Strain Partitioning and Frictional Behavior of Opalinus Clay During Fault Reactivation

The Opalinus Clay (OPA) formation is considered a suitable host rock candidate for nuclear waste storage. However, the sealing integrity and long-term safety of OPA are potentially compromised by pre-existing natural or artificially induced faults. Therefore, characterizing the mechanical behavior and microscale deformation mechanisms of faults and the surrounding rock is relevant for predicting repository damage evolution. In this study, we performed triaxial tests using saw-cut samples of the shaly and sandy facies of OPA to investigate the influence of pressure and mineral composition on the deformation behavior during fault reactivation. Dried samples were hydrostatically pre-compacted at 50 MPa and then deformed at constant strain rate, drained conditions and confining pressures (pc) of 5–35 MPa. Mechanical data from triaxial tests was complemented by local strain measurements to determine the relative contribution of bulk deformation and fault slip, as well as by acoustic emission (AE) monitoring, and elastic P-wave velocity measurements using ultrasonic transmissions. With increasing pc, we observe a transition from brittle deformation behavior with highly localized fault slip to semi-brittle behavior characterized by non-linear strain hardening with increasing delocalization of deformation. We find that brittle localization behavior is limited by pc at which fault strength exceeds matrix yield strength. AEs were only detected in tests performed on sandy facies samples, and activity decreased with increasing pc. Microstructural analysis of deformed samples revealed a positive correlation between increasing pc and gouge layer thickness. This goes along with a change from brittle fragmentation and frictional sliding to the development of shear zones with a higher contribution of cataclastic and granular flow. Friction coefficient at fault reactivation is only slightly higher for the sandy (µ ~ 0.48) compared to the shaly facies (µ ~ 0.4). Slide-hold-slide tests performed after ~ 6 mm axial shortening suggest stable creeping and long-term weakness of faults at the applied conditions. Our results demonstrate that the mode of fault reactivation highly depends on the present stress field and burial history

The mineralogical and lithogeochemical footprint of the George Fisher Zn-Pb-Ag massive sulphide deposit in the Proterozoic Urquhart Shale Formation, Queensland, Australia

The Proterozoic Carpentaria Province (McArthur basin and Mount Isa Inlier) in northern Australia comprises a number of world class clastic dominated (CD-type) Zn-Pb massive sulphide deposits, formally known as SEDEX deposits. In order to identify the geochemical footprint of any mineralizing system it is necessary to characterize compositional variability of the host rock to mineralization. In the southern Carpentaria, establishing the baseline composition of the host rock is complicated by varying degrees of tectonic overprint, a lack of metamorphic indicator minerals, and the overall size of the ore forming systems. In this study, samples from drill-holes intersecting the main ore bodies at the world class George Fisher CD-type massive sulphide deposit have been compared to samples from a drill-hole intersecting barren, correlative lithologies of the Urquhart Shale Formation (ca. 1654 Ma). Bulk rock lithogeochemical (X-ray fluorescence, inductively coupled plasma mass spectrometry and LECO) and mineralogical (X-ray diffraction) analyses have been combined with petrographic observations to (1) establish the baseline composition of the Urquhart Shale Formation and (2) determine the geochemical and mineralogical footprint of the CD-type system at George Fisher. The absence of metamorphic indicator minerals, combined with the preservation of illite in un-mineralized Urquhart Shale, suggests that in this part of the Mount Isa area, the host rocks did not reach greenschist facies conditions (>300 degrees C). Chlorite in the un-mineralized Urquhart Shale is very fine grained (<= 10 mu m) within interstitial pore spaces with other phyllosilicates (e.g., illite), and is interpreted to be diagenetic in origin. Relative to the un-mineralized Urquhart Shale, the first stage of sulphide mineralization (Zn-dominated, stratabound) at George Fisher is associated with decreased abundances of albite, chlorite, and calcite, and higher abundances of dolomite and phyllosilicates (muscovite and phlogopite). These mineralogical transformations are associated with strong minor and trace element depletion (Sr and Na) and enrichment (Tl and Mn). An element index based on this suite of elements (GF index = 10(400Tl+Mn/10Sr+Na)) is highly effective in differentiating between the background Urquhart Shale Formation and the alteration footprint at George Fisher and may provide an additional tool for geochemical exploration programmes in the Mount Isa area. This study affirms the benefit of combining lithogeochemical, mineralogical, and petrographic data in order to understand the host rock baseline composition and the alteration footprint of Carpentaria CD-type massive sulphide systems

