Hamburg, Universiẗat, Diss., 1999.

Göttingen, Universiẗat, Diss., 2000.

Zirkon är ett mycket viktigt mineral inom geokronologin. Tack vare dess specifika kristallstruktur tassmå mängder uran och andra spårämnen upp av zirkonen vid dess bildning. Det är möjligt attbestämma en bergarts ålder genom att beräkna förhållandet mellan de radioaktiva ämnena och dessstabila slutprodukter som bildas hos zirkonen med tiden. Olika metoder och tekniker har sedandenna upptäckt utvecklats i snabb takt.Grötingengraniten har tidigare daterats med hjälp av TIMS till en ålder mellan 1,74 och 1,75 miljarderår. Denna datering har visats sig mycket osäker varför ett nytt försök till att bestämma dess ålder harplanerats in inom den närmsta framtiden. Innan man utför en sådan datering görs alltid enmikroskopisk förstudie där zirkonerna hos bergartsprovet avbildas med hjälp av olika sorterstekniker. De strukturer som kan identifieras hos zirkonerna kan sedan avslöja viktig information omvilka geologiska processer som verkat på bergarten.Syftet med denna studie var att extrahera ett antal zirkoner från Grötingengraniten för att undersökadess yttre morfologi och inre strukturer. Detta gjordes under både ett vanligt optiskt mikroskop ochett svepelektronmikroskop där BSE användes. Zirkonerna i provet uppvisade många olika strukturerfrån tydligt zonerade zirkoner till i stort sätt helt opåverkade och homogena zirkoner. Trots den storavariationen mellan strukturerna bland zirkonerna kan slutsatser dras om att denna granit troligtvisinte har påverkats av några postmagmatiska processer. Däremot syns tydliga tecken på attmagmatiska fluider funnits tillgängligt hos bergarten vid ett eller flera tillfällen. Många zirkoneruppvisar nämligen olika typer av flytstrukturer som bildats då fluider trängt in i zirkonen ochomfördelat den kemiska sammansättningen. Med tanke på att de flesta zirkoner i provet hadegenomgått en kraftig metamiktisering är det inte särskilt anmärkningsvärt att det tidigare försöket tillatt datera denna granit gav ett relativt dåligt resultat.

Freiburg i. Br., Univ., Diss., 2008.

Thèse--Géochimie--Rennes I, 1989. / Textes en français et en anglais. Résumés en anglais. Bibliogr. p. 134-154.

Univ., Diss., 2009--Frankfurt (Main). / Engl. Übers. des Hauptsacht.: U-Pb geochronology, Hf isotopy and trace element geochemistry of detrital zircons from recent sediments of the Orange and Vaal river system in South Africa.

The Karoo-aged basins evolved from assembly to break-up of the supercontinent Gondwana and were filled by denudating major mountain ranges accompanied by vast sedimentary recycling processes. A succession of rift episodes caused the emergence of a great number of these intra-cratonic basins throughout the Gondwana interior, e.g. the Aranos, Karasburg and Huab basins, which are scattered across today’s Namibia. This evolution may be split into a Permian to early Triassic and a Jurassic phase. The Karoo I phase is confined by ‘passive’ continental rifting and a retro-arc extension at the SW margin of Gondwana. The early Jurassic Karoo II rifting phase of east Africa eventually disintegrated Gondwana and led to the opening of the West Indian Ocean. A terminal early Cretaceous rifting phase led towards the opening of the southern Atlantic Ocean and ended the Gondwana supercontinent sedimentary regime. In the course of this evolution, the Namibian late Paleozoic to Mesozoic sedimentary record yields evidence for changing climates from icehouse towards extreme hothouse conditions. As based on sporadic datings the timeline of this evolution remains mostly unclear. The lack of data is in great contrast to the importance of determining the speed of major climate changes. In addition, sediment fluxes within such a supercontinent regime are not well studied but are key in understanding sediment dynamics during severe ecological and environmental changes. Therefore, this thesis tries to establish a timeframe of the sedimentary deposits for the Namibian Karoo Supergroup sedimentary deposits and furthermore tries to explore the laws of sediment dispersal prevailing in southern Gondwana. In order to answer these research questions a comprehensive dataset comprised of 41 samples with more than 5.700 U-Th-Pb LA-ICP-MS age determinations and over 1.000 Lu-Hf isotopic measurements on single zircon grains of siliciclastic rock material of the vast majority of all Permo- Carboniferous to early Cretaceous Karoo-aged Namibian formations was compiled. All of the investigated zircon crystals were also studied with respect to their grain morphology, including length, width, surface, and roundness, providing valuable information concerning transport distances and energies. In combination with whole-rock geochemical data of a majority of the investigated samples, they help deciphering the sedimentary deposition history during the Gondwana supercontinent cycle. A compiled set of southern African U-Th-Pb zircon age data is of great help interpreting sediment fluxes and inferring provenance areas. The onset of Karoo-aged sedimentation is recorded within the Aranos and Karasburg Basin successions and is represented by glacially induced diamictites of the Dwyka Group partially resting directly on pre-Cambrian basement complexes. In places, two distinct E-W directed ice advances are present. The deposition of these glacial diamictites was prior to 296 Ma, as two ash beds incorporated within the overlying shale successions yield Asselian deposition ages. Further hints concerning ice-induced deposition disappear at the Sakmarian-Artinskian boundary, as the lowermost succession of the Ecca Group yields a maximum deposition age of ca. 290 Ma, documenting the end of the Dwyka ice age in the southern Namibian