (730-850°C, 5-7 kbar). This early metamorphic event possibly reflects a Proterozoic tectonometamorphic cycle. The subsequent metamorphic stages span from intermediate-P amphibolite facies to greenschist-grade conditions. They document the tectonometamorphic reactivation of the High Grade Gneiss Complex as a consequence of the Ross-age thickening and exhumation history of the northern Shackleton Range crystalline rocks
Public awareness and perceptions of invasive alien species in small towns
No full textCITATION: Jubase, N., Shackleton, R. T. & Measey, J. 2021. Public awareness and perceptions of invasive alien species in small towns. Biology, 10:1322, doi:10.3390/biology10121322.The original publication is available at https://www.mdpi.comInvasive alien species (IAS) are a growing threat globally and cause a variety of ecological,
economic, and social impacts. People can introduce IAS and facilitate their spread, and can also
implement, support, or oppose their management. Understanding local knowledge, awareness, and
perceptions are therefore crucial if management and policy are to be effective. We administered
questionnaires to members of the public in eight small towns along the Berg River Catchment in the
biodiverse fynbos biome of South Africa. We aimed to assess: (1) awareness of IAS by the general
public, (2) local perceptions of the impacts associated with IAS, (3) whether awareness of IAS is
correlated with demographic covariates and IAS density, and (4) people’s willingness to detect, report,
and support IAS management. Overall, 262 respondents participated in the survey. Most respondents
(65%) did not know what IAS are, and 10% were unsure. Many respondents also perceived IAS
as beneficial. Using a logistic regression, we found that IAS density, educational level, and gender
influenced people’s knowledge and perceptions about IAS in the region. There were a small number
(4%) of respondents currently detecting and reporting IAS, but many respondents were interested
to learn more. We concluded that people living in small towns in the Western Cape of South Africa
remain largely unaware of IAS and their impacts. It is crucial to increase awareness-raising initiatives,
and build support and engagement in management of IAS in small towns.https://www.mdpi.com/2079-7737/10/12/1322Publisher's versio
Web 2.0: Hypertext by Any Other Name?
No full textWeb 2.0 is the popular name of a new generation of Web applications, sites and companies that emphasis openness, community and interaction. Examples include technologies such as Blogs and Wikis, and sites such as Flickr. In this paper we compare these next generation tools to the aspirations of the early Hypertext pioneers to see if their aims have finally been realized
Geochemistry on rocks from Shackleton Range
No full textDuring the GEISHA expedition (Geologische Expedition in die Shackleton Range 1987/88), the Pioneers Escarpment was visited and sampled extensively for the first time. Most of the rock types encountered represent amphibolite facies metamorphics, but evidence for granulite facies conditions was found in cores of garnet. These conditions must have been at least partly reached during the peak of metamorphism.
For the Pioneers Escarpment a varicolored succession of sedimentary and bimodal volcanic origin is typical. It comprises: quartzites muscovite quartzite, sericite quartzite, fuchsite quartzite, garnet-quartz schists etc.; pelites: mica schists and plagioclase or plagioclase-microcline gneisses, aluminous schists; marls and carbonates: grey meta-limestones, carbonaceous quartzites, but also pure white, often fine-grained, saccharoidal marble, or a variety of tremolite marble, olivine (forsterite) marble, diopside-clinopyroxene-tremolite marble, etc.; basic volcanic rocks: amphibole fels, amphibolite schist, garnet amphibolite, and acidic to intermediate volcanic rocks: garnet-biotite schist, epidote-biotite-plagioclase gneiss, microcline gneiss.
These rocks are considered to be a supracrustal unit, called the Pioneers Group. In the easternmost parts of the Pioneers Escarpment, e.g. at Vindberget, nonmetamorphic shales, sandstones and greywackes crop out, which are cover rocks of possibly Jurassic age. These metasediments, which represent a quartz-pelite-carbonate (QPC) association, indicate that deposition took place on a stable shelf, i.e. on the submerged rim of a craton. Marine shallow-water sedimentation including marls and aluminous clays form the protoliths. The volcanics may be part of a bimodal volcanics-arkose-conglomerate (BVAC) association.
