Comment on: Discovery of the fossiliferous Cu Brei Formation (Lower Devonian) in the Kon Tum Block (South Viet Nam): Tong-Dzuy Thanh, Than Duc Duyen, Nguyen Huu Hung, Bui Phu My     

Henri Maluski   《Journal of Asian Earth Sciences》2008,31(4-6):562-563

The publication of Tong-Dzuy Thanh et al. calls for two remarks: The metamorphism in the “Kon Tum block” cannot be younger than Permian because the outcrop they describe is not metamorphic. Their very interesting discovery is a new piece of evidence for the exotic origin of the Dien Binh Series.  相似文献   

Evolution of the fogwater composition in Strasbourg (France) from 1990 to 1999     

Pierre Herckes  Henri Wortham  Philippe Mirabel  Maurice Millet   《Atmospheric Research》2002,64(1-4)

The chemical composition of fogwater has been studied in the city of Strasbourg (France) from 1990 to 1999. During these years, fogwater samples have been collected and analysed for major ions and trace metals. This paper reports on the analysis of the collected dataset. The analysis revealed a significant decrease in acidity of approximately one pH unit over the course of the study. This decrease in acidity appears to be linked to a decrease in SO_2(g) and the resulting SO₄²⁻. Trace metal concentrations have also strongly decreased over the 10-year period. Pb concentrations, following the elimination of leaded gasoline, decreased by more than one order of magnitude.  相似文献   

Reply to Baker and Genty’s comments on “A test of annual resolution in stalagmite using tree rings”     

Julio L. Betancourt  Henri D. Grissino-Mayer  Matt W. Saltzer  Thomas W. Swetnam 《Quaternary Research》2003,59(3):479

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Exhumation Paths of High-Pressure-Low-Temperature Metamorphic Rocks from the Lycian Nappes and the Menderes Massif (SW Turkey): a Multi-Equilibrium Approach   总被引：1，自引：0，他引：1  

RIMMELE  GAETAN; PARRA  TEDDY; GOFFE  BRUNO; OBERHANSLI  ROLAND; JOLIVET  LAURENT; CANDAN  OSMAN 《Journal of Petrology》2005,46(3):641-669

The Menderes Massif and the overlying Lycian Nappes occupy anextensive area of SW Turkey where high-pressure–low-temperaturemetamorphic rocks occur. Precise retrograde P–T pathsreflecting the tectonic mechanisms responsible for the exhumationof these high-pressure–low-temperature rocks can be constrainedwith multi-equilibrium P–T estimates relying on localequilibria. Whereas a simple isothermal decompression is documentedfor the exhumation of high-pressure parageneses from the southernMenderes Massif, various P–T paths are observed in theoverlying Karaova Formation of the Lycian Nappes. In the uppermostlevels of this unit, far from the contact with the MenderesMassif, all P–T estimates depict cooling decompressionpaths. These high-pressure cooling paths are associated withtop-to-the-NNE movements related to the Akçakaya shearzone, located at the top of the Karaova Formation. This zoneof strain localization is a local intra-nappe contact that wasactive in the early stages of exhumation of the high-pressurerocks. In contrast, at the base of the Karaova Formation, alongthe contact with the Menderes Massif, P–T calculationsshow decompressional heating exhumation paths. These paths areassociated with severe deformation characterized by top-to-the-eastshearing related to a major shear zone (the Gerit shear zone)that reflects late exhumation of high-pressure parageneses underwarmer conditions. KEY WORDS: exhumation; high-pressure–low-temperature metamorphism; multi-equilibrium P–T estimates; Lycian Nappes; Menderes Massif  相似文献   

The need for national deep decarbonization pathways for effective climate policy     

Chris Bataille  Henri Waisman  Michel Colombier  Laura Segafredo  Jim Williams  Frank Jotzo 《Climate Policy》2016,16(4):S7-S26

