Age, origin and significance of a new middle MIS 3 tephra horizon identified within a long-core sequence from Les Echets, France     

DANIEL VERES  SIWAN M. DAVIES  BARBARA WOHLFARTH  FRANK PREUSSER  STEFAN WASTEGÅRD  LINDA AMPEL  ANNE HORMES  GÖRAN POSSNERT  JEAN-PAUL RAYNAL  GÉRARD VERNET 《Boreas: An International Journal of Quaternary Research》2008,37(3):434-443

A new tephra has been identified within a long core (EC 3) sequence recovered from Les Echets, near Lyon, France. This visible tephra was discovered as part of a high resolution multiproxy re-investigation of the Les Echets sequence. Independent chronological information suggests that the tephra is c . 2 000–45 000 years old, and geochemical analysis indicates that it is of basanitic composition. The latter suggests a possible origin in the Eifel; however, as yet, no other volcanic events or deposits can be correlated to the Les Echets tephra. New sedimentological and chronological data are presented indicating that the tephra falls within an interval that most likely correlates with Dansgaard–Oeschger events 12-9. Thus, this tephra could potentially be an important middle MIS 3 marker horizon in central Europe if it can be traced in other palaeorecords.  相似文献   

Transport of continental air to the subantarctic Indian Ocean     

YVES J. BALKANSKI  DANIEL J. JACOB 《Tellus. Series B, Chemical and physical meteorology》1990,42(1):62-75

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GALLIC TRAJECTORIES OF GEOGRAPHY AND THE SELF     

DANIEL W. GADE 《Geographical review》1999,89(1):122-128

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A STATISTICAL FRAMEWORK FOR TREE‐RING RECONSTRUCTION OF HIGH‐MAGNITUDE MASS MOVEMENTS: CASE STUDY OF SNOW AVALANCHES IN EASTERN CANADA          下载免费PDF全文

DANIEL GERMAIN 《Geografiska Annaler: Series A, Physical Geography》2016,98(4):303-311

This paper investigates the application of the peaks‐over‐threshold method in combination with fitting of the generalized Pareto distribution for estimating the frequency of high‐magnitude geomorphic events, on the basis of tree‐ring data. In particular, attention is focused on extreme value distribution of tree‐ring responses and in the minimum threshold or index number required to assure the past occurrence of high‐magnitude events. The objective is to set a threshold, adapted to the sample distribution, which will make the distinction between high‐magnitude years and remaining years, where the response of sampled trees is too weak to be attributed to a high‐magnitude geomorphic event. The statistical framework proposed is based on the statistics of extremes. Through the use of simple, strong and effective mathematics, this model should strengthen the position of dendrogeomorphology in the evaluation and management of natural hazards.  相似文献   

Oil-weathering behavior in Arctic environments     

JAMES R. PAYNE  G. DANIEL McNABB  JR.  JOHN R. CLAYTON.  JR. 《Polar research》1991,10(2):631-662

Oil-weathering processes in ice-free subarctic and Arctic waters include spreading, evaporation, dissolution, dispersion of whole-oil droplets into the water column, photochemical oxidation, water-in-oil emulsification, microbial degradation, adsorption onto suspended particulate material, ingestion by organisms, sinking, and sedimentation. While many of these processes also are important factors in ice-covered waters, the various forms of sea ice (depending on the active state of ice growth, extent of coverage and/or decay) impart drastic, if not controlling, changes to the rates and relative importance of different oil-weathering mechanisms. Flow-through seawater wave-tank experiments in a cold room at −35°C and studies in the Chukchi Sea in late winter provide data on oil fate and effects for a variety of potential oil spill scenarios in the Arctic. Time-series chemical weathering data are presented for Prudhoe Bay crude oil released under and encapsulated in growing first-year columnar ice through spring breakup.  相似文献   

An accurate interpolating scheme for semi-Lagrangian advection on an unstructured mesh for ocean modelling     

DANIEL Y. LE ROUX  CHARLES A. LIN  ANDREW STANIFORTH 《地球，A辑:动力气象学与海洋学》1997,49(1):119-138

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Ancient oceans and continental margins of the Alpine-Mediterranean Tethys: deciphering clues from Mesozoic pelagic sediments and ophiolites   总被引：1，自引：0，他引：1  

DANIEL BERNOULLI  HUGH C. JENKYNS† 《Sedimentology》2009,56(1):149-190

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Dosage du Fluor dans les Etalons Géochimiques Du CRPG et de l'ANRT     

GERARD JECKO  DANIEL RAVAINE 《Geostandards and Geoanalytical Research》1977,1(2):136-136

La teneur en fluor, déterminée au moyen d'une électrode spécifique d'ions dans quelques standards géochimiques, est présentée.  相似文献   

High-Grade Fluid Metasomatism on both a Local and a Regional Scale: the Seward Peninsula, Alaska, and the Val Strona di Omegna, Ivrea-Verbano Zone, Northern Italy. Part II: Phosphate Mineral Chemistry   总被引：1，自引：0，他引：1  

HARLOV  DANIEL E.; FORSTER  HANS-JURGEN 《Journal of Petrology》2002,43(5):801-824

This study explores the origin and geochemical evolution ofapatite, monazite, and xenotime along two metamorphic traverses.The first, from the Kigluaik Mountains, Seward Peninsula, Alaska,consists of a localized (85 cm) orthopyroxene–clinopyroxene-bearingdehydration zone. The second consists of orthopyroxene ±clinopyroxene-bearing granulite facies metabasite layers interlayeredwith metapelites over a 3–4 km traverse, along the ValStrona, Ivrea–Verbano Zone, Northern Italy (IVZ). In bothdehydration zones small Th- and U-poor inclusions of monaziteand/or xenotime occur in the apatite. These inclusions are metasomaticallyinduced and nucleated within the apatite via the coupled substitutionsNa⁺ + (Y + REE)³⁺ = 2 Ca²⁺ and Si⁴⁺ + (Y + REE)³⁺ = P⁵⁺ + Ca²⁺.These are not present in apatite from the original amphibolitefacies gneiss. Apatite, in both dehydration zones, also showsa relative increase in both F and Cl compared with apatite fromthe amphibolite facies zone. Granulite facies metabasites inthe IVZ also contain isolated monazite grains, which range fromuniform to complexly zoned in Th the (13–30·1 mol% ThSiO₄). These are the product of breakdown and subsequentmobilization of the lanthanides and actinides from monazite-(Ce)in the metapelite layers into the metabasite layers at the startof granulite facies metamorphism. KEY WORDS: apatite; monazite; xenotime; KCl–NaCl brines; metasomatism; phosphate minerals; charnockite–enderbite; granulite facies metamorphism  相似文献   

The hyperbolic shape triangle as a tool for discriminating populations of sediment samples of closely connected origin     

DANIEL HARTMANN  CHRISTIAN CHRISTIANSEN† 《Sedimentology》1992,39(4):697-708

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