碰撞与花岗岩——碰撞是构造事件,不是构造环境

碰撞与花岗岩的关系是学术界关心的问题,但是,当前在碰撞与花岗岩关系的研究中存在许多误区.本文认为,碰撞是地壳浅部的构造事件,不属于构造环境范畴.碰撞本身不产生花岗岩,花岗岩形成需要热,热主要来自地幔,是来自地幔的热使下地壳底部熔融才形成了花岗岩.碰撞和碰撞后花岗岩地球化学性质不同,原因与碰撞或碰撞后无关,而与碰撞导致的地壳厚度变化有关.碰撞不是构造环境,现今所用的花岗岩构造环境判别图如果包含有碰撞的内容全部是错误的.     

Morality,mobility and citizenship: Legitimising mobile subjectivities in a contested outdoors

In this article, we examine articulations of mobile citizenship produced through the discursive practices of state agencies, drawing in particular on a study of the contested reconfiguration of outdoor citizenship in Norway. Whilst increased participation and diversity in outdoor activities is highly valued and encouraged because of its social benefits, moral landscapes of the outdoors may be part of settling and reinforcing social differences and existing power relations. The article identifies three discursive normativities through which state officials negotiate mobility and outdoor citizenship; knowledge, skills and socialisation; engaging (with) nature; deserving (in) the outdoors. These normativities serve as a basis for a critical discussion of different aspects of outdoor movement, and how social identities interact with the citizen responsibilities assigned to different forms of mobility, such as mountain biking, skiing and walking. The article demonstrates how and why certain outdoor practices, spaces and boundaries of citizenship are both fluid and critically negotiated by the state officials. By bringing together theories of moral landscapes, mobility and citizenship, the article contributes to understandings of the politics of mobility, and particularly the theorisation of how morality works in relation to different dimensions of mobility. It also highlights how the contestation of mobile citizenship is an issue in rural as well as urban realms.     

Mega-RTAs and LDCs: Trade is not for the poor

Various upcoming large regional trade agreements dealing with new generation trade issues and involving the developed, as well as several emerging market developing economies, exclude the Least Developed Countries (LDCs). The LDCs are not strategically important enough for the other players to figure in these agreements. Nonetheless, these have important implications for the LDCs, particularly in terms of loss of preferential market access. Such preferential access, the paper argues, is likely to get confined to the WTO’s multilateral framework in the longer-term leaving LDCs little strategic economic space outside the WTO.     

TP or not TP,that is the question

We give here a comparative study on the mathematical analysis of two (classes of) discretization schemes for the computation of approximate solutions to incompressible two-phase flow problems in homogeneous porous media. The first scheme is the well-known finite volume scheme with a two-point flux approximation, classically used in industry. The second class contains the so-called approximate gradient schemes, which include finite elements with mass lumping, mixed finite elements, and mimetic finite differences. Both (classes of) schemes are nonconforming and can be expressed using discrete function and gradient reconstructions within a variational formulation. Each class has its specific advantages and drawbacks: monotony properties are natural with the two-point finite volume scheme, but meshes are restricted due to consistency issues; on the contrary, gradient schemes can be used on general meshes, but monotony properties are difficult to obtain.     

Cenozoic Eurasia is not a single rigid plate: Paleomagnetic evidence

The widely distributed Cenozoic paleomagnetic inclination anomaly in Asia is usually attributed to either a widespread error of magnetic field recording due to an inclination flattening mechanism in sediments, or to the persistence of an anomalous non-dipolar component of the geomagnetic field throughout the Tertiary. Based on an analysis of the Asian paleomagnetic database for Meso-Cenozoic times, we suggest that instead this puzzling anomaly results from an overlooked global plate tectonics cause where the wide so-called Eurasian plate would have suffered from previously undetected transpressive north–south relative movements between its western and eastern ends since the Cretaceous. These relative movements are most probably accommodated by a component of right-lateral shear movement distributed in the Tornquist–Tesseyre zone, and a localized left-lateral shear movement in the Ural Mountain chain during the Tertiary. Therefore, Eurasia was not the single rigid plate that Cenozoic plate reconstructions have accepted.     