Constraining global average temperatures to 2 °C above pre-industrial levels will probably require global energy system emissions to be halved by 2050 and complete decarbonization by 2100. In the nationally orientated climate policy framework codified under the Paris Agreement, each nation must decide the scale and method of their emissions reduction contribution while remaining consistent with the global carbon budget. This policy process will require engagement amongst a wide range of stakeholders who have very different visions for the physical implementation of deep decarbonization. The Deep Decarbonization Pathways Project (DDPP) has developed a methodology, building on the energy, climate and economics literature, to structure these debates based on the following principles: country-scale analysis to capture specific physical, economic and political circumstances to maximize policy relevance, a long-term perspective to harmonize short-term decisions with the long-term objective and detailed sectoral analysis with transparent representation of emissions drivers through a common accounting framework or ‘dashboard’. These principles are operationalized in the creation of deep decarbonization pathways (DDPs), which involve technically detailed, sector-by-sector maps of each country’s decarbonization transition, backcasting feasible pathways from 2050 end points. This article shows how the sixteen DDPP country teams, covering 74% of global energy system emissions, used this method to collectively restrain emissions to a level consistent with the 2 °C target while maintaining development aspirations and reflecting national circumstances, mainly through efficiency, decarbonization of energy carriers (e.g. electricity, hydrogen, biofuels and synthetic gas) and switching to these carriers. The cross-cutting analysis of country scenarios reveals important enabling conditions for the transformation, pertaining to technology research and development, investment, trade and global and national policies.

Policy relevance

In the nation-focused global climate policy framework codified in the Paris Agreement, the purpose of the DDPP and DDPs is to provide a common method by which global and national governments, business, civil society and researchers in each country can communicate, compare and debate differing concrete visions for deep decarbonization in order to underpin the necessary societal and political consensus to design and implement short-term policy packages that are consistent with long-term global decarbonization.  相似文献   

Oxygen and organic carbon fluxes in sediments of the Bay of Biscay     

Aurélia Mouret  Pierre Anschutz  Bruno Deflandre  Gwénaëlle Chaillou  Christelle Hyacinthe  Jonathan Deborde  Henri Etcheber  Jean-Marie Jouanneau  Antoine Grémare  Pascal Lecroart 《Deep Sea Research Part I: Oceanographic Research Papers》2010,57(4):528-540

The relationship between particulate organic carbon (POC) concentrations measured in modern sediment and fluxes of exported POC to the sediment surface needs to be understood in order to use POC content as a proxy of paleo-environmental conditions. The objective of our study was to compare POC concentrations, POC mineralization rates calculated from O₂ consumption and POC burial rates. Benthic O₂ distributions were determined in 58 fine-grained sediment cores collected at different periods at 14 stations in the southeastern part of the Bay of Biscay with depths ranging from 140 to 2800 m. Depth-dependent volume-specific oxygen consumption rates were used to assess rates of aerobic oxidation of organic matter (OM), assuming that O₂ consumption solely was related to heterotrophic activity at the sediment–water interface. Heterogeneity of benthic O₂ fluxes denoted changes in time and space of fresh organic material sedimentation. The most labile fraction of exported POC engendered a steep decrease in concentration in the upper 5 mm of vertical O₂ profiles. The rupture in the gradient of O₂ microprofile may be related to the bioturbation-induced mixing depth of fast-decaying carbon. Average diffusive O₂ fluxes showed that this fast-decaying OM flux was much higher than buried POC, although diffusive O₂ fluxes underestimated the total sediment oxygen demand, and thus the fast-decaying OM flux to the sediment surface. Sedimentary POC burial was calculated from sediment mass accumulation rate and the organic carbon content measured at the top of the sediment. The proportion of buried POC relative to total exported POC ranged at the most between 50% and 10%, depending on station location. Therefore, for a narrow geographic area like the Bay of Biscay, burial efficiency of POC was variable. A fraction of buried POC consisted of slow-decaying OM that was mineralized within the upper decimetres of sediment through oxic and anoxic processes. This fraction was deduced from the decrease with depth in POC concentration. At sites located below 500 m water depth, where the fast-decaying carbon did not reach the anoxic sediment, the slow-decaying pool may control the O₂ penetration depth. Only refractory organic material was fossilized in sedimentary records at locations where labile OM did not reach the anoxic portion of the sediment.  相似文献   

SrNdPb geochemical morphology between 10° and 17°N on the Mid-Atlantic Ridge: A new MORB isotope signature     

