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  • 1
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    A new practical and economical technique for the obtention of high quality thin section photographs with the help of a simple optical microscope (2010)
    Universitätsverlag Göttingen
    Details
    Publication Date: 2021-03-29
    Description: Microscopic study is an indispensable step in the determination of the petrographic characteristics of rocks. In Cameroon just like in most developing countries, simple polarizing microscopes of the 20th Century constitute the only available material for macroscopic studies. A major difficulty encountered in the use of these instruments resides in the realisation of photographs of the different parts of the thin section that require illustrations. The technique that has been used upto now has been inefficient and unsatisfactory. Faced with this recurrent situation, we thought of setting up a new, semi-modern, practical and very economical technique for photographing the thin section.
    Description: conference
    Keywords: 551 ; VAE 120 ; VGB 400 ; VKA 130 ; Methodik {Strukturgeologie} ; Optische Bestimmungsmethoden {Mineralogie} ; Optische Petrographie ; Dünnschliffmikroskopie ; Mikrofotographie
    Language: German
    Type: anthologyArticle , publishedVersion
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  • 2
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    Über die mechanischen Ursachen von parallelen Abschiebungen (2010)
    Universitätsverlag Göttingen
    Details
    Publication Date: 2021-03-29
    Description: Gruppen von parallel einfallenden Abschiebungen treten in der Natur sehr häufig und in unterschiedlichsten Dimensionen auf. Existierende, überwiegend experimentelle Arbeiten führen einheitliches Einfallen auf laterale Festigkeitsschwankungen oder, vor allem, auf horizontale Scherspannungen zurück (e.g. Brun et al. 1994, Behn et al. 2002). Einheitliche horizontale Scherspannungen im großen Maßstab werden mit einer konsistenten Fließrichtung in der mittleren und/oder unteren Kruste erklärt. Beobachtungen in einigen der bedeutensten Rift-Systeme lassen jedoch beide Erklärungen als zentrale Ursache unwahrscheinlich erscheinen. In der Basin-and-Range-Provinz in den westlichen Vereinigten Staaten ändert sich die Einfallrichtung von parallelen Abschiebungen im Streichen der Störungen, so dass strukturelle Domänen mit intern einheitlicher Einfallrichtung entstehen, die von Blattverschiebungen untereinander getrennt werden. Eine solche Geometrie ließe sich nur mit bizarren Fließmustern in der Unterkruste erklären. Wir präsentieren numerische Extensionsexperimente von sprödem Material, das auf einem linear-viskosen Substrat ruht... In unseren Modell sind parallele Abschiebungen nicht, wie bisher angenommen, auf einheitlichen horizontalen Scherstress, sondern auf vertikale Normalspannungen zurückzuführen, d.h. auf den Widerstand, den das viskose Substrat vertikalen Blockbewegungen in der spröden Lage entgegensetzt. Wenn unser Modell richtig ist, würde das für Gebiete wie die Basin-and- Range-Provinz bedeuten, dass die spröde Oberkruste auf einer wenige Kilometer dicken, viskosen mittleren Kruste liegt, die wiederum ein festeres Substrat hat. Die Unterkruste müsste deutlich fester sein als die mittlere Kruste. Es scheint, dass Folgen von parallelen Abschiebungen häufig in dünnen, niedrig viskosen Lagen (etwa Ton oder Salz) wurzeln.
    Description: conference
    Keywords: 551 ; VAE 830 ; VAE 130 ; VAE 120 ; VBE 000 ; Bruchschollenstrukturen {Geologie} ; Geomechanik ; Methodik {Strukturgeologie} ; Modellierung von Prozessen in der Geosphäre ; Bruchscholle ; Abschiebung 〈Geologie〉 ; Geomechanik ; Numerisches Modell
    Language: German
    Type: anthologyArticle , publishedVersion
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  • 3
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    Separation of magnetic subfabrics by high-field, lowtemperature torque measurements (2010)
    Universitätsverlag Göttingen
    Details
    Publication Date: 2021-03-29
    Description: The anisotropy of magnetic susceptibility (AMS) can serve as a good indicator of strain in deformed carbonate rocks with diamagnetic susceptibility (Owens and Rutter 1978; de Wall 2000). However, the magnetic fabric due to the diamagnetic carbonate minerals is usually very weak and interpretation of the AMS in these rocks is often complicated by the presence of paramagnetic and ferromagnetic phases which overprint the diamagnetic subfabric. For this reason contributions from ferromagnetic and paramagnetic minerals to the AMS should be separated for a reliable interpretation of the AMS. Ferromagnetic contributions to the AMS can be separated by high-field measurements, using a torque magnetometer (Martin- Hernandez and Hirt 2001). The remaining paramagnetic and diamagnetic contributions can be discriminated by their different temperature dependencies. The paramagnetic susceptibility increases as an inverse function of temperature, whereas the diamagnetic part remains constant. Altogether, AMS measurements at high fields and low temperatures allow for the discrimination of all three subfabrics. Test measurements with the high-field torque magnetometer at liquid nitrogen temperature were performed. It is possible to keep the specimens at low temperature over the measurement period using a cryostat. The main problem is the suppression of mechanical disturbances during the measurement so that the sensitivity of the instrument is retained. The torque of paramagnetic minerals increases strongly at low temperature which results in an amplification of the paramagnetic subfabric. The quantitative separation of diamagnetic and paramagnetic subfabric is under investigation. The result is promising when there is a significant diamagnetic signal.