Anatomy of a subduction complex: architecture of the Franciscan Complex,California, at multiple length and time scales

The Franciscan Complex of California records over 150 million years of continuous E-dipping subduction that terminated with conversion to a dextral transform plate boundary. The Franciscan comprises mélange and coherent units forming a stack of thrust nappes, with significant along-strike variability, and downward-decreasing metamorphic grade and accretion ages. The Franciscan records progressive subduction, accretion, metamorphism, and exhumation, spanning the extended period of subduction, rather than events superimposed on pre-existing stratigraphy. High-pressure (HP) metamorphic rocks lack a thermal overprint, indicating continuity of subduction from subduction initiation at ca. 165 Ma to termination at ca. 25 Ma. Accretionary periods may have alternated with episodes of subduction erosion that removed some previously accreted material, but the complex collectively reflects a net addition of material to the upper plate. Mélanges (serpentinite and siliciclastic matrix) with exotic blocks have sedimentary origins as submarine mass transport deposits, whereas mélanges formed by tectonism comprise disrupted ocean plate stratigraphy and lack exotic blocks. The former are interbedded with and grade into coherent siliciclastic units. Palaeomegathrust horizons, separating nappes accreted at different times, appear restricted to narrow zones of <100 m thickness. Exhumation of Franciscan units, both coherent and mélange, was accommodated by significant extension of the hanging wall and cross-sectional extrusion. The amount of total exhumation, as well as exhumation since subduction termination, needs to be considered when comparing Franciscan architecture to modern and ancient subduction complexes. Equal dextral separation of folded Franciscan nappes and late Cenozoic (post-subduction) units across strands of the (post-subduction) San Andreas fault system shows that the folding of nappes took place prior to subduction termination. Dextral separation of similar clastic sedimentary suites in the Franciscan and the coeval Great Valley Group forearc basin is approximately that of the San Andreas fault system, precluding major syn-subduction strike-slip displacement within the Franciscan.     

To accrete or not accrete,that is the question

Along modern convergent margins tectonic processes span a spectrum from accretion to erosion. The process of accretion is generally recognized because it leaves a geologic record, whereas the process of erosion is generally hypothetical because it produces a geologic hiatus. Major conditions that determine the dominance of accretion or erosion at modern convergent margins are: 1) rate and direction of plate convergence, 2) sediment supply and type in the trench, and 3) topography of the subducting ocean floor. Most change in structure has been ascribed to plate motion, but both erosion and accretion are observed along the same convergence margin. Thus sediment supply and topography are probably of equivalent importance to plate motion because both erosion and accretion are observed under constant conditions of plate convergence.The dominance of accretion or erosion at a margin varies with the thickness of trench sediment. In a sediment flooded trench, the proportions of subducted and accreted sediment are commonly established by the position of a decollement along a weak horizon in the sediment section. Thus, the vertical variation of sediment strength and the distribution of horizontal stress are important factors. Once deformation begins, the original sediment strength is decreased by sediment remolding and where sediment thickens rapidly, increases in pore fluid pressure can be pronounced.In sediment-starved trenches, where the relief of the subducting ocean floor is not smoothed over, the front of the margin must respond to the topography subducted as well as that accreted. The hypothesized erosion by the drag of positive features against the underside of the upper plate (a high stress environment) may alternate with erosion due to the collapse of a margin front into voids such as graben (a low stress environment).

---

Zusammenfassung Entlang modernen konvergierenden Plattenrändern können tektonische Prozesse ein weites Spektrum von Anlagerung bis Erosion umspannen. Der Prozeß der Anlagerung wird generell erkannt, weil er eine geologische Folge aufbaut. Demgegenüber bleibt der Prozeß der Erosion im allgemeinen hypothetisch, weil er einen Hiatus hinterläßt. Die wesentlichen Bedingungen, die das Vorherrschen von Anlagerung oder Erosion bestimmen, sind: 1) Richtung und Rate der Plattenkonvergenz. 2) Sedimentlieferung und-art im Graben. 3) Topographie des subduzierenden Ozeanbodens. Die meisten Wechsel in der Struktur werden der Plattenbewegung zugeschrieben, aber sowohl Erosion als auch Anlagerung sind an demselben konvergierenden Plattenrand beobachtet worden. Daher sind wahrscheinlich die Sedimentanlieferung und die Topographie von gleichrangiger Bedeutung im Hinblick auf die Plattenbewegung, weil Erosion und Anlagerung unter konstanten Bedingungen von Plattenkonvergenz beobachtet werden.Das Vorherrschen von Anlagerung oder Erosion entlang einem Plattenrand variiert mit der Mächtigkeit der Grabensedimente. In einem sedimentbeladenen Graben werden die Verhältnisse von subduzierten und angelagerten Sediment im allgemeinen etabliert durch die Lage einer Abschiebung entlang einem schwachen Horizont innerhalb des Sedimentstapels. Daher sind die Variation der Sedimentfestigkeit in der Vertikalen sowohl als auch die Verteilung der horizontalen Spannungen bedeutende Faktoren. Sobald die Deformation beginnt, nimmt die ursprüngliche Sedimentfestigkeit ab durch die Umgestaltung des Sediments und dort, wo die Sedimentmächtigkeit rasch zunimmt, steigt der Porenwasserdruck deutlich an.In sedimentarmen Gräben, wo das Relief des subduzierten Ozeanbodens nicht ausgeglättet wird, muß die Front des Plattenrandes sowohl auf die subduzierte Topographie reagieren als auch auf die der Anlagerungsgefüge. Die hypothetische Erosion durch den Widerstand der positiven morphologischen Formen gegenüber der Unterseite der höher gelegenen Platte (ein environment hoher Spannungen) kann alternieren mit Erosion, die auf dem Kollabieren eines Plattenrandes in Hohlräume wie etwa in Gräben hinein beruht (ein environment niedriger Spannungen).