Geochemical analyses support the assumption of volcanic protoliths. This is demonstrated especially by the elevated amounts of the immobile, incompatible high-field-strength elements (HFSE) Nb, Ta, Ti, Y, and Zr encountered in some of the gneisses. Microscopic investigation suggests the existence of ortho-amphibolites. This is confirmed by the geochemistry. A bimodal volcanic association is evident. The amphibolites plot in both the tholeiite and calc-alkaline fields. The acidic volcanics are mainly rhyolitic.
The sediments and volcanics were subjected to conditions of 10-11 kbar and 600°C during the peak of metamorphism, i.e. granulite facies metamorphism, which can be deduced from the Fe mole ratios of 0.71-0.73 in the garnet cores. Due to the relatively low temperatures, no anatectic melting took placc. The rims of the garnets show a Fe mole ratio of 0.84-0.86, and the coexisting mineral association garnet-biotite-staurolite-kyanite indicate amphibolite facies. The thermobarometry shows P-T conditions of 5-6 kbar and 570-580°C for this stage.
The metamorphic history indicates deep burial at depths down to 35 km (subduction?) i.e. high pressure metamorphism, followed by pressure release due to uplift associated with retrograde metamorphism. This may have happened during a pre-Ross metamorphic event or orogeny. The Ross Orogeny at about 500 Ma probably just led to the weak greenschist facies overprint that is evident in the rocks of the Pioneers Group.
Finally, sedimentation resumed in the area of the present Shackleton Range, or at least in the eastern part of the Pioneers Escarpment, probably when detritus from erosion of the basement (Read Group and Pioneers Group) was deposited, forming sandstones and greywackes of possibly Jurassic age. There is no indication that these sediments belong to the former Turnpike Bluff Group
Recovery theorem: expounded and applied
No full textIncludes bibliographical references.This dissertation is concerned with Ross' (2011) Recovery Theorem. It is generally held that a forward-looking probability distribution is unobtainable from derivative prices, because the market's risk-preferences are conceptually inextricable from the implied real-world distribution. Ross' result recovers this distribution without making the strong preference assumptions assumed necessary under the conventional paradigm. This dissertation aims to give the reader a thorough understanding of Ross Recovery, both from a theoretical and practical point of view. This starts with a formal delineation of the model and proof of the central result, motivated by the informal nature of Ross' working paper. This dissertation relaxes one of Ross' assumptions and arrives at the equivalent conclusion. This is followed by a critique of the model and assumptions. An a priori discussion only goes so far, but potentially problematic assumptions are identified, chief amongst which being time additive preferences of a representative agent. Attention is then turned to practical application of the theorem. The author identifies a number of obstacles to applying the result { some of which are somewhat atypical and have not been directly addressed in the literature { and suggests potential solutions. A salient obstacle is calibrating a state price matrix. This leads to an implementation of Ross Recovery on the FTSE/JSE Top40. The suggested approach is found to be workable, though certainly not the final word on the matter. A testing framework for the model is discussed and the dissertation is concluded with a consideration of the findings and the theorem's applicability
Timor-Leste human development report 2011 : managing natural resources for human development : developing the non-oil economy to achieve the MDGs
No full textPrincipal Author John G Taylor, Coordinator Rui Gomes, Authors, Technical Background Papers Tobias N. Rasmussen, Andrew Rosser, Martin Sandbu, Michael Ross, Tibor van Staveren, Ricardo F. Neupert, Rui A. Gomes, John G Taylor, Sonny Harmadi, Hafiz Pash
PESI - a taxonomic backbone for Europe
No full textThis is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
The attached file is the published version of the article.NHM Repositor
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