TY - JOUR A1 - Nasdala, Lutz A1 - Wildner, Manfred A1 - Wirth, Richard A1 - Groschopf, Nora A1 - Pal, Dipak C. A1 - Möller, Andreas T1 - Alpha particle haloes in chlorite and cordierite N2 - Effects of the impact of natural long-term irradiation with alpha particles in one chamosite and one cordierite sample were characterised in detail using electron microprobe, Raman microprobe, optical absorption spectroscopy (cordierite only), and transmission electron microscopy (TEM; cordierite only) analysis. In both cases, the impact of He- 4 cores (alpha particles) that were emitted from actinide-bearing mineral inclusions has caused the formation of radiation damage haloes in the host mineral. These haloes have maximum radii of about 33 mu m (chamosite) and 47 mu m (cordierite). They show notably changed optical properties, i.e., intensified absorption of light as recognised by brown (chamosite) and yellow (cordierite) pleochroism and enhanced or even anomalous interference colours. In spite of the significant disturbance of their short range order, alpha particle haloes are characterised by generally low degrees of structural radiation damage. This is indicated by rather moderate broadening of vibrational bands and, in the case of cordierite, apparently undisturbed electron diffraction patterns in the TEM. Intensive damage, virtually close to an amorphous state, was only found in cordierite up to a few tens of nanometres away from actinide-bearing inclusions. This damage is mainly assigned to recoils of heavy nuclei upon emission of an alpha particle, which have particle trajectory lengths that are three orders of magnitude shorter than those of the alpha particles. Similar to observations on biotite, alpha particle haloes in chamosite and cordierite as observed in the optical microscope may be considered as representative of a very early stage of the metamictisation process Y1 - 2006 UR - http://www.springerlink.com/content/105515 ER - TY - JOUR A1 - Möller, Andreas T1 - Constraints on age and duration of metamorphic events from in-situ U-Pb dating and geochemical characterization of zircon Y1 - 2005 SN - 0016-7037 ER - TY - JOUR A1 - Möller, Andreas A1 - Post, Nicholas J. A1 - Hensen, Bastiaan J. T1 - Crustal residence history and Gamet Sm-Nd ages of high-grade metamorphic rocks from the Windmill Islands area, East Antarctica N2 - Nd whole-rock data from the Windmill Islands area yield early Proterozoic to middle Archaean Nd model ages. These crustal residence times are consistent with regional correlations with other parts of Antarctica (Bunger Hills, Denman Glacier area) and the Albany-Fraser Orogen of south-western Australia during the Mid-Proterozoic and thus support reconstructions with a continuous Mid-Proterozoic orogen in these areas. The new Nd isotope data provide strong evidence that no age boundary exists between the higher- and lower-grade parts of the Windmill Islands area, and that the metamorphic complex represents a single terrane with a common crustal history. The data support the notion of a time- link between the occurrence of intrusive charnockites (C-type magmas) and high-grade metamorphism. The magmatic rocks and orthogneisses in the area are interpreted to have a mixed source consisting of older crustal components, i.e. older sediments (ca. 3.2-2.6 Ga) and a younger mafic component (ca. 1.9 Ga). Two garnet Sm-Nd isochrons yield ages of 1156±17 Ma and 1137±2.5 Ma and are identical to SHRIMP U-Pb results on monazite from these samples. A garnet Sm-Nd age of 1123±13 Ma for the Ford granite is significantly younger than the SHRIMP U-Pb zircon age for this sample. The difference relates to the different closure temperature of each isotopic system and is thus interpreted as initial cooling after granulite facies metamorphism. Keywords. East Antarctica - Granulites - Garnet-whole rock isochrons - Intrusive charnockite - Nd model ages Y1 - 2002 UR - http://link.springer.de/link/service/journals/00531/contents/02/00291/paper/s00531-002-0291-x.pdf ER - TY - JOUR A1 - Möller, Andreas A1 - Nelson, D. R. T1 - Influence of matrix effects on U-Th-Pb dating of monazite by ion microprobe Y1 - 2005 SN - 0016-7037 ER - TY - JOUR A1 - Möller, Andreas A1 - O'Brien, Patrick J. A1 - Kennedy, Allen A1 - Kröner, Alfred T1 - Linking growth episodes of zircon and metamorphic textures to zircon chemistry : an example from the ultra-high temperature granulites of Rogaland (SW Norway) Y1 - 2003 ER - TY - JOUR A1 - Debatin, Franziska A1 - Möllmer, Jens A1 - Mondal, Suvendu Sekhar A1 - Behrens, Karsten A1 - Möller, Andreas A1 - Staudt, Reiner A1 - Thomas, Arne A1 - Holdt, Hans-Jürgen T1 - Mixed gas adsorption of carbon dioxide and methane on a series of isoreticular microporous metal-organic frameworks based on 2-substituted imidazolate-4-amide-5-imidates JF - Journal of materials chemistry N2 - In this work the adsorption of CO2 and CH4 on a series of isoreticular microporous metal-organic frameworks based on 2-substituted imidazolate-4-amide-5-imidates, IFP-1-IFP-6 (IFP Imidazolate Framework Potsdam), is studied firstly by pure gas adsorption at 273 K. All experimental isotherms can be nicely described by using the Toth isotherm model and show the preferred adsorption of CO2 over CH4. At low pressures the Toth isotherm equation exhibits a Henry region, wherefore