    Description: conference
    Keywords: 551 ; TQB 000 ; TOT 310 ; VAE 120 ; Erdmagnetische Verfahren {Geophysik} ; Gesteinsmagnetismus {Geophysik} ; Methodik {Strukturgeologie} ; Magnetische Suszeptibilität ; Drehmagnetometer
    Language: German
    Type: anthologyArticle , publishedVersion
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  • 4
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    Gefügecharakterisierung von Calcitmyloniten und Marmoren bezüglich senkrecht zueinander stehender Faltenteilstrukturen, Alpi Apuane, Italien (2010)
    Universitätsverlag Göttingen
    Details
    Publication Date: 2021-03-29
    Description: Im nördlichen Teil des Appenin in Italien ist der metamorphe Komplex der Alpi Apuane in Form eines tektonischen Fensters sehr gut aufgeschlosssen. Die metamorphen Gesteine der Alpi Apuane — Metakarbonate, Kiesel- und Karbonatschiefer sowie Phyllite — sind aufgrund der Kollision der korsischsardischen Mikroplatte mit der italienischen Halbinsel im mm bis km- Maßstab verfaltet worden. Im zentralen Teil der Alpi Apuane biegt das generelle N–S Streichen der Faltenstrukturen in eine E–W Richtung um. Faltenstrukturen mit senkrecht zueinander stehenden Faltenachsen sind charakteristisches Strukturmerkmal u.a. ‘Metamorpher Kernkomplexe’ und Schlüssel zum Verständnis von Deformationsgeschichte und mechanismen. Die Entwicklung dieser Strukturen wird kontrovers diskutiert...
    Description: conference
    Keywords: 551 ; VEF 200 ; VKB 292 ; VKB 270 ; VKA 200 ; VAE 140 ; VAE 120 ; Italien {Geologie} ; Metamorphe Komplexe, übriges Europa {Petrologie} ; Produkte mechanischer Deformation {Petrologie} ; Gefügekunde der Gesteine ; Gesteinsdeformation {Strukturgeologie} ; Methodik {Strukturgeologie} ; Apuaner Alpen ; Karbonatgestein ; Marmor ; Deformation 〈Geologie〉 ; Faltentektonik ; Gefüge 〈Gesteinskunde〉
    Language: German
    Type: anthologyArticle , publishedVersion
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  • 5
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    Evolution and structure of the Upper Rhine Graben — quantitative insights from numerical modelling approaches (2010)
    Universitätsverlag Göttingen
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    Publication Date: 2021-03-29
    Description: The Upper Rhine Graben forms the major segment of the Cenozoic Rift system of Western Europe. Although the rift was the target of many seismic and geological investigations, the style of lithospheric extension below the inferred faults, the depth to detachment, and the amounts of horizontal extension and lateral translation are still being debated. In this study, the date base to the Upper Rhine Graben was subjected to a finite element approach in order to include thermomechanical processes of the lithosphere as well as erosion and sedimentation. The study concentrated on the consequences of extension and lateral translational events on the structure and evolution in terms of basin geometry, sediment layer thicknesses, Moho elevation, and shoulder uplift on a lithospheric scale. The numerical approach was three dimensional in order to incorporate the lateral crustal heterogenities in the Upper Rhine area and the varying ambient stress field...
    Description: conference
    Keywords: 551 ; VEB 145 ; VAE 840 ; VAE 400 ; VAE 120 ; VBE 000 ; Rhein-Main-Tiefland {Geologie} ; Rifts {Geologie} ; Tektogenese {Geologie} ; Methodik {Strukturgeologie} ; Modellierung von Prozessen in der Geosphäre ; Oberrheingraben ; Tektonik ; Rifting ; Numerisches Modell
    Language: German
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  • 6
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    Application of Photogrammetry in Geology: 3D Investigation of Rock Fracture Distributions (2010)
    Universitätsverlag Göttingen
    Details
    Publication Date: 2021-03-29
    Description: Geology as a science has an important visual component and the knowledge of any geologist is deeply linked to visual experience of rock outcrops, thin sections and analytical images. One of the shortcomings of most geological images such as maps, cross sections and outcrop photographs is that they are 2D, while processes geologists are interested in are typically occurring in 3D space. The 3D geometry of faults, fractures and joints is crucial to quantify geological processes related to fracture mechanics, such as hydrothermal mineralization and ground water flow, but also geotechnical problems such as rock mass stability. A number of studies have shown that some geological structures can be described with a scale invariant, fractal distribution. So far these observations on which these findings are based were restricted to one and two dimensions and has been difficult to obtain a full spatial geometric picture of fracture sets from rock outcrops, because much of the rock is not directly accessible. However, without taking into account the spatial distribution of geological structures the true geometry of joint patterns cannot be fully described and scaling laws, fractal or not, cannot be derived. We present images of joint patterns based on datasets acquired by digital photographs which are processed to three dimensional images using the photogrammetry software Siro3D. This technique allows to obtain a highly accurate 3D picture of the visible outcrop. The spatial pattern of joints in nature is investigated using the software SiroJoint. For the analysis of joint systems a large data set was collected from the Heavitree Quarzite at Ormiston Gorge, near Alice Springs. The Heavitree Quartzite is fragmented by a spectacularly regular three-dimensional joint pattern, which is repeated at different scales and therefore represents a perfect laboratory for our investigations (Hobbs 1993). Siro3D generates a spatially fully referenced 3D image from overlapping digital images, such that each pixel of the image is assigned spatial coordinates. The software SiroJoint routinely constructs planes from the intersection of the rock-face with the linear trace of planar features (Poropat 2001). It provides stereographic plots of structural elements and additionally measures joint persistence, area, and joint spacing. Our measurements allow to analyse geometrical scaling relationships of joint sets with high accuracy and will help explore the character of their 3D complexity. Several hundred joint planes were defined with SiroJoint in an Ormiston Gorge outcrop. Three different joint sets can be distinguished. Joint set one and two are characterized by steeply inclined planes with joint spacings ranging between 2 cm to 40 cm and 2 cm to 10m respectively. Both joints sets depict a power law distribution in joint spacing/frequency plots. The third set is defined by a subhorizontal orientation. It shows a very regular spacing in the meter scale and lacks an exponential distribution. We intend to use the results as a basis to compare observed fracture pattern with those generated by computational methods like Iterated Function Systems. This might help to understand how physical rock properties influence the spatial complexity of fracture systems and develop constitutive scaling relationships for certain rock types.