area. The lowermost Ecca Group deposits of the Huab Basin yield a maximum deposition age of ca. 295 Ma, suggesting an earlier termination of the Dwyka ice age in the north. The uppermost strata of the Aranos and Karasburg Basins were dated ca. 265 Ma and 255 Ma, respectively, revealing a disparate depositional history. Due to a lack of datable ash beds as well as no detrital zircon grain ages near the assumed sedimentation age it was not possible to determine a detailed sedimentation history for the Huab, Kunene River, and Waterberg Basin deposits. Detrital zircon U-Th-Pb ages are routinely used in order to trace siliciclastic sedimentary rocks to their bedrock sources, deriving transport directions. This classic ‘source-to-sink’ approach is most likely obscured by several cycles of sediment homogenization processes. A majority of all investigated samples yield high portions of detrital zircon fractions of late Mesoproterozoic (950-1150 Ma) and Neoproterozoic (440-650 Ma) age. In addition, all Jurassic and Cretaceous samples yield a prominent Permian age fraction of 250-280 Ma, suggesting a Gondwanides orogen provenance. Thus, the investigated siliciclastic rocks consist of already recycled sedimentary material. This observation is supported by a high degree of zircon grain roundness. As of zircon grain hardness long transport distances are necessary to achieve latter. This suggests that one sedimentary sink is source for the next sedimentary cycle. A comparison with the detrital zircon record of other southern Gondwanan Permo-Carboniferous successions shows similar results, strongly pointing towards a supercontinent-wide sedimentary recycling regime. Therefore, detrital zircon age patterns within supercontinent scenarios reflect large-scale sedimentary processes rather than primary provenance information.:1 Introduction 1 1.1 Evolution of the Namibian landscape from Carboniferous to Cretaceous times 2 1.2 Thesis format 5 1.3 References 5 2 Methods 10 2.1 Sample preparation and zircon morphometrics 10 2.2 U-Th-Pb age determination 10 2.3 Lu-Hf model age determination via LA-(MC)-ICP-MS 12 2.4 Geochemical analysis 12 2.5 Comparative statistics 12 2.6 References 13 3 Study I: The Permo-Carboniferous Dwyka Group of the Aranos Basin (Namibia) – How detrital zircons help understanding sedimentary recycling during a major glaciation 15 3.1 Introduction 17 3.2 Regional geological setting 17 3.2.1 Geology of the Permo-Carboniferous Dwyka Group (Aranos Basin) 19 3.2.2 Paleotectonic significance of the Dwyka formations 22 3.3 Methods 24 3.4 Results 26 3.5 Discussion 30 3.5.1 Significance of zircon morphologies for sediment fluxes 32 3.5.2 Potential sedimentation rates and source areas indicated by U-Pb age data 35 3.5.3 Implications for the evolution of the Dwyka Group 42 3.6 Conclusions 46 3.7 References 47 4 Study II: The evolution of the southern Namibian Karoo-aged basins: Implications from detrital zircon geochronologic and geochemistry data 63 4.1 Introduction 64 4.2 Geology of the Aranos and Karasburg basins 66 4.3 Tectonic and structural framework of the southern African Karoo aged basins 70 4.4 Methods 71 4.5 Results 75 4.6 Discussion 80 4.6.1 Timing of the Formation of the Aranos and Karasburg basins 80 4.6.2 Provenance and evolution of the upper Paleozoic Aranos and Karasburg basins 85 4.6.3 Implications for the Karoo-aged basin sedimentary record 93 4.7 Conclusions 95 4.8 References 98 5 Study III: Mesozoic deposits of SW Gondwana (Namibia): Unravelling Gondwanan sedimentary dispersion drivers by detrital zircon 109 5.1 Introduction 110 5.2 Geological background 113 5.2.1 Evolution of the southwestern Gondwanan Mesozoic successions 113 5.2.2 Namibian Mesozoic successions 117 5.3 Methods 120 5.4 Results 123 5.5 Discussion 130 5.5.1 Protosources of the sediments 130 5.5.2 Recycling dynamics of the Mesozoic sediments 133 5.6 Conclusions 139 5.7 References 140 6 Study IV: Tracing southern Gondwanan sedimentary paths: A case study of northern Namibian Karoo-aged sedimentary rocks 153 6.1 Introduction 154 6.2 Geological setting 156 6.2.1 SW Gondwanan rifting history and sediment dispersal 156 6.2.2 The northern Namibian Karoo-aged Huab Basin and Kunene section 157 6.3 Methods 161 6.4 Results 165 6.5 Discussion 175 6.5.1 Timing of deposition of the Huab Basin strata 175 6.5.2 Protosources of the sediments 176 6.5.3 Detrital zircon grain morphology and isotope analysis 178 6.5.4 The northern Namibian Karoo-aged basins within the southern Gondwanan framework 185 6.6 Conclusions 186 6.7 References 187 7 Conclusions and outlook 199 8 Supplements 201

This thesis results from a pilot study which, driven by repeatedly surprising results, opens up a reliable method of geochronology for Quaternary research. There have been repeated attempts to expand the limits of normal use of U-Pb dating. Geologists typically use U-Pb dating on detrital zircons (DZ) for dating and provenance studies on rocks older than the Cenozoic era. We tested several tephra layers in Utah and New Mexico, USA, with published 40 Ar/ 39 Ar ages between 1.3 and 1.6 Ma and found that the ages derived from clustered U-Pb dating are reliable, even though they were discordant. We used one of these tephra layers in the La Sal Mountains, Utah, to assign a minimum age to slope deposit layers (cover beds) underlying the tephra bed. In doing so, we discovered that we could not only identify unconformities between layers by means of palaeopedology. But that - although they were similar to one another regarding physical and chemical properties - they were not the same at all in terms of the provenance of their aeolian matter as derived from U-Pb analysis of detrital zircons, as one could actually assume. The source of