地学研究对海岸带综合治理的部分贡献

地学是地质学、地球物理学和自然地理学的专称。运用地学手段对海岸带进行综合治理（ICZM）是当前海岸带持续开发战略面临的一项重要任务。“可持续”发展意思就是在保护环境的前提下对海岸地区及其资源进行管理，并要把它当成一个长期的具体任务来完成。要想进行ICZM必须要有广博的知识，需要了解海洋和海岸岩石的成因和特征、沉积物和地形的特征，还要了解天气和气候、海洋水体以及海洋中包含的生物等。海岸体系这些组成部分的基本地学知识是ICZM得以实施的基础，因为地学可以帮助明确再生和非再生资源以及它们对经济发展的潜在作用，从人类健康、安全和生物环境保护这两个方面弄清和确定经济发展已经和将要对环境产生的影响，特别从人类健康和工程风险这些方面弄清和确定发展过程中会有哪些限制因素和灾害；通过环境基本条件和监控变化来区分自然环境变化和人类活动导致的变化等。     

黄河口及渤海中南部沉积物工程特性及其机理

采用Ｋａｓｔｅｎ取样器从黄河口及渤海湾中南部海底沉积物中取样，对样品通过土工性质、微结构研究以及粘土矿物分析，阐明本研究区三维空间展布的海底沉积物形成机理及其工程地质规律，论证水动力作用和斜坡不稳定性对工程特性和微结构的重要影响．     

Short period internal waves over the Huanghe (Yellow River) delta front

Internal waves with periods of about 5 minutes and trough to crest heights of up to 6.2 m were observed acoustically over the actively accreting delta front of the Huanghe (Yellow River) in the western portion of the Gulf of Bohai, Peoples Republic of China. The radian frequency of the internal waves was close to the locally-observed Brunt-Vaisala frequency. Through the relatively short (one hour) duration of an internal wave train, the amplitude was observed to decrease progressively with time. These internal waves may cause resuspension of delta-front sediments.     

Quartz deformation mechanisms during Barrovian metamorphism: Implications from crystallographic orientation of different generations of quartz in pelites

The behaviour of quartz during metamorphism is studied based on two case studies from the Barrovian terrains of Sulitjelma in arctic Scandinavia and Loch Tay in the Central Highlands Dalradian of Scotland. Both terrains preserve evidence for metamorphism in pelites involving nucleation and growth of garnet at different times in the deformation history. Data are presented on the size, shape and crystallographic orientation of quartz preserved as inclusions in garnet and as grains in the surrounding matrix. While quartz-grains remain small and dispersed between mica grains, deformation appears to be dominated by grain-boundary sliding accommodated by dissolution–precipitation. At amphibolite facies, textural coarsening occurs by dissolution of small quartz grains and growth of larger quartz grains, coupled with segregation of quartz from mica. As a result, quartz deforms by dislocation creep, developing crystallographic preferred orientations (CPO) consistent with both coaxial and non-coaxial strain. Quartz CPOs with <0001> axes lying parallel to foliation and stretching direction are commonly developed, and best explained by mechanical rotation of inequant (detrital?) quartz grains. There is no evidence for selective entrapment of quartz inclusions in garnet on the basis of quartz crystallographic orientation.     

From geometry to dynamics of microstructure: using boundary lengths to quantify boundary misorientations and anisotropy

The microstructure of a quartzite experimentally deformed and partially recrystallised at 900 °C, 1.2 GPa confining pressure and strain rate 10⁻⁶/s was investigated using orientation contrast and electron backscatter diffraction (EBSD). Boundaries between misoriented domains (grains or subgrains) were determined by image analysis of orientation contrast images. In each domain, EBSD measurements gave the complete quartz lattice orientation and enabled calculation of misorientation angles across every domain boundary. Results are analysed in terms of the boundary density, which for any range of misorientations is the boundary length for that range divided by image area. This allows a more direct comparison of misorientation statistics between different parts of a sample than does a treatment in terms of boundary number.The strain in the quartzite sample is heterogeneous. A 100×150 μm low-strain partially recrystallised subarea C was compared with a high-strain completely recrystallised subarea E. The density of high-angle (>10°) boundaries in E is roughly double that in C, reflecting the greater degree of recrystallisation. Low-angle boundaries in C and E are produced by subgrain rotation. In the low-angle range 0–10° boundary densities in both C and E show an exponential decrease with increasing misorientation. The densities scale with exp(−θ/λ) where λ is approximately 2° in C and 1° in E; in other words, E has a comparative dearth of boundaries in the 8–10° range. We explain this dearth in terms of mobile high-angle boundaries sweeping through and consuming low-angle boundaries as the latter increase misorientation through time. In E, the density of high-angle boundaries is larger than in C, so this sweeping would have been more efficient and could explain the relative paucity of 8–10° boundaries.The boundary density can be generalised to a directional property that gives the degree of anisotropy of the boundary network and its preferred orientation. Despite the imposed strain, the analysed samples show that boundaries are not, on average, strongly aligned. This is a function of the strong sinuosity of high-angle boundaries, caused by grain boundary migration. Low-angle boundaries might be expected, on average, to be aligned in relation to imposed strain but this is not found.Boundary densities and their generalisation in terms of directional properties provide objective measures of microstructure. In this study the patterns they show are interpreted in terms of combined subgrain rotation and migration recrystallisation, but it may be that other microstructural processes give distinctive patterns when analysed in this fashion.     

