Chronology of Vesuvius’ activity from A.D. 79 to 1631 based on archeomagnetism of lavas and historical sources     

Claudia?PrincipeEmail author  Jean?Claude?Tanguy  Simone?Arrighi  Anna?Paiotti  Maxime?Le?Goff  Ugo?Zoppi 《Bulletin of Volcanology》2004,66(8):703-724

The activity of Vesuvius between A.D. 79 and 1631 has been investigated by means of precise archaeomagnetic dating of primary volcanic deposits and taking into account the stratigraphy of lavas and tephra, historical written accounts, archaeological evidence related to the developing urbanisation, and radiocarbon ages. We found that the historical records are highly useful in constraining the timing of the main events, even if the data are often too scarce and imprecise for ascertaining the details of all phases of activity, especially their magnitude and emplacement of all the deposit types. In addition, some eruptions that took place in the 9^th and 10^th centuries appear to be unnoticed by historians. The archaeomagnetic study involved 26 sites of different lavas and 2 pyroclastic deposits. It shows that within the 15 centuries which elapsed between A.D. 79 and 1631, the effusive activity of Vesuvius clustered in the relatively short period of time between A.D. 787 and 1139 and was followed by a 5-century-long repose period. During this time Vesuvius prepared itself for the violent explosive eruption of 1631. The huge lavas shaping the morphology of the coast occurred largely through parasitic vents located outside the Mount Somma caldera. One of these parasitic vents is located at low elevation, very close to the densely inhabited town of Torre Annunziata. Among the various investigated lavas, a number of which were previously attributed to the 1631 eruption, none is actually younger than the 12^th century. Therefore it is definitively concluded that the destructive 1631 event was exclusively explosive.Editorial handling: J. McPhie  相似文献   

Removal of ammonia toxicity in marine sediment TIEs: a comparison of Ulva lactuca,zeolite and aeration methods   总被引：5，自引：0，他引：5  

Burgess RM  Pelletier MC  Ho KT  Serbst JR  Ryba SA  Kuhn A  Perron MM  Raczelowski P  Cantwell MG 《Marine pollution bulletin》2003,46(5):607-618

Toxicity Identification Evaluations (TIEs) can be used to determine the specific toxicant(s), including ammonia, causing toxicity observed in marine sediments. Two primary TIE manipulations are available for characterizing and identifying ammonia in marine sediments: Ulva lactuca addition and zeolite addition. In this study, we compared the efficacy of these methods to (1) remove NH(x) and NH(3) from overlying and interstitial waters and (2) reduce toxicity to the amphipod Ampelisca abdita and mysid Americamysis bahia using both spiked and environmentally contaminated sediments. The utility of aeration for removing NH(x) and NH(3) during a marine sediment TIE was also evaluated preliminarily. In general, the U. lactuca and zeolite addition methods performed similarly well at removing spiked NH(x) and NH(3) from overlying and interstitial waters compared to an unmanipulated sediment. Toxicity to the amphipod was reduced approximately the same by both methods. However, toxicity to the mysid was most effectively reduced by the U. lactuca addition indicating this method functions best with epibenthic species exposed to ammonia in the water column. Aeration removed NH(x) and NH(3) from seawater when the pH was adjusted to 10; however, very little ammonia was removed at ambient pHs ( approximately 8.0). This comparison demonstrates both U. lactuca and zeolite addition methods are effective TIE tools for reducing the concentrations and toxicity of ammonia in whole sediment toxicity tests.  相似文献   

From partial melting to retrogression in the Pointe Geologie migmatitic complex: a history of heterogeneous distribution of fluids     

Anne Pelletier  Michel Guiraud  Ren-Pierre Menot 《Lithos》2005,81(1-4):153-166

In the Pointe Géologie area (66°40 S; 140°00 E; Terre Adélie, East Antarctica), the Paleoproterozoic basement consists in a migmatitic complex of metasedimentary origin. Metasediments underwent a thermal event, leading to the high-grade amphibolite facies assemblages biotite–cordierite–sillimanite and to dehydration melting reactions at 4–6 kbar and 700±50 °C, followed by retrogression in greenschist facies.