---

Résumé Le long des bords des plaques convergentes actuelles, l'action tectonique couvre une gamme de processus qui va de l'accrétion à l'erosion. Un processus d'accrétion est d'ordinaire démontré par les traces géologiques qui qu'il laisse, tandis qu'un processus d'érosion, engendrant un hiatus géologique, est geéralement hypothétique. Les principales conditions qui déterminent la prédominance de l'un ou de l'autre processus sont: 1) la cinématique (vitesse et direction) de la convergence; 2) la quantité et la nature de l'apport sédimentaire dans la fosse; 3) la topographie du fond océanique en voie de subduction. La plupart des changements de structure ont été rapportés à la cinématique des plaques. Cependant des actions d'érosion et d'accrétion sont observés le long d'une même bordure convergente; par conséquent l'apport sédimentaire et la topographie océanique jouent probablement un rôle aussi important que la cinématique des plaques.La prédominance de l'accrétion ou de l'érosion le long d'une jonction dépend de l'épaisseur des sédiments de la fosse. Dans une fosse remplie de sédiments, les proportions de sédiments subductés et accrétionnés sont communément déterminés par la position, dans la série sédimentaire, d'un horizon peu résistant le long duquel s'opère un décollement. Il en résulte que les variations verticales de compétence des sédiments et la distribution des contraintes horizontales sont des facteurs importants. Dès que la déformation commence, la résistance mécanique originelle des sédiments est abaissée par leur fluage et, là où les sédiments s'épaississent rapidement, il peut y avoir accroissement marqué de la pression des fluides intersticiels.Dans des fosses pauvres en sédiments, et lorsque le relief du fond océanique en subduction n'est pas aplani, la position du contact des plaques doit résulter autant de la topographie de la plaque descendante que de celle de la plaque supérieure. L'érosion hypothétique due à l'entraînement de formes de relief sous la plaque supérieure (situation de contraintes élevées) peut alterner avec une érosion due à l'effondrement du bord de la plaque par un mécanisme de type «>graben»< (situation de contraintes basses).

---

. , , , , . . . , : ) ; ) ; ) . , . , , , . . , . , , . , . , , . , , , . ( ) , , .: ( ).

     

Beyond flexible citizenship: Towards a study of many Chinese transnationalisms

Over the last decade, flexible citizenship has contributed much to our understandings of how contemporary Chinese migrate across the world in late capitalism. This corpus has not only called attention to the manifold strategies that these migrants adopt to inhabit multiple spaces, but has also elucidated how transnational migration can be deployed for the purposes of capital accumulation and enhancement of one’s lifestyle. This paper argues that the current fixation on the flexible strategies of the Chinese ‘shuttling’ between the East and West inevitably occludes other logics of mobilities that may be more germane for other (neglected) segments of the ‘new Chinese diaspora’. Through its consistent rehearsal, the present preoccupation may have led to an inadvertent reification of flexible citizenship, as the paradigmatic model of modern-day Chinese mobilities. In an effort to move the discussion forward, this paper weaves a deliberately dissonant story with the narratives of 50 Singaporean Chinese migrants who are living in, or who have returned to Singapore from, New York or the Californian-Bay Area. The viewpoints offered by these less ‘conventional’ Chinese subjects not only diverge from the usual ‘strategic’ or ‘calculative’ storylines among the Hong Kongers and Taiwanese, but also uncover distinctive assemblages that span across multi-sited and transcultural contexts. Although this paper has no intentions to discredit flexible citizenship, it hopes to have begun the process of decentring the locus of our knowledge pertaining to the subject, drawing attention to the possibility of alternative realities within many Chinese transnationalisms.     

