About 24 % of the land surface in the northern hemisphere are underlayed by permafrost in various states. Permafrost aggradation occurs under special environmental conditions with overall low annual precipitation rates and very low mean annual temperatures. Because the general permafrost occurrence is mainly driven by large-scale climatic conditions, the distribution of permafrost deposits can be considered as an important climate indicator. The region with the most extensive continuous permafrost is Siberia. In northeast Siberia, the ice- and organic-rich permafrost deposits of the Ice Complex are widely distributed. These deposits consist mostly of silty to fine-grained sandy sediments that were accumulated during the Late Pleistocene in an extensive plain on the then subaerial Laptev Sea shelf. One important precondition for the Ice Complex sedimentation was, that the Laptev Sea shelf was not glaciated during the Late Pleistocene, resulting in a mostly continuous accumulation of permafrost sediments for at least this period. This shelf landscape became inundated and eroded in large parts by the Holocene marine transgression after the Last Glacial Maximum. Remnants of this landscape are preserved only in the present day coastal areas.<br><br> Because the Ice Complex deposits contain a wide variety of palaeo-environmental proxies, it is an excellent palaeo-climate archive for the Late Quaternary in the region. Furthermore, the ice-rich Ice Complex deposits are sensible to climatic change, i.e. climate warming. Because of the large-scale climatic changes at the transition from the Pleistocene to the Holocene, the Ice Complex was subject to extensive thermokarst processes since the Early Holocene.<br><br> Permafrost deposits are not only an environmental indicator, but also an important climate factor. Tundra wetlands, which have developed in environments with aggrading permafrost, are considered a net sink for carbon, as organic matter is stored in peat or is syn-sedimentary frozen with permafrost aggradation. Contrary, the Holocene thermokarst development resulted in permafrost degradation and thus the release of formerly stored organic carbon. Modern tundra wetlands are also considered an important source for the climate-driving gas methane, originating mainly from microbial activity in the seasonal active layer.<br><br> Most scenarios for future global climate development predict a strong warming trend especially in the Arctic. Consequently, for the understanding of how permafrost deposits will react and contribute to such scenarios, it is necessary to investigate and evaluate ice-rich permafrost deposits like the widespread Ice Complex as climate indicator and climate factor during the Late Quaternary. Such investigations are a pre-condition for the precise modelling of future developments in permafrost distribution and the influence of permafrost degradation on global climate.<br><br> The focus of this work, which was conducted within the frame of the multi-disciplinary joint German-Russian research projects "Laptev Sea 2000" (1998-2002) and "Dynamics of Permafrost" (2003-2005), was twofold. First, the possibilities of using remote sensing and terrain modelling techniques for the observation of periglacial landscapes in Northeast Siberia in their present state was evaluated and applied to key sites in the Laptev Sea coastal lowlands. The key sites were situated in the eastern Laptev Sea (Bykovsky Peninsula and Khorogor Valley) and the western Laptev Sea (Cape Mamontovy Klyk region). For this task, techniques using CORONA satellite imagery, Landsat-7 satellite imagery, and digital elevation models were developed for the mapping of periglacial structures, which are especially indicative of permafrost degradation. The major goals were to quantify the extent of permafrost degradation structures and their distribution in the investigated key areas, and to establish techniques, which can be used also for the investigation of other regions with thermokarst occurrence. Geographical information systems were employed for the mapping, the spatial analysis, and the enhancement of classification results by rule-based stratification. The results from the key sites show, that thermokarst, and related processes and structures, completely re-shaped the former accumulation plain to a strongly degraded landscape, which is characterised by extensive deep depressions and erosional remnants of the Late Pleistocene surface. As a results of this rapid process, which in large parts happened within a short period during the Early Holocene, the hydrological and sedimentological regime was completely changed on a large scale. These events resulted also in a release of large amounts of organic carbon. Thermokarst is now the major component in the modern periglacial landscapes in terms of spatial extent, but also in its influence on hydrology, sedimentation and the development of vegetation assemblages. Second, the possibilities of using remote sensing and terrain modelling as a supplementary tool for palaeo-environmental reconstructions in the investigated regions were explored. For this task additionally a comprehensive cryolithological field database was developed for the Bykovsky Peninsula and the Khorogor Valley, which contains previously published data from boreholes, outcrops sections, subsurface samples, and subsurface samples, as well as additional own field data. The period covered by this database is mainly the Late Pleistocene and the