    Description: conference
    Keywords: 551 ; VAE 120 ; VBH 000 ; VAE 150 ; Methodik {Strukturgeologie} ; Fernerkundung ; Strukturelle Erscheinungen {Strukturgeologie} ; Klüftung ; Bruch 〈Geologie〉 ; Photogrammetrie ; Dreidimensionale Rekonstruktion
    Language: German
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  • 7
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    Effect of crystallography and temperature on the development of quartz high-angle grain boundaries in metamorphic rocks (2010)
    Universitätsverlag Göttingen
    Details
    Publication Date: 2021-03-29
    Description: Grain boundary migration during dynamic recrystallization of quartz results in grain boundary suturing of various extent. The geometry of the sutured boundaries is affected not only by temperature, strain rate, finite strain and differential stress, but also by internal properties such as the defect distribution and crystallographic orientations. Consequently, the grain boundary geometry may provide information about these conditions and properties. In continuation of a previous study (Kuntcheva et al.) the complete crystallographic orientation of quartz grain boundaries was measured, based on a combination of electron backscatter diffraction (EBSD) and universal-stage (U-stage) measurements. For this purpose a sample of granite from the northern Aar Massif (Central Alps, Switzerland) was taken, deformed at temperatures up to 300–350°C at the end of the Lepontine event of the Alpine Orogenesis...
    Description: conference
    Keywords: 551 ; VKA 200 ; VAE 120 ; VAE 130 ; Gefügekunde der Gesteine ; Methodik {Strukturgeologie} ; Geomechanik ; Aare-Massiv ; Granitgneis ; Quarz ; Rekristallisationstextur
    Language: German
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  • 8
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    Remote Sensing Analyses of Neotectonic Active Regions in East-Kamchatka (2010)
    Universitätsverlag Göttingen
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    Publication Date: 2021-03-29
    Description: The tectonic history of the Kamchatka Peninsula is dominated by continuous accumulation and amalgamation of terranes with different origins, which were delivered by convergence between the Pacific plate and in former times, the Kula plate against Eurasia (Freitag, 2002). The Kronotsky and Cape Kamchatka Peninsulas show that the collision of terranes and the resulting tectonics are still important for major parts of East-Kamchatka. While the collision of the Kronotsky Peninsula is sorely influenced by the convergence of the Pacific plate, the Cape Kamchatka Peninsula is affected by the collision of the Aleutian Arc with Kamchatka, what gives the opportunity to compare two different processes that resulted in the amalgamation of terranes to Kamchatka.
    Description: conference
    Keywords: 551 ; VEG 190 ; VAE 400 ; VAE 300 ; VAE 120 ; VBJ 000 ; Koriakia-Kamtchatkasystem {Geologie} ; Tektogenese {Geologie} ; Epirogenese {{Geologie}} ; Methodik {Strukturgeologie} ; Satellitenbildgeologie ; Kamtschatka 〈Oblast〉 ; Neotektonik ; Fernerkundung
    Language: German
    Type: anthologyArticle , publishedVersion
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  • 9
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    Empirische Feldstudien über elektromagnetische Emissionen in Gesteinen unter aktiven Krustenspannungen (2010)
    Universitätsverlag Göttingen
    Details
    Publication Date: 2021-03-29
    Description: In den vergangenen Jahren wurden von den Mitgliedern unseres Departments mehrere Feldstudien über elektromagnetische Emissionen in tektonisch aktiven Regionen durchgeführt. Die Untersuchungsgebiete lagen in Südspanien, Sizilien, Malta, Eger-Graben/Tschechische Republik und die Provence/Frankreich als auch in Süd-Chile. Das Ziel dieser Untersuchungen war die Erfassung der größten horizontalen Spannungs-Richtung in der oberen Erdkruste. Dazu wurden die Intensität des elektromagnetischen Feldes in Bezug zu der Orientierung einer Richtantenne gemessen. Diese Ergebnisse wurden mit aktiven Stress-Richtungen verglichen die aus Doorstopper-Messungen, Bohrloch- Randausbrüchen, Herdflächenlösungen und neotektonischen Strukturanalysen gewonnen wurden. Die Richtungen der größten Horizontalspannungen stimmen sehr gut mit der Orientierung der maximalen elektromagnetischen Emission überein.
    Description: conference
    Keywords: 551 ; VAE 120 ; VAE 130 ; TQD 000 ; Methodik {Strukturgeologie} ; Geomechanik ; Elektrische Verfahren {Geophysik} ; Erdkruste ; Spannung 〈Geologie〉 ; Spannungszustand ; Elektromagnetisches Verfahren
    Language: German
    Type: anthologyArticle , publishedVersion
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  • 10
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    Neutron time-of-flight texture measurements in Dubna: Status and developments (2010)
    Universitätsverlag Göttingen
    Details
    Publication Date: 2021-03-29
    Description: The multidetector texture diffractometer SKAT (from Russian: Spektrometer Kolitshestvennovo Analiza Tekstury) at the pulsed reactor IBR-2 in Dubna, Russia, started operation in March 1997 and is open for users from all countries. Application of time-of-flight (TOF) diffraction to texture measurements offers the opportunity to record complete diffraction patterns, i.e., to measure several pole figures simultaneously. To allow high spectral resolution for measurements on polyphase geological samples with many diffraction patterns, the instrument was placed at the end of an over 100m long flight path. In this paper, we will summarize advantages and disadvantages of the SKAT, as well as intended improvements.