Laure Dosso  Barry B. Hanan  Henri Bougault  Jean-Guy Schilling  Jean-Louis Joron 《Earth and Planetary Science Letters》1991,106(1-4)

Basalts dredged along the Mid-Atlantic Ridge axis between 10°N and 17°N have been studied for their trace element characteristics [1]. To give complementary information on mantle source history and magma genesis, these samples have been analysed for their SrNdPb isotopic compositions. There is a good correlation between the structure of the ridge axis which shows a topographic anomaly centered around 14°N and hygromagmaphile element ratios such as Rb/Sr, (Nb/Zr)_N or Sm/Nd as well as isotopic ratios plotted as a function of latitude. The samples coming from the 14°N topographic high show new MORB SrNd isotopic characteristics which pictured in a classical mantle array diagram, put their representative points close to HIMU sources of ocean islands such as St. Helena, Tubuaïand Mangaia. The 14°N mantle source presents geochemical characteristics which indicate mantle differentiation processes and a mantle history that are more distinct than so far envisaged from typical MORB data. Pb data indicates that the 14°N mantle source cannot be the result of binary mixing between a depleted mantle and a HIMU-type source. Rather, the enriched endmember could itself be a mixture of Walvis-like and HIMU-like materials. The geochimical observations presented favour the model of an incipient ridge-centered plume, in agreement with [1].  相似文献   

Late variscan tectonic evolution by thinning of earlier thickened crust. An Ar---Ar study of the Montagne Noire, southern Massif Central, France     

Henri Maluski  Sylvie Costa  Helmut Echtler 《Lithos》1991,26(3-4):287-304

⁴⁰Ar---³⁹Ar age determinations on samples selected on deformational criteria form the basis of a proposal of a new detailed tectonometamorphic history of the Montagne Noire (the southern part of the Massif Central, France).

This range is classically divided into a cover and an axial gneissic and migmatitic core which was metamorphosed under high T/medium P conditions. The basement is structurally overlain by epimetamorphic Paleozoic sediments in the north. In the south, equivalent rocks form a well-known pile of recumbent nappes. The Variscan history of this area comprises early shortening and thickening of the continental crust. The climax of this event took place around 320 Ma ago, as is shown by previous Rb---Sr data and by ⁴⁰Ar---³⁹Ar measurements. New developments in structural analyses have led to a better understanding of the late evolution of the area in terms of diapiric uplift of the core. South-southwestwards verging recumbent nappes have been emplaced and were weakly metamorphosed in their lower parts. This movement was accompanied and followed by dextral extensional wrenching of the Paleozoic cover along the northern and southern margins of the axial zone. Attendantly, ductile shear zones were formed.

In order to decipher the complex history, three structural levels have been dated with the ⁴⁰Ar---³⁹Ar method. These levels are: (1) The migmatitic and gneissic series in the axial core, where micas yield ages of c. 315 Ma; (2) Mylonites from the northern and southern shear zones where biotites and muscovites yield ages of c. 310 Ma; (3) Muscovites and biotites from the epimetamorphic nappe structures yielding ages of c. 297 Ma. The later ages may represent a younger thermal pulse. These data are compared and discussed in the light of previous radiometric studies of the area and precise biostratigraphic constraints. A detailed geodynamic evolution of the studied segment is proposed.  相似文献   

Sites occupancy of Fe3+ in Garfield Nontronite: A spectroscopic study     

Dominique Bonnin  Georges Calas  Hélène Suquet  Henri Pezerat 《Physics and Chemistry of Minerals》1985,12(1):55-64

New data on the structure of Garfield nontronite have been produced by the use of different spectroscopic techniques: Mössbauer spectroscopy, optical spectroscopy, X-ray absorption edges and EXAFS and NMR. The tetrahedral iron content is found to be no higher than 1 percent. All iron atoms belong to the octahedral sheet excluding the possibility of the presence of non crystallized phases. Some ambiguities remain about the coherence of the octahedral sheet because of the presence of two doublets in the Mössbauer spectrum and at least two lineshapes in NMR spectra of OH which correspond to different environments.  相似文献   

Unconvincing evidence against the blocking temperature concept?     

Christian Chopin  Henri Maluski 《Contributions to Mineralogy and Petrology》1982,80(4):386-390

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