Pedosedimentary development of part of a Late Quaternary loess‐palaeosol sequence in northwest Argentina     

Rob A. Kemp  Matthew King  Philip Toms  Edward Derbyshire  Jos Manuel Sayago  Miriam M. Collantes 《第四纪科学杂志》2004,19(6):567-576

The field properties, magnetic susceptibility, particle size, calcium carbonate content, soil micromorphology and optical luminescence ages of the upper 6.1 m and lowermost 4.7 m of the 45 m loess–palaeosol sequence at El Lambedero in the Tafí del Valle region of Tucumán Province (Sierras Pampeanas, northwest Argentina) have been used to set up a partial stratigraphy and chronology, as well as a basic pedosedimentary model of loess accumulation, palaeosol development, reworking and erosion for the site. The minimum ages derived from the basal part of the section suggest that loess began to accumulate some time before 165 ka. A thick and well‐developed pedocomplex in the upper profile is correlated with at least the latter part of marine isotope stage (MIS) 5, whereas the overlying palaeosol may be attributable to pedogenic activity during MIS 3. The absence of material younger than 33 ka close to the surface of this rounded spur landform is probably the result of either non‐deposition or erosional stripping in response to climatic change, or episodic uplift in this seismically active region. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

Effects of the forced resettlement of a community from an agricultural settlement to a high-rise building     

Miriam Billig 《GeoJournal》2016,81(1):123-137

The objective of this study was to understand the implications of forced displacement and resettlement of a rural community to an extremely different built environment in urban setting. Based on the Inglehart’s theory of cultural shifts we were able to delineate the process by which changes in physical environment caused significant changes in the community social structure and community members’ cultural identities. The collective characteristics that had once united and strengthened the community’s social structure began to dwindle. Meanwhile, a growing tendency towards individualistic characteristics gradually increased, causing the weakening and eventual dissolution of both the community and its social structure. The gradual process of community changes was reflected in the subjective narratives presented by community residents in a series of in-depth interviews conducted 4 years after the evacuation, in their new homes. Till that time, the community finally broke up, most of its members spreading out to live in various other areas. The study findings will be incorporated into a framework for resettlement policy on appropriate housing for resettled communities.  相似文献   

Value of information analysis in rock engineering: a case study of a tunnel project in Äspö Hard Rock Laboratory     

Miriam S. Zetterlund  Tommy Norberg  Lars O. Ericsson  Jenny Norrman  Lars Rosén 《Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards》2015,9(1):9-24

Geoengineering prognoses are often based on data from a limited number of investigations of soil and rock mass. There is generally a desire to reduce the uncertainty in the prognoses while minimising the investigation costs. Value of Information Analysis (VOIA) is a support for decisions regarding investigation strategies and the aim of this paper is to present methodology for VOIA that takes into account four decision alternatives where the input data could be provided by experts. The methodology will be applied in a case study where the value of information related to an investigation borehole will be calculated. The results indicate that the value of information of the borehole is low compared with the realisation costs of the investigation. It was found that models for VOIA in underground construction projects are complex but that the analysis can be simplified with extensive use of expert knowledge and calculations of the value of perfect information as a benchmark for investigation strategies.  相似文献   

Writing difference differently          下载免费PDF全文

Karen Fisher  Miriam Williams  Stephen FitzHerbert  Lesley Instone  Michelle Duffy  Sarah Wright  Sandie Suchet‐Pearson  Kate Lloyd  Laklak Burarrwanga  Ritjilili Ganambarr  Merrkiyawuy Ganambarr‐Stubbs  Banbapuy Ganambarr  Djawundil Maymuru  Bawaka Country 《New Zealand geographer》2015,71(1):18-33

This paper investigates the writing of situated knowledge and explores the possibilities of enacting difference by writing differently. We present a selection of research stories in which carrier bags, sounds, baskets, gardens and potatoes are interpreted less as objects of research or metaphors to aid in analysing phenomena, than as mediators of the stories. Our stories emphasise the ontological politics of engaging with and representing the relational, the messy, the spontaneous, the unpredictable, the non‐human and bodily experiences. These stories demonstrate how writing is performative and how it is integral to the production of knowledge.  相似文献   

Early and Middle Pleistocene Faunal and hominins dispersals through Southwestern Asia     

Ofer Bar-Yosef  Miriam Belmaker 《Quaternary Science Reviews》2011,30(11-12):1318-1337

This review summarizes the paleoecology of the Early and Middle Pleistocene of southwestern Asia, based on both flora and fauna, retrieved from a series of ‘windows’ provided by the excavated sites. The incomplete chrono-stratigraphy of this vast region does not allow to accept the direct chronological correlation between the available sites and events of faunal and hominin dispersals from Africa. It also demonstrates that hominins survived in a mixed landscape of open parkland with forested surrounding hills. In addition, the prevailing environmental conditions are not sufficient to explain successful adaptations to new ecological niches away from the African savanna of the bearers of ‘core and flake’ and the Acheulian industries, The differences in knapping and secondary shaping of stone artifacts probably reflect the learned traditions of different groups of hominins. The current distribution of lithic industries across Eurasia is undoubtedly incomplete due to lack of cultural continuities as well as paucity of field research in several sub-regions. This observation supports the contention that what we view as a constant stream of migrants was actually interrupted many times. The continuous occupation of southwestern Asia by the makers of the Acheulian is in contrast with neighboring regions such as the Iranian plateau and Eastern Europe. A more complex model is required to explain the recorded Eurasian archaeological–cultural mosaic.  相似文献   

