Formation of iddingsite veins in the martian crust by centripetal replacement of olivine: evidence from the nakhlite meteorite Lafayette

The Lafayette meteorite is an olivine clinopyroxenite that crystallized on Mars ∼1300 million years ago within a lava flow or shallow sill. Liquid water entered this igneous rock ∼700 million years later to produce a suite of secondary minerals, collectively called ‘iddingsite’, that occur as veins within grains of augite and olivine. The deuterium/hydrogen ratio of water within these secondary minerals shows that the aqueous solutions were sourced from one or more near-surface reservoirs. Several petrographically distinct types of veins can be recognised by differences in their width, shape, and crystallographic orientation. Augite and olivine both contain veins of a very fine grained hydrous Fe- and Mg-rich silicate that are ∼1-2 micrometres in width and lack any preferred crystallographic orientation. These narrow veins formed by cementation of pore spaces that had been opened by fracturing and probably in response to shock. The subset of olivine-hosted veins whose axes lie parallel to (001) have serrated walls, and formed by widening of the narrow veins by interface coupled dissolution-precipitation. Widening started by replacement of the walls of the narrow precursor veins by Fe-Mg silicate, and a crystallographic control on the trajectory of the dissolution-precipitation front created micrometre-scale {111} serrations. The walls of many of the finely serrated veins were subsequently replaced by siderite, and the solutions responsible for carbonation of olivine also partially recrystallized the Fe-Mg silicate. Smectite was the last mineral to form and grew by replacement of siderite. This mineralization sequence shows that Lafayette was exposed to two discrete pulses of aqueous solutions, the first of which formed the Fe-Mg silicate, and the second mediated replacement of vein walls by siderite and smectite. The similarity in size, shape and crystallographic orientation of iddingsite veins in the Lafayette meteorite and in terrestrial basalts demonstrates a common microstructural control on water-mineral interaction between Mars and Earth, and indicates that prior shock deformation was not a prerequisite for aqueous alteration of the martian crust

The origin of alteration “orangettes” in Dhofar 019: Implications for the age and aqueous history of the shergottites

The shergottites are the largest group of Martian meteorites, and the only group that has not been found to contain definitive evidence of Martian aqueous alteration. Given recent reports of current liquid water at the surface of Mars, this study aimed to investigate in detail the possibility of Martian phyllosilicate within shergottite Dhofar 019. Optical and scanning electron microscopy, followed by transmission electron microscopy, confirmed the presence of alteration orangettes, with a layered structure consisting of poorly ordered Mg-phyllosilicate and calcite. These investigations identified maskelynite dissolution, followed by Mg-phyllosilicate and calcite deposition within the dissolution pits, as the method of orangette production. The presence of celestine within the orangette layers, the absence of shock dislocation features within calcite, and the Mg-rich nature of the phyllosilicate, all indicate a terrestrial origin for these features on Dhofar 019

Development through global value chains and the achievement of decent work : challenges to work and representational processes

The co-ordination of global production and trade within value chains has amplified debates concerning the impact of globalisation on labour, especially for developing countries. Whilst many development agencies argue for value chain insertion and upgrading as optimistic development pathways, many studies suggest a nuanced, conditional evaluation of the potential impacts on labour. One fundamental aspect of labour rights and conditions concerns representation and representational processes: that is, as encapsulated by the social dialogue component of Decent Work, whether representation is both effective and autonomous. This paper uses a model of organisational identity to deepen our understanding of the impacts of value chain insertion and upgrading on labour. It uses three studies of labour conditions in value chains in one country (Brazil) to evaluate the effectiveness and challenges to representation at the local level. These studies come from the food production (tomatoes), fruit collection/processing (passion fruit) and metals (refrigeration/washer) sectors and encompass industrial unions, rural unions and cooperatives. Whilst further work is required on the local, national and international contexts surrounding these studies, the analysis does suggest amplified and new complications for organisational identity as a result of value chain engagement. This adds another component to recent (but general) conceptual-empirical considerations of labour in value chains (Knorringa & Pegler, 2006). Responding to this, and the re-juvenation of representation, requires not only well linked strategies at local and international levels (thus substantial resources) but that representative organisations confront many developments which, potentially, also hold out promising opportunities for labour (e.g. Corporate Social Responsibility and Human Resource Management strategies)

Employer 'Dependence' and Worker 'Allegiance' within the Factory of the Future: Evidence From Brazil

