Zircon from historic eruptions in Iceland: reconstructing storage and evolution of silicic magmas   总被引：3，自引：0，他引：3  

Tamara L. Carley  Calvin F. Miller  Joseph L. Wooden  Ilya N. Bindeman  Andrew P. Barth 《Mineralogy and Petrology》2011,102(1-4):135-161

Zoning patterns, U-Th disequilibria ages, and elemental compositions of zircon from eruptions of Askja (1875 AD), Hekla (1158 AD), ?r?faj?kull (1362 AD) and Torfaj?kull (1477 AD, 871 AD, 3100 BP, 7500 BP) provide insights into the complex, extended, histories of silicic magmatic systems in Iceland. Zircon compositions, which are correlated with proximity to the main axial rift, are distinct from those of mid-ocean ridge environments and fall at the low-Hf edge of the range of continental zircon. Morphology, zoning patterns, compositions, and U-Th ages all indicate growth and storage in subvolcanic silicic mushes or recently solidified rock at temperatures above the solidus but lower than that of the erupting magma. The eruptive products were likely ascending magmas that entrained a zircon ??cargo?? that formed thousands to tens of thousands of years prior to the eruptions.  相似文献   

Ensemble reconstruction of the atmospheric column from surface pressure using analogues   总被引：1，自引：1，他引：0  

Pascal Yiou  Tamara Salameh  Philippe Drobinski  Laurent Menut  Robert Vautard  Mathieu Vrac 《Climate Dynamics》2013,41(5-6):1333-1344

We present a statistical method to reconstruct continuous atmospheric fields on various pressure levels, given a constraint at the surface. The method is based on analogues of circulation and taking into consideration the time sequence of the analogues. The method is tested on the 2001–2011 period, with an emphasis on the year 2010. We base the atmospheric reconstruction on reanalysis data from 1948 to 2000, and use a constraint of sea-level pressure for 2001–2011. The pattern correlation scores appear to be significant most of the time, although score flaws are occasionally detected. Those flaws are mainly due to the time continuity constraint that is imposed on the reconstruction, which lowers the possibility of finding matching analogues. This method offers an ensemble of atmospheric reconstructions, and presents a computationally cheap alternative to data assimilation for a climate model, although with lower scores.  相似文献   

Decentralization and the cultural politics of natural resource management in Kerala,India     

Tamara Nair 《Singapore journal of tropical geography》2014,35(3):397-411

The state of Kerala in India is known for its active civil society and the massive decentralization campaign launched in 1996. However marginalization of tribal communities hampers the state's decentralized environmental management strategies. The proposed construction of a dam along the Chalakkudy River will displace two colonies of the Kadar tribe in Chalakkudy and Athirapilly towns, destroy habitats of local wildlife and devastate unique riverine vegetation endemic to the region. This brings to light issues of social and environmental justice as well as a wider responsibility to protect and preserve unique flora and fauna. The state's decentralization strategies, as they relate to tribal communities, lack consideration of local power distribution and cultural conditioning. This raises questions about the state's role in social justice as well as biodiversity conservation. In 2010 and 2011, the author's interviews in Chalakkudy and Athirapilly towns reveal that tribal communities perceive that their place in society restricts their contribution regarding natural resource management and use. The paper suggests that unless the culture of planning and decision making in the state are changed, decentralized strategies will be ineffective, resulting in a predominately top‐down approach towards natural resource management, and will negate Kerala's goal of democratic decentralization.  相似文献   

Surface abundances of light elements for a large sample of early B-type stars – II. Basic parameters of 107 stars     

Leonid S. Lyubimkov  Tamara M. Rachkovskaya  Sergey I. Rostopchin  David L. Lambert 《Monthly notices of the Royal Astronomical Society》2002,333(1):9-26

Effective temperatures T _eff, surface gravities log  g and interstellar extinctions A _V are found for 107 B stars. Distances d of the stars, which are based on the derived T _eff, log  g and A _V values, show good agreement with those obtained from the Hipparcos parallaxes. Comparing the T _eff and log  g values with evolutionary computations, we infer masses, radii, luminosities, ages and relative ages of the stars. Empirical relations between the T _eff and log  g parameters, on the one hand, and the photometric indices Q , [ c ₁] and β , on the other hand, are constructed; these relations give a fast method for the T _eff and log  g estimation of early and medium B stars. Inclusion of the infrared J , H and K colours into the T _eff, log  g and A _V determination shows that (i) the T _eff and log  g parameters are altered only slightly; (ii) the A _V value is rather sensitive to these colours, so an accuracy better than 0.05 mag in the JHK data is necessary for precise A _V evaluation.  相似文献   

The Erzincan earthquake of 13 March 1992 in Eastern Turkey: tectonic aspects     

Vladimir G. Trifonov  M. Salih Bayractutan  Arkadiy S. Karakhanian  Tamara P. Ivanova 《地学学报》1993,5(2):184-189