Holocene, but also the basal deposits of the sedimentary sequence, interpreted as Pliocene to Early Pleistocene, are contained. Remote sensing was applied for the observation of periglacial strucures, which then were successfully related to distinct landscape development stages or time intervals in the investigation area. Terrain modelling was used for providing a general context of the landscape development. Finally, a scheme was developed describing mainly the Late Quaternary landscape evolution in this area. A major finding was the possibility of connecting periglacial surface structures to distinct landscape development stages, and thus use them as additional palaeo-environmental indicator together with other proxies for area-related palaeo-environmental reconstructions. In the landscape evolution scheme, i.e. of the genesis of the Late Pleistocene Ice Complex and the Holocene thermokarst development, some new aspects are presented in terms of sediment source and general sedimentation conditions. This findings apply also for other sites in the Laptev Sea region. / Die vorliegende Arbeit wurde im Rahmen der multidisziplinären Deutsch-Russischen Verbundprojekte "Laptev See 2000" (1998-2002) und "Dynamik des Permafrost" (2003-2005) erstellt.<br> Etwa 24 % der Landoberfläche der Erde sind von Permafrost unterlagert. Die ausgedehntesten Permafrostgebiete befinden sich heute in Sibirien. In Nordostsibirien, das während der letzten Eiszeit nicht von Inlandeismassen bedeckt bedeckt war, lagerten sich während dieser Zeit mächtige eisreiche Permafrostsedimente ab. Die durch den nacheiszeitlichen Meeresspiegelanstieg um ca. 120 Meter nur noch in den heutigen Küstengebieten erhaltenen Ablagerungen sind zum Teil hervorragende Paläoklimaarchive, die verschiedenste fossile organische Überreste der Eiszeitlichen Fauna und Flora konserviert haben. Aber auch die Sedimente und das enthalten Grundeis enthalten Klimainformationen z.B. die aus Mineralogie, Ablagerungsmilieu oder geochemischer und isotopenchemischer Zusammensetzung gewonnen werden können.<br><br> Der hohe Eisgehalt in den Sedimenten führte mit Beginn der holozänen Warmzeit zur Bildung von Thermokarst und Thermo-Erosion, d.h. zu starken Zersetzungserscheinungen durch Auftauen und Erosion. Thermokarst beschreibt das Schmelzen des Grundeises und die gleichzeitig stattfindende tiefe Absenkung der betroffenen Landoberfläche. Thermokarst geht mit der Bildung von Thermokarstseen einher, deren Wasserkörper ein zusätzlicher Wärmespeicher ist und das Auftauen des darunter liegenden Permafrost verstärken kann. In Sibirien, aber auch anderen Regionen der Arktis, sind weite Gebiete von Thermokarst betroffen. Der Einfluss dieser klimabedingten großräumigen Landschaftsveränderungen in Permafrostgebieten auf den lokalen, regionalen und auch globalen Stoff- und Energiehaushalt ist bisher nur wenig untersucht. Die vorliegende Arbeit beschäftigt sich mit der Charakterisierung und Evolution von periglazialen Landschaften im nordsibirischen Laptevsee-Gebiet, die seit dem Beginn des Holozän von solchen klimatisch bedingten Veränderungen betroffen sind, und liefert damit ein Puzzleteil zum einen für die Rekonstruktion der Landschaft und Landschaftsentwicklung als auch Vorraussetzungen für das Verständnis der großräumig wirkenden geologischen und geomorphologischen Veränderungsprozesse. Die generellen Schwerpunkte, für die die vorliegende Arbeit Informationen liefert, sind die Charakterisierung von periglazialen Relief- und Oberflächentypen und die Bestimmung ihrer räumlichen Verbreitung, die Identifizierung und Quantifizierung einzelner geologischer und geomorphologischer Prozesse in diesen Landschaften, und die Rekonstruktion der Entwicklung periglazialer Landschaften im Spätquartär für Schlüsselgebiete im Küstengebiet der nordsibirischen Laptevsee.<br><br> Um diese generellen Schwerpunkte zu erreichen, werden verschiedene Einzelziele in der Arbeit verfolgt:<br><br> Die Entwicklung and Anwendung von Satellitenfernerkundungstechniken zur Analyse periglazialer Landschaften in Nordsibirien. Dazu werden hochauflösende Corona-Satellitendaten und multispektrale Landsat-7 Satellitendaten verwendet.<br> Die Untersuchung von Satellitenbildern, mit dem Schwerpunkt auf Oberflächen, die von der Zersetzung des eisreichen Permafrosts betroffen sind<br> Die Entwicklung von hochauflösenden digitalen Geländemodellen für die geomorphologische Analyse in zwei Schlüsselgebieten<br> Die räumliche Untersuchung der gewonnenen Daten mit Hilfe von geographischen Informationssystemen, mit einem Schwerpunkt auf Form, Verteilung und Außmaß von holozänem Thermokarst<br> Das Sammeln und Auswerten von Felddaten, mit Schwerpunkt auf Oberflächeneigenschaften periglazialer Landschaften und der Zusammensetzung der Permafrostablagerungen<br> Die Anwendung der gewonnenen Daten zur Unterstützung, Verbesserung und Ausweitung der lokal gewonnenen Felddaten und Paläoumweltrekonstruktionen, sowie die datengestützte Entwicklung von Vorstellungen zur Landschaftsgenese<br><br> Weite, Permafrost-dominierte Küstentiefländer der heutigen Laptevsee in Nordost-Sibirien sind durch die spätpleistozänen Ablagerungen des Eiskomplex aufgebaut. Diese zumeist schluffig bis mittelsandigen Ablagerungen sind durch einen sehr großen Eisgehalt in Form von verteiltem Grundeis und großer syngenetischer Eiskeile, sowie einem relativ hohen Anteil an organischen Resten gekennzeichnet. Mit Beginn der holozänen Klimaerwärmung kam es zur weitläufigen Bildung von Thermokarst.