Abstract: Some commentators have suggested that employers who modernise their factory operations will become dependent on the skills and attitudes of their employees. Others go beyond this and suggest that workers in modernised firms will be persuaded to go 'beyond contract' due to the emergence of a strong and direct form of attachment to their employer. Moreover, with 'us and them' attitudes removed, it is uncertain what effect this may have on workers' attitudes to the union. This paper puts these debates about factory modernisation and workers' attitudes to the employer and the union to the test using detailed data from the Brazilian white goods industry during the 1990s. The research suggests the following in respect to this 'axis of allegiance'. First, workers can be persuaded to think in terms of an effort bargain which includes issues beyond just remuneration. Many employees are also taking a more inward-looking, 'employer positive' approach. However, their degree of attachment to the modernised firm is both limited and contingent on future, expected benefits. Secondly, in terms of the worker-union relation, the cynicism of Brazilian workers to unions may have been heightened by the policies of the modernising firm. While part of this result may be due to the modernising firms' selection policies, the union's 'electorate' may also have shifted its priorities. Despite this, many workers would still like unions to have an active and independent role. Yet this is dependent on union policies being directed towards the promotion of worker's key (and often new) workplace concerns. Finally, while these results are influenced by the Brazilian context they do raise questions about the attitudinal and behavioural underpinnings of modernisation in any environment. As long as employers act to minimise the risk to which they may become more dependent on workers, employee behaviour will, at best, only appear to indicate that they have more allegiance to the employer. Moreover, workers' concerns about workplace modernisation policies suggest that unions may not necessarily become more ineffectual and irrelevant

Sustainable Value Chains and Labour - Linking Chain and "Inner Drivers"

Global value chains are driven by considerations of cost and efficiency but just as much by power relations. This appears evident from studies of industrial relations and labour outcomes within value chains, especially those where drivenness is most explicit. Within a context of disaggregated but more coordinated production across borders, the standards “industry” continues to grow as a regulatory structure of chain outcomes. Yet the processes by which many workers and communities continue to be made flexible, vulnerable and voiceless, within value chains, are not so clear. The research discussed in this paper is aimed at exploring the feasibility of labour rights promotion within the context of sustainable global value chains. By this it is meant that the conditions of work and livelihoods (e.g. at the beginning of chains) are “decent/good” and that these are compatible with the reproductability of their environment. A central concern is how to improve the conceptual lenses we use to analyse labour outcomes, and their governance, within value chains. This ISS (Brazil-Holland) project is based on a desire to more effectively link 1) the actors which drive chains, with 2) considerations of work, livelihoods and security for the workers and communities (i.e. their “inner” drivers) supplying those chains. The question of this research derives from a comparison of the “logic” (e.g. efficiency) of these chain drivers vis a vis the “logic” of those at the beginning of chains. The fundamental starting question concerning sustainability is thus whether such competing “logics” can be resolved within global value chains? The concept of governmentality expands the theoretical frame for the consideration of how messages /rules/norms are established, transmitted and contested across these chains. Labour process analysis (expanded with considerations of gender, livelihoods and human security) is suggested for use with those at the beginning of chains. Chains are not static - they are “webs of interaction, where negotiation takes place between actors (and with institutions) at each node” (Loconto, 2010, p. 217). The substantive evaluation of Decent Work, livelihoods and Human Security possibilities in a sustainable context therefore requires research into the existence and viability of multiple “logics” between nodes within such chains. Such studies have much to contribute – to academic and conceptual debates on labour rights and sustainable development, to Government policies in respect to fair trade, sustainability, procurement and human rights and, to the policies and strategies of social movements and other civic actors

Fluid inclusions in Lafayette: a record of ancient Martian hydrology

No abstract available

Movement of Four Satellite-Monitored Polar Bears in Lancaster Sound, Northwest Territories

Four female polar bears, fitted with satellite-monitored transmitters at Lancaster Sound, N.W.T. during May 1979, were tracked to determine seasonal distribution, movements relative to ice conditions, and home range. Most locations (68.7%, n = 46) of satellite-tracked bears were on landfast ice, 13.4% (n = 9) on old pack ice, 13.4% (n = 9) on land, 3.0% (n = 2) on bergy water, and 1.5% (n = 1) on young pack ice. These observations support the conclusions of mark-recapture studies in the area, that landfast ice is favored until breakup when bears move onto land. Data from the satellite-tracked bears indicate that they had home ranges.Key words: polar bear, telemetry, satelliteMots clés: ours blanc, télémesure, satellit

Predictive Ability of QCD Sum Rules for Excited Baryons

The masses of octet baryons are calculated by the method of QCD sum rules. Using generalized interpolating fields, three independent sets of QCD sum rules are derived which allow the extraction of low-lying N* states with spin-parity 1/2+, 1/2- and 3/2- in both the non-strange and strange channels. The predictive ability of the sum rules is examined by a Monte-Carlo based analysis procedure in which the three phenomenological parameters (mass, coupling, threshold) are treated as free parameters simultaneously. Realistic uncertainties in these parameters are obtained by simultaneously exploring all uncertainties in the QCD input parameters. Those sum rules with good predictive power are identified and their predictions are compared with experiment where available.Comment: 33 pages, 2 figure