aeolian matter mixed to these layers has changed decisively from layer to layer. The findings also allowed tentatively assigning palpable source areas for each layer. Since this had demonstrated the feasibility of a provenance approach, we then extended our study regionally to cover beds of the central Great Basin (GB) and the northern Colorado Plateau (CP). Using a published sequence-stratigraphic approach based upon stratigraphically consistent phases of soil development, we attempted to study cover beds from the same two Upper Quaternary time slices. We expanded our range of methods by end-member modelling analyzes (EMMA) and the analysis of surface and shape of detrital zircons. We used statistical methods such as multidimensional scaling (MDS) and density functions (probability density functions and kernel density estimations) to visualize similarities and distances of age distributions. The MDS and the density functions showed very clearly that the patterns of ages between the GB and the CP can be divided into two groups that differ from one another. This is probably due to different transport cascades of the zircons to and within both areas. Due to the lack of databases on the morphology of in-situ zirconia, it is not yet possible to draw precise conclusions about transport routes from them, although we have probably been able to identify traces of several stages of aeolian transport on many zircons. Conclusions can also be drawn about detrital zircons that were transported to the sampling point purely by the kinetic energy of volcanic eruptions during the Cretaceous (Cordilleran magmatic arc) and the Paleogene (strong volcanism within the study area). Moreover, we can show main similarities of the layers across the CP. Although they are separated spatially and temporally, they have a similar age distribution. The only exception here is the upper La Sal Mountains profile, for which I have several assumptions as to why this is so. We did not have enough conclusions for the reconstruction of the palaeoenvironmental conditions during the layer and soil formation phases; further investigations will have to follow. However, we show that a provenance study on Quaternary layers and further conclusions from the results are possible and would like to condense this approach for the study area in the future, but also try to transfer it to other study areas.:Abstract .......................................................................................................................3 Kurzfassung ................................................................................................................5 Contents ......................................................................................................................7 List of figures ............................................................................................................ 11 List of tables ............................................................................................................. 13 List of abbreviations and units .................................................................................. 14 1 Introduction ........................................................................................................... 16 1.1 Research questions ........................................................................................... 16 1.2 Cover beds ......................................................................................................... 17 1.3 Palaeosols .......................................................................................................... 17 1.4 Study area .......................................................................................................... 18 1.5 Zircons ............................................................................................................... 21 1.6 Thesis format ...................................................................................................... 23 2 Capability of U-Pb dating of zircons from Quaternary tephra: Jemez Mountains, NM, and La Sal Mountains, UT, USA ....................................................................... 24 2.1 Abstract .............................................................................................................. 25 2.2 Kurzfassung ....................................................................................................... 25 2.3 Introduction ........................................................................................................ 26 2.4 Geological setting ............................................................................................... 27 2.4.1 Jemez Mountains, New Mexico ...................................................................... 27 2.4.2 La Sal Mountains, Utah ................................................................................... 30 2.5 Methods ............................................................................................................. 30 2.6 Results and discussion ..................................................................................... 33 2.6 Conclusions ........................................................................................................ 38 Data availability ........................................................................................................ 38 Competing interests.................................................................................................. 38 Acknowledgements .................................................................................................. 38 2.7 References ......................................................................................................... 