TY - THES A1 - Neuharth, Derek T1 - Evolution of divergent and strike-slip boundaries in response to surface processes T1 - Die Entwicklung divergenter und transversaler Plattengrenzen unter dem Einfluss von Erdoberflächenprozessen N2 - Plate tectonics describes the movement of rigid plates at the surface of the Earth as well as their complex deformation at three types of plate boundaries: 1) divergent boundaries such as rift zones and mid-ocean ridges, 2) strike-slip boundaries where plates grind past each other, such as the San Andreas Fault, and 3) convergent boundaries that form large mountain ranges like the Andes. The generally narrow deformation zones that bound the plates exhibit complex strain patterns that evolve through time. During this evolution, plate boundary deformation is driven by tectonic forces arising from Earth’s deep interior and from within the lithosphere, but also by surface processes, which erode topographic highs and deposit the resulting sediment into regions of low elevation. Through the combination of these factors, the surface of the Earth evolves in a highly dynamic way with several feedback mechanisms. At divergent boundaries, for example, tensional stresses thin the lithosphere, forcing uplift and subsequent erosion of rift flanks, which creates a sediment source. Meanwhile, the rift center subsides and becomes a topographic low where sediments accumulate. This mass transfer from foot- to hanging wall plays an important role during rifting, as it prolongs the activity of individual normal faults. When rifting continues, continents are eventually split apart, exhuming Earth’s mantle and creating new oceanic crust. Because of the complex interplay between deep tectonic forces that shape plate boundaries and mass redistribution at the Earth’s surface, it is vital to understand feedbacks between the two domains and how they shape our planet. In this study I aim to provide insight on two primary questions: 1) How do divergent and strike-slip plate boundaries evolve? 2) How is this evolution, on a large temporal scale and a smaller structural scale, affected by the alteration of the surface through erosion and deposition? This is done in three chapters that examine the evolution of divergent and strike-slip plate boundaries using numerical models. Chapter 2 takes a detailed look at the evolution of rift systems using two-dimensional models. Specifically, I extract faults from a range of rift models and correlate them through time to examine how fault networks evolve in space and time. By implementing a two-way coupling between the geodynamic code ASPECT and landscape evolution code FastScape, I investigate how the fault network and rift evolution are influenced by the system’s erosional efficiency, which represents many factors like lithology or climate. In Chapter 3, I examine rift evolution from a three-dimensional perspective. In this chapter I study linkage modes for offset rifts to determine when fast-rotating plate-boundary structures known as continental microplates form. Chapter 4 uses the two-way numerical coupling between tectonics and landscape evolution to investigate how a strike-slip boundary responds to large sediment loads, and whether this is sufficient to form an entirely new type of flexural strike-slip basin. N2 - Plattentektonik beschreibt die Bewegung starrer tektonischer Platten an der Erdoberfläche sowie deren komplexe Deformation an drei Arten von Plattengrenzen: 1) divergenten Grenzen wie Grabenbrüchen und mittelozeanische Rücken, 2) transversalen Grenzen, an denen Platten gegeneinander verschoben werden, wie die San-Andreas-Verwerfung, und 3) konvergenten Grenzen, die große Gebirgszüge wie die Anden bilden. Diese schmalen Deformationszonen, die Platten begrenzen, weisen meist komplexe Dehnungsmuster auf, die sich im Laufe der Zeit entwickeln. Während dieser Entwicklung wird die Verformung der Plattengrenzen durch tektonische Kräfte aus dem tiefen Erdinneren und der Lithosphäre, aber auch durch Oberflächenprozesse, welche topografische Erhebungen erodieren und die daraus resultierenden Sedimente in tiefer gelegenen Gebieten ablagern, angetrieben. Durch das Zusammenwirken und die Rückkopplung dieser Faktoren entwickelt sich die Erdoberfläche in einer extrem dynamischen Art und