TY - THES A1 - Schleicher, Anja Maria T1 - The significance of clay minerals in active fault zones N2 - Die vorliegende Habilitationsschrift umfasst Forschungsergebnisse aus Studien, die sich mit Fluid-Gesteins-Wechselwirkungen und Deformationsprozessen in aktiven Störungszonen befassen, wobei der Einfluss der Tonminerale auf das geochemische und hydromechanische Verhalten dieser Störungen im Vordergrund steht. Kernproben (core) und Bohrklein (cuttings) aus vier verschiedenen Bohrprojekten an der San Andreas Störung (USA), der Nankai Trough Subduktionszone und der Japan Trench Subduktionszone (Japan), sowie der Alpine Störung in Neuseeland wurden untersucht. Die von ICDP (International Continental Scientific Drilling Program) und IODP (International Ocean Discovery Program) unterstützten Projekte verfolgen alle das Ziel, das Verhalten von Erdbeben besser zu verstehen. In Kapitel 1 werden in einer kurzen Einleitung die allgemeinen thematischen Grundlagen und Ziele der Arbeit beschrieben. Kapitel 2 umfasst den Stand der Forschung, eine kurze Beschreibung der einzelnen Bohrprojekte und Standorte, sowie eine Zusammenfassung der wichtigsten Messmethoden. Kapitel 3 beinhaltet insgesamt zehn wissenschaftliche Arbeiten, die alle in einem methodisch-thematischen Zusammenhang stehen. Die Manuskripte wurden in den Jahren 2006-2015 veröffentlicht, wobei weitere Arbeiten aus diesem Themenbereich im Literaturverzeichnis vermerkt sind. Sie gehen auf unterschiedliche Fragestellungen um die Bildung und das Verhalten von Tonmineralen in aktiven Störungszonen ein. Insgesamt sechs Publikationen beinhalten Daten und Forschungsergebnisse, die im Rahmen des SAFOD Projektes, USA (San Andreas Fault Observatory at Depth) erstellt wurden. Hier wurde vor allem auf die Fluid-Gesteins-Wechselwirkungsprozesse im Störungsgestein und die daraus resultierende Bildung von Tonmineralen eingegangen. Drei weitere Arbeiten wurden im Rahmen des NanTroSEIZE Projektes, Japan (Nankai Trough Seismogenic Zone Experiment) und des JFAST Projektes, Japan (Japan Trench Fast Drilling Project) erstellt. Hier steht vor allem das Verhalten von quellfähigen Tonmineralen auf sich ändernde Umgebungsbedingungen (z.B. Temperatur und Feuchtigkeit) im Mittelpunkt. Die zehnte hier vorgestellte Veröffentlichung betrifft Analysen rund um das DFDP Projekt (Deep Fault Drilling Project) in Neuseeland, wobei hier die Deformation von Tonmineralen und das hydro-mechanische Verhalten der Störungszone im Vordergrund stehen. In neun Veröffentlichungen war ich als Erstautor für die Vorbereitung des Projektes, das Erstellen der Daten und die Fertigstellung der Manuskripte zuständig. In einer Publikation war ich als Mitautorin für die elektronenmikroskopischen Analysen und deren Interpretation verantwortlich. Die wichtigsten Ergebnisse der in Kapitel 3 vorgelegten Arbeiten werden in Kapitel 4 unter Berücksichtigung neuer Publikationen diskutiert. Nach der Beschreibung der Thesen in Kapitel 5 werden in Kapitel 6 „Outlook“ die Highlights zukünftiger Forschungspläne am GFZ näher beschrieben. Die Habilitationsschrift endet mit dem Anhang, in welchem unter anderem das Laborequipment genauer beschrieben wird, sowie die Publikationen, Konferenzbeiträge und Lehrbeiträge aufgelistet sind. N2 - The habilitation thesis presented here includes results from several studies dealing with fluid-rock interactions and rock deformation processes in active fault zones. The focus in all of these studies is on the influence of clay minerals on the geochemical and the hydro-mechanical behavior of the fault rocks. The research was conducted on rock cores and cuttings from four scientific drilling projects at the San Andreas Fault (USA), the Nankai Trough subduction zone and the Japan Trench subduction zone (Japan), as well as the Alpine Fault in New Zealand. These ICDP (International Continental Scientific Drilling Program) and IODP (International Ocean Discovery Program) funded projects were all conducted with the aim to monitor and better understand earthquakes. Chapter 1 contains a short introduction to the topic with basic principles and objectives regarding the research approach. Chapter 2 describes the state of the art in clay mineral and fault zone science, gives a short description of the individual drilling projects and their locations on which the research was based, and summarizes the most important analytical methods used. Chapter 3 comprises ten peer-reviewed publications that are connected thematically and methodologically. The papers were published in the years 2006-2015, and additional related publications including myself as co-author are given in the literature list. The ten publications address different questions concerning the formation of clay minerals and processes of fluid-rock interaction in active fault zones. Six papers contain results from the SAFOD drilling project, USA (San Andreas Fault Observatory at Depth), with the main focus on fluid-rock interaction processes in fault rocks and the formation and location of clay minerals. Three publications report on research from the NanTroSEIZE drilling project (Nankai Trough Seismogenic Zone Experiment) and the JFAST drilling project (Japan Trench Fast Drilling Project). Both projects are situated in Japan. Here, the swelling behavior of smectite clay minerals in relation to changing environmental conditions (e.g. temperature and/or