Henry's law constants for CO2 and CH4 uptake could be determined and ideal selectivity (alpha CO2/CH4) has been calculated. Secondly, selectivities were calculated from mixture data by using nearly equimolar binary mixtures of both gases by a volumetric-chromatographic method to examine the IFPs. Results showed the reliability of the selectivity calculation. Values of (alpha CO2/CH4) around 7.5 for IFP-5 indicate that this material shows much better selectivities than IFP-1, IFP-2, IFP-3, IFP-4 and IFP-6 with slightly lower selectivity (alpha CO2/CH4) = 4-6. The preferred adsorption of CO2 over CH4 especially of IFP-5 and IFP-4 makes these materials suitable for gas separation application. Y1 - 2012 U6 - https://doi.org/10.1039/c2jm15811f SN - 0959-9428 VL - 22 IS - 20 SP - 10221 EP - 10227 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Möller, Andreas A1 - O'Brien, Patrick J. A1 - Kennedy, Allen A1 - Kröner, Alfred T1 - Polyphase zircon in ultrahigh-temperature granulites (Rogaland, SW Norway) : constraints for Pb diffusion in zircon N2 - SHRIMP U-Pb ages have been obtained for zircon in granitic gneisses from the aureole of the Rogaland anorthosite-norite intrusive complex, both from the ultrahigh temperature (UHT; >900 °C pigeonite-in) zone and from outside the hypersthene-in isograd. Magmatic and metamorphic segments of composite zircon were characterised on the basis of electron backscattered electron and cathodoluminescence images plus trace element analysis. A sample from outside the UHT zone has magmatic cores with an age of 1034 ± 7 Ma (2{sigma}, n = 8) and 1052 ± 5 Ma (1{sigma}, n = 1) overgrown by M1 metamorphic rims giving ages between 1020 ± 7 and 1007 ± 5 Ma.In contrast, samples from the UHT zone exhibit four major age groups:(1) magmatic cores yielding ages over 1500 Ma(2) magmatic cores giving ages of 1034 ± 13 Ma (2{sigma}, n = 4) and 1056 ± 10 Ma (1{sigma}, n = 1)(3) metamorphic overgrowths ranging in age between 1017 ± 6 Ma and 992 ± 7 Ma (1{sigma}) corresponding to the regional M1 Sveconorwegian granulite facies metamorphism, and(4) overgrowths corresponding to M2 UHT contact metamorphism giving values of 922 ± 14 Ma (2{sigma}, n = 6). Recrystallized areas in zircon from both areas define a further age group at 974 ± 13 Ma (2{sigma}, n = 4).This study presents the first evidence from Rogaland for new growth of zircon resulting from UHT contact metamorphism. More importantly, it shows the survival of magmatic and regional metamorphic zircon relics in rocks that experienced a thermal overprint of c. 950 °C for at least 1 Myr. Magmatic and different metamorphic zones in the same zircon are sharply bounded and preserve original crystallization age information, a result inconsistent with some experimental data on Pb diffusion in zircon which predict measurable Pb diffusion under such conditions. The implication is that resetting of zircon ages by diffusion during M2 was negligible in these dry granulite facies rocks. Imaging and Th/U-Y systematics indicate that the main processes affecting zircon were dissolution-reprecipitation in a closed system and solid-state recrystallization during and soon after M1. Y1 - 2002 ER - TY - JOUR A1 - Möller, Andreas A1 - Hensen, Bastiaan J. A1 - Armstrong, Richard A. A1 - Mezger, Klaus A1 - Ballévre, Michel T1 - U-Pb zircon and monazite age constraints on granulite-facies metamorphism and deformation in the Strangways Metamorphic Complex (central Australia) N2 - The age of Proterozoic granulite facies metamorphism and deformation in the Strangways Metamorphic Complex (SMC) of central Australia is determined on zircon grown in syn-metamorphic and syn-deformational orthopyroxene-bearing, enderbitic, veins. SHRIMP zircon studies suggest that M1-M2 and the correlated periods of intense deformation (D1-D2) are part of a single tectonothermal event between 1,717-2 and 1,732-7 Ma. It is considered unlikely that the two metamorphic phases (M1, M2) suggested by earlier work represent separate events occurring within 10-25 Ma of each other. Previous higher estimates for the age of M1 granulite metamorphism in the SMC (Early Strangways event at ca. 1,770 Ma) based on U-Pb zircon dating of granitic, intrusive rocks, are not believed to relate to the metamorphism, but to represent pre-metamorphic intrusion ages. Conventional multi-grain U-Pb monazite analyses on high-grade metasediments from three widely spaced localities in the western SMC yield 207Pb/235U ages between 1,728-11 and 1,712-2 Ma. The age range of the monazites corresponds to the SHRIMP zircon ages in the granulitic veins and is interpreted to record monazite growth (prograde in the metasedimentary rocks). The data imply a maximum time-span of 30 Ma for high-grade metamorphism and deformation in the SMC. There is, thus, no evidence for an extremely long period of continuous high- temperature conditions from 1,770 to ca. 1,720 Ma as previously proposed. The results firmly establish that the SMC has a very different high-grade metamorphic history than the neighbouring Harts Range, where upper amphibolite facies metamorphism in the Palaeozoic caused widespread growth or recrystallization of monazite. Y1 - 2003 UR - http://www.springerlink.com/app/home/ content.asp?wasp=nnkjymtwwjhb0ylpgw97&referrer=contribution&format=2&page=1&pagecount=18 ER -