Weise. An divergenten Grenzen beispielsweise dünnen Zugspannungen die Lithosphäre aus, was zu einer Hebung und anschließenden Erosion der Flanken eines Grabenbruchs führt, wobei wiederum Sedimente freigesetzt werden. Währenddessen sinkt das Zentrum des Grabens ab und wird zu einer topografischen Senke, in der sich Sedimente ablagern. Diese Massenumverteilung vom Fuß zum Hang einer Verwerfung spielt eine wichtige Rolle, da er die Aktivität einzelner Verwerfungen verlängert. Durch anhaltende Divergenz werden Kontinente schließlich auseinandergerissen, wodurch der Erdmantel an die Erdoberfläche gefördert und neue ozeanische Kruste gebildet wird. Aufgrund des komplexen Zusammenspiels zwischen tektonischen Kräften aus dem tiefen Erdinneren und der Massenumverteilung an der Erdoberfläche ist es von entscheidender Bedeutung, die Rückkopplungen zwischen diesen beiden Bereichen zu verstehen. In dieser Studie möchte ich Einblicke zu zwei Hauptfragen geben: 1) Wie entwickeln sich divergierende Plattengrenzen? 2) Wie wird diese Entwicklung auf einer großen zeitlichen und einer kleinen strukturellen Skala durch die Veränderung der Oberfläche durch Erosion und Sedimentation beeinflusst? In drei Kapiteln untersuche ich die Entwicklung von divergenten und streichenden Plattengrenzen anhand numerischer Modelle. In Kapitel 2 wird die Entwicklung von Grabenbrüchen anhand zweidimensionaler Modelle im Detail erforscht. Dabei extrahiere ich Verwerfungen aus einer Reihe von Modellen und korreliere sie über die Zeit, um zu untersuchen, wie sich Verwerfungsnetzwerke räumlich und zeitlich entwickeln. Durch die bidirektionale Kopplung des Geodynamik-Codes ASPECT und des Erdoberflächen-Codes FastScape untersuche ich, wie diese Verwerfungsnetzwerk und der Grabenbruch im Allgemeinen durch die Erosionseffizienz des Systems, welche viele Faktoren wie Lithologie oder Klima abbildet, beeinflusst werden. In Kapitel 3 untersuche ich die Entwicklung eines Grabenbruchs aus einer dreidimensionalen Perspektive. In diesem Kapitel analysiere ich wie sich gegeneinander versetzte Grabenbrüche verbinden und wann sich dabei schnell rotierende kontinentale Mikroplatten bilden. In Kapitel 4 nutze ich die entwickelte bidirektionale Kopplung zwischen Geodynamik und Erdoberflächenprozessen, um zu verstehen, wie transversale Plattengrenzen auf Sedimentlasten reagieren und ob die ausreicht, um einen völlig neue Art von Sedimentbecken in dieser Umgebung zu formen. KW - geodynamics KW - numerical modelling KW - rift KW - strike-slip KW - surface processes KW - microplate KW - FastScape KW - ASPECT KW - ASPECT KW - FastScape KW - Geodynamik KW - Mikroplatte KW - numerische Modellierung KW - Rift KW - Blattverschiebung KW - Oberflächenprozesse Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-549403 ER - TY - JOUR A1 - Neuharth, Derek A1 - Brune, Sascha A1 - Wrona, Thilo A1 - Glerum, Anne A1 - Braun, Jean A1 - Yuan, Xiaoping T1 - Evolution of rift systems and their fault networks in response to surface processes JF - Tectonics N2 - Continental rifting is responsible for the generation of major sedimentary basins, both during rift inception and during the formation of rifted continental margins. Geophysical and field studies revealed that rifts feature complex networks of normal faults but the factors controlling fault network properties and their evolution are still matter of debate. Here, we employ high-resolution 2D geodynamic models (ASPECT) including two-way coupling to a surface processes (SP) code (FastScape) to conduct 12 models of major rift types that are exposed to various degrees of erosion and sedimentation. We further present a novel quantitative fault analysis toolbox (Fatbox), which allows us to isolate fault growth patterns, the number of faults, and their length and displacement throughout rift history. Our analysis reveals that rift fault networks may evolve through five major phases: (a) distributed deformation and coalescence, (b) fault system growth, (c) fault system decline and basinward localization, (d) rift migration, and (e) breakup. These phases can be correlated to distinct rifted margin domains. Models of asymmetric rifting suggest rift migration is facilitated through both ductile and brittle deformation within a weak exhumation channel that rotates