    Description: conference
    Keywords: 551 ; VAE 120 ; VGA 440 ; VGB 900 ; VKA 200 ; Methodik {Strukturgeologie} ; Sonstige Methoden {Mineralogie: Kristallographie} ; Sonstige: Luminiszens etc. {Mineralogie} ; Gefügekunde der Gesteine ; Dubna ; SKAT ; Neutronendiffraktrometer ; Neutronendiffraktrometrie ; Texturanalyse
    Language: German
    Type: anthologyArticle , publishedVersion
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  • 11
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    Tertiäre Landoberflächen in Mitteldeutschland als Anzeiger tektonischer Bewegungen — Eine Rekonstruktion mittels Einsatz von Geo-Informationssystemen (2010)
    Universitätsverlag Göttingen
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    Publication Date: 2021-03-29
    Description: Aus der Verteilung und Lage tertiärer und quartärer Ablagerungen in Mitteleuropa lassen sich tertiäre Paläooberflächen rekonstruieren. Die spätere Verstellung dieser Oberflächen erlaubt es, die vertikalen Krustenbewegungen der jüngeren und jüngsten geologischen Vergangenheit zu quantifizieren. Diese Hebungs- und Senkungsbewegungen sind nur wenig durch die lokale Heraushebung der mitteldeutschen Mittelgebirge beeinflusst. Sie sind vor allem die Folge sehr großräumiger Verstellungen der Erdkruste zwischen Nordsee und Fichtelgebirge, bei denen Prozesse im Erdmantel einen entscheidenden Einfluss im großräumigen (mitteleuropäischen) Maßstab haben.
    Description: conference
    Keywords: 551 ; VAG 130 ; VEB 210 ; VAE 400 ; VAE 120 ; VBF 000 ; Paläogeomorphologie {Geomorphologie} ; Deutschland {Geologie} ; Tektogenese {Geologie} ; Methodik {Strukturgeologie} ; Elektronische Datenverarbeitung in der Geologie ; Mitteldeutschland ; Tertiär ; Quartär ; Hebung 〈Geologie〉 ; Rezente Krustenbewegung ; Geoinformationssystem ; Fossile Erdoberfläche ; Rekonstruktion
    Language: German
    Type: anthologyArticle , publishedVersion
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  • 12
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    Structural investigation and strain analysis of a polyphase flower structure in the Lower Saxony Basin, Germany (2010)
    Universitätsverlag Göttingen
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    Publication Date: 2021-03-29
    Description: The Lower Saxony Basin (LSB) is a part of the post-Variscan Central European Basin System. We used a 3-D reflection seismic dataset in the northern LSB, provided by RWE-DEA AG, Hamburg (c.f. Lohr et al. submitted) for our investigation, which is concerned with the detailed structural and kinematic analysis of a flower structure within Mesozoic strata. This data is used in turn to determine input parameters for further 3-D geometrical retro-deformation. The retro-deformation verifies our assumptions about the structure and tectonic processes, and gives further information about sub-seismic strain distribution with respect to the branch faults of the flower structure.
    Description: conference
    Keywords: 551 ; TQC 220 ; TSB 000 ; VAE 820 ; VAE 830 ; VEB 110 ; VAE 120 ; VBE 000 ; Reflexionsseismik {Geophysik} ; Mitteleuropa {Geophysik} ; Sedimentationsbecken als Erdkrustentypen {Geologie} ; Bruchschollenstrukturen {Geologie} ; Norddeutsche Senke {Geologie} ; Methodik {Strukturgeologie} ; Modellierung von Prozessen in der Geosphäre ; Niedersächsiches Becken ; Dreidimensionale Seismik ; Strukturgeologie ; Modell
    Language: German
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  • 13
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    Electromagnetic radiation (EMR) and its interpretation in terms of stresses in the lithosphere (2010)
    Universitätsverlag Göttingen
    Details
    Publication Date: 2021-03-29
    Description: Electromagnetic radiation (EMR) as measured at the surface of the lithosphere or underground shows preferred orientations, which can be related to microcracks and other brittle structures at micro and nano scales (see Bahat et al. 2005 and references therein). During the last years, numerous studies showed the applicability of EMR measurements for the determination of active fractures and stress orientations. EMR is determined with a ‘Cerescope’, which picks up EMR signals at frequencies from 5– 50 kHz (Obermeyer, 2005) with a ferrite aerial and processes them electronically so that the results can be displayed on a screen or copied to a computer. With the help of oriented EMR measurements, intensity variations are determined, which can be related to preferred crack fracture orientations. From this information, orientations of the principal stresses can be calculated. In addition, the intensity of the EMR is related to stress magnitudes...
    Description: conference
    Keywords: 551 ; TQD 000 ; VAE 120 ; VAE 150 ; VAE 140 ; Elektrische Verfahren {Geophysik} ; Methodik {Strukturgeologie} ; Strukturelle Erscheinungen {Strukturgeologie} ; Gesteinsdeformation {Strukturgeologie} ; Lithosphäre ; Fraktographie ; Spannungstensor ; Elektromagnetisches Verfahren
    Language: German
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  • 14
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    Mikrostruktur und Textur nach Scherverformungsversuchen an Hämatiterzen (2010)
    Universitätsverlag Göttingen
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    Publication Date: 2021-03-29
    Description: Die Beziehungen zwischen der Mikrostruktur und der kristallografischen Vorzugsorientierung (Textur) von Hämatiterzen der gebänderten Eisenerzformation (BIF) in Brasilien wurden in vielen Veröffentlichungen behandelt, z.B. Quade et. al. 2000, Rosière et al. 2001, Bascou et al. 2002. Polfiguren dieser Hämatiterze zeigen kreisförmige bis elliptische c-Achsen-Maxima, die um den Pol der Foliation liegen. Die Pole der Prismenflächen liegen auf Großkreisen in der Foliationsebene und die Maxima auf diesen fallen mit der Lineation zusammen. Die Entstehung dieser Regelung wird auf Scherverformungprozesse zurückgeführt. Bei experimentellen Stauchversuchen an polykristallinem Hämatit gab es Anzeichen der Bildung eines c-Achsenmaximums senkrecht zur Kompressionsrichtung (Siemes et al. 2003). Da zu vermuten war, dass Gleiten parallel zur Basis des Hämatits Ursache der Regelung ist, wurden die Gleitmechanismen an experimentell verformten Hämatiteinkristallen bestimmt (Siemes et al. 2006). In diesem Beitrag werden neue Scherexperimente an polykristallinen Hämatitaggregaten vorgestellt...
