Corinne Singeisen / Master’s Thesis at the Department of Earth Science /
ETH Zurich, Switzerland
Rock avalanche(s) Kandersteg: A reconstruction of landscape evolution in Kandertal based on field mapping, cosmogenic radionuclide dating and runout modelling
Supervisors: PD Dr. Susan Ivy-Ochs and Dr. Andrea Wolter
The aim of this master project is to develop an understanding of the age and failure of the rock ava-lanche in Kandersteg. The deposit of this prehistoric rock avalanche stretches over a long distance from the village of Kandersteg in the South towards Reckenthal/Frutigen in the North. The failure scarp of this giant rock avalanche is exposed below the Fisistock. So far, little is understood about the failure of the massive rock avalanche and the deposit has not been dated directly.
The support of CHQUAT allowed to carry out intense field work in Kandersteg during one week in Sep-tember. Fieldwork included mapping of the boulder lithologies in the rock avalanche deposit as well as taking samples of the boulders and the failure plane for cosmogenic nuclide dating. Additionally, landform mapping as well as structural measurements of bedrock outcrops were performed. The re-sults obtained from field investigations will be analysed in detail and complemented with laboratory work and runout modelling to shed light on landscape evolution in the Kander valley.
Kristina Ernst / Master’s Thesis at the Department of Earth Science /
ETH Zurich, Switzerland
Investigation of the Impact of Exfoliation Joints on Rock Fall Hazards in the Grimsel Area of Switzerland
Supervisors: Dr. Martin Ziegler, Prof. Dr. Simon Loew
The study area for my Master’s thesis is situated in the Canton of Bern in the Upper Aar valley, close to the border of the Canton of Wallis. This area is known as the Grimsel region or upper Hasli valley, which hosts major hydropower infrastructures. Within the last few years, several rock falls have occurred from steep slopes, some of which reached important traffic infrastructures. During my field work sessions in summer 2015 and summer/fall 2016 I focused on investigating rock fall events in the main valley, striking NNW-SSE between south of Guttannen and the Grimsel Pass and about ENE-WSW along Lake Grimsel up to the end of the Unteraar Glacier. The major goal of my thesis is to identify the impact of exfoliation joints on past and more recent rock fall events and to investigate whether the rock fall events (type, frequency, amount of debris) differ for these two valley sections. The mapped pattern of rock fall deposits in the main valleys is put into context with the Late Glacial deglaciation history. Seven rock fall prone slopes, distributed about evenly within the study area, were investigated in detail. In order to obtain high-resolution photographs and photogrammetric 3D models as a base for rock mass structural analyses and kinematic modelling of these sites we flew over four carefully chosen rock slopes with an Unmanned Aerial Vehicle (UAV). For the remaining three sites ground-based photo data were taken. The 3D models were analyzed with respect to rock mass fracture orientations (especially tectonic and exfoliation joints) using the software 3DM Analyst by Adam Technology. The fracture data were then used to conduct kinematic analyses with Dips and Swedge by Rocscience. First results show that exfoliation joints play a key role in rock fall releases, as they were existing in all the examined models. Rock fall and debris flow deposits do positively correlate with the mapped extents of exfoliation fractures.
I am very grateful for the financial support from the Swiss Society for Quaternary Research (CH-QUAT), which substantially helped me in conducting this fieldwork. With their support I could spent four great weeks of mapping in the Grimsel region.
Ewelina Opyrchal and Olivia Kronig/ Labor für Ionenstrahlphysik /
ETH Zürich, Switzerland
8th International Geochronology Summer School 2016, Bergün
With the support of the CH-QUAT it was possible to participate the 8th International Geochronology Summer School 2016, which took place in early September in Bergün, Switzerland. During this week we deepened our knowledge on various dating techniques and learned more about reconstruction of geomorphic processes and environmental parameters. Besides the lectures and exercises taught by experts, also a practical field excursion was part of the course. There we learned how to take samples for cosmogenic nuclide exposure dating, use a Schmidt- Hammer, look and interpret weathering rims. We also drilled tree cores and processed them for dendrochronological analyses under the microscope. A highlight was to listen to the presentations of all participants and to see what other PhD students around the world are working on and to get new insights in completely different topics.
During these sessions Olivia Kronig presented a part of her project, which is to date the stabilization age of relict rockglaciers using cosmogenic nuclide exposure dating. The aim is to use relict rockglaciers as a local climate indicator to elucidate the still poorly understood climate variations during the early Lateglacial.
Ewelina Opyrchal presented a part of the study on the late Pleistocene deglaciation history of the Tatra Mountains. She investigates glacial cirques using a combined approach of geomorphological mapping, cosmogenic nuclide exposure dating and Schmidt- Hammer measurement to reconstruct the chronology and extent of the youngest glacier advances and the timing of deglaciation.
Labor für Ionenstrahlphysik
HPK G 26
Nemiah Ladd / Eawag - Swiss Federal Institute of Aquatic Science and Technology / Kastanienbaum, Switzerland
Support from CH-QUAT facilitated the participation of Dr. Nemiah Ladd at the American Geophysical Union’s Fall Meeting in San Francisco, where she presented work from her postdoc at Eawag. Nemiah’s research is focused on understanding how environmental variables affect isotope fractionation in lacustrine algae. Hydrogen isotopes of lipids produced by algae have been proposed as a proxy for water isotopes, which would be useful for reconstructing past hydroclimate using lipids preserved in lake sediments. However, a number of factors, including temperature, growth rate, and species assemblage, may influence the magnitude of the offset (or fractionation) between lake water hydrogen isotopes and algal lipid hydrogen isotopes. Previous investigations into these effects have mostly been with marine algae in laboratory settings. Nemiah’s work addresses this gap by studying how hydrogen isotope fractionation changes seasonally with temperature, productivity, and species assemblage in Greifensee and Vierwaldstättersee.