39 3 Cover beds older than the mid-Pleistocene revolution and the provenance of their aeolian components, La Sal Mountains, Utah, USA ........................................ 42 3.1 Abstract .............................................................................................................. 43 3.2 Introduction ........................................................................................................ 43 3.3 Material and methods ........................................................................................ 44 3.3.1 The La Sal Mountains tephra layer ................................................................. 44 3.3.2 Cover beds and palaeosols............................................................................. 45 3.3.3 Samples and analyses .................................................................................... 46 3.4 Results and discussion ...................................................................................... 49 3.5 Conclusions ....................................................................................................... 56 Acknowledgments ................................................................................................... 58 Summary information A. Supplementary data ......................................................... 58 3.6 References ........................................................................................................ 58 4 Zircon provenance of Quaternary cover beds using U-Pb dating: regional differences in the south-western USA ...................................................................... 63 4.1 Abstract .............................................................................................................. 64 4.2 Introduction ........................................................................................................ 65 4.3 Materials ............................................................................................................. 66 4.3.1 Study areas ..................................................................................................... 66 4.3.2 Stratigraphy and sampling sites ...................................................................... 68 4.3.3 Palaeolake deposits ........................................................................................ 71 4.3.4 Potential sources of detrital zircons ................................................................ 71 4.4 Methods ............................................................................................................. 75 4.4.1 End-member modelling of grainsize composition ........................................... 75 4.4.2 U-Pb dating ..................................................................................................... 75 4.4.3 Zircon dimensions and surfaces ..................................................................... 77 4.4.4 Statistical and graphical representations ........................................................ 78 4.5 Results and discussion ...................................................................................... 79 4.5.1 Aeolian contribution to cover beds .................................................................. 79 4.5.2 Zircon morphology .......................................................................................... 82 4.5.3 Age distributions of detrital zircons ................................................................. 88 4.5.4 Multidimensional scaling (MDS) ..................................................................... 94 4.6 Conclusions ....................................................................................................... 98 Appendix ................................................................................................................ 102 Acknowledgements ................................................................................................ 102 4.7 References ....................................................................................................... 103 5 Extended summary .............................................................................................. 118 5.1 Synthesis .......................................................................................................... 118 5.2 Regional differences and similarities ................................................................ 123 5.3 Outlook ............................................................................................................. 128 6 Supplementary Information ................................................................................. 130 6.1 Supplementary material chapter ‘Capability of U-Pb dating of zircons from Quaternary tephra: Jemez Mountains, NM, and La Sal Mountains, UT, USA’........ 130 6.1.1 Raw data electron microprobe analyses of glass shards from tephra layers .131 6.1.2 Raw data U-Pb ratios and calculated ages for all samples ............................137 6.2 Supplementary material chapter 3 ‘Cover beds older than the mid-Pleistocene revolution and the provenance of their eolian components, La Sal Mountains, Utah, USA’ .............................................................................................................. 160 6.3 Supplementary material chapter 4 ................................................................... 