Resource Model Updating For Compositional Geometallurgical Variables

In the field of mineral resources extraction, one main challenge is to meet production targets in terms of geometallurgical properties. These properties influence the processing of the ore and are often represented in resource modeling by coregionalized variables with a complex relationship between them. Valuable data are available about geometalurgical properties and their interaction with the beneficiation process given sensor technologies during production monitoring. The aim of this research is to update resource models as new observations become available. A popular method for updating is the ensemble Kalman filter. This method relies on Gaussian assumptions and uses a set of realizations of the simulated models to derive sample covariances that can propagate the uncertainty between real observations and simulated ones. Hence, the relationship among variables has a compositional nature, such that updating these models while keeping the compositional constraints is a practical requirement in order to improve the accuracy of the updated models. This paper presents an updating framework for compositional data based on ensemble Kalman filter which allows us to work with compositions that are transformed into a multivariate Gaussian space by log-ratio transformation and flow anamorphosis. This flow anamorphosis, transforms the distribution of the variables to joint normality while reasonably keeping the dependencies between components. Furthermore, the positiveness of those variables, after updating the simulated models, is satisfied. The method is implemented in a bauxite deposit, demonstrating the performance of the proposed approach.

     

Resource depletion,peak minerals and the implications for sustainable resource management

Today's global society is economically, socially and culturally dependent on minerals and metals. While metals are recyclable, terrestrial mineral deposits are by definition ‘non-renewable’ over human timescales and their stocks are thus finite. This raises the spectre of ‘peak minerals’ – the time at which production from terrestrial ores can no longer rise to meet demand and where a maximum (peak) production occurs. Peak minerals prompts a focus on the way minerals can be sustainably used in the future to ensure the services they provide to global society can be maintained.As peak minerals approaches (and is passed in some cases), understanding and monitoring the dynamics of primary mineral production, recycling and dematerialisation, in the context of national and global discussions about mineral resources demand and the money earned from their sale, will become essential for informing and establishing mechanisms for sustainable mineral governance and use efficiency into the future. Taking a cross-scale approach, this paper explores the economic and productivity impacts of peak minerals, and how changes in the mineral production profile are influenced not only by technological and scarcity factors, but also by environmental and social constraints. Specifically we examine the impacts of peak minerals in Australia, a major global minerals supplier, and the consequences for the Asia-Pacific region, a major destination for Australia's minerals.This research has profound implications for local and regional/global sustainability of mineral and metal use. The focus on services is useful for encouraging discussion of transitions in how such services can be provided in a future more sustainable economy, when mineral availability is constrained. The research also begins to address the question of how we approach the development of strategies to maximise returns from mineral wealth over generations.     

Wildfire preparedness,community cohesion and social–ecological systems

The consequences of wildfires are felt in susceptible communities around the globe on an annual basis. Climate change predictions in places like the south-east of Australia and western United States suggest that wildfires may become more frequent and more intense with global climate change. Compounding this issue is progressive urban development at the peri-urban fringe (wildland–urban interface), where continued infrastructure development and demographic changes are likely to expose more people and property to this potentially disastrous natural hazard. Preparing well in advance of the wildfire season is seen as a fundamental behaviour that can both reduce community wildfire vulnerability and increase hazard resilience – it is an important element of adaptive capacity that allows people to coexist with the hazardous environment in which they live. We use household interviews and surveys to build and test a substantive model that illustrates how social cohesion influences the decision to prepare for wildfire. We demonstrate that social cohesion, particularly community characteristics like ‘sense of community’ and ‘collective problem solving’, are community-based resources that support both the adoption of mechanical preparations, and the development of cognitive abilities and capacities that reduce vulnerability and enhance resilience to wildfire. We use the results of this work to highlight opportunities to transfer techniques and approaches from natural hazards research to climate change adaptation research to explore how the impacts attributed to the social components of social–ecological systems can be mitigated more effectively.     

Anatomy of a continental subduction zone: The main mantle thrust in Northern Pakistan

The Himalayas form an ideal natural laboratory to study the deformation processes of continental crust during collision orogeny. New information is presented concerning the structural evolution of the Main Mantle thrust zone in the Himalayas of N Pakistan, in the region around Nanga Parbat. The hanging-wall lies at relatively high levels within the Kohistan arc terrane which has been emplaced onto Indian continental rocks. This thrust probably originated as a breakback structure in the hanging-wall to the pre-collisional (oceanic) subduction zone. The present hanging-wall contains a shear zone of about 1 km width developed under amphibolite facies conditions. Simple shear dominant strains have developed new fabrics parallel to the main thrust zone. However, these structures are redeformed by discrete extensional and compressional shears within about 100 m of the thrust contact, again developed under amphibolite facies conditions. The footwall consists of an old basement complex (the Nanga Parbat gneisses) overlain by a distinct suite of metasediments now at amphibolite facies. This cover assemblage of psammites, pelites and marbles with local metabasites consistently lies directly against rocks derived from the Kohistan arc along the MMT. The absence of structures suggestive of consistent rheological contrasts within the cover assemblages suggests that the vast majority of the deformation features they contain were developed only once they experienced substantial tectonic overburdens. Prior to this the Indian cover rocks will have been »passively« subducted beneath the Kohistan arc until into amphibolite facies. We discuss these inferences in terms of evolving shear zone width with time and comment on the implications for predicting the character of mid-deep crustal shear zones, particularly from seismic reflection profiles.