In most of the archipelago, K-feldspar gneisses (KFG) are characterized by a Sil+Crd+Kfs+Bt assemblage and many K-feldspar-rich leucosomes. Locally, a spectacular rock type occurs as North dipping bands of about 10 m thick and consists in nodular gneisses (NG) that display less abundant, K-feldspar-poor leucosomes.

Commonly, the retrograde imprint facies is quite weak in KFG and only expressed by sporadic Bt–Ms±And equilibrium assemblage, whereas it developed more extensively in NG. A pseudosection calculated at constant P=4 kbar shows that the differences between NG and KFG assemblages can be considered to be mainly driven by difference in H₂O proportions and much less by differences in FeO/MgO or K₂O/MgO ratios. The hydrated assemblage (Bt–Ms nodules) in NG requires at least 10–20% more H₂O than the Crd+Kfs+Sil/And assemblage does in KFG. Parageneses and mineral compositions indicate that this difference in H₂O occurred early in the history, at least as early as the anatectic stage. Therefore, differences between NG and KFG are related to the variation in partial melting features (water distribution, proportion of melt extraction), which appears to be spatially controlled by cryptic tectonic structures. The particular shape and orientation of NG bands are interpreted as a complex history of melt extraction in the Pointe Géologie area which could involve a two stage melting process.  相似文献   

Mesure de l’âge de la coulée Volcanique du Puy de la Vache (Auvergne) par la méthode du carbone 14     

H. Pelletier  G. Delibrias  J. Labeyrie  M. -Th. Perquis 《Bulletin of Volcanology》1960,23(1):53-54

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Desert pavement dynamics: numerical modeling and field‐based calibration     

Jon D. Pelletier  Michael Cline  Stephen B. DeLong 《地球表面变化过程与地形》2007,32(13):1913-1927

Desert pavements are widely used as a relative surface‐dating tool because they are progressively better developed on surfaces ranging from thousands to hundreds of thousands of years in age. Recent work, however, has highlighted the dynamic nature of pavements and undermined their use as surface‐age indicators. Quade (2001) proposed that latest Pleistocene vegetation advances destroyed all Mojave Desert pavements above 400 m elevation, making all such pavements Holocene in age. In an effort to reconcile young‐pavement evidence with their widespread use as Pleistocene surface‐age indicators, we developed a numerical model based on the classic conceptual model in which pavements co‐evolve with their underlying eolian epipedons over millennial timescales. In this co‐evolutionary process, fine‐grained eolian deposition and A_v‐horizon development within the eolian epipedon promotes surface clast motion and pavement development, enhancing the eolian‐sediment‐trapping ability of the pavement in a positive feedback. Model results illustrate the multi‐scale nature of pavement dynamics: pavements may require tens of thousands of years to fully develop from a newly abandoned alluvial surface, but may heal over timescales of decades to centuries if a mature eolian epipedon is present. As such, there is no inconsistency between rapid pavement healing and a Pleistocene age for the underlying alluvial surface. To calibrate the model, we conducted surficial geologic mapping and pavement‐sedimentological analysis on two desert piedmonts. Our study areas include both proximal and distal fan environments, illustrating the role of parent‐material texture in controlling the mode of pavement formation. Using available geochronology, our work provides a rigorous calibration of pavement formation rates in our study areas and provides evidence supporting the use of pavements as local relative surface‐age indicators over Holocene to late Pleistocene timescales. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

Mount Etna eruptions of the last 2,750 years: revised chronology and location through archeomagnetic and <Superscript>226</Superscript>Ra-<Superscript>230</Superscript>Th dating     

