Erratum to: Magmato-sedimentary Carboniferous to Jurassic evolution of the western Tauern window,Eastern Alps (constraints from U-Pb zircon dating and geochemistry)     

Petra Veselá  Frank Söllner  Friedrich Finger  Axel Gerdes 《International Journal of Earth Sciences》2012,101(2):603-603

  相似文献   

Sources of and variations in tropospheric CO in Central Siberia: Numerical experiments and observations at the Zotino Tall Tower Observatory     

Yu. A. Shtabkin  K. B. Moiseenko  A. I. Skorokhod  A. V. Vasileva  M. Heimann 《Izvestiya Atmospheric and Oceanic Physics》2016,52(1):45-56

Contributions of climatically significant natural and anthropogenic emission sources in northern Eurasia to seasonal carbon monoxide (CO) variations observed at the Zotino Tall Tower Observatory (ZOTTO) in Central Siberia in 2007–2011 have quantitatively been estimated using the GEOS-Chem chemical transport model. It is shown that the formation of a stable continental pollution plume from sources in Western Europe, European Russia and southern Siberia during winter plays an important role in the regional balance of surface CO and allows one to explain 55–80% of the amplitude of the CO annual cycle observed at the ZOTTO station (~70–90 ppbv). During the warm period, the effect of the anthropogenic factor is weakly pronounced, and the background concentration of CO is regulated, first and foremost, by the oxidation of biogenic volatile organic compounds and fire activity in the region.  相似文献   

Zircon trace element chemistry at sub-micrometer resolution for Tarawera volcano,New Zealand,and implications for rhyolite magma evolution     

Sonja Storm  Axel K. Schmitt  Phil Shane  Jan M. Lindsay 《Contributions to Mineralogy and Petrology》2014,167(4):1-19

Zoned crystals can be important recorders of magmatic processes in space and time. However, in most situations, the temporal dimension is difficult to quantify. Here, we have employed secondary ion mass spectrometry depth profiling to excavate parallel pits into non-polished crystal faces of zircon to obtain ~5 μm resolution U–Th disequilibrium ages (one pit) that can be correlated with trace element zoning at sub-μm resolution derived from a second pit. Data from 17 crystals representing each of the four rhyolite eruptions of Tarawera volcano, an intra-caldera edifice within the Okataina Volcanic Centre, reveal diverse zircon growth conditions over time. Most crystals display rimward depletions in Zr/Hf and Ti, broadly consistent with cooling and crystallization. However, a significant fraction of crystals lacks these patterns and displays rimward trace element variations consistent with isothermal or prograde crystallization. Oscillatory zonation patterns in Y, Th, and U are superimposed on the Zr/Hf and Ti trends. Despite the limited number of crystals analyzed in this way, the striking lack of ubiquitous trace element zoning patterns in crystals from the same hand sample implies that fractional crystallization upon cooling was punctuated by magma recharge and crystal mixing affecting different parts of the magma reservoir. By combining data from all crystals, a systematic change to more heterogeneous trace element abundances is revealed by zircon crystal domains <45 ka following the Rotoiti caldera-forming eruption. This contrasts with the more uniform conditions of zircon crystallization lasting >100 ka prior to caldera formation and is best explained by the post-caldera system consisting of small, isolated melt pockets that evolved independently. An important conclusion is that the zircon ‘cargo’ in volcanic rocks reflects thermally and compositionally divergent processes that act near simultaneously in a magma storage region and not exclusively the conditions in the eruptible magma.  相似文献   

Active Region Formation through the Negative Effective Magnetic Pressure Instability     

Koen Kemel  Axel Brandenburg  Nathan Kleeorin  Dhrubaditya Mitra  Igor Rogachevskii 《Solar physics》2013,287(1-2):293-313

The negative effective magnetic-pressure instability operates on scales encompassing many turbulent eddies, which correspond to convection cells in the Sun. This instability is discussed here in connection with the formation of active regions near the surface layers of the Sun. This instability is related to the negative contribution of turbulence to the mean magnetic pressure that causes the formation of large-scale magnetic structures. For an isothermal layer, direct numerical simulations and mean-field simulations of this phenomenon are shown to agree in many details, for example the onset of the instability occurs at the same depth. This depth increases with increasing field strength, such that the growth rate of this instability is independent of the field strength, provided the magnetic structures are fully contained within the domain. A linear stability analysis is shown to support this finding. The instability also leads to a redistribution of turbulent intensity and gas pressure that could provide direct observational signatures.  相似文献   

Trace elements and cathodoluminescence of quartz in stockwork veins of Mongolian porphyry-style deposits   总被引：1，自引：0，他引：1  

Axel Müller  Richard Herrington  Robin Armstrong  Reimar Seltmann  Douglas J. Kirwin  Nina G. Stenina  Andreas Kronz 《Mineralium Deposita》2010,45(7):707-727

The combination of scanning electron microscope–cathodoluminescence (CL), fluid inclusion analysis and high-resolution electron probe microanalysis of Al, Ti, K and Fe in vein quartz has yielded results permitting a greater understanding of the complex mineralisation of the Central Oyu Tolgoi and Zesen Uul porphyry-style deposits, southern Mongolia. These data demonstrate the relationship between quartz precipitation, dissolution and ore deposition as the mineralising fluid chemistry changed through time. Four major quartz generations are identified in the A-type veins from the stockworks of both the Central Oyu Tolgoi (OTi to OTiv) and Zesen Uul deposits (ZUi to ZUiv). Despite differences in the associated alteration and mineralisation style, the observed CL textures and trace element signatures of the quartz generations are comparable between deposits. The OTi and ZUi stage formed both the primary network of A-type veins and pervasive silicification of the host rock. Using the Ti-in-quartz geothermometer, crystallisation temperatures for OTi and ZUi of between 598°C and 880°C are indicated. The main stage of sulphide mineralisation was accompanied by the dissolution of pre-existing quartz (OTi and ZUi) and precipitation of a weakly luminescent generation of quartz (OTii and ZUii) with a low Ti content, reflected in a calculated temperature drop from approximately 700°C to 340°C in Central Oyu Tolgoi and 445°C in Zesen Uul. OTii and ZUii stage quartzes show high and variable Al concentrations. The next stage of quartz in both deposits (OTiii and ZUiii) forms a fine network of veins in cracks formed in pre-existing quartz. OTiii and ZUiii quartz contain measurable fluid inclusions of moderate salinity (3–17.1 wt.% NaCl eq.), entrapped in the temperature range 256°C to 385°C. OTiii and ZUiii are not related to any sulphide mineralisation. The final OTiv and ZUiv stages are characterised by quartz–calcite micro-breccias that penetrate the A-type veins. Based on the calculated entrapment temperatures, the OTiv/ZUiv stage crystallised between 212°C and 335°C, and the quartz is characterised by elevated but variable Al and Fe contents. The CL and trace element signatures of the OTi to OTiii and ZUi to ZUiii stages of the two Mongolian porphyries show similar features to those observed in porphyry-style deposits from other regions. This suggests that a common sequence of quartz crystallisation occurs during the formation of early veins in many porphyry copper systems.  相似文献