Late diagenesis of illite-smectite in the Podhale Basin, southern Poland: Chemistry, morphology, and preferred orientation

Well-characterized samples from the Podhale Basin, southern Poland, formed the basis for exploring and illuminating subtle diagenetic changes to a mudstone toward the upper end of the diagenetic window, prior to metamorphism.Transmission electron microscopy (TEM) performed on dispersed grains and ion-beam thinned preparations, selected area diffraction patterns,and chemistry by TEM-EDS (energy dispersive spectra) augmented mineralogy and fabric data. The deepest samples show no change in their percent illite in illite-smectite (I-S), yet I-S–phase octahedral Fe3+ and Al3+ are statistically different between samples. A decrease in the Fe3+ concentration in the octahedral sheet correlates with an increase in I-S fabric intensity and apparent crystallinity. The D-statistic from the Kolmogorov-Smirnov test on TEM- EDS data describes statistical differences in the I-S chemistry. Previous work on these samples showed a significant increase in the preferred orientation of the I-S phase across the smectite to illite transition and a significant slowdown in the rate of development of preferred orientation beyond the termination of smectite illitization. Lattice fringe images describe an I-S morphology that coalesces into larger and tighter packets with increasing burial temperature and a decrease in I-S packet contact angle, yet some evidence for smectite collapse structures is retained. The deepest sample shows the thickest, most coherent I-S packets. We propose that the deepest samples in the Podhale Basin describe the precursor stage in phyllosilicate fabric preferred orientation increase from diagenesis into metamorphism, where continued evolution of crystallite packets and associated crystallinity create higher I-S fabric intensities as the structural formulae of I-S approach an end-member composition

