Mineral Chemistry of Mildly Alkalic Basalts from the 25 Ma Mont Crozier Section, Kerguelen Archipelago: Constraints on Phenocryst Crystallization Environments     

DAMASCENO  DIMITRI; SCOATES  JAMES S.; WEIS  DOMINIQUE; FREY  FREDERICK A.; GIRET  ANDRE 《Journal of Petrology》2002,43(7):1389-1413

Phenocryst compositions and mineral–melt equilibria inthe mildly alkalic basalts from the 25 Ma Mont Crozier sectionon the Kerguelen Archipelago are used to estimate the depthsat which magmas stalled and crystallized and to constrain therole of crustal structure in the evolution of magmas producedby the Kerguelen mantle plume. The Crozier section, of nearly1000 m height, consists of variably porphyritic flows (up to21 vol. % phenocrysts), dominated by plagioclase ± clinopyroxene± olivine ± Fe–Ti oxides. Feldspars showan extreme range of compositions from high-Ca plagioclase (An₈₈)to sanidine and variable textures that are related to extensivefractionation, degassing, and mixing in relatively low-pressure(sub-volcanic) magma chambers. Although clinopyroxene is a minorphenocryst type (0–3 vol. %), its non-quadrilateral components,principally Al (1·9–8·6 wt % Al₂O₃), varywidely. The results of clinopyroxene–liquid thermobarometryand clinopyroxene structural barometry indicate that the Croziermagmas crystallized at pressures ranging from  相似文献   

Density dependence of forbidden transitions within 3s 23p 53d of the coronal ion Fe IX     

Eberhard Haug 《Solar physics》1979,61(2):311-317

The relative populations of metastable levels within the configuration 3s ²3p ⁵3d of the ion Fe ix have been calculated as a function of electron density N _e . The results are used to derive emissivities of the most intense lines originating from these levels. Comparison with observations confirms the proposed identifications. The density dependence of some line ratios may be used to determine N _e .  相似文献   

Contribution of electron-electron bremsstrahlung to solar hard X-radiation during flares     

Eberhard Haug 《Solar physics》1975,45(2):453-458

The bremsstrahlung produced in collisions of energetic electrons with thermal electrons and protons of a hydrogen plasma is calculated. The importance of electron-electron bremsstrahlung to the X-radiation in solar flares is discussed.  相似文献   

Intrusive rocks in the ophiolitic mélange of Crete – Witnesses to a Late Cretaceous thermal event of enigmatic geological position     

Alexander Langosch  Eberhard Seidel  Heinz-Günter Stosch  Martin Okrusch 《Contributions to Mineralogy and Petrology》2000,139(3):339-355

The ophiolitic mélange in the uppermost tectonic unit of the Cretan nappe pile contains crystalline slices which consist of a low-pressure/high-temperature metamorphic sequence and synmetamorphic intrusions, ranging in composition from diorite to granite. The plutonic rocks conform to two different igneous suites, dominated by diorites in eastern, and granites in central Crete, displaying I-type and A-type characters, respectively. Some of the granites from central Crete are classified as transitional I/S-type. They are closely associated with migmatitic paragneisses. Based on major and trace element, REE, Sr- and Nd-isotope geochemistry, the mafic members of both suites are derived from a depleted mantle source. The higher concentrations of P and Ti in the mafic members of the igneous suite in central Crete and the deviant trend of the whole suite may be explained by a different mantle source or a lower degree of partial melting. In both suites, magmatic evolution was governed by fractional crystallization of amphibole/clinopyroxene, plagioclase and minor phases. In addition, mixing or mingling of compositionally different magmas is indicated for the intrusive suite of eastern Crete whereas in central Crete the magma composition was at least partially modified through assimilation of (meta)pelites. The geochemical results suggest that the plutonic rocks formed in a supra-subduction zone setting. However, a formation during continental lithospheric extension cannot be ruled out. Published and new Rb–Sr and K–Ar dates on amphiboles and biotites from intrusive rocks and their metamorphic country rocks show that the peak of the low-P/high-T metamorphism and the intrusion of the two igneous suites testify to the same thermal event of Late Cretaceous age. A similar Late Cretaceous association of metamorphic and plutonic rocks has been described from the uppermost tectonic unit in the Attic–Cycladic Crystalline Complex. Together with the Cretan occurrences, they form a small sector radiating SSW along a distance of 300 km, across the general trend of the tectonic zones in the Hellenic orogen. This N–S alignment is regarded as a primary feature which may delineate the frontier zone between the Hellenides and the Taurides. The real paleogeographic position and geodynamic significance of the Late Cretaceous low-pressure/high-temperature belt, however, remains enigmatic. Received: 1 June 1999 / Accepted: 2 February 2000  相似文献   

Volcanism at the Edge of the Hawaiian Plume: Petrogenesis of Submarine Alkalic Lavas from the North Arch Volcanic Field   总被引：5，自引：3，他引：2  

