Kinematic and mechanical quantification of fault related fold structures

Kurzvortrag im Rahmen der Verleihung des Otto Ampferer-Preises 2006

Faults in the earth crust occur within large range of scales from intracrystalline scale over mesoscopic to several km-scale. Depending on the rheological conditions and amount of displacement within these zones of discontinuity, a wide range of fault rocks like fault breccias, fault gouges, cataclasites, psoudotachylites or mylonites can form. In many cases, deformation associated with faulting is not only limited to the fault rock alone, but rather forms a combination with continuous near field deformation in the wall rock, a process that is generally called fault-related folding.

The correct interpretation and recognition auf fault related folds is fundamental for the reconstruction of progressive development and history of fault kinematics, as well as prediction in areas of limited exposure. On the basis of brittle fault analyses, numerical modelling and 3D visualization of natural fault-related folds of various scales presented in this talk, the importance of flow perturbations around faults and their progressive development will be emphasised as an alternative concept to existing fault-related fold models.

The following differentiation criteria between these two approaches are: 1) The fault does not necessarily maintain a stable orientation but may rotate during progressive development. 2) Fault drag can change from reverse to normal along the fault. 3) The displacement along the fault has its maximum in the centre of the fault and decreases to zero in both directions, downsection and upsection towards fixed fault tips. It is therefore recommended to consider models that are based on flow perturbation theory for future analyses or reinterpretation of fault-related fold structures.

Ampferer2006 Wiesmayr

Die Schnittstelle zwischen Oberrheingraben und Faltenjura: Alte Brüche - junge Erdbeben

Kurzvortrag im Rahmen der Verleihung des Otto Ampferer-Preises 2006

Die weitere Umgebung Basels, zwischen dem Südrand des Oberrheingrabens und dem Faltenjura, ist eine geologische Schnittstelle zwischen einem Teil des westeuropäischen känozoischen Grabensystems und dem nördlichen Alpenvorland. Seit dem Jungpaläozoikum wurde diese Zone durch ein Wechselspiel dehnender und kompressiver Spannungen geprägt. Tektonische Aktivität manifestiert sich rezent durch - im regionalen Vergleich - erhöhte historische und instrumentelle Seismizität. Im Zuge einer Dissertation an der Universität Basel sammelte Kamil Ustaszewski Indizien, die eine kompressive und potentiell seismogene Reaktivierung von Verwerfungen im kristallinen Untergrund seit dem späten Pliozän nahelegen. Dies gelang durch die Kombination geologischer, geomorphologischer und geophysikalischer Daten, sowie anhand von Einblicken, die aus dynamisch skalierten Analogmodellen gewonnen wurden.

Ampferer2006 Ustaszewski

Subaerial exposure and flooding surfaces of carbonate platforms

Kurzvortrag im Rahmen der Verleihung des Otto Ampferer-Preises 2006

The correct identification and interpretation of subaerial exposure and flooding of carbonate platforms is fundamental for the reconstruction of the depositional, tectonic and eustatic history of an area and can improve reservoir and seal predictions in carbonate rocks. Both, subaerial exposure and flooding with concomitant sediment starvation may generate significant bounding surfaces (exposure and flooding surfaces) in the stratigraphic record. The purpose of this paper is to refine the petrographic and geochemic characteristics of exposure and flooding surfaces. Furthermore differences and similarities between burial and meteoric diagenetic overprints in carbonate rocks are evaluated.

Ampferer2006 Sattler

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