    Description: conference
    Keywords: 551 ; VAE 120 ; VAE 140 ; VBB 000 ; VKB 270 ; VKB 120 ; Methodik {Strukturgeologie} ; Gesteinsdeformation {Strukturgeologie} ; Experimentelle Geologie ; Produkte mechanischer Deformation {Petrologie} ; Petrologie der Vulkanite ; Eisenerz ; Hämatit ; Torsionsversuch ; Scherung 〈Geologie〉 ; Experiment ; Texturanalyse ; Mikrostruktur
    Language: German
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  • 15
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    Correlation of magnetic fabric and crystallographic preferred orientations of naturally deformed carbonate — mica rocks from the Alpi Apuane in Italy and the Damara Orogen in Namibia (2010)
    Universitätsverlag Göttingen
    Details
    Publication Date: 2021-03-29
    Description: The anisotropy of magnetic susceptibility (AMS) is a time-efficient method to describe crystallographic preferred orientations of rocks and has been applied in a wide field of sedimentary, metamorphic and magmatic geology. The method, however, suffers from limitations which mainly result from the interference of diamagnetic, paramagnetic and ferromagnetic fabrics (de Wall 2005) — the term ferromagnetism is used in a wider sense here, including e.g. ferrimagnetism. The AMS is an integral parameter which describes a crystallographic preferred orientation as an ellipsoid. The quantitative correlation of the AMS with the crystallographic preferred orientations should help to allow a closer view at the applicability and the limitations of the AMS analysis (see also Schmidt et al. 2006 a, b)... The results of this study are based on a large variety of fabric types of carbonate-mica marbles and mylonites, i.e. varying mica content, grain sizes, grain shapes, types and intensities of the crystallographic preferred orientation. The presented first correlations of the AMS and CPO for the single mineral phases in general demonstrate a good matching. Regarding the comparison of texture types and the AMS, limitations are possible. While single c-axis maxima and girdle-like c-axis distributions can be also distinguished by the AMS, it is obvious that distinguishing between these types and the double c-axis type is not possible at the present stage.
    Description: conference
    Keywords: 551 ; TOT 310 ; VKA 200 ; VAE 140 ; VEF 200 ; VER 200 ; VKB 270 ; VAE 120 ; Gesteinsmagnetismus {Geophysik} ; Gefügekunde der Gesteine ; Gesteinsdeformation {Strukturgeologie} ; Italien {Geologie} ; Namibia {Geologie} ; Produkte mechanischer Deformation {Petrologie} ; Methodik {Strukturgeologie} ; Apuaner Alpen ; Damara Orogen ; Karbonatgestein ; Deformation 〈Geologie〉 ; Magnetische Suszeptibilität ; Kristallorientierung ; Korrelationsanalyse
    Language: German
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  • 16
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    Quantification and sensitivity of fault seal parameters demonstrated in an integrated reservoir modelling work flow. A case study on the Njord Field, Halten Terrace, Norway (2010)
    Universitätsverlag Göttingen
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    Publication Date: 2021-03-29
    Description: The primary objective of this paper is to present a fault seal case study from the Njord Field, offshore Norway. The study utilised analogue field studies as well as core descriptions and petrophysical well data in order to evaluate the sealing potential of large to medium scale faults that segment the reservoir. Dynamic data and 4D seismic information was used to calibrate the results through multiple fault seal scenarios.