三个印度洋区域天然气水合物的产状和地下水文学对比研究     

Miriam Kastner  Marta Torres  杨金玉  马明永 《海洋地质前沿》2008,24(11):35-36

2006年度印度洋天然气水合物规划（NG—HP）的目标是调查控制印度近海天然气水合物分布及其特征的地质因素,以便最终评价作为潜在能源的天然气水合物的开采可能性。海洋中聚集的天然气水合物的总量是巨大的,大约25000～10000亿t。  相似文献   

Key structural parameters affecting earthquake ground motion in 2D and 3D sedimentary structures     

Peter Moczo  Jozef Kristek  Pierre-Yves Bard  Svetlana Stripajová  Fabrice Hollender  Zuzana Chovanová  Miriam Kristeková  Deborah Sicilia 《Bulletin of Earthquake Engineering》2018,16(6):2421-2450

Alluvial valleys generate strong effects on earthquake ground motion (EGM). These effects are rarely accounted for even in site-specific studies because of (a) the cost of the required geophysical surveys to constrain the site model, (b) lack of data for empirical prediction, and (c) poor knowledge of the key controlling parameters. We performed 3D, 2D and 1D simulations for six typical sedimentary valleys of various width and depth, and for a variety of modifications of these 6 “nominal models” to investigate sensitivity of EGM characteristics to impedance contrast, attenuation, velocity gradient and geometry. We calculated amplification factors, and 2D/1D and 3D/2D aggravation factors for 10 EGM characteristics, using a representative set of recorded accelerograms to account for input motion variability. The largest values of the amplification and aggravation factors are found for the Arias intensity and cumulative absolute velocity, the lowest for the root-mean-square acceleration. The aggravation factors are largest for the vertical component. For each model, at least one EGM characteristic exhibits a significant 2D/1D aggravation factor, while all EGM characteristics exhibit significant 2D/1D aggravation factor on the vertical component. For all investigated sites, there is always an area in the valley for which 1D estimates are not sufficient. 2D estimates are insufficient at several sites. The key structural parameters are the shape ratio and overall geometry of the sediment-bedrock interface, impedance contrast at the sediment-bedrock interface, and attenuation in sediments. The amplification factors may largely exceed the values that are usually considered in GMPEs between soft soils and rock sites.  相似文献   

Microstructures documenting Cenozoic extension processes in the northern continental margin of the South China Sea     

Liheng Sun  Xiaolong Huang  Yingde Jiang  Joann Miriam Stock 《International Geology Review》2020,62(7-8):1094-1107

ABSTRACT

In order to investigate the thinning process of the northern continental margin of the South China Sea, petrographic and microstructural analysis were carried out on 20 greenschistfacies mylonite samples, which were obtained from Site U1504 of IODP Expedition 367/368 in the Outer Margin High of the region. The mineral assemblage of the greenschist-facies mylonite is chlorite + epidotite + albite (Ab = 94.7–99.9) + quartz, which contains 10-30% gravel components. Microstructural analysis indicates that the greenschist-facies mylonite experienced two episodes of deformation：early ductile deformation followed by a later stage of brittle deformatio. Both episodes of deformation suggest an extensional environment. The extensive development of bulging recrystallization (BLG) of quartz, microscopic fractures and fine granulation of albite suggest that the temperature of ductile deformation is about 300-400°C, compatiable with a ductile shearing at shallow crust levels (~5-10 km). Petrographic features suggest that the greenschist-facies mylonite might originate from volcanic sedimentary rocks or sedimentary rocks affected by the intrusion of mafic magma. Combined with seismic interpretation, we propose that the greenschist-facies mylonite might be formed by crustal exhumation after thick Mesozoic sediments were denuded by a major extension.  相似文献   

Probabilistic long-term reservoir operation employing copulas and implicit stochastic optimization     

&#;vila  Leandro  Mine  Miriam R. M  Kaviski  Eloy 《Stochastic Environmental Research and Risk Assessment (SERRA)》2020,34(7):931-947

Stochastic Environmental Research and Risk Assessment - This paper explores and combines implicit stochastic optimization (ISO) with copula functions to simulate long-term operating policies for a...  相似文献   

Evidence of field-scale shifts in transpiration dynamics following bark beetle infestation: Stomatal conductance responses     

Meijun Li  Wei Shao  Ye Su  Miriam Coenders-Gerrits  Jerker Jarsjö 《水文研究》2024,38(5):e15162

Amplified eruptive outbreaks of bark beetles as a consequence of climate change can cause tree mortality that significantly affects terrestrial water and carbon fluxes. However, the lack of field-scale observations of underlying physiological mechanisms currently hampers the expression of such ecosystem disturbances in predictive modelling. Based on a unique flux tower dataset from a subalpine forest located in the Rocky Mountains, mechanisms of stomatal response to an extensive bark beetle outbreak were investigated using various models and parametrizations. The datasets cover a decade, including the periods of pre-infestation, infestation, and post-infestation. Field measurements showed considerable decreases in evapotranspiration (ET), transpiration (T), and leaf area index (LAI) during the two-year infestation period compared to the pre-infestation period. Model interpretations of observed water and carbon fluxes indicated that the overall reductions in T were not solely due to decreased LAI, but also to changes in physiological behaviours. The summer season's canopy-scale stomatal conductance was significantly reduced during the infestation period, from 0.0018 to 0.0011 m s⁻¹. One primary reason for the observed variations is likely that the bark beetle infestation hampers the water transport in the xylem. The damage of xylem has important implications for water use efficiency (WUE), which also significantly influences the parameterization of stomatal conductance. When using stomatal conductance models to forecast ecosystem dynamics, it is crucial to recalibrate the model's parameters to ensure the accurate depiction of stomatal dynamics during various infestation periods. The neglect of the temporal variability of canopy-scale stomatal conductance under ecosystem disturbances (e.g., bark beetle infestations) in current earth system models, therefore, requires specific attention in assessments of large-scale water and carbon balances.  相似文献