humidity) was investigated. The last publication included here concerns a study from the DFDP project (Deep Fault Drilling Project) in New Zealand, where I investigated the deformation of clay minerals on the context of the hydro-mechanical behavior of the fault zone rocks. I was first author in nine of the publications and in charge of the project preparation, measurements and data analyses, and the completion of the manuscript. As co-author on the other publication I was responsible for electronmicroscopy analyses (SEM and TEM) and their interpretation. The key results from the publications in Chapter 3 are discussed in Chapter 4 with additional considerations from more recent papers. Following the major theses in Chapter 5, Chapter 6 highlights a future research project in clay mineralogy research at the GFZ. An appendix includes more detailed descriptions of the laboratory equipment and lists of all publications, conference contributions and teaching courses and modules. KW - fault zone KW - Störungszone KW - clay mineral KW - fluid-rock interaction KW - Tonminerale KW - Fluid-Gesteins Wechselwirkung Y1 - 2019 ER - TY - JOUR A1 - Konrad-Schmolke, Matthias A1 - O'Brien, Patrick J. A1 - Zack, Thomas T1 - Fluid Migration above a Subducted Slab-Constraints on Amount, Pathways and Major Element Mobility from Partially Overprinted Eclogite-facies Rocks (Sesia Zone, Western Alps) JF - Journal of petrology N2 - The Western Alpine Sesia-Lanzo Zone (SLZ) is a sliver of eclogite-facies continental crust exhumed from mantle depths in the hanging wall of a subducted oceanic slab. Eclogite-facies felsic and basic rocks sampled across the internal SLZ show different degrees of retrograde metamorphic overprint associated with fluid influx. The weakly deformed samples preserve relict eclogite-facies mineral assemblages that show partial fluid-induced compositional re-equilibration along grain boundaries, brittle fractures and other fluid pathways. Multiple fluid influx stages are indicated by replacement of primary omphacite by phengite, albitic plagioclase and epidote as well as partial re-equilibration and/or overgrowths in phengite and sodic amphibole, producing characteristic step-like compositional zoning patterns. The observed textures, together with the map-scale distribution of the samples, suggest open-system, pervasive and reactive fluid flux across large rock volumes above the subducted slab. Thermodynamic modelling indicates a minimum amount of fluid of 0 center dot 1-0 center dot 5 wt % interacting with the wall-rocks. Phase relations and reaction textures indicate mobility of K, Ca, Fe and Mg, whereas Al is relatively immobile in these medium-temperature-high-pressure fluids. Furthermore, the thermodynamic models show that recycling of previously fractionated material, such as in the cores of garnet porphyroblasts, largely controls the compositional re-equilibration of the exhumed rock body. KW - fluid migration KW - subduction KW - fluid-rock interaction KW - Sesia Zone Y1 - 2011 U6 - https://doi.org/10.1093/petrology/egq087 SN - 0022-3530 VL - 52 IS - 3 SP - 457 EP - 486 PB - Oxford Univ. Press CY - Oxford ER - TY - JOUR A1 - Konrad-Schmolke, Matthias A1 - Zack, Thomas A1 - O'Brien, Patrick J. A1 - Barth, Matthias T1 - Fluid migration above a subducted slab - Thermodynamic and trace element modelling of fluid-rock interaction in partially overprinted eclogite-facies rocks (Sesia Zone, Western Alps) JF - Earth & planetary science letters N2 - The amount and composition of subduction zone fluids and the effect of fluid-rock interaction at a slab-mantle interface have been constrained by thermodynamic and trace element modelling of partially overprinted blueschist-facies rocks from the Sesia Zone (Western Alps). Deformation-induced differences in fluid flux led to a partial preservation of pristine mineral cores in weakly deformed samples that were used to quantify Li, B, Stand Pb distribution during mineral growth, -breakdown and modification induced by fluid-rock interaction. Our results show that Li and 13 budgets are fluid-controlled, thus acting as tracers for fluid-rock interaction processes, whereas Stand Pb budgets are mainly controlled by the fluid-induced formation of epidote. Our calculations show that fluid-rock interaction caused significant Li and B depletion in the affected rocks due to leaching effects, which in turn can lead to a drastic enrichment of these elements in the percolating fluid. Depending on available fluid-mineral trace element distribution coefficients modelled fluid rock ratios were up to 0.06 in weakly deformed samples and at least 0.5 to 4 in shear zone mylonites. These amounts lead to time integrated fluid fluxes of up to 1.4-10(2) m(3) m(-2) in the weakly deformed rocks and 1-8-10(3) m(3) m(-2) in the mylonites. Combined thermodynamic and trace element models can be used to quantify metamorphic fluid fluxes and the associated element transfer in complex, reacting rock systems and help to better understand commonly observed fluid-induced trace element trends in rocks and minerals from different geodynamic environments. KW - fluid-rock interaction KW - subduction zone KW - fluid migration KW - slab-mantle interface KW - trace element transport Y1 - 2011 U6 - https://doi.org/10.1016/j.epsl.2011.09.025 SN - 0012-821X VL - 311 IS - 3-4 SP - 287 EP - 298 PB - Elsevier CY - Amsterdam ER -