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Zusammenfassung Der Himalaya bildet ein ideales, natrliches Laboratorium für Untersuchungen von Deformationsprozessen in kontinentalen Krustengesteinen während der Kollision bzw. Orogenese. Hier werden neue Daten vorgelegt, die sich mit der strukturellen Entwicklung der Hauptmantelüberschiebung im Himalaya von Nordpakistan im Gebiet um den Nanga Parbat befassen. Die Hangendeinheiten oberhalb der Störung liegen in einem relativ hohen Niveau innerhalb des »Kohistan arc terrane«, das auf die indischen Kontinentalgesteine überschoben wurde. Diese Überschiebung entstand wahrscheinlich als Rücküberschiebungsstruktur im Hangenden der Subduktionszone vor der Kollision. Im Hangenden befindet sich eine ca. 1 km breite Scherzone, die sich unter amphibolitfaziellen Bedingungen gebildet hat. Die durch »simple shear« erzeugten Deformationen sind mit ihren neuen Gefügen parallel zur Hauptüberschiebungszone ausgerichtet. Die Gefüge wurden nachfolgend von Extensionsund Kompressionsbewegungen im Bereich von ca. 100 m um den Überschiebungskontakt erneut unter amphibolitfaziellen Bedingungen erfaßt und deformiert. Das Liegende der Hauptüberschiebung besteht aus einem alten Basementkomplex (den Nanga Parbat Gneisen), die von deutlich abgesetzten, amphibolitfaziellen Metasedimenten überlagert werden. Diese Sedimenthülle bestehend aus Psammiten, Peliten und Marmoren mit lokalen Metabasiten stößt entlang der MMT direkt gegen die Gesteine des Kohistanbogens. Das Fehlen von Strukturen, die auf gleichbleibende rheologische Unterschiede hinweisen würde, läßt vermuten, daß der Großteil der in ihnen enthaltenen Deformationsgefüge auf einmal während beträchtlicher tektonischer Auflast entstanden ist. Vorher wurden die indischen Hüllgesteine »passiv« unter den Kohistanbogen bis in den Bereich der Amphibolitfazies subduziert. Die Folgerungen aus der sich über die Zeit entwickelnden Breite dieser Scherzone werden diskutiert und die Bedeutung für die Vorhersage der Charakteristik von mitteltiefen krustalen Scherzonen, insbesondere in Verbindung mit seismischen Reflektionsprofilen betont.

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Résumé L'Himalaya constitue un laboratoire naturel idéal pour l'étude des processus de déformation de la croûte continentale au cours d'une orogenèse de collision. Les auteurs présentent des informations nouvelles relatives à l'évolution structurale de la zone du Main Mantle Thrust dans la région du Nanga Parbat au nord du Pakistan. Le toit de cet accident occupe un niveau assez élevé dans le «Kohistan arc Terrane» qui a été charrié sur les roches du continent indien. Le charriage doit probablement son origine à une structure en retour apparue au-dessus de la zone de subduction pré-collisionnelle (océanique). Le toit actuel de l'accident contient une zone de glissement (shear zone) épaisse d'environ 1 km et formée dans les conditions du facies des amphibolites. Les déformations engendrées par glissement simple (simple shear) ont développé de nouvelles fabriques parallèles à la surface de charriage. Cependant, dans une tranche d'une centaine de mètres à partir du contact du charriage, ces structures ont été reprises par des cisaillements extensionnels ou compressionnels, toujours dans les conditions du facies des amphibolites.Le mur de l'accident est formé d'un complexe ancien (le gneiss du Nanga Parbat) surmonté d'une série de métasédiments distincts qui présentent aujourd'hui le facies des amphibolites. Cette couverture de psammites, de pélites, de marbres et de métabasites locales est directement en contact le long du MMT avec l'arc du Kohistan. L'absence, dans cette couverture, de structures témoignant de contrastes rhéologiques marqués, suggère que la grande majorité des structures déformatives n'y ont été développées qu'après un enfouissement tectonique important. Avant cela, les roches de la couverture indienne ont dû être subductées passivement sous l'arc du Kohistan, jusqu'au facies des amphibolites. Les auteurs discutent ces conclusions en termes d'évolution temporelle d'une shear zone et en commentant les implications dans le domaine de la prédiction du caractère des shear zones de profondeur crustale moyenne, en particulier à partir des profils de sismique réflexion.

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