This thesis deals with the role of precipitation on erosion and landscape formation in the Nepal Himalayas. I investigate all successive steps involved in the erosion process: 1) Starting from the evaluation of precipitation datasets, 2) the transfer of precipitation to river discharge, 3) the mobilization and transport of material out of the mountain range, 4) and finally, erosion constrains over longer time-scales. I show that the dataset derived from the interpolation of rain gauge data performs best in the Himalayas. I demonstrate the importance of an until now unconsidered, major compartment of the Himalayan discharge cycle, which I identify as a fractured basement aquifer, and estimate the snow and ice melt contribution to the Himalayan rivers. Erosion rates calculated from suspended sediment fluxes and cosmogenic nuclide analysis range between 0.1 and 4 mm/yr. The rivers in the Nepal Himalayas are supply limited and the hillslopes as contributing source are transport limited. Last I show that over several thousand years erosion is not related with precipitation, but with relief. / Cette thèse porte sur le rôle des précipitations sur l’érosion et la formation des reliefs dans l’Himalaya Népalais. J’étudie chaque étape du processus d’érosion : 1) Evaluation des bases de données de précipitations, 2) Transfert des précipitations au débit fluvial, 3) Mobilisation et transport du matériel dans le bassin versant, et enfin 4) Mécanismes d’érosion sur de longues échelles de temps. Je montre que la base de données de précipitations obtenue par interpolation de données pluviométriques est la plus performante pour la région de l\'Himalaya. Je démontre l’importance d’une composante majeure, jusqu’alors ignorée, du cycle de débit de l’Himalaya que j’identifie comme étant les aquifères de sous-sol fracturé, et j’évalue la contribution de la fonte des neiges et glaces aux rivières Himalayennes. Les taux d’érosion calculés à partir des flux de sédiments en suspension et des analyses de nucléides cosmogéniques varient de 0.1 à 4 mm/a. Les rivières au Népal sont limitées par l’apport sédimentaire alors que les versants, en tant que source de sédiments, sont limités par le transport. Enfin, je montre que l’érosion sur des milliers d’années ne dépend des précipitations mais du relief. / Die vorliegende Arbeit beschäftigt sich mit der Rolle des Niederschlag bei Erosions- und Oberflächenprozessen im nepalesischen Himalaja. Ich untersuche die Abfolge der Erosionspsozesse im Himalaja: 1) Ausgehend von der Bewertung von Niederschlagsdatensätzen, 2) die Prozesse der Abflussbildung in Flüssen, 3) die Mobilisierung und Transport von Material, 4) und Erosionsraten über längere Zeiträume. Ich zeige, dass interpolierte Niederschlagsdaten die beste Qualität im Himalaya haben. Ich zeige auf, wie wichtig der bislang unberücksichtigt Grundwasserzwischenspeicher für die Abflussbildung im Himalaya ist und schätze den Anteil der Schnee-und Eisschmelze an dem Gesamtabfluss der Flüssen im Himalaja. Erosionsraten die mittels Schwebestofffracht und der Analyse kosmogener Nukluide berechnet wurden, liegen zwischen 0,1 und 4 mm pro Jahr. Der Sedimenttransport in den Flüssen in Nepal ist limitiert durch die Verfügbarkeit von transportierbarem Material, während der Transport und die Mobilisierung auf den Hängen durch die Verfügbarkeit von Wasser limitiert ist. Zudem sind die Erosionsraten über mehrere Jahrhundert nicht von der Niederschlagsverteilung abhängig sondern vom Relief.