Unpacking race,party and class from below: Surveying citizenship in the Msunduzi municipality

On the basis of a 2008 survey conducted in the Msunduzi municipality in the KwaZulu-Natal province, the paper begins an exploration of the character of popular politics and citizenship in South Africa. Embracing a ‘citizen-centred’ methodology informed by participation literatures, and sensibilities to the ‘work in progress’ character of African cities from urban studies debates, the paper interrogates the mainstream liberal-participatory model of citizenship in South Africa, and the critiques of current South African politics informed by these notions, specifically the ‘racial census’ and ‘dominant party syndrome’ analyses. Taken together these views can be read as characterising South African politics as a game for individual citizens governed by liberal rules, but played by racial and/or partisan groups in exclusionary ways, thus distorting liberal democratic mechanisms of representation and accountability. The paper also examines evidence for an alternative class-based analysis of one aspect of citizenship, namely, protest against poor local governance.The paper looks to unpack this ‘liberal model versus racialised communitarian practice’ imaginary by, on the one hand, demonstrating the ways in which citizenship is not racialised, or is asymmetrically racialised. Indeed, other than party allegiances and trust in key offices, very little by way of what citizens do, believe or think of themselves follows discrete racial lines. Similar points hold for partisanship too. On the other hand, the paper does not redeem the liberal-democratic model as there is also evidence of trust in government when it is not deserved based on performance, but more importantly, evidence that citizens embrace ‘informal’ means to secure their rights. A good example of this is protestors who are also more likely to vote than non-protestors. Taken together, these findings affirm both the way in which the racial and partisan legacy of the past is being undone by new institutions and practices, and suggest the complex intersection of these with networks of personal relations which characterise the local politics of most African cities.     

Labouring geography: Negotiating scales, strategies and future directions

In our editorial introduction to this themed issue on labour geography, we outline some important on-going debates in the relatively young field of labour geography and suggest future directions for research. First, there is the key question of labour as an active agent in the production of economic landscapes. The agency of labour will likely remain a defining feature of labour geography, but perhaps it is not as important to construct theoretical analytical boundaries as it is to define labour geography as a political project. Second, debates continue surrounding the production of scale and the multiscalarity of organized labour. Third, labour geographers have yet to engage in any sustained fashion with unpacking the complex identities of workers and the way in which those identities simultaneously are shaped by and shape the economic and cultural landscape. Fourth, there is some debate on the costs and benefits of a ‘normative’ labour geography which emphasizes what workers and their organizations ‘could’ or even ‘should’ do. Lastly, we challenge the assumption that labour geographers have not yet asserted themselves as activists in their own right. We conclude the editorial by introducing the articles included in the issue. While these articles may not address every gap in the literature, they do contribute in significant ways to move the labour geography project forward.     

Police, politics, and the right to the city

Space and spatiality have recently been at the core of debates concerning the political possibilities of the city. The arguments advanced in this paper might be seen as an attempt to contribute to these debates through a reflection on the spatiality of (in) justice, politics, and the right to the city. The case of French urban policy, with its focus on distressed urban areas, and the `suburban problem' in France are used as examples to make arguments more concrete.     

Neritic and pelagic carbonate sedimentation in the marine environment: ignorance is not bliss

Synthesis of available data allows us to define general patterns of late Quaternary carbonate production and sedimentation in the global ocean. During high stands of sea level, the neritic and pelagic environments appear to sequester approximately similar amounts of carbonate, whereas during low stands of sea level the decreased neritic zone produces and accumulates approximately an order of magnitude less carbonate. Assuming that global accumulation of deep-sea carbonates remains more or less constant during glacially induced changes in sea level, the ocean becomes depleted with respect to calcium carbonate during high stands and recharges during low stands. Before we can achieve a better understanding of the global carbonate system, however, we need a better understanding of key environments and processes: (a) production and accumulation on continental shelves both as potential sinks (accumulation) and as sources (export to the deep sea); (b) a better measure of pelagic carbonate production; and (c) late Quaternary (late Pleistocene and Holocene) mass accumulation rates in the deep sea.     

Water governance in New Mexico: Adjudication,law, and geography

Water rights adjudications lie at the intersection of law, space, and the geography of resource governance, combining elements of field cartography, archival research, and judicial supervision and decree. However, few geographers have examined the water rights adjudications now active in most western US states. Using case material and ethnographic vignettes from a larger geographic project on water rights and governance in New Mexico, I examine water adjudication as a vital instrument in the state’s pursuit of spatial knowledge. Resources and water users are seen by the state through this process, while at the same time, water users may elude or confuse state legibility. In this process, altered forms of governance are produced. Here, I explore how the formalizing of water rights in New Mexico has articulated new legal-spatial relationships, which are often viewed differently by state and local agents. I then examine the products of adjudications and the tension between local and expert knowledge in natural resources governance over being seen and governed by the state and the struggle to retain local autonomy and governance in water management.     

