Listric versus planar normal fault geometry: an example from the Eisenstadt-Sopron Basin (E Austria)

Abstract

In a gravel pit at the eastern margin of the Eisenstadt-Sopron Basin, a satellite of Vienna Basin (Austria), Neogene sediments are exposed in the hanging wall of a major normal fault. The anticlinal structure and associated conjugated secondary normal faults were previously interpreted as a rollover anticline above a listric normal fault. The spatial orientation and distribution of sedimentary horizons and crosscutting faults were mapped in detail on a laser scan of the outcrop wall. Subsequently, in order to assess the 3D distribution and geometry of this fault system, a series of parallel ground penetrating radar (GPR) profiles were recorded behind the outcrop wall. Both outcrop and GPR data were compiled in a 3D structural model, providing the basis for a kinematic reconstruction of the fault plane using balanced cross-section techniques. However, the kinematic reconstruction results in a geologically meaningless normal fault cutting downand up-section. Additionally, no evidence for a weak layer serving as ductile detachment horizon (i.e. salt or clay horizon) can be identified in stratigraphic profiles. Instead, the observed deflection of stratigraphic horizons may be caused by a displacement gradient along a planar master fault, with a maximum displacement in the fault centre, decreasing towards the fault tips. Accordingly, the observed deflection of markers in the hanging wall-and in a nearby location in the footwall of the normal fault-is interpreted as large-scale fault drag along a planar fault that records a displacement gradient, instead of a rollover anticline related to a listric fault.

Fault dip variations related to elastic layering

“…A listric fault usually flattens downwards (Shelton 1984;Spahić et al 2011) with a low-angle plane lying on a (as often assumed) undeformed basement (Mauduit & Brun 1998). Even if listric faults are more common in extensional environments (Maloney et al 2012), they can also occur in compressional regimes (Groshong 2006).…”

The impact of ellipsoidal particle shape on pebble breakage in gravel

“…For this study a sampling site was found in a gravel pit south of St. Margarethen (Burgenland, Austria). The outcrop is located at the eastern margin of the Neogene Eisenstadt-Sopron Basin [18,19] , a satellite basin of the Vienna Basin [20] , and exposes deltaic gravel of Miocene age (11.9–11.6 Ma) [14] . The gravel is mainly composed of limestone pebbles (85%), but dolomite (5%), sandstone (5%) and quartz (5%) pebbles, also occur.…”

Fault Structure Reconstruction From Magnetic Anomalies Using an Improved Backtracking Search Optimization Algorithm

“…Therefore, the characterization of active faults is one of the most important research topics in geophysics. For this purpose, various geophysical prospecting methods such as electrical resistivity (Arjwech et al., 2021), gravity (Hiramatsu et al., 2019), magnetic (Khalil, 2016), electromagnetic (Martí et al., 2020), self‐potential (Saribudak & Hauwert, 2017), and ground‐penetrating radar (Dujardin et al., 2014) are commonly used (Spahić et al., 2010). The magnetic method measures variations in the Earth's magnetic field caused by changes in the magnetic properties of the rocks.…”