Entrepreneurship Education Monitor 2018: für MINT-Studiengänge in Ostdeutschland

In Deutschland ist in Sachen Entrepreneurship an Hochschulen in den vergangenen 20 Jahren viel geschehen. Seit 1998 befördert das EXIST-Programm Gründungsgeist an Hochschulen. Laut der Forschungsgemeinschaft Gründungsforschung e.V. existieren insgesamt 134 Entrepreneurship-Professuren, davon 32 in Ostdeutschland. Es gibt eine Vielzahl an Wettbewerben und Förderprogrammen für Gründerinnen und Gründer. Für alle an den Hochschulen, die sich schon für das Thema Unternehmertum interessieren und mit dem Gedanken einer eigenen Gründung spielen, ist gut gesorgt. Es gibt hinreichend viele Anlaufstellen und Fördermöglichkeiten an und im Umfeld der Hochschulen. Doch eine Herausforderung ist es bis heute, potenzielle Gründerinnen und Gründer und weitere Akteure an Hochschulen überhaupt für unternehmerisches Denken und Handeln zu sensibilisieren. Vorhandene Angebote erreichen die, die interessiert sind und nicht jene, die noch nicht darüber nachgedacht haben. Eine weitere Herausforderung gibt es. Sensibilisierung für unternehmerisches Denken und Handeln geschieht im Rahmen des Studiums, jedoch leider nicht für alle Studierenden. Ein Blick auf die Hochschulebene zeigt, dass noch vor fünf Jahren vor allem Studierende der Wirtschaftswissenschaften von Angeboten rund um das Thema Entrepreneurship profitierten (Gründungsradar, 2013; Kulicke et al., 2012). Die „Interdisziplinarität in der Gründungsförderung und die Ausschöpfung des Potenzials in nicht wirtschaftswissenschaftlichen Fächern sind also noch ausbaufähig“ (Gründungsradar, 2013: 12). Gerade im Kontext der technischen und naturwissenschaftlichen Disziplinen, der sogenannten MINT-Fächer, liegen Potenziale für zukünftige technologische und ggf. auch unternehmerische Innovationen. Die Zielgruppe dieser Studierenden wird jedoch bislang kaum erreicht. Ein sicherer Weg, Studierende zu erreichen, ist die universitäre Lehre entlang des Studiencurriculums. Es gibt verschiedene Argumente, die für eine breite curriculare Verankerung von Entrepreneurship Education an Hochschulen sprechen. So wird dies im wissenschaftlichen Diskurs diskutiert (Nelson & Byers, 2008; Semrau, Fischbach & Schober, 2011) und im politischen Diskurs klar unterstützt; so versteht sich die Europäische Kommission als Katalysator, um Entrepreneurship Education zu einem Basiselement im Bildungssystem zu machen (Europäische Kommission, 2018). Hier liegen Ursprung und Idee dieser Studie. Es war bisher nicht klar, wie die Chancen für Studierende der MINT-Fächer stehen, während ihres Studiums mit Entrepreneurship in Kontakt zu kommen. Es gibt eine Vielzahl von Studien, die sich mit der Umsetzung von Maßnahmen zur Sensibilisierung unternehmerischen Denkens und Handelns auf Hochschulebene beschäftigen. Umfassende Analysen, welche auf Studiengangebene analysieren, ob und inwiefern dort Inhalte mit Bezug zu Entrepreneurship verankert sind, sind kaum vorhanden (Gossel & Kalka, 2015). An dieser Stelle setzt die vorliegende Studie an. Für das wichtige Segment der MINT-Studiengänge wird im Rahmen einer Vollerhebung in sechs ostdeutschen Bundesländern ermittelt, ob und inwiefern dort Inhalte mit Bezug zu Entrepreneurship curricular verankert sind. Ziel der Studie ist es, so breit und so tief wie möglich zu erfassen, wie es um den Erwerb unternehmerischer Kompetenzen in den MINT-Studiengängen steht. Von der Verbreitung der Ergebnisse der Studie erhoffen wir uns eine Belebung der Diskussion rund um Entrepreneurship Education an Hochschulen in Deutschland. Gründungssensibilisierung ist und bleibt eine Daueraufgabe in der Hochschulbildung. Denjenigen Akteuren, die sich für eine nachhaltige Gründungssensibilisierung in der Hochschullehre einsetzen, jenen, die Studiengänge überarbeiten und Curricula modernisieren, und denjenigen, die darüber entscheiden, ob es Mittel und Personal an Hochschulen für Aufgaben der Entrepreneurship Education in der Hochschullehre gibt, soll diese Studie als Argumentations- und Diskussionsgrundlage dienen

Eine deskriptive Bestandsaufnahme von Entrepreneurship Education in MINT-Studiengängen in sechs Bundesländern

ZusammenfassungWährend die Bedeutung des Lehrens und Lernens unternehmerischer Kompetenzen auch in MINT-Studiengängen von der Forschung intensiv diskutiert und politisch weithin gefordert wird, stellt sich die Frage, inwieweit Entrepreneurship Education tatsächlich in den jeweiligen Curricula verankert ist. Die vorliegende Arbeit liefert deshalb einen Überblick über den Status quo der curricularen Verankerung von Entrepreneurship Education am Beispiel der Hochschulen der sechs ostdeutschen Bundesländer einschließlich Berlin. Für alle 1361 MINT-Studiengänge an 58 Hochschulen wurde eine Dokumentenrecherche und -analyse von Studiengangdokumenten durchgeführt. Die Ergebnisse der Untersuchung zeigen eine geringe Verankerung von Entrepreneurship Education in den Curricula der MINT-Studiengänge mit indes auffälligen Unterschieden zwischen den Fächergruppen.Schlüsselwörter: Entrepreneurship Education, MINT, curriculare Verankerung___________A descriptive study of entrepreneurship education in STEM degree courses in six German LaenderAbstractWhile the importance of teaching and learning entrepreneurial competencies also in STEM degree courses is intensively discussed in research and widely demanded politically, the question remains to what extent entrepreneurship education is part of the respective curricula. This study delivers an overview of the status quo of curricular anchoring of entrepreneurship education in STEM degree courses for the six East German Laender including Berlin. For a total of 1361 STEM degree courses from 58 East German higher education institutions, an in-depth search and analysis of course documents was conducted. The results show a slight anchoring of entrepreneurship education in the curricula of STEM degree courses. However, noticeable differences between the detailed fields of study can be observed.Keywords: entrepreneurship education, STEM, curricular anchorin