175 6.3.1 SI1 Raw U-Pb ratios and calculated ages ......................................................175 6.3.2 SI 3 Grainsize diagrams of samples of the present study (except for PL)......266 6.3.3 SI 4 Zircon morphology data .........................................................................269 6.3.3.1 Great Basin .................................................................................................269 6.3.3.2 Colorado Plateau ........................................................................................289 7 References (excluding chapters 2, 3 and 4) ....................................................... 308 8 Acknowledgements ............................................................................................. 312 / Diese Arbeit ist das Ergebnis einer Pilotstudie, die aufgrund immer wieder neuer, unerwarteter Ergebnisse eine zuverlässige geochronologische Methode für die Quartärforschung eröffnet. Es wurde mehrfach versucht, die üblichen Grenzen der Verwendung der U-Pb-Datierung zu erweitern. In der Geologie wird die U-Pb-Datierung an detritischen Zirkonen (DZ) normalerweise für Datierungs- und Provenienzstudien an Gesteinen, die älter als das Känozoikum sind, eingesetzt. Wir haben mehrere Tephra-Schichten in Utah und New Mexico, USA, mit veröffentlichten 40 Ar/ 39 Ar-Altern zwischen 1.3 und 1.6 Ma getestet und festgestellt, dass die Alter, die aus den Clustern der U-Pb-Datierungen abgeleitet wurden, zuverlässig sind, obwohl sie diskordant waren. Wir haben eine dieser Tephra-Schichten in den La Sal Mountains, Utah, verwendet, umlagernden Deckschichten ein Mindestalter zuzuweisen. Dabei stellten wir fest, dass wir nicht nur mittels Paläopädologie Schichtgrenzen zwischen Schichten ausweisen konnten. Sondern dass sie sich, obwohl sie sich in Bezug auf physikalische und chemische Eigenschaften ähneln, in Bezug auch auf die Herkunft ihres äolischen Materials (abgeleitet aus der U-Pb-Analyse der DZ) überhaupt nicht glichen, wie man eigentlich annehmen könnte. Die Herkunft des eingemischten äolischen Materials hat sich von Schicht zu Schicht entscheidend verändert. Die Ergebnisse ermöglichten es auch, jeder Schicht konkrete wahrscheinliche Liefergebiete zuzuweisen. Da dies die Möglichkeit einer Provenienz-Analyse belegt hatte, erweiterten wir unsere Studie regional auf Deckschichten des zentralen Great Basin (GB) und des nördlichen Colorado Plateaus (CP). Unter Verwendung eines publizierten sequenz-stratigraphischen Ansatzes, der auf stratigraphisch konsistenten Phasen der Bodenentwicklung basiert, haben wir versucht, Deckschichten aus denselben beiden oberen quartären Zeitscheiben zu untersuchen. Wir erweiterten unser Methodenspektrum um End Member-Modellierung (EMMA) und die Analyse der Oberfläche und Form von DZ. Wir verwendeten statistische Methoden wie mehrdimensionale Skalierung (MDS) und Dichtefunktionen (Wahrscheinlichkeitsdichtefunktionen und Kerndichteschätzungen), um Ähnlichkeiten und Abstände von Altersverteilungen zu visualisieren. MDS und Dichtefunktionen zeigten deutlich, dass GB und CP unterschiedliche Altersspektren aufweisen. Dies ist wahrscheinlich auf unterschiedliche Transportkaskaden der Zirkone in beide und innerhalb beider Gebiete zurückzuführen. Aufgrund des Fehlens von Datenbanken zur Morphologie von gesteinsbürtigen Zirkonen kann man daraus noch keine genauen Rückschlüsse über Transportwege ziehen, obwohl wir wahrscheinlich an vielen Zirkonen Spuren mehrerer Schritte des äolischen Transports identifizieren konnten. Es liegen auch DZ vor, die vermutlich ausschließlich durch die kinetische Energie von Vulkanausbrüchen während der Kreidezeit (Cordilleran Magmatic Arc) und des Paläogens (starker Vulkanismus innerhalb des Untersuchungsgebiets) zum Probenahmepunkt transportiert wurden. Darüber hinaus können wir Ähnlichkeiten zwischen den verschiedenen Schichten im CP zeigen. Obwohl sie räumlich und zeitlich getrennt sind, haben sie eine ähnliche Altersverteilung. Die einzige Ausnahme hiervon ist das Profil der höheren La Sal Mountains, wofür es mehrere mögliche Gründe gibt. Wir konnten nicht genügend Erkenntnisse für die Rekonstruktion der paläoökologischen Bedingungen während der Schicht- und Bodenbildungsphasen gewinnen; weitere Untersuchungen müssen folgen. Wir zeigen jedoch, dass eine Provenienzstudie an quartären Schichten und weiterreichende Schlussfolgerungen möglich sind, und möchten diesen Ansatz für das Untersuchungsgebiet in Zukunft verdichten, aber auch versuchen, ihn auf andere Untersuchungsgebiete zu übertragen.:Abstract .......................................................................................................................3 Kurzfassung ................................................................................................................5 Contents ......................................................................................................................7 List of figures ............................................................................................................ 11 List of tables ............................................................................................................. 13 List of abbreviations and units .................................................................................. 14 1 Introduction ........................................................................................................... 16 1.1 Research questions ........................................................................................... 16 1.2 Cover beds ......................................................................................................... 17 1.3 Palaeosols .......................................................................................................... 17 1.4 Study area .......................................................................................................... 18 1.5 Zircons ............................................................................................................... 