No description available.

No description available.

No description available.

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

This thesis deals with the role of precipitation on erosion and landscape formation in the Nepal Himalayas. I investigate all successive steps involved in the erosion process: 1) Starting from the evaluation of precipitation datasets, 2) the transfer of precipitation to river discharge, 3) the mobilization and transport of material out of the mountain range, 4) and finally, erosion constrains over longer time-scales. I show that the dataset derived from the interpolation of rain gauge data performs best in the Himalayas. I demonstrate the importance of an until now unconsidered, major compartment of the Himalayan discharge cycle, which I identify as a fractured basement aquifer, and estimate the snow and ice melt contribution to the Himalayan rivers. Erosion rates calculated from suspended sediment fluxes and cosmogenic nuclide analysis range between 0.1 and 4 mm/yr. The rivers in the Nepal Himalayas are supply limited and the hillslopes as contributing source are transport limited. Last I show that over several thousand years erosion is not related with precipitation, but with relief. / Cette thèse porte sur le rôle des précipitations sur l’érosion et la formation des reliefs dans l’Himalaya Népalais. J’étudie chaque étape du processus d’érosion : 1) Evaluation des bases de données de précipitations, 2) Transfert des précipitations au débit fluvial, 3) Mobilisation et transport du matériel dans le bassin versant, et enfin 4) Mécanismes d’érosion sur de longues échelles de temps. Je montre que la base de données de précipitations obtenue par interpolation de données pluviométriques est la plus performante pour la région de l\'Himalaya. Je démontre l’importance d’une composante majeure, jusqu’alors ignorée, du cycle de débit de l’Himalaya que j’identifie comme étant les aquifères de sous-sol fracturé, et j’évalue la contribution de la fonte des neiges et glaces aux rivières Himalayennes. Les taux d’érosion calculés à partir des flux de sédiments en suspension et des analyses de nucléides cosmogéniques varient de 0.1 à 4 mm/a. Les rivières au Népal sont limitées par l’apport sédimentaire alors que les versants, en tant que source de sédiments, sont limités par le transport. Enfin, je montre que l’érosion sur des milliers d’années ne dépend des précipitations mais du relief. / Die vorliegende Arbeit beschäftigt sich mit der Rolle des Niederschlag bei Erosions- und Oberflächenprozessen im nepalesischen Himalaja. Ich untersuche die Abfolge der Erosionspsozesse im Himalaja: 1) Ausgehend von der Bewertung von Niederschlagsdatensätzen, 2) die Prozesse der Abflussbildung in Flüssen, 3) die Mobilisierung und Transport von Material, 4) und Erosionsraten über längere Zeiträume. Ich zeige, dass interpolierte Niederschlagsdaten die beste Qualität im Himalaya haben. Ich zeige auf, wie wichtig der bislang unberücksichtigt Grundwasserzwischenspeicher für die Abflussbildung im Himalaya ist und schätze den Anteil der Schnee-und Eisschmelze an dem Gesamtabfluss der Flüssen im Himalaja. Erosionsraten die mittels Schwebestofffracht und der Analyse kosmogener Nukluide berechnet wurden, liegen zwischen 0,1 und 4 mm pro Jahr. Der Sedimenttransport in den Flüssen in Nepal ist limitiert durch die Verfügbarkeit von transportierbarem Material, während der Transport und die Mobilisierung auf den Hängen durch die Verfügbarkeit von Wasser limitiert ist. Zudem sind die Erosionsraten über mehrere Jahrhundert nicht von der Niederschlagsverteilung abhängig sondern vom Relief.

