Isotope fractionation under simulated space conditions     

G. Arrhenius  R. Fitzgerald  S. Markus  C. Simpson 《Astrophysics and Space Science》1978,55(2):285-297

  相似文献   

Observations of the Directional Characteristics of Sea Waves     

J. H. Simpson 《Geophysical Journal International》1969,17(1):93-120

  相似文献   

Developing support structures for ethnic minorities in Slovakia     

Fiona Simpson 《GeoJournal》2000,50(2-3):127-131

Ethnic minorities are facing increasing problems of social exclusion in Central and Eastern Europe. The complex nature of the transition from socialism means that the institutional framework to support them is still being established. Whilst non-governmental organisations (NGOs) have a crucial role to play in promoting a more inclusive society, through improving access to local democratic structures for otherwise excluded groups and acting as fora for improved community participation throughout the region, their development remains fraught with problems. Examination of the experiences of one such organisation, ETNO Agentura based in northern Slovakia, provides an insight into the problems and opportunities arising as community representatives work together to provide social support for ethnic minorities. The paper outlines key issues arising from the case of ETNO Agentura, including difficulty in gaining access to supporting finance and securing long term financial viability, the lack of institutional capacity of local authorities to become receptive to their views, and implicit socio-cultural barriers to ethnic minority representation in community participation processes. Developing a fuller understanding of these problems and the measures required to overcome them is a central part of establishing a more effective role for NGOs within post socialist societies. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

TWO EPISODES OF MONAZITE CRYSTALLIZATION DURING METAMORPHISM AND CRUSTAL MELTING IN THE EVEREST REGION OF THE NEPALESE HIMALAYA   总被引：4，自引：2，他引：2  

Robert L. Simpson  Randall R. Parrish  Mike P. Searle  David J. Waters WT  ”BX 《地学前缘》2000,(Z1)

TWO EPISODES OF MONAZITE CRYSTALLIZATION DURING METAMORPHISM AND CRUSTAL MELTING IN THE EVEREST REGION OF THE NEPALESE HIMALAYA  相似文献   

Interpreting the Viking Age to Medieval period transition in Norse Orkney through cultural soil and sediment analyses     

Ian A. Simpson  James H. Barrett  Karen B. Milek 《Geoarchaeology》2005,20(4):355-377

The transition from the Viking Age (ca. A.D. 800–1050) to the Medieval period (ca. A.D. 1050–1500) saw the development of widening trade activities that incorporated peripheral North Atlantic polities into mainstream Europe and contributed to the intensification of marineresource exploitation and agricultural production in these localities. As yet, there is only limited understanding of these intensification processes and their interrelationships, particularly at a local, site‐based level. Through the micromorphological analysis of cultural soils and sediments at Quoygrew, Westray, Orkney, we explore the characteristics of farming and fishing activity during the Viking Age–Medieval transition period and establish their chronological relationships. The study demonstrates: (1) that intensification took place from ca. A.D. 966–1162 on an already existing Viking Age settlement, (2) that intensification of fishing activity occurred prior to the intensification of arable agriculture, and (3) that the Quoygrew site continued throughout this period as an economically diverse permanent settlement. When viewed in a wider North Atlantic context, these findings indicate that intensification of different economic activities proceeded at different rates and that intensification of specialized economic activities during the transition from the Viking Age to the Medieval period was dependent on existing knowledge of local environments. © 2005 Wiley Periodicals, Inc.  相似文献   

The importance of choosing precipitation datasets          下载免费PDF全文

Micheal J. Simpson  Adam Hirsch  Kevin Grempler  Anthony Lupo 《水文研究》2017,31(25):4600-4612

Precipitation data are important for hydrometeorological analyses, yet there are many ways to measure precipitation. The impact of station density analysed by the current study by comparing measurements from the Missouri Mesonet available via the Missouri Climate Center and Community Collaborative Rain, Hail, and Snow (CoCoRaHS) measurements archived at the program website. The CoCoRaHS data utilize citizen scientists to report precipitation data providing for much denser data resolution than available through the Mesonet. Although previous research has shown the reliability of CoCoRaHS data, the results here demonstrate important differences in details of the spatial and temporal distribution of annual precipitation across the state of Missouri using the two data sets. Furthermore, differences in the warm and cold season distributions are presented, some of which may be related to interannual variability such as that associated with the El Niño and Southern Oscillation. The contradictory results from two widely‐used datasets display the importance in properly choosing precipitation data that have vastly differing temporal and spatial resolutions. With significantly different yearly aggregated precipitation values, the authors stress caution in selecting 1 particular rainfall dataset as conclusions drawn could be unrepresentative of the actual values. This issue may be remediated by increased spatiotemporal coverage of precipitation data.  相似文献   

Potential evidence for slab detachment from the flexural backstripping of a foredeep: Insight on the evolution of the Pescara basin (Italy)          下载免费PDF全文

Paolo Mancinelli  Cristina Pauselli  Giorgio Minelli  Massimiliano R. Barchi  Guy Simpson 《地学学报》2018,30(3):222-232

The discrepancy between the size of the Apenninic chain and the depth of the Adriatic foredeep is investigated using 2D flexural backstripping on well‐constrained depth‐converted cross‐sections in the Pescara basin (Central Italy). The procedure consisted of removal, uplift, unfolding and unfaulting of the Pliocene–Pleistocene foreland deposits to produce a palaeogeographic map of the basin at the end of the Messinian and to constrain sedimentary rates since the Miocene. Results are found to support the contribution of an external load to the foreland evolution together with the Apenninic chain load. The interplay of the two types of loads resulted in spatial and temporal variations of the foredeep evolution that are quantified by palaeogeographic maps and sedimentation rates obtained through backstripping. Results are interpreted as representing the effects of a southward‐migrating wave linked to slab detachment beneath the Adriatic foredeep. This procedure can be useful to investigate similar problems on other chains worldwide.  相似文献   