subhorizontally and remains active at low angles. In sedimentation-starved settings, this channel satisfies the conditions for serpentinization. We find that SP are not only able to enhance strain localization and to increase fault longevity but that they also reduce the total length of the fault system, prolong rift phases and delay continental breakup. KW - rifts KW - fault network KW - surface processes KW - geodynamics Y1 - 2022 U6 - https://doi.org/10.1029/2021TC007166 SN - 0278-7407 SN - 1944-9194 VL - 41 IS - 3 PB - American Geophysical Union CY - Washington ER - TY - JOUR A1 - Pingel, Heiko A1 - Alonso, Ricardo N. A1 - Altenberger, Uwe A1 - Cottle, John A1 - Strecker, Manfred T1 - Miocene to Quaternary basin evolution at the southeastern Andean Plateau (Puna) margin (ca. 24°S lat, Northwestern Argentina) JF - Basin research N2 - The Andean Plateau of NW Argentina is a prominent example of a high-elevation orogenic plateau characterized by internal drainage, arid to hyper-arid climatic conditions and a compressional basin-and-range morphology comprising thick sedimentary basins. However, the development of the plateau as a geomorphic entity is not well understood. Enhanced orographic rainout along the eastern, windward plateau flank causes reduced fluvial run-off and thus subdued surface-process rates in the arid hinterland. Despite this, many Puna basins document a complex history of fluvial processes that have transformed the landscape from aggrading basins with coalescing alluvial fans to the formation of multiple fluvial terraces that are now abandoned. Here, we present data from the San Antonio de los Cobres (SAC) area, a sub-catchment of the Salinas Grandes Basin located on the eastern Puna Plateau bordering the externally drained Eastern Cordillera. Our data include: (a) new radiometric U-Pb zircon data from intercalated volcanic ash layers and detrital zircons from sedimentary key horizons; (b) sedimentary and geochemical provenance indicators; (c) river profile analysis; and (d) palaeo-landscape reconstruction to assess aggradation, incision and basin connectivity. Our results suggest that the eastern Puna margin evolved from a structurally controlled intermontane basin during the Middle Miocene, similar to intermontane basins in the Mio-Pliocene Eastern Cordillera and the broken Andean foreland. Our refined basin stratigraphy implies that sedimentation continued during the Late Mio-Pliocene and the Quaternary, after which the SAC area was subjected to basin incision and excavation of the sedimentary fill. Because this incision is unrelated to baselevel changes and tectonic processes, and is similar in timing to the onset of basin fill and excavation cycles of intermontane basins in the adjacent Eastern Cordillera, we suspect a regional climatic driver, triggered by the Mid-Pleistocene Climate Transition, caused the present-day morphology. Our observations suggest that lateral orogenic growth, aridification of orogenic interiors, and protracted plateau sedimentation are all part of a complex process chain necessary to establish and maintain geomorphic characteristics of orogenic plateaus in tectonically active mountain belts. KW - Andean Plateau KW - NW Argentina KW - Puna KW - river incision KW - sediment routing KW - surface processes Y1 - 2019 U6 - https://doi.org/10.1111/bre.12346 SN - 0950-091X SN - 1365-2117 VL - 31 IS - 4 SP - 808 EP - 826 PB - Wiley CY - Hoboken ER - TY - THES A1 - Schröder, Sarah T1 - Modelling surface evolution coupled with tectonics T1 - Modellierung von Oberflächenprozessen gekoppelt mit Tektonik BT - A case study for the Pamir BT - Eine Fallstudie zum Pamir N2 - This study presents the development of 1D and 2D Surface Evolution Codes (SECs) and their coupling to any lithospheric-scale (thermo-)mechanical code with a quadrilateral structured surface mesh. Both SECs involve diffusion as approach for hillslope processes and the stream power law to reflect riverbed incision. The 1D SEC settles sediment that was produced by fluvial incision in the appropriate minimum, while the supply-limited 2D SEC DANSER uses a fast filling algorithm to model sedimantation. It is based on a cellular automaton. A slope-dependent factor in the sediment flux extends the diffusion equation to nonlinear