Terrain surfaces conserve human activities in terms of textures and structures. With reference to archaeological questions, the geological archive is investigated by means of models regarding anthropogenic traces. In doing so, the high-resolution digital terrain model is of inestimable value for the decoding of the archive. The evaluation of these terrain models and the reconstruction of historical surfaces is still a challenging issue. Due to the data collection by means of LiDAR systems (light detection and ranging) and despite their subsequent pre-processing and filtering, recently anthropogenic artefacts are still present in the digital terrain model. Analysis have shown that elements, such as contour lines and channels, can well be extracted from a highresolution digital terrain model. This way, channels in settlement areas show a clear anthropogenic character. This fact can also be observed for contour lines. Some contour lines representing a possibly natural ground surface and avoid anthropogenic artefacts. Comparable to channels, noticeable patterns of contour lines become visible in areas with anthropogenic artefacts. The presented work ow uses functionalities of ArcGIS and the programming language R.¹ The method starts with the extraction of contour lines from the digital terrain model. Through macroscopic analyses based on geomorphological expert knowledge, contour lines are selected representing the natural geomorphological character of the surface. In a first step, points are determined along each contour line in regular intervals. This points and the corresponding height information which is taken from an original digital terrain model is saved as a point cloud. Using the programme library gstat, a variographic analysis and the use of a Kriging-procedure based on this follow. The result is a digital terrain model filtered considering geomorphological expert knowledge showing no human degradation in terms of artefacts, preserving the landscape-genetic character and can be called a prehistoric terrain model.

Currently in archaeological studies digital elevation models are mainly used especially in terms of shaded reliefs for the prospection of archaeological sites. Hesse (2010) provides a supporting software tool for the determination of local relief models during the prospection using LiDAR scans. Furthermore the search for relicts from WW2 is also in the focus of his research.¹ In James et al. (2006) the determined contour lines were used to reconstruct locations of archaeological artefacts such as buildings.² This study is much more and presents an innovative workflow of determining historical high resolution terrain surfaces using recent high resolution terrain models and sedimentological expert knowledge. Based on archaeological field studies (Franconian Saale near Bad Neustadt in Germany) the sedimentological analyses shows that archaeological interesting horizon and geomorphological expert knowledge in combination with particle size analyses (Köhn, DIN ISO 11277) are useful components for reconstructing surfaces of the early Middle Ages.³ Furthermore the paper traces how it is possible to use additional information (extracted from a recent digital terrain model) to support the process of determination historical surfaces. Conceptual this research is based on methodology of geomorphometry and geo-statistics. The basic idea is that the working procedure is based on the different input data. One aims at tracking the quantitative data and the other aims at processing the qualitative data. Thus, the first quantitative data were available for further processing, which were later processed with the qualitative data to convert them to historical heights. In the final stage of the work ow all gathered information are stored in a large data matrix for spatial interpolation using the geostatistical method of Kriging. Besides the historical surface, the algorithm also provides a first estimation of accuracy of the modelling. The presented workflow is characterized by a high exibility and the opportunity to include new available data in the process at any time.

Soil erosion by water is a main form of land degradation worldwide. The problem has been addressed, among others, in the United Nations Sustainability Goals. However, for mitigation of erosion consequences and adequate management of affected areas, reliable information on the magnitude and spatial patterns of erosion is needed. Although such need is often addressed by erosion modelling, precise erosion monitoring is necessary for the calibration and validation of erosion models and to study erosion patterns in landscapes. Conventional methods for quantification of rill erosion are based on labour-intensive field measurements. In contrast, remote sensing techniques promise fast, non-invasive, systematic and larger-scale surveying. Thus, the main objective of this study was to develop and evaluate automated and transferable methodologies for mapping the spatial extent of erosion rills from a single acquisition of remote sensing data. Data collected by an uncrewed aerial vehicle was used to deliver a highly detailed digital elevation model (DEM) of the analysed area. Rills were classified by two methods with different settings. One approach was based on a series of decision rules applied on DEM-derived geomorphological terrain attributes. The second approach utilized the random forest machine learning algorithm. The methods were tested on three agricultural fields representing different erosion patterns and vegetation covers. Our study showed that the proposed methods can ensure recognition of rills with accuracies between 80 and 90% depending on rill characteristics. In some cases, however, the methods were sensitive to very small rill incisions and to similar geometry of rills to other features. Additionally, their performance was influenced by the vegetation structure and cover. Besides these challenges, the introduced approach was capable of mapping rills fully automatically at the field scale and can, therefore, support a fast and flexible assessment of erosion magnitudes.