FREY  F. A.; CLAGUE  D.; MAHONEY  J. J.; SINTON  J. M. 《Journal of Petrology》2000,41(5):667-691

Submarine lavas erupted onto the Hawaiian arch 200–400km north of Oahu show that the areal extent of Hawaiian volcanismis much larger than previously recognized. The North Arch volcanicfield comprises 25 000 km² of  相似文献   

Holocene sedimentary evolution of a mid-ocean atoll lagoon,Maldives, Indian Ocean     

Lars Klostermann  Eberhard Gischler 《International Journal of Earth Sciences》2015,104(1):289-307

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A new azhdarchoid pterosaur from the Cenomanian (Late Cretaceous) of Lebanon     

Ross A. Elgin  Eberhard Frey 《Swiss Journal of Geoscience》2011,104(1):21-33

A new pterosaur, Microtuban altivolans gen. et sp. nov., is described from the Sannine Formation of northern Lebanon. The specimen is the first pterosaur from the Early Cenomanian (Late Cretaceous) locality of Hjoûla and is regarded as the most complete pterosaur fossil discovered from Africa. While postcranial characters indicate a possible relationship with members of the Thalassodromidae or Chaoyangopteridae, the specimen possesses an exceptionally short wing-finger phalanx 4, forming only 1.1% of the total length of the wing-finger. Its appearance along with an unnamed ornithocheiroid from the slightly younger locality of Hâqel suggests that a number of pterosaur taxa existed within the local area, perhaps living on exposed carbonate platforms.  相似文献   

Impact of chemical and meteorological boundary and initial conditions on air quality modeling: WRF-Chem sensitivity evaluation for a European domain     

Mathias Ritter  Mathias D. Müller  Oriol Jorba  Eberhard Parlow  L.-J. Sally Liu 《Meteorology and Atmospheric Physics》2013,119(1-2):59-70

This study evaluates the impact of different chemical and meteorological boundary and initial conditions on the state-of-the-art Weather Research and Forecasting (WRF) model with its chemistry extension (WRF-Chem). The evaluation is done for July 2005 with 50 km horizontal resolution. The effect of monthly mean chemical boundary conditions derived from the chemical transport model LMDZ-INCA on WRF-Chem is evaluated against the effect of the preset idealized profiles. Likewise, the impact of different meteorological initial and boundary conditions (GFS and Reanalysis II) on the model is evaluated. Pearson correlation coefficient between these different runs range from 0.96 to 1.00. Exceptions exists for chemical boundary conditions on ozone and for meteorological boundary conditions on PM₁₀, where coefficients of 0.90 were obtained. Best results were achieved with boundary and initial conditions from LMDZ-INCA and GFS. Overall, the European simulations show encouraging results for observed air pollutant, with ozone being the most and PM₁₀ being the least satisfying.  相似文献   

2002 Kuiper prize lecture: Dust Astronomy     

Eberhard Grün  Ralf Srama  Sascha Kempf  Stefan Helfert 《Icarus》2005,174(1):1-14

Dust particles, like photons, carry information from remote sites in space and time. From knowledge of the dust particles' birthplace and their bulk properties, we can learn about the remote environment out of which the particles were formed. This approach is called “Dust Astronomy” which is carried out by means of a dust telescope on a Dust Observatory in space. Targets for a dust telescope are the local interstellar medium and nearby star forming regions, as well as comets and asteroids. Dust from interstellar and interplanetary sources is distinguished by accurately sensing their trajectories. Trajectory sensors may use the electric charge signals that are induced when charged grains fly through the detector. Modern in-situ dust impact detectors are capable of providing mass, speed, physical and chemical information of dust grains in space. A Dust Observatory mission is feasible with state-of-the-art technology. It will (1) provide the distinction between interstellar dust and interplanetary dust of cometary and asteroidal origin, (2) determine the elemental composition of impacting dust particles, and (3) monitor the fluxes of various dust components as a function of direction and particle masses.  相似文献   

Initial Calibration of the Atmospheric Imaging Assembly (AIA) on the Solar Dynamics Observatory (SDO)     

Paul Boerner  Christopher Edwards  James Lemen  Adam Rausch  Carolus Schrijver  Richard Shine  Lawrence Shing  Robert Stern  Theodore Tarbell  Alan Title  C. Jacob Wolfson  Regina Soufli  Eberhard Spiller  Eric Gullikson  David McKenzie  David Windt  Leon Golub  William Podgorski  Paola Testa  Mark Weber 《Solar physics》2012,275(1-2):41-66

The Atmospheric Imaging Assembly (AIA) instrument onboard the Solar Dynamics Observatory (SDO) is an array of four normal-incidence reflecting telescopes that image the Sun in ten EUV and UV wavelength channels. We present the initial photometric calibration of AIA, based on preflight measurements of the response of the telescope components. The estimated accuracy is of order 25%, which is consistent with the results of comparisons with full-disk irradiance measurements and spectral models. We also describe the characterization of the instrument performance, including image resolution, alignment, camera-system gain, flat-fielding, and data compression.  相似文献