21 1.6 Thesis format ...................................................................................................... 23 2 Capability of U-Pb dating of zircons from Quaternary tephra: Jemez Mountains, NM, and La Sal Mountains, UT, USA ....................................................................... 24 2.1 Abstract .............................................................................................................. 25 2.2 Kurzfassung ....................................................................................................... 25 2.3 Introduction ........................................................................................................ 26 2.4 Geological setting ............................................................................................... 27 2.4.1 Jemez Mountains, New Mexico ...................................................................... 27 2.4.2 La Sal Mountains, Utah ................................................................................... 30 2.5 Methods ............................................................................................................. 30 2.6 Results and discussion ..................................................................................... 33 2.6 Conclusions ........................................................................................................ 38 Data availability ........................................................................................................ 38 Competing interests.................................................................................................. 38 Acknowledgements .................................................................................................. 38 2.7 References ......................................................................................................... 39 3 Cover beds older than the mid-Pleistocene revolution and the provenance of their aeolian components, La Sal Mountains, Utah, USA ........................................ 42 3.1 Abstract .............................................................................................................. 43 3.2 Introduction ........................................................................................................ 43 3.3 Material and methods ........................................................................................ 44 3.3.1 The La Sal Mountains tephra layer ................................................................. 44 3.3.2 Cover beds and palaeosols............................................................................. 45 3.3.3 Samples and analyses .................................................................................... 46 3.4 Results and discussion ...................................................................................... 49 3.5 Conclusions ....................................................................................................... 56 Acknowledgments ................................................................................................... 58 Summary information A. Supplementary data ......................................................... 58 3.6 References ........................................................................................................ 58 4 Zircon provenance of Quaternary cover beds using U-Pb dating: regional differences in the south-western USA ...................................................................... 63 4.1 Abstract .............................................................................................................. 64 4.2 Introduction ........................................................................................................ 65 4.3 Materials ............................................................................................................. 66 4.3.1 Study areas ..................................................................................................... 66 4.3.2 Stratigraphy and sampling sites ...................................................................... 68 4.3.3 Palaeolake deposits ........................................................................................ 71 4.3.4 Potential sources of detrital zircons ................................................................ 71 4.4 Methods ............................................................................................................. 75 4.4.1 End-member modelling of grainsize composition ........................................... 75 4.4.2 U-Pb dating ..................................................................................................... 75 4.4.3 Zircon dimensions and surfaces ..................................................................... 77 4.4.4 Statistical and graphical representations ........................................................ 78 4.5 Results and discussion ...................................................................................... 79 4.5.1 Aeolian contribution to cover beds .................................................................. 79 4.5.2 Zircon morphology .......................................................................................... 82 4.5.3 Age distributions of detrital zircons ................................................................. 88 4.5.4 Multidimensional scaling (MDS) ..................................................................... 94 4.6 Conclusions ....................................................................................................... 98 Appendix ................................................................................................................ 