    Description: conference
    Keywords: 551 ; VRE 100 ; VRE 700 ; VSD 000 ; VAE 120 ; VAE 150 ; VAE 840 ; Exploration / Prospektion von Kohlenwasserstofflagerstätten ; Tektonik ; Nordeuropa {Fossile Energieträger} ; Methodik {Strukturgeologie} ; Strukturelle Erscheinungen {Strukturgeologie} ; Rifts {Geologie} ; Norwegen ; Erdöllagerstätte ; Störung 〈Geologie〉 ; Abdichtung ; Stochastisches Modell
    Language: German
    Type: anthologyArticle , publishedVersion
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  • 17
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    Die neogene Entwicklung des zentralen Tien Schan, Kasachstan. Erste Ergebnisse von Apatit-Spaltspurdatierungen und morphotektonischer Analyse von Satellitendaten (2010)
    Universitätsverlag Göttingen
    Details
    Publication Date: 2021-03-29
    Description: Der Tien Schan ist ein etwa E–W erstrecktes, rund 2500km langes und bis 250km breites Gebirge in Zentralasien. Einzelne Gipfel sind über 7000m hoch. Obwohl durch die Kollision Indiens mit Asien entstanden, ist der Tien Schan ein Intraplatten-Orogen, dessen Hebung lange nach dem Beginn der Kollision vor 50Ma und weit nördlich der Sutur einsetzte (Sobel & Dumitru 1997). Von Tibet ist der Tien Schan durch das kaum deformierte Tarim-Becken getrennt. Hohe und schroffe Topographie, starke Seismizität (Molnar & Ghose 2000) und GPS-Daten zeigen, dass das Orogen auch heute sehr aktiv ist (Abdrakhmatov et al. 1996, Reigber et al. 2001). Der Tien Schan nimmt gegenwärtig etwa 40% der Gesamtkonvergenz Indiens mit Asien auf. Die Struktur des Tien Schan wird dominiert von E–Wstreichenden, nach N und S gerichteten Überschiebungen (Avouac et al. 1993, Yin et al. 1998), die sich meist deutlich in der Morphologie äußern. Auffallend ist die großräumige Gliederung des Orogens durch NW–SE-streichende dextrale Blattverschiebungen, die auch in das nördliche Vorland reichen (Tapponnier & Molnar 1979). Den Unterbau des Tien Schan bildet ein paläozoisches Akkretionsorogen (Zonenshajn et al. 1990). Im Mesozoikum entstand eine ausgedehnte Fastebene. In der späten Kreide oder dem frühen Tertiär setzte die Ablagerung kontinentaler Serien ein, die im jüngeren Känozoikum sehr mächtig werden. Die synorogenen Sedimente liegen manchmal konkordant, oft aber auch deutlich winkeldiskordant auf dem paläozoischen Sockel. In beiden Fällen bilden sie häufig asymmetrische Falten, die oft mit Störungen verknüpft sind. Geländestufen und ein starker Einfluss auf die Entwicklung des Entwässerungsnetzes weisen viele Störungen als gegenwärtig aktiv aus. Unser Untersuchungsgebiet liegt im Südosten Kasachstans. Es umfasst die Nordflanke des Tien Schan und seinen zentralen Teil mit den höchsten Erhebungen. Im Untersuchungsgebiet liegt das nach E propagierende Ende eines seismisch aktiven Störungssystems, das weiter westlich die nördliche Randstörung des Gebirges bildet, wo es unter der Millionenstadt Almaty (Alma- Ata) verläuft und eine ernste Bedrohung darstellt. Die Entwicklung dieses Störungssystems soll über verschiedene Zeitskalen mit verschiedenen Methoden untersucht werden...
    Description: conference
    Keywords: 551 ; VAE 811 ; VBN 500 ; VEG 340 ; VEG 160 ; VEK 000 ; VBJ 000 ; VAE 120 ; Alpidische Orogene {Geologie} ; Geochronologie einzelner Regionen im allgemeinen ; Kasachstan {Geologie} ; Zentral-kasachischer Schild und benachbarte Gebirgszüge {Geologie} ; Zentralasien {Geologie} ; Satellitenbildgeologie ; Methodik {Strukturgeologie} ; Tien Schan ; Neogen ; Tektogenese ; Hebung 〈Geologie〉 ; Apatit ; Kernspaltspurenmethode ; Satellitenbildauswertung
    Language: German
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  • 18
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    Measurement of calcite crystallographic-preferred orientations by magnetic anisotropy and comparison to diffraction methods (2010)
    Universitätsverlag Göttingen
    Details
    Publication Date: 2021-03-29
    Description: The anisotropy of magnetic susceptibility (AMS) of rocks reflects the preferred orientations of minerals. Therefore AMS is a quick and easy way to characterize rock fabrics (Hrouda 1982,Borradaile 1988); the obtained result is also called the magnetic fabric of the rock. The method has been often used to measure the orientation of ferromagnetic minerals, mainly magnetite, but in recent studies it has been increasingly used to measure textures of paramagnetic minerals as phyllosilicates (Lüneburg et al. 1999, Cifelli et al. 2004). A further application is the measurement of diamagnetic textures, especially calcite textures. Calcite is suitable for the AMS method, because it has a high magnetic anisotropy with the minimum susceptibility along the crystallographic c-axis. Therefore a preferred orientation of the c-axes, which can be induced by deformation, generates a magnetic fabric...
    Description: conference
    Keywords: 551 ; VKA 200 ; VAE 120 ; TQB 000 ; TOT 310 ; VGA 410 ; Gefügekunde der Gesteine ; Methodik {Strukturgeologie} ; Erdmagnetische Verfahren {Geophysik} ; Gesteinsmagnetismus {Geophysik} ; Röntgenanalyse {Mineralogie: Kristallographie} ; Calzit ; Magnetische Suszeptibilität ; Kristallorientierung ; Röntgendiffraktometrie ; Neutronendiffraktometrie ; Vergleichsmessung
    Language: German
    Type: anthologyArticle , publishedVersion
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  • 19
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    Influence of viscosity on growth of high pressure phases in computer experiments (2010)
    Universitätsverlag Göttingen
    Details
    Publication Date: 2021-03-29
    Description: The general aim of the project is the examination of microstructures that develop under HP conditions in computer experiments. Starting point is an interest in the dynamics of HP phase transitions, as for instance the probably catastrophic phase-change event of olivine to spinel in the upper mantle. This is either explained by large overpressure or failure during the development of micro-structures during the growth of the spinel phase. Experimental results on this subject are rare, and do not lead by themselves to a deeper insight into the complicated stress/strain/volumechange/ micro-crack relationships of the transition. We developed a central force spring model, where particles can undergo a phase change using parameters of olivine and spinel. The algorithm is capable of simulating the local growth of the mentioned phases on the basis of direction-dependant rate laws. In the current context newtonian viscosity is added to the previously solely elastic system, since under HP/HT conditions the viscous flow within the material will have a large influence on the distribution of elastic energies, which in turn have an important influence on the driving force of the transition. Thus we are dealing with a visco-elastic system, which will be subjected to timedependant strain.