Nemiah Ladd, PhD
NSF-EAR postdoctoral fellow
Swiss Federal Institute of Aquatic Science and Technology (Eawag)
Department of Surface Waters Research and Management
6047 Kastanienbaum, Switzerland
Nasim Mozafari Amiri /Institute of Geological Sciences/
University of Bern
The support of CH-QUAT allowed Nasim Mozafari Amiri to attend the American Geophysical Unioin’s Fall Meeting (AGU) in San Francisco (USA) from 12-16 December 2016, where she gave a presentation with the title:
Holocene Time-slip history of normal fault scarps in western Turkey: 36Cl surface exposure dating
Author: Nasim Mozafari Amiri
Co-authors: Ökmen Sümer, Dmitry Tikhomirov, Çağlar Özkaymak, Bora Uzel, Susan Ivy-Ochs, Christof Vockenhuber, Hasan Sözbilir & Naki Akçar
Bedrock fault scarps built in carbonates are the most direct evidence of past earthquakes to reconstruct long-term seismic outline using 36Cl cosmogenic nuclides. The western Anatolia is an active seismic region, in which several major graben systems are formed mainly in carbonates commenced by roughly N-S extensional regime since the early Miocene. The oldest known earthquake in the Eastern Mediterranean and Middle East dates back to 464 B.C. However, to evaluate the earthquake pattern, a complete seismic data over a large time-scale is required. For modelling of seismic periods, a Matlab® code is used based on acceleration of production rate of 36Cl following exposure of fresh material to cosmic rays. By measuring the amount of cosmogenic 36Cl versus height on the fault surface, the timing of significant ruptures and vertical displacements are explored. The best scenario is obtained with the minimum difference between the modelled and measured 36Cl. An ideal target spot is a minimum-eroded surface with length of at least two meters from the intersection of the fault with colluvium. After continuous marking of 10 cm height and 15 cm width on the fault, the samples of 3 cm thick are collected. The geometrical factors of scarp dip, scarp height, top surface dip and colluvium dip are measured. Topographic shielding, density of the fault scarp and colluvium are also estimated. Afterwards, the samples are physically and chemically prepared in laboratory for elemental analysis and AMS measurements.
In this study, we collected 584 samples from seven major faults in western Anatolia. Our first results indicate five earthquake sequences in the Priene-Sazlı fault since early Holocene with a recurrence interval of approximately 2000 years and slip of 1.3 to 2.9 meters. The two most recent ruptures are correlated with 1955 and 68 AD earthquakes. A slip rate of roughly 1 mm/yr throughout the activity periods is estimated. Regarding the rupture length, the fault has potential of producing earthquake with magnitude of 6.9 and concluded to be a seismogenic fault. Mugirtepe fault was exposed in ca. 6 kyr ago with about 2.5 meters vertical displacement. Manastır fault has also experienced a cluster of ruptures in ca. 2 kyr ago and displaced about 4 meters vertically. Slip rates of 0.4 and 2 mm/yr are calculated for Mugırtepe and Manastır faults.
Nasim Mozafari Amiri
Institut für Geologie
Growth constratins and environmental influences on a modern stromatolite, Lagoa Vermelha, Brasil
Ko-Autoren: Irka Hajdas, Crisogono Vasconcelos
Von Februar bis September 2015 erarbeitete ich zum Abschluss meines Studiums der Erdwissenschaften an der ETH Zürich meine Masterarbeit zum Thema Stromatolithen. Stromatolithen sind laminierte Ablagerungen, die sich v.a. in der frühen Erdzeit in flachem warmem Salzwasser bildeten. Mit einem besseren Verständnis der Wachstumsstrukturen moderner Stromatolithen können anhand von fossilen Stücken die Umweltbedingungen auf der frühen Erde erforscht werden. Das heutige Vorkommen von Stromatolithen beschränkt sich auf wenige Orte, beispielsweise östlich von Rio de Janeiro, Brasilien. Das Wachstumsverhalten dieser modernen Stromatolithen zu untersuchen wurde zum Thema meiner Masterarbeit. Während der Ausfällung von einzelnen Karbonatschichten, die einen Stromatolithen bilden, wird die chemische Zusammensetzung des Wassers, in dem sich die Karbonate bilden, gespeichert. Anhand von verschiedenen geochemischen Analysen und Radiocarbon Datierungen dieser Karbonatschichten können die Umweltbedingungen rekonstruiert werden, in denen die einzelnen Schichten ausgefällt wurden. So können beispielsweise Veränderungen der Wasserzirkulation oder Temperaturschwankungen zu bestimmten Zeitpunkten festgestellt werden. Darüber hinaus tragen die Resultate der Radicarbon Datierungen dazu bei, die raren Informationen über zeitliche und räumliche Verteilung von 14C Reservoir Altern in der Küstenregion Brasiliens zu erweitern. Um die Ergebnisse zu Vertiefen und mit einem Poster zu präsentieren, reiste ich im April 2016 mit der Unterstützung von CH-QUAT an die europäische Konferenz für Geowissenschaften nach Wien.
Sylvie Bruggmann, PhD Student
University of Copenhagen
Faculty of Sciences
Department of geosciences and natural resource management
Section for Geology: Geochemical, Mineralogical and Petrological Earth Science
Øster Voldgade 10
1350 Copenhagen K