When hazard avoidance is not an option: lessons learned from monitoring the postdisaster Oso landslide,USA

On 22 March 2014, a massive, catastrophic landslide occurred near Oso, Washington, USA, sweeping more than 1 km across the adjacent valley flats and killing 43 people. For the following 5 weeks, hundreds of workers engaged in an exhaustive search, rescue, and recovery effort directly in the landslide runout path. These workers could not avoid the risks posed by additional large-scale slope collapses. In an effort to ensure worker safety, multiple agencies cooperated to swiftly deploy a monitoring and alerting system consisting of sensors, automated data processing and web-based display, along with defined communication protocols and clear calls to action for emergency management and search personnel. Guided by the principle that an accelerating landslide poses a greater threat than a steadily moving or stationary mass, the system was designed to detect ground motion and vibration using complementary monitoring techniques. Near real-time information was provided by continuous GPS, seismometers/geophones, and extensometers. This information was augmented by repeat-assessment techniques such as terrestrial and aerial laser scanning and time-lapse photography. Fortunately, no major additional landsliding occurred. However, we did detect small headscarp failures as well as slow movement of the remaining landslide mass with the monitoring system. This was an exceptional response situation and the lessons learned are applicable to other landslide disaster crises. They underscore the need for cogent landslide expertise and ready-to-deploy monitoring equipment, the value of using redundant monitoring techniques with distinct goals, the benefit of clearly defined communication protocols, and the importance of continued research into forecasting landslide behavior to allow timely warning.

     

HIV and AIDS in Africa: a geographic analysis at multiple spatial scales

This study offers an alternative method rooted in GIS techniques and spatial analysis to estimate HIV/AIDS prevalence over space from an incomplete surveillance data set and explain the variation of those estimates. The results clearly show that the HIV/AIDS epidemic is complex and that it is interconnected with other geographic, historical, economic and cultural phenomena which help explain its spatial spread and variation. The regression models which were developed in this paper illustrated that variables which measure the historical context of colonialism such as resource exploitation and labor migration, gender, culture, contemporary global forces, poverty and disease burden have all contributed variously to the rapid spread of this disease both in space and time. The policy implication is that concentrating on behavior change or therapy alone may not turn the epidemic around. The attack needs to be multifaceted and interdisciplinary taking into consideration the context and the economic and social realities at multiple spatial scales.     

Between beds and sequences: stratigraphic organization at intermediate scales in the Quaternary of the Virginia coast, USA

ABSTRACT Stratigraphy presupposes a hierarchy of scales of spatial organization supplemented at the small‐scale end by sedimentological concepts (beds, bed sets and bed cosets) and, at larger spatial scales, by sequence‐stratigraphic concepts (systems tracts, parasequences, sequences). Between these two end‐members are intermediate‐scale bodies described as ‘lithofacies’, or simply ‘facies’. A more restricted concept, granulometric facies, can be described in terms of horizontal grain‐size gradients (‘facies change’) and cyclic vertical grain‐size gradients (‘stratification’). Assemblages of facies so defined (also called depositional systems) are not random, but occur in a limited suite of patterns. Such assemblages may be linked to two classes of bounding surfaces, a source diastem (the immediate source of the sediment) and a surface of closure (if preserved), between which is sandwiched a transgressive or regressive, basinward‐fining facies succession. Systems‐bounding surfaces are notably more continuous than internal (gradational) facies boundaries. By thus restricting the definition of a facies assemblage (depositional system), it is possible to describe the Quaternary of the Virginia coast with as few as 12 systems. Depositional systems in the Quaternary of the Virginia coast are allometric, in that any system can be derived from any other by plastic expansion of one or more facies relative to another, or by simple symmetry operations. Self‐similarity prevails across this intermediate scale of stratigraphic organization. Facies assemblages (depositional systems) consist of event beds, which themselves have erosional basal boundaries and internal successions of microfacies. At larger spatial scales, depositional systems are repeated, either autocyclic repetitions forced by processes within the basin of deposition or allocyclic repetitions, as ‘parasequences’ and high‐frequency sequences. In the Virginia Quaternary, systems architecture is compatible with sequence architecture and nests conformably within its framework, but analysis of systems architecture reveals rules beyond those governing sequence architecture.