    Description: conference
    Keywords: 551 ; VKA 200 ; VBE 000 ; VKA 110 ; VAE 120 ; Gefügekunde der Gesteine ; Modellierung von Prozessen in der Geosphäre ; Gesteinsbestimmung ; Methodik {Strukturgeologie} ; Hochdruckparagenese ; Viskosität ; Olivin ; Spinell ; Kristallisation ; Computersimulation
    Language: German
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  • 20
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    Strukturgeologische Studien als Beitrag zum Erfolg tiefengeothermischer Projekte (2010)
    Universitätsverlag Göttingen
    Details
    Publication Date: 2021-03-29
    Description: Bei der tiefen Geothermie werden zur Schaffung eines künstlichen geothermischen Reservoirs unterirdische Wärmetauscher erzeugt. Zur Wärme- und Stromerzeugung wird dann wiederholt Wasser in den Untergrund verpresst, welches erhitzt und wieder gefördert wird. Dafür werden im Allgemeinen Systeme aus Injektions- und Förderbohrungen (‚Dubletten‘) von 2–5km Tiefe verwendet, um die erforderlichen Temperaturen zu erreichen. Der kritische Parameter für die wirtschaftliche Nutzbarkeit geothermischer Reservoire (‚Erfolg‘) ist jedoch eine nötige hohe Permeabilität. In den meisten Reservoiren müssen zu niedrige natürliche Permeabilitäten — oder zu kleine Wärmeaustauschflächen — durch die Öffnung bzw. Scherung vorhandener Brüche oder die Erzeugung künstlicher hydraulischer Brüche erhöht werden (‚Reservoirstimulation‘). Um Stimulationen erfolgreich durchzuführen, müssen dabei das vorhandene Bruchsystem und das gegenwärtige Spannungsfeld möglichst genau bekannt sein. Dafür sind strukturgeologische Studien von besonderer Bedeutung (vgl. Philipp et al. 2005)...
    Description: conference
    Keywords: 551 ; TOO 000 ; TQF 000 ; VAE 120 ; Geothermik {Geophysik} ; Geothermische Verfahren {Geophysik} ; Methodik {Strukturgeologie} ; Geothermische Energie ; Strukturgeologie ; Buntsandstein ; Klüftung
    Language: German
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  • 21
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    Neue Perspektiven der Texturanalytik von Gesteinen mit konventioneller Röntgenbeugung (2010)
    Universitätsverlag Göttingen
    Details
    Publication Date: 2021-03-29
    Description: Technische Entwicklungen und verbesserte Messmethoden haben in den vergangenen 15 Jahren in der Gesteinstexturanalyse zu einer zunehmenden Nutzung vor allem der Elektronen- und Neutronenbeugung geführt. Dabei ist die Anwendung der Röntgentexturanalyse in der Geologie in den Hintergrund getreten. Neue technische Optionen dieser Methode, wie sie zum Beispiel für die Qualitätskontrolle in der Siliziumchipherstellung entwickelt worden sind, haben noch keinen Eingang in die Gesteinstexturanalyse gefunden. Steht die volumenbezogene Gesamttexturanalyse im Vordergrund, so hat die Röntgenbeugung spezifische Vorteile. Gegenüber der Elektronenbeugung am Rasterelektronenmikroskop (Backscatter Electron Diffraction) ist keine aufwendige Probenpräparation notwendig und es kann ein wesentlich größeres Probenvolumen erfasst werden. Gegenüber der Neutronenbeugung ist die Röntgenbeugung wesentlich kostengünstiger und die zur Verfügung stehende Messzeit ist im Prinzip unbeschränkt. Nachteile der Röntgentexturanalyse sind die notwendige Messdatenkorrektur aufgrund der Defokussierung des Messstrahls im Verlauf der Messung (Ullemeyer & Weber 1994), die unter Umständen schlechte Auflösung bezüglich Gitterabstand d, und das gegenüber der Neutronenbeugung wesentlich geringere messbare Probenvolumen. Die Anwendung der Röntgentexturanalyse war daher klassischerweise auf monophase und feinkörnige Gesteine beschränkt. Um diese Nachteile der Röntgentexturanalyse kostengünstig zu minimieren, wurde für die Abteilung Strukturgeologie und Geodynamik des Geowissenschaftlichen Zentrums der Universität Göttingen ein neues Röntgentexturgoniometer auf der Basis von neu entwickelten standardisierten Bauteilen für die Gesteinstexturanalyse individuell konfiguriert und die Messdatenauswertestrategie angepasst.
    Description: conference
    Keywords: 551 ; VAE 120 ; VKA 200 ; VGB 500 ; Methodik {Strukturgeologie} ; Gefügekunde der Gesteine ; Röntgenographische Methoden {Mineralogie} ; Gefüge 〈Gesteinskunde〉 ; Röntgentexturanalyse
    Language: German
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  • 22
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    The effect of water, temperature and strain rate on the dislocation creep microstructure, recystallized grain size and flow stress of quartz (2010)
    Universitätsverlag Göttingen
    Details
    Publication Date: 2021-03-29
    Description: Since the work of Griggs & Blacic (1965) it is well known that the crystal plastic flow strength of ‘wet’ quartz samples is much lower than that of ‘dry’ samples deformed at the same conditions, and the general effect of water on dislocation creep microstructures has been documented (e.g. Hirth & Tullis 1992), but its effect on the recrystallized grain size has not been quantified. The recrystallized grain size is the most reliable and most easily measurable microstructural feature to derive flow stresses from natural mylonites (e.g. White 1979, Kohlstedt et al. 1980). In a recent experimental study, a well-constrained recrystallized grain size piezometer for quartz (Stipp & Tullis 2003) was calibrated using natural as-is quartzites; the use of a molten salt cell at high confining pressure (1.5GPa) in a Griggs-type apparatus allowed good stress resolution (Green & Borch 1989). There has been some debate as to whether there is any independent effect of water on the recrystallized grain size piezometer. Two laboratory studies on olivine aggregates (at different pressures) report contradictory results; van der Wal et al. (1993) found that the recrystallized grain size piezometer is independent of the water content, whereas Jung & Karato (2001) observed a water-dependence of the piezometer. In this study, we have investigated changes in the recrystallized grain size and other deformation microstructures of quartz within dislocation creep regimes 2 and 3 of Hirth & Tullis (1992). Deformation experiments on Black Hills quartzite with three different initial water contents (as-is, wateradded and vacuum-dried) were carried out in order to evaluate the effect of water on the recrystallized grain size / flow stress piezometer...