Jean-Claude Tanguy  Michel Condomines  Maxime Le Goff  Vito Chillemi  Santo La Delfa  Giuseppe Patanè 《Bulletin of Volcanology》2007,70(1):55-83

A careful re-examination of the well-known written documents pertaining to the 2,750-year-long historical period of Mount Etna was carried out and their interpretation checked through the high-accuracy archeomagnetic method (>1,200 large samples), combined with the ²²⁶Ra-²³⁰Th radiochronology. The magnetic dating is based upon secular variation of the direction of the geomagnetic field (DGF) and estimated to reach a precision of  ±40 years for the last 1,200 years, and ±100 to 200 years up to circa 150 B.C. Although less precise, the ²²⁶Ra-²³⁰Th method provides a unique tool for distinguishing between historic and prehistoric lavas, which in some cases might have similar DGFs. We show that despite the abundance of details on ancient historical eruptions, the primary sources of information are often too imprecise to identify their lava flows and eruptive systems. Most of the ages of these lavas, which are today accepted on the geological maps and catalogues, were attributed in the 1800s on the basis of their morphology and without any stratigraphical control. In fact, we found that 80% of the “historically dated” flows and cones prior to the 1700s are usually several hundreds of years older than recorded, the discrepancies sometimes exceeding a millennium. This is proper the case for volcanics presumed of the “1651 east” (actually ∼1020), “1595” (actually two distinct flows, respectively, ∼1200 and ∼1060), “1566” (∼1180), “1536” (two branches dated ∼1250 and ∼950), “1444” (a branch dated ∼1270), “1408” (lower branches dated ∼450 and ∼350), “1381” (∼1160), “1329” (∼1030), “1284” (∼1450 and ∼700), “1169 or 812” (∼1000) eruptions. Conversely, well-preserved cones and flows that are undated on the maps were produced by recent eruptions that went unnoticed in historical accounts, especially during the Middle Ages. For the few eruptions that are recorded between A.D. 252 and 750 B.C., none of their presumed lava flows shows a DGF in agreement with that existing at their respective dates of occurrence, most of these flows being in fact prehistoric. The cinder cones of Monpeloso (presumed “A.D. 252”) and Mt. Gorna (“394 B.C.”), although roughly consistent magnetically and radiochronologically with their respective epochs, remain of unspecified age because of a lack of precision of the DGF reference curve at the time. It is concluded that at the time scale of the last millennia, Mount Etna does not provide evidence of a steady-state behavior. Periods of voluminous eruptions lasting 50 to 150 years (e.g., A.D. 300–450, 950–1060, 1607–1669) are followed by centuries of less productive activity, although at any time a violent outburst may occur. Such a revised history should be taken into account for eruptive models, magma output, internal plumbing of the volcano, petrological evolution, volcano mapping and civil protection.  相似文献   

Short-term measures for the control of ozone peaks: expertise from CTM simulations     

Fanny Lasry  Isabelle Coll  Sylvain Fayet  Maxime Havre  Robert Vautard 《Journal of Atmospheric Chemistry》2007,57(2):107-134

In Europe, in case of the observation or the forecast of a photochemical event, punctual and local reductions in anthropogenic emissions can be triggered at the regional scale. Although the necessity for the establishment of such measures appears to be justified by bad air quality records over large European cities, individual short-term action plans (STAPs) have been blindly elaborated by regional authorities. Moreover, as they impose industrial and road traffic emission restrictions, these measures have an elevated economical cost. It is consequently crucial to determine their efficiency and potential for ozone peak reduction. The study presented in this paper aims to draw up an expertise on standard European STAPs, through the example of a French Mediterranean city. The objective is to determine and investigate the impact of current STAPs on ozone peak formation and to test ways to optimise their efficiency. In this frame, a set of emission scenarios has been elaborated and tested with the chemistry-transport model CHIMERE on the Berre–Marseille area. Simulations have shown that the tested action plans are not sufficient to eradicate severe ozone peaks and that more drastic restrictions on emissions are required to significantly affect ozone plumes. However, results also showed that the potential for ozone reduction remains small, with a maximum impact of only 5 ppbv for feasible STAPs. Finally, a temporal analysis of the ozone-emission relationship was engaged in order to optimise their application.  相似文献   