102 Acknowledgements ................................................................................................ 102 4.7 References ....................................................................................................... 103 5 Extended summary .............................................................................................. 118 5.1 Synthesis .......................................................................................................... 118 5.2 Regional differences and similarities ................................................................ 123 5.3 Outlook ............................................................................................................. 128 6 Supplementary Information ................................................................................. 130 6.1 Supplementary material chapter ‘Capability of U-Pb dating of zircons from Quaternary tephra: Jemez Mountains, NM, and La Sal Mountains, UT, USA’........ 130 6.1.1 Raw data electron microprobe analyses of glass shards from tephra layers .131 6.1.2 Raw data U-Pb ratios and calculated ages for all samples ............................137 6.2 Supplementary material chapter 3 ‘Cover beds older than the mid-Pleistocene revolution and the provenance of their eolian components, La Sal Mountains, Utah, USA’ .............................................................................................................. 160 6.3 Supplementary material chapter 4 ................................................................... 175 6.3.1 SI1 Raw U-Pb ratios and calculated ages ......................................................175 6.3.2 SI 3 Grainsize diagrams of samples of the present study (except for PL)......266 6.3.3 SI 4 Zircon morphology data .........................................................................269 6.3.3.1 Great Basin .................................................................................................269 6.3.3.2 Colorado Plateau ........................................................................................289 7 References (excluding chapters 2, 3 and 4) ....................................................... 308 8 Acknowledgements ............................................................................................. 312

Effect of electrochemical absorption of hydrogen has been studied on the Zr-based amorphous alloys. The influence of hydrogen absorption on the stability of the amorphous phase and its crystallisation was investigated. Additionally, the cathodic hydrogen reaction mechanism on the surface of the alloy, the reversibility of the absorbed hydrogen and the hydrogen diffusion in the alloy were studied. These alloys are able to absorb large amounts of hydrogen (>1:1 hydrogen to metal ratio) but a rearrangement of the amorphous matrix takes place so that Cu rich areas are detected on the surface and Zr-hydride may precipitate. The thermal stability and crystallisation behaviour depends on the hydrogen concentration in the alloy. At low hydrogen concentration, the thermal stability deteriorates and primary crystallisation of Cu and/or Cu-rich phases is observed. At high hydrogen concentration, primary crystallisation of Zr-hydride takes place. The cathodic polarisation behaviour of amorphous Zr-based alloys as derived from Tafel plots reveals three characteristic potential regions reflecting the different mechanisms of hydrogen on the surface. In the Tafel region, hydrogen discharge and adsorption takes place on the alloy surface as fast steps reactions followed by the rate determining electrodic desorption reaction step in competition with hydrogen absorption as a fast step. In the further negative potential region, the current density is independent on the potential as both the Volmer and the Heyrowsky reactions take place at the same rate and the hydrogen mass transfer from the solution to the electrode surface is the rate-determining step. In the high polarisation region, all the partial hydrogen reactions take place intensively. The reversibility of the absorbed hydrogen tests reflects the possibility of hydrogen desorption from different energy sites in the amorphous alloy. The diffusion of hydrogen in the Zr-based alloys is comparable with that in the crystalline Pd and it is reduced in the pre-hydrogenated samples.

Die Herstellung keramischer Filter für den Einsatz in der Eisen- und Stahlschmelzfiltration ist mittels viskoplastischer Formgebung möglich. Es wurden keine Trägermaterialien verwendet und weitestgehend wurde ohne Zusatz organischer Additive gearbeitet. Wesentliche Ziele der Anwendung dieser Technologie waren dabei eine Festigkeitssteigerung gegenüber herkömmlichen Schaumkeramikfiltern, da keine Hohlstege, sondern Vollstrukturen erzeugt werden und die Kostenreduzierung der Gesamtbilanz, da der Brennprozess günstiger wird (es werden keine Filteranlagen mehr benötigt) und Kosten für Schäume entfallen. Eine entsprechende Struktur kann mit der Kolbenpresse in Form von ungeordneten Strängen erzeugt werden - die so genannten Spaghettifilter. Die Auswertung der Gussstücke aus Gießversuchen mit Eisenschmelze wurde mittels 3D-CT Röntgentomographie durchgeführt. Der Filtrationswirkungsgrad der Schaumfilter ist nach dieser Methode höher als der der Spaghettifilter. Die 3D CT Röntgentomographie kommt eventuell als eine einfache und zerstörungsfreie Methode zur Beurteilung der Filtrationswirkung in Frage. Das Anlegen einer Spannung im System Filter / Schmelze zeigt nach ersten Versuchen chancenreiche Ergebnisse. Durch den Polarisationseffekt kann eine Erhöhung der Abscheideeffizienz bei Schaumkeramikfiltern erreicht werden kann. Die Spaghettifilter zeigen keine Erhöhung durch spannungsunterstützte Filtration.