    Description: conference
    Keywords: 551 ; VKA 200 ; VAE 120 ; VAE 140 ; VHB 400 ; VKA 120 ; VKB 270 ; Gefügekunde der Gesteine ; Methodik {Strukturgeologie} ; Gesteinsdeformation {Strukturgeologie} ; Oxide und Hydroxide {Mineralogie} ; Experimentelle Petrologie ; Produkte mechanischer Deformation {Petrologie} ; Quarzit ; Deformation 〈Geologie〉 ; Experiment ; Quarz ; Rekritallisationstextur
    Language: German
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  • 23
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    Quartz microstructures in nature and experiment — evidence of rapid plastic deformation and subsequent annealing (2010)
    Universitätsverlag Göttingen
    Details
    Publication Date: 2021-03-29
    Description: Quartz microstructures produced in short-term deformation and annealing experiments are compared with those in naturally deformed vein quartz in cores from the Long Valley Exploratory Well (Long Valley Caldera, California). The experiments are designed to simulate i) co-seismic deformation of quartz in the uppermost plastosphere and ii) annealing during post-seismic stress relaxation. The experiments are performed in a modified Griggs type solid medium apparatus. Natural polycrystalline quartz samples (grain size on the order of millimetres) are deformed at a temperature of 400°C, a confining pressure of 2GPa, and strain rates of ca. 10−4 s−1. The differential stress reaches 2–4GPa and the irreversible axial shortening is typically a few percent. In some experiments the samples have subsequently been annealed for ca. 14–15 h at elevated temperatures of 800–1000°C and low stresses (quasi-hydrostatic or nonhydrostatic conditions)...
    Description: conference
    Keywords: 551 ; VKA 200 ; VAE 120 ; VAE 140 ; VHB 400 ; VKA 120 ; VGF 300 ; Gefügekunde der Gesteine ; Methodik {Strukturgeologie} ; Gesteinsdeformation {Strukturgeologie} ; Oxide und Hydroxide {Mineralogie} ; Experimentelle Petrologie ; Experimentelle Mineralogie ; Quarz ; Deformation 〈Geologie〉 ; Experiment ; Mikrostruktur ; Rekristallisationstextur
    Language: German
    Type: anthologyArticle , publishedVersion
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  • 24
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    Experimental study of the evolution of fault gouge in layered sand–clay sequences (2010)
    Universitätsverlag Göttingen
    Details
    Publication Date: 2021-03-29
    Description: This study focuses on clay smear processes during fault gouge evolution in sand-clay sequences at depths up to 2 km. A clay-rich fault gouge can dramatically lower the fault’s permeability, and prediction of this process is therefore relevant in groundwater modelling and hydrocarbon geology (Fulljames et al. 1997, Yielding et al 1997, van der Zee et al. 2003, 2005). We constructed an ‘underwater’ sandbox to deform layered sand-clay models of 20 × 40 × 20 cm above a 70°-dipping rigid basement fault. The experiments are run completely watersaturated to allow deformation of wet clay and cohesionless sand. The basement fault moves at 20 to 120mmh−1 to a maximum offset of 60 mm. We use quartz sand with grain size between 0.1 to 0.4mm and an illite-rich clay with a water content between 28 and 55 wt.%. Water content of the clay is used to control its shear strength and state of consolidation...
    Description: conference
    Keywords: 551 ; VAE 140 ; VAE 120 ; VAE 130 ; VBB 000 ; VKA 120 ; VKB 270 ; Gesteinsdeformation {Strukturgeologie} ; Methodik {Strukturgeologie} ; Geomechanik ; Experimentelle Geologie ; Experimentelle Petrologie ; Produkte mechanischer Deformation {Petrologie} ; Verwerfung ; Störungsletten ; Experiment
    Language: German
    Type: anthologyArticle , publishedVersion
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  • 25
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    Crystal distribution patterns and their anisotropy behaviour in igneous rocks: towards an automated quantification, first results (2010)
    Universitätsverlag Göttingen
    Details
    Publication Date: 2021-03-29
    Description: Since approximately two decades fractal geometry offers tools for the quantification of rock fabrics, and new methods are currently under development to investigate the inhomogeneity of crystal distributions, grain- and phase-boundary patterns as well as their anisotropy behaviour (Kruhl et al. 2004). These methods are now adapted for automated processing and suitable to quantify the inhomogeneity and anisotropy of rock fabrics from macro to microscale. Applications for quantifying inhomogeneity are mainly based on the box-counting and map-counting (Peternell 2002) methods, for anisotropy behaviour mainly based on modified Cantor-dust methods and provide fractal dimensions, fractal-dimension isolines and azimuthal anisotropies of fractal dimension (AAD, Volland & Kruhl 2004). For instance, the results provide information about the local variations of fabric patterns and their prefer orientation behaviour at macro and microscale.
    Description: conference
    Keywords: 551 ; VAE 120 ; VKA 200 ; VAE 140 ; Methodik {Strukturgeologie} ; Gefügekunde der Gesteine ; Gesteinsdeformation {Strukturgeologie} ; Magmatisches Gestein ; Gefüge 〈Gesteinskunde〉 ; Fraktalgeometrie ; Anisotropie
    Language: German
    Type: anthologyArticle , publishedVersion
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