Constraints on mineralization, fluid‐rock interaction, and mass transfer during faulting at 2–3 km depth from the SAFOD drill hole

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/94888/1/jgrb15975.pd

On the origin and processes controlling the elemental and isotopic composition of carbonates in hypersaline Andean lakes

H.J. and J.W.B. Rae acknowledge funding from the European Research Council under the European Union’s Horizon 2020 research and innovation program (grant agreement 805246).The Altiplano-Puna Plateau of the Central Andes hosts numerous lakes, playa-lakes, and salars with a great diversity and abundance of carbonates forming under extreme climatic, hydrologic, and environmental conditions. To unravel the underlying processes controlling the formation of carbonates and their geochemical signatures in hypersaline systems, we investigated coupled brine-carbonate samples in a high-altitude Andean lake using a wide suite of petrographic (SEM, XRD) and geochemical tools (δ2H, δ18O, δ13C, δ11B, major and minor ion composition, aqueous modelling). Our findings show that the inflow of hydrothermal springs in combination with strong CO2 degassing and evaporation plays an important role in creating a spatial diversity of hydro-chemical sub-environments allowing different types of microbialites (microbial mounds and mats), travertines, and fine-grained calcite minerals to form. Carbonate precipitation occurs in hot springs triggered by a shift in carbonate equilibrium by hydrothermal CO2 degassing and microbially-driven elevation of local pH at crystallisation. In lakes, carbonate precipitation is induced by evaporative supersaturation, with contributions from CO2 degassing and microbiological processes. Lake carbonates largely record the evaporitic enrichment (hence salinity) of the parent water which can be traced by Na, Li, B, and δ18O, although other factors (such as e.g., high precipitation rates, mixing with thermal waters, groundwater, or precipitation) also affect their signatures. This study is of significance to those dealing with the fractionation of oxygen, carbon, and boron isotopes and partitioning of elements in natural brine-carbonate environments. Furthermore, these findings contribute to the advancement in proxy development for these depositional environments.Peer reviewe

Constraining clay hydration state and its role in active fault systems

To understand the role of hydrated clay minerals in active fault systems, a humidity chamber connected to an X‐ray diffractometer was used to determine the adsorption of water onto and/or into the crystal structure of smectite. This new type of analysis was carried out under specific temperature and humidity conditions, using powdered clay size fractions (< 2 µm) of rock samples from the San Andreas Fault (USA) and the Nankai Trough (Japan). Pressure cannot be controlled, but does not significantly affect clay swelling at shallow conditions. Air‐dried samples show a discrete smectite phase that swells after traditional ethylene glycolation to an interlayer distance of 1.5 and 1.7 nm. Using the humidity chamber, however, the samples show a shorter interlayer distance, between 1.09 and 1.54 nm. Based on our analysis, we show that (i) ethylene glycol overestimates the size of the interlayer space, and therefore water content, so is a crude maximum only; (ii) interlayer swelling occurs in smectite clay minerals at all temperatures between 25 and 95°C; and (iii) particle orientation increases with increasing humidity, indicating a higher mobility of smectite from interlayer hydration. Detailed characterization of the hydration state of smectite under original conditions is critical for understanding of clay‐fluid interaction, the mechanical behavior during fault displacements, and fluid budgets at depth. We propose that humidity chamber experiments should be the new standard procedure to constrain swelling characteristics of natural and synthetic clay minerals. Key Points Investigating smectite swelling behavior Humidity chamber connected to an X‐ray diffractometer Implications for weak fault behaviorPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/98123/1/ggge20077.pd

Mineralogical characterization of protolith and fault rocks from the SAFOD Main Hole

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/94865/1/grl22060.pd