A novel nuclear forensic tool involving deposit type normalized rare earth element signatures   总被引：1，自引：0，他引：1       下载免费PDF全文

Tyler L. Spano  Antonio Simonetti  Thomas Wheeler  Grace Carpenter  Devonee Freet  Enrica Balboni  Corinne Dorais  Peter C. Burns 《地学学报》2017,29(5):294-305

Identifying the provenance of uranium‐rich materials is a critical objective of nuclear forensic analysis. Rare earth element (REE) distributions within uranium ores are well‐established forensic indicators, but quantifying and correlating trace element signatures for U ores to known deposits has thus far involved intricate statistical analyses. This study reports average chondrite normalized (CN)‐REE signatures for important U deposit types worldwide, which are then employed to evaluate U ore paragenesis using a simple linear regression analysis. This technique provides a straightforward method that can aid in determining the deposit type of U ores based on their REE abundances, and combined with other forensic indicators (e.g. radiogenic isotope signatures) can provide essential provenance information for nuclear materials.  相似文献   

Drivers of afforestation in Northern Vietnam: Assessing local variations using geographically weighted regression   总被引：2，自引：0，他引：2  

Floriane Clement  Didier Orange  Meredith Williams  Corinne Mulley  Michael Epprecht 《Applied geography (Sevenoaks, England)》2009,29(4):561-576

This article identifies drivers of forest transition in a province of Northern Vietnam between 1993 and 2000 by applying geographically weighted regression (GWR) analysis to remotely sensed and statistical data. The regression model highlighted the spatial variation of the relationship between the percentage of land afforested and its proximate causes. Factors identified as having a major impact on afforestation are: the presence or proximity of a wood-processing industry, the distance to highways, and land allocation to households. Whereas the two former variables are in most areas of the province positively correlated with afforestation, an unexpected negative correlation was observed for the latter. The analysis of these results, supported by an in-depth knowledge of the area and of the political context, leads to the conclusion that, during the time period considered, afforestation was largely driven by state organisations on protected state-owned land, and forestry was not a significant component of household economic activities.  相似文献   

Re-examination of the temperature-dependent relationship between δ<Superscript>18</Superscript>O<Subscript>diatoms</Subscript> and δ<Superscript>18</Superscript>O<Subscript>lake water</Subscript> and implications for paleoclimate inferences     

Julien Crespin  Florence Sylvestre  Anne Alexandre  Corinne Sonzogni  Christine Paillès  Marie-Elodie Perga 《Journal of Paleolimnology》2010,44(2):547-557

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Happy Jack Uraninite: A New Reference Material for High Spatial Resolution Analysis of U‐Rich Matrices     

Corinne Dorais  Antonio Simonetti  Loretta Corcoran  Tyler L. Spano  Peter C. Burns 《Geostandards and Geoanalytical Research》2020,44(1):125-132

There is currently a lack of well‐characterised matrix‐matched reference materials (RMs) for forensic analysis of U‐rich materials at high spatial resolution. This study reports a detailed characterisation of uraninite (nominally UO_2+x) from the Happy Jack Mine (UT, USA). The Happy Jack uraninite can be used as a RM for the determination of rare earth element (REE) mass fractions in nuclear materials, which provide critical information for source attribution purposes. This investigation includes powder X‐ray diffraction (pXRD) data, as well as major, minor and trace element abundances determined using a variety of micro‐analytical techniques. The chemical signature of the uraninite was investigated at the macro (cm)‐scale with micro‐X‐ray fluorescence (µXRF) mapping and at high spatial resolution (tens of micrometre scale) using electron probe microanalysis (EPMA) and laser ablation‐inductively coupled plasma‐mass spectrometry (LA‐ICP‐MS) analyses. Based on EPMA results, the uraninite is characterised by homogeneous UO₂ and CaO contents of 91.57 ± 1.49% m/m (2s uncertainty) and 2.70 ± 0.38% m/m (2s), respectively. Therefore, CaO abundances were used as the internal standard when conducting LA‐ICP‐MS analyses. Overall, the major element and REE compositions are homogeneous at both the centimetre and micrometre scales, allowing this material to be used as a RM for high spatial resolution analysis of U‐rich samples.  相似文献   

Ordinary chondrite-related giant (>800 μm) cosmic spherules from the Transantarctic Mountains, Antarctica     

Clément Suavet  Carole Cordier  Luigi Folco  Corinne Sonzogni 《Geochimica et cosmochimica acta》2011,75(20):6200-6210