The tectonic significance of the Erzincan earthquake of 13 March, 1992 in Eastern Turkey is discussed. The intersection of the North Anatolian and The East Anatolian strike-slip fault zones has resulted in formation of the Erzincan pull-apart basin and new seismically active fault branches on its northeastern side. Local concentrations of surface ruptures strike along the most active branches of the North Anatolian fault zone (N300W) for 62 km. They are usually open fractures with northeastern sides uplifted up to 20 cm and rarely with dextral offset up to 10 cm. These secondary ruptures manifest indirectly oblique seismic fault displacement corresponding to the Late Quaternary motion on the fault zone, although at the surface the dextral component has been suppressed relative to the vertical one.  相似文献   

Mid-Holocene vertebrate bone Concentration-Lagerstätte on oceanic island Mauritius provides a window into the ecosystem of the dodo (Raphus cucullatus)     

Kenneth F. Rijsdijk  Julian P. Hume  Frans Bunnik  F.B. Vincent Florens  Claudia Baider  Beth Shapiro  Johannes van der Plicht  Anwar Janoo  Owen Griffiths  Lars W. van den Hoek Ostende  Holger Cremer  Tamara Vernimmen  Perry G.B. De Louw  Assenjee Bholah  Salem Saumtally  Nicolas Porch  James Haile  Mike Buckley  Matthew Collins  Edmund Gittenberger 《Quaternary Science Reviews》2009,28(1-2):14-24

Although the recent history of human colonisation and impact on Mauritius is well documented, virtually no records of the pre-human native ecosystem exist, making it difficult to assess the magnitude of the changes brought about by human settlement. Here, we describe a 4000-year-old fossil bed at Mare aux Songes (MAS) in south-eastern Mauritius that contains both macrofossils (vertebrate fauna, gastropods, insects and flora) and microfossils (diatoms, pollen, spores and phytoliths). With >250 bone fragments/m² and comprising 50% of all known extinct and extant vertebrate species (n_s = 44) of Mauritius, MAS may constitute the first Holocene vertebrate bone Concentration-Lagerstätte identified on an oceanic volcanic island. Fossil remains are dominated by extinct giant tortoises Cylindraspis spp. (63%), passerines (～10%), small bats (7.8%) and dodo Raphus cucullatus (7.1%). Twelve radiocarbon ages [four of them duplicates] from bones and other material suggest that accumulation of fossils took place within several centuries. An exceptional combination of abiotic conditions led to preservation of bones, bone collagen, plant tissue and microfossils. Although bone collagen is well preserved, DNA from dodo and other Mauritian vertebrates has proved difficult. Our analysis suggests that from ca 4000 years ago (4 ka), rising sea levels created a freshwater lake at MAS, generating an oasis in an otherwise dry environment which attracted a diverse vertebrate fauna. Subsequent aridification in the south-west Indian Ocean region may have increased carcass accumulation during droughts, contributing to the exceptionally high fossil concentration. The abundance of floral and faunal remains in this Lagerstätte offers a unique opportunity to reconstruct a pre-human ecosystem on an oceanic island, providing a key foundation for assessing the vulnerability of island ecosystems to human impact.  相似文献   

Ellipticity of dark matter haloes with galaxy–galaxy weak lensing     

Rachel Mandelbaum  Christopher M. Hirata  Tamara Broderick  Uro&#; Seljak  Jonathan Brinkmann 《Monthly notices of the Royal Astronomical Society》2006,370(2):1008-1024

  相似文献   

The role of fulvic acid composition in the photosensitized degradation of aquatic contaminants   总被引：2，自引：0，他引：2  

Jennifer J. Guerard  Penney L. Miller  Tamara D. Trouts  Yu-Ping Chin 《Aquatic Sciences - Research Across Boundaries》2009,71(2):160-169

  相似文献   

Stochastic downscaling method: application to wind refinement     

Frédéric Bernardin  Mireille Bossy  Claire Chauvin  Philippe Drobinski  Antoine Rousseau  Tamara Salameh 《Stochastic Environmental Research and Risk Assessment (SERRA)》2009,23(6):851-859

In this article, we propose a new stochastic downscaling method: provided a numerical prediction of wind at large scale, we aim to improve the approximation at small scales thanks to a local stochastic model. We first recall the framework of a Lagrangian stochastic model borrowed from Pope. Then, we adapt it to our meteorological framework, both from the theoretical and numerical viewpoints. Finally, we present some promising numerical results corresponding to the simulation of wind over the Mediterranean Sea.  相似文献   

Silicic magma petrogenesis in Iceland by remelting of hydrothermally altered crust based on oxygen isotope diversity and disequilibria between zircon and magma with implications for MORB   总被引：1，自引：0，他引：1  

Ilya Bindeman  Andrey Gurenko  Tamara Carley  Calvin Miller  Erwan Martin  Olgeir Sigmarsson 《地学学报》2012,24(3):227-232

  相似文献