diffusion. The discharge accumulation is achieved with the D8-algorithm and an improved drainage accumulation routine. Lateral incision enhances the incision's modelling. Following empirical laws, it incises channels of several cells width. The coupling method enables different temporal and spatial resolutions of the SEC and the thermo-mechanical code. It transfers vertical as well as horizontal displacements to the surface model. A weighted smoothing of the 3D surface displacements is implemented. The smoothed displacement vectors transmit the deformation by bilinear interpolation to the surface model. These interpolation methods ensure mass conservation in both directions and prevent the two surfaces from drifting apart. The presented applications refer to the evolution of the Pamir orogen. A calibration of DANSER's parameters with geomorphological data and a DEM as initial topography highlights the advantage of lateral incision. Preserving the channel width and reflecting incision peaks in narrow channels, this closes the huge gap between current orogen-scale incision models and observed topographies. River capturing models in a system of fault-bounded block rotations reaffirm the importance of the lateral incision routine for capturing events with channel initiation. The models show a low probability of river capturings with large deflection angles. While the probability of river capturing is directly depending on the uplift rate, the erodibility inside of a dip-slip fault speeds up headward erosion along the fault: The model's capturing speed increases within a fault. Coupling DANSER with the thermo-mechanical code SLIM 3D emphasizes the versatility of the SEC. While DANSER has minor influence on the lithospheric evolution of an indenter model, the brittle surface deformation is strongly affected by its sedimentation, widening a basin in between two forming orogens and also the southern part of the southern orogen to south, east and west. N2 - Im Rahmen dieser Studie werden 1D und 2D Erosionsmodelle im Gebirgsmaßstab implementiert und mit Modellen für tektonische Deformation gekoppelt. Die Kopplungsmethode erlaubt unterschiedlich räumliche und zeitliche Auflösungen im tektonischen und im Erosionsmodell. Es werden sowohl vertikale als auch horizontale Bewegungen zwischen den Modellen transferiert. Darüber hinaus enthält die Kopplungsmethode ein Glättungsverfahren, um eventuelle Instabilitäten des tektonischen Modelles zu kompensieren. Beide Erosionsmodelle beziehen Hangerosion, Flusseinschneidung und Sedimentation ein. Der 1D Code nutzt Hack's Law, um die Wassermengen zu berechnen. Er garantiert Massenerhaltung, indem er Sedimente in Senken speichert. Das 2D Erosionsmodell DANSER basiert auf einem zellulären Automaten. Ein zusätzlicher steigungsabhängiger Faktor erweitert lineare zu nichtlinearer Diffusion. Wassermengen werden mit Hilfe des D8-Algorithmus und einer veränderten Form von O'Callaghans (1984) Algorithmus akkumuliert. Laterale Einschneidung, berechnet durch einen neuen Verteilungs-Algorithmus, verbessert die Modellierung von Flusssystemen. Flüsse sind dabei repräsentiert durch eine unterschiedliche Anzahl an Zellen orthogonal zur Fließrichtung. Ihre Breite wird nach empirischen Gesetzen ermittelt. Die präsentierten Anwendungen dienen der Studie des Pamirgebirges. Zunächst werden die Modellparameter anhand von Einschneidungs- und Erosionsraten sowie Sedimentdurchflüssen kalibriert. Ein digitales Höhenmodell dient als Anfangstopographie und zur Extraktion von Flussprofilen. Laterale Einschneidung zeigt eine deutliche Verbesserung zu bisher vorhandenen Modellen. Sie ermöglicht die Erhaltung der Flussbreite und zeigt hohe Einschneidungsraten in engen Flusspassagen. Modelle von Flussanzapfungen in einem System paralleler Verwerfungen bestätigen die Wichtigkeit von lateraler Einschneidung für Flussanzapfungsmodelle, die Hangerosion einbeziehen. Während die Modelle eine geringe Wahrscheinlichkeit von Flussanzapfungen mit hohem Ablenkungswinkel zeigen, belegen sie auch, dass deren (allgemeine) Wahrscheinlichkeit direkt von der Hebungsrate der Verwerfungen abhängt. Die Erodibilität beschleunigt lediglich die Geschwindigkeit von Flussanzapfungen. Ein Modell, das die Codes SLIM 3D und DANSER koppelt, dokumentiert die vielseitige