In order to identify the parent bodies of cosmic spherules (melted micrometeorites) with porphyritic olivine (PO) and cryptocrystalline (CC) textures, we measured the oxygen isotopic composition of 15 giant (>800 μm) cosmic spherules recovered in the Transantarctic Mountains, Antarctica, with IR-laser fluorination/mass spectrometry, and we conducted a characterization of their petrographic and magnetic properties. Samples include 6, 8 and 1 spherules of PO, CC and barred olivine (BO) textural types, respectively. Eleven spherules (∼70% of the total: 4/6 PO and 6/8 CC, and the BO spherule) are related to ordinary chondrites based on oxygen isotopic compositions. Olivines in ordinary chondrite-related spherules have compositions Fa_8.5-11.8, they are Ni-poor to Ni-rich (0.04-1.12 wt.%), and tend to be richer in CaO than other spherules (0.10-0.17 wt.%). Ordinary-chondrite related spherules also have high magnetite contents (∼2-12 wt.%). One PO and one CC spherules are related to previously identified ¹⁷O-enriched cosmic spherules for which the parent body is unknown. One CC spherule has an oxygen isotopic signature relating it to CM/CR carbonaceous chondrites. The majority of PO/CC cosmic spherules derive from ordinary chondrites; this result exemplifies how the texture of cosmic spherules is not only controlled by atmospheric entry heating conditions but also depends on the parent body, whether be it through orbital parameters (entry angle and velocity), or chemistry, mineralogy, or grain size of the precursor.  相似文献   

The late Neoproterozoic Enganepe ophiolite, Polar Urals, Russia: An extension of the Cadomian arc?     

J. H. Scarrow  V. Pease  C. Fleutelot  V. Dushin 《Precambrian Research》2001,110(1-4)

The Enganepe ophiolite, Polar Urals was formed at 670 Ma and records a diverse geochemical association of tholeiite, arc-tholeiite, adakite, and OIB-like lithologies. This constrains the tectonic setting of the protolith of the ophiolite to an oceanic island-arc, with ridge-trench interaction most readily explaining the diverse compositions. The initiation of intra-ocean subduction and the development of the Enganepe island arc off the eastern margin of Baltica probably pre-dated the formation of the Enganepe ophiolite, i.e. prior to 670 Ma. The timing of island-arc magmatism is similar in age to that recorded off Avalon in the Cadomian arc. We propose that the active margin of Baltica in the Vendian is an extension of the Cadomian arc. This requires the northeast margin of Baltica (present-day coordinates) to have been in a southerly position in the Vendian, in agreement with proposed tectonic reconstructions. Consequently, the post-Rodinia continental amalgamation, Pannotia, had active ocean-continent convergence along its entire southerly (west Avalonia and Amazonian cratons) margin at the time of its break-up.  相似文献   

Geochemical evidence of hydrothermal recharge in Lake Baringo,central Kenya Rift Valley     

Corinne Tarits  Robin W. Renaut  Jean‐Jacques Tiercelin  Alain Le Hriss  Jo Cotten  Jean‐Yves Cabon 《水文研究》2006,20(9):2027-2055

Lake Baringo, a freshwater lake in the central Kenya Rift Valley, is fed by perennial and ephemeral rivers, direct rainfall, and hot springs on Ol Kokwe Island near the centre of the lake. The lake has no surface outlet, but despite high evaporation rates it maintains dilute waters by subsurface seepage through permeable sediments and faulted lavas. New geochemical analyses (major ions, trace elements) of the river, lake, and hot spring waters and the suspended sediments have been made to determine the main controls of lake water quality. The results show that evaporative concentration and the binary mixing between two end members (rivers and thermal waters) can explain the hydrochemistry of the lake waters. Two zones are recognized from water composition. The southern part of the lake near sites of perennial river inflow is weakly influenced by evaporation, has low total dissolved species (TDS), and has a seasonally variable load of mainly detrital suspended sediments. In contrast, waters of the northern part of the lake show evidence for strong evaporation (TDS of up to eight times inflow). Authigenic clay minerals and calcite may be precipitating from those more concentrated fluids. The subaerial hot‐spring waters have a distinctive chemistry and are enriched in some elements that are also present in the lake water. Comparison of the chemical composition of the inflowing surface waters and lake water shows (1) an enrichment of some species (HCO₃^?, Cl, SO₄^2?, F, Na, B, V, Cr, As, Mo, Ba and U) in the lake, (2) a depletion in SiO₂ in the lake, and (3) a possible hydrothermal origin for most F. The rare earth element distribution and the F/Cl and Na/Cl ratios give valuable information on the rate of mixing of the river and hydrothermal fluids in the lake water. Calculations imply that thermal fluids may be seeping upward locally into the lake through grid‐faulted lavas, particularly south of Ol Kokwe Island. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