Mineral Processing Symposium — Société de l'Industrie Minérale — Toulouse, 1975     

Maxime Brandela 《International Journal of Mineral Processing》1976,3(1):97-100

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The Lithium, Boron and Beryllium content of serpentinized peridotites from ODP Leg 209 (Sites 1272A and 1274A): Implications for lithium and boron budgets of oceanic lithosphere   总被引：2，自引：0，他引：2  

Flurin Vils  Laure Pelletier  Othmar Müntener 《Geochimica et cosmochimica acta》2008,72(22):5475-5504

Despite the key importance of altered oceanic mantle as a repository and carrier of light elements (B, Li, and Be) to depth, its inventory of these elements has hardly been explored and quantified. In order to constrain the systematics and budget of these elements we have studied samples of highly serpentinized (>50%) spinel harzburgite drilled at the Mid-Atlantic Ridge (Fifteen-Twenty Fracture zone, ODP Leg 209, Sites 1272A and 1274A). In-situ analysis by secondary ion mass spectrometry reveals that the B, Li and Be contents of mantle minerals (olivine, orthopyroxene, and clinopyroxene) remain unchanged during serpentinization. B and Li abundances largely correspond to those of unaltered mantle minerals whereas Be is close to the detection limit. The Li contents of clinopyroxene are slightly higher (0.44-2.8 μg g⁻¹) compared to unaltered mantle clinopyroxene, and olivine and clinopyroxene show an inverse Li partitioning compared to literature data. These findings along with textural observations and major element composition obtained from microprobe analysis suggest reaction of the peridotites with a mafic silicate melt before serpentinization. Serpentine minerals are enriched in B (most values between 10 and 100 μg g⁻¹), depleted in Li (most values below 1 μg g⁻¹) compared to the primary phases, with considerable variation within and between samples. Be is at the detection limit. Analysis of whole rock samples by prompt gamma activation shows that serpentinization tends to increase B (10.4-65.0 μg g⁻¹), H₂O and Cl contents and to lower Li contents (0.07-3.37 μg g⁻¹) of peridotites, implying that—contrary to alteration of oceanic crust—B is fractionated from Li and that the B and Li inventory should depend essentially on rock-water ratios. Based on our results and on literature data, we calculate the inventory of B and Li contained in the oceanic lithosphere, and its partitioning between crust and mantle as a function of plate characteristics. We model four cases, an ODP Leg 209-type lithosphere with almost no igneous crust, and a Semail-type lithosphere with a thick igneous crust, both at 1 and 75 Ma, respectively. The results show that the Li contents of the oceanic lithosphere are highly variable (17-307 kg in a column of 1 m × 1 m × thickness of the lithosphere (kg/col)). They are controlled by the primary mantle phases and by altered crust, whereas the B contents (25-904 kg/col) depend entirely on serpentinization. In all cases, large quantities of B reside in the uppermost part of the plate and could hence be easily liberated during slab dehydration. The most prominent input of Li into subduction zones is to be expected from Semail-type lithosphere because most of the Li is stored at shallow levels in the plate. Subducting an ODP Leg 209-type lithosphere would mean only very little Li contribution from the slab. Serpentinized mantle thus plays an important role in B recycling in subduction zones, but it is of lesser importance for Li.  相似文献   

Nickel dispersion and enrichment at the bottom of the regolith: formation of pimelite target-like ores in rock block joints (Koniambo Ni deposit,New Caledonia)     

Michel Cathelineau  Benoît Quesnel  Pierre Gautier  Philippe Boulvais  Clément Couteau  Maxime Drouillet 《Mineralium Deposita》2016,51(2):271-282

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