Volcanology and petrology of Mathews Tuya,northern British Columbia,Canada: glaciovolcanic constraints on interpretations of the 0.730 Ma Cordilleran paleoclimate   总被引：1，自引：1，他引：0  

Benjamin R. Edwards  James K. Russell  Kirstie Simpson 《Bulletin of Volcanology》2011,73(5):479-496

Petrological, volcanological and geochronological data collected at Mathews Tuya together provide constraints on paleoclimate conditions during formation of the edifice. The basaltic tuya was produced via Pleistocene glaciovolcanism in northern British Columbia, Canada, and is located within the Tuya volcanic field (59.195°N/130.434°W), which is part of the northern Cordilleran volcanic province (NCVP). The edifice comprises a variety of lithofacies, including columnar-jointed lava, pillow lava, massive dikes, and volcaniclastic rocks. Collectively these deposits record the transition from an explosive subaqueous to an effusive subaerial eruption environment dominated by Pleistocene ice. As is typical for tuyas, the volcaniclastic facies record multiple fragmentation processes including explosive, quench and mechanical fragmentation. All samples from Mathews Tuya are olivine-plagioclase porphyritic alkali olivine basalts. They are mineralogically and geochemically similar to nearby glaciovolcanic centers from the southeastern part of the Tuya volcanic field (e.g., Ash Mountain, South Tuya, Tuya Butte) as well as the dominant NCVP rock type. Crystallization scenarios calculated with MELTS account for variations between whole rock and glass compositions via low pressure fractionation. The presence of olivine microphenocrysts and the absence of pyroxene phenocrysts constrain initial crystallization pressures to less than 0.6 GPa. The eruption of Mathews Tuya occurred between 0.718 ± 0.054 Ma and 0.742 ± 0.081 Ma based on ⁴⁰Ar/³⁹Ar geochronology (weighted mean age of 0.730 Ma). The age determinations provide the first firm documentation for large (>700 m thick), pre-Fraser/Wisconsin glaciers in north-central British Columbia ~0.730 Ma, and correlate in age with glaciovolcanic deposits in Russia (e.g., Komatsu et al. Geomorph 88: 352-366, 2007) and with marine isotopic evidence for large global ice volumes ~0.730 Ma.  相似文献   

The role of biodegradation and photo-oxidation in the transformation of terrigenous organic matter   总被引：1，自引：0，他引：1  

Xiaojuan Feng  Katherine M. Hills  Andr J. Simpson  Joann K. Whalen  Myrna J. Simpson 《Organic Geochemistry》2011,42(3):262-274

Microbial and photochemical decomposition are two major processes regulating organic matter (OM) transformation in the global carbon cycle. However, photo-oxidation is not as well understood as biodegradation in terms of its impact on OM alteration in terrigenous environments. We examined microbial and photochemical transformation of OM and lignin derived phenols in two plant litters (corn leaves and pine needles). Plant litter was incubated in the laboratory over 3 months and compositional changes to OM were measured using nuclear magnetic resonance (NMR) and gas chromatography-mass spectrometry. We also examined the susceptibility of soil organic matter (SOM) to ultraviolet (UV) radiation. Solid-state ¹³C NMR spectra showed that O-alkyl type structures (mainly from carbohydrates) decreased during biodegradation and the loss of small carbohydrates and aliphatic molecules was observed by solution-state ¹H NMR spectra of water extractable OM from biodegraded litters. Photochemical products were detected in the aliphatic regions of NaOH extracts from both litter samples by solution-state ¹H NMR. Photo-oxidation also increased the solubility of SOM, which was attributed to the enhanced oxidation of lignin derived phenols and photochemical degradation of macromolecular SOM species (as observed by diffusion edited ¹H NMR). Overall, our data collectively suggests that while biodegradation predominates in litter decomposition, photo-oxidation alters litter OM chemistry and plays a role in destabilizing SOM in soils exposed to UV radiation.  相似文献   

A palaeolimnological meta-database for assessing the ecological status of lakes   总被引：1，自引：0，他引：1  

Richard W. Battarbee  David Morley  Helen Bennion  Gavin L. Simpson  Michael Hughes  Viktorija Bauere 《Journal of Paleolimnology》2011,45(4):405-414

We describe a palaeolimnological meta-database (“LakeCores”) that includes information for lakes in Europe that have been cored for studies of recent environmental change. Only cores with intact mud-water interfaces and good chronologies for the last ~100–200 years are currently included. The information provided in the database includes the general characteristics of the lakes cored, the methods used for dating and analysis and the bibliographic source of the information selected. At present the database contains information on 1847 studies from 975 sites. Here we use the database to identify cores for which diatom-based pH and total phosphorus (TP) reconstructions have been derived and, from an inspection of the relevant papers, we compile summary data for the timing and extent of acidification and eutrophication of lakes across Europe. We show that there were few cases of acidification and eutrophication in Europe prior to about 1850, and therefore that conditions prior to 1850 can be used for reference with respect to current attempts to restore surface waters to “good ecological status”. We also show the extent to which pH and TP levels have changed across the continent both for all lakes, and, in the case of TP, for lakes of different types covering a range of alkalinities, altitudes, water depths and surface areas.  相似文献