Long-term fluctuations in volcanic activity: implications for future environmental impact     

Hazel Rymer  Corinne A. Locke  rea Borgia  Maria Martinez  Jorge Brenes  Rodolfo Van der Laat  Glyn Williams-Jones 《地学学报》2009,21(4):304-309

Acidic crater lakes at persistently active volcanoes act as both an index and a moderator of volcanic processes. A catastrophic drop in lake level can therefore lead to serious local environmental damage. In the early 1990s, the crater lake at Poás volcano, Costa Rica diminished, and acid aerosols erupted with devastating consequences for local health, environment and economy. The first indications of this event can be  retrospectively identified to have started from 1985, on the basis of our unique 20-year data time series, which provides evidence for the shallow intrusion of magma. New data presented in this article show similar trends and we conclude that Poás has now entered another active period with renewed intrusion. Severe environmental damage in this region is expected within the next few years if the current trend continues.  相似文献   

Geomorphology of desert sand dunes: A review of recent progress   总被引：2，自引：0，他引：2  

Ian Livingstone  Giles F.S. Wiggs  Corinne M. Weaver 《Earth》2007,80(3-4):239-257

Through the 1980s and 1990s studies of the geomorphology of desert sand dunes were dominated by field studies of wind flow and sand flow over individual dunes. Alongside these there were some attempts numerically to model dune development as well as some wind tunnel studies that investigated wind flow over dunes. As developments with equipment allowed, field measurements became more sophisticated. However, by the mid-1990s it was clear that even these more complex measurements were still unable to explain the mechanisms by which sand is entrained and transported. Most importantly, the attempt to measure the stresses imposed by the wind on the sand surface proved impossible, and the use of shear (or friction) velocity as a surrogate for shear stress also failed to deliver. At the same time it has become apparent that turbulent structures in the flow may be as or more important in explaining sand flux. In a development paralleled in fluvial geomorphology, aeolian geomorphologists have attempted to measure and model turbulent structures over dunes. Progress has recently been made through the use of more complex numerical models based on computational fluid dynamics (CFD). Some of the modelling work has also suggested that notions of dune ‘equilibrium’ form may not be particularly helpful. This range of recent developments has not meant that field studies are now redundant. For linear dunes careful observations of individual dunes have provided important data about how the dunes develop but in this particular field some progress has been made through ground-penetrating radar images of the internal structure of the dunes.

The paradigm for studies of desert dune geomorphology for several decades has been that good quality empirical data about wind flow and sand flux will enable us to understand how dunes are created and maintain their form. At least some of the difficulty in the past arose from the plethora of undirected data generated by largely inductive field studies. More recently, attention has shifted–although not completely–to modelling approaches, and very considerable progress has been made in developing models of dune development. It is clear, however, that the models will continue to require accurate field observations in order for us to be able to develop a clear understanding of desert sand dune geomorphology.  相似文献   

Speleoseismology: A critical perspective     

Arnfried Becker  Colin A. Davenport  Urs Eichenberger  Eric Gilli  Pierre-Yves Jeannin  Corinne Lacave 《Journal of Seismology》2006,10(3):371-388

Speleoseismology is the investigation of earthquake records in caves. Traces can be seen in broken speleothems, growth anomalies in speleothems, cave sediment deformation structures, displacements along fractures and bedding plane slip, incasion (rock fall) and co-seismic fault displacements. Where earthquake origins can be proven, these traces constitute important archives of local and even regional earthquake activity. However, other processes that can generate the same or very similar deformation features have to be excluded before cave damage can be interpreted as earthquake induced. Most sensitive and therefore most valuable for the tracing of strong earthquake shocks in caves are long and slender speleothems, such as soda straws, and deposits of well-bedded, water-saturated silty sand infillings, particularly in caves close to the earth's surface. Less easily proven is a co-seismic origin of an incasion and other forms of cave damage. The loads and creep movements of sediment and ice fillings in caves can cause severe damage to speleothems which have been frequently misinterpreted as evidence of earthquakes. For the dating of events in geological archives, it is important to demonstrate that such events happened at approximately the same time, i.e. within the error bars of the dating methods. A robust earthquake explanation for cave damage can only be achieved by the adoption of appropriate methods of direct dating of deformation events in cave archives combined with correlation of events in other geological archives outside caves, such as the deformation of lake and flood-plain deposits, locations of rock falls and active fault displacements.  相似文献