Verwendbarkeit des neuen Codes: Es zeigt einen geringen Einfluss von Oberflächenprozessen auf die Lithosphärendeformation, während die Sedimentationsroutine erheblich auf spröde Oberflächendeformationen einwirkt. Das Modell legt nahe, dass Sedimentation ein zwischen zwei entstehenden Gebirgen gelegenes Becken weitet. Außerdem weitet sich der südlich von der interkontinentalen Kollisionszone gelegene Teil des Gebirge-Models ebenfalls durch Sedimentation. KW - erosion KW - coupling KW - SEC KW - surface evolution KW - thermo-mechanics KW - surface processes KW - DANSER KW - Pamir KW - Tien-Shan KW - Tian-Shan KW - tectonics KW - modelling KW - modeling KW - numerical model KW - simulation KW - surface KW - fluvial incision KW - hillslope diffusion KW - finite differences KW - finite elements KW - Eulerian grid KW - DANSER KW - DANSER KW - Erosion KW - Modellierung KW - Tektonik KW - Koppelung KW - SEC KW - numerische Modellierung KW - Oberflächenprozesse KW - Pamir KW - Tien-Shan KW - Tian-Shan KW - Tiefendeformation KW - Software KW - Simulation KW - Oberfläche KW - fluviale Einschneidung KW - Hangerosion KW - finite Differenzen KW - finite Elemente KW - Eulerische Gitter Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-90385 ER - TY - JOUR A1 - Ballato, Paolo A1 - Landgraf, Angela A1 - Schildgen, Taylor F. A1 - Stockli, Daniel F. A1 - Fox, Matthew A1 - Ghassemi, Mohammad R. A1 - Kirby, Eric A1 - Strecker, Manfred T1 - The growth of a mountain belt forced by base-level fall: Tectonics and surface processes during the evolution of the Alborz Mountains, N Iran JF - Earth & planetary science letters N2 - The idea that climatically modulated erosion may impact orogenic processes has challenged geoscientists for decades. Although modeling studies and physical calculations have provided a solid theoretical basis supporting this interaction, to date, field-based work has produced inconclusive results. The central-western Alborz Mountains in the northern sectors of the Arabia-Eurasia collision zone constitute a promising area to explore these potential feedbacks. This region is characterized by asymmetric precipitation superimposed on an orogen with a history of spatiotemporal changes in exhumation rates, deformation patterns, and prolonged, km-scale base-level changes. Our analysis suggests that despite the existence of a strong climatic gradient at least since 17.5 Ma, the early orogenic evolution (from similar to 36 to 9-6 Ma) was characterized by decoupled orographic precipitation and tectonics. In particular, faster exhumation and sedimentation along the more arid southern orogenic flank point to a north-directed accretionary flux and underthrusting of Central Iran. Conversely, from 6 to 3 Ma, erosion rates along the northern orogenic flank became higher than those in the south, where they dropped to minimum values. This change occurred during a similar to 3-Myr-long, km-scale base-level lowering event in the Caspian Sea. We speculate that mass redistribution processes along the northern flank of the Alborz and presumably across all mountain belts adjacent to the South Caspian Basin and more stable areas of the Eurasian plate increased the sediment load in the basin and ultimately led to the underthrusting of the Caspian Basin beneath the Alborz Mountains. This underthrusting in turn triggered a new phase of northward orogenic expansion, transformed the wetter northern flank into a new pro-wedge, and led to the establishment of apparent steady-state conditions along the northern orogenic flank (i.e., rock uplift equal to erosion rates). Conversely, the southern mountain front became the retro-wedge and experienced limited tectonic activity. These observations overall raise the possibility that mass-distribution processes during a pronounced erosion phase driven by base-level changes may have contributed to the inferred regional plate-tectonic reorganization of the northern Arabia-Eurasia collision during the last similar to 5 Ma. (C) 2015 Elsevier B.V. All rights reserved. KW - orogenic processes KW - surface processes KW - base-level fall KW - erosion KW - rock uplift KW - knickpoints Y1 - 2015 U6 - https://doi.org/10.1016/j.epsl.2015.05.051 SN - 0012-821X SN - 1385-013X VL - 425 SP - 204 EP - 218 PB - Elsevier CY - Amsterdam ER -