Tracing an Intra-montane Fault: An Interdisciplinary Approach
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Tracing an Intra-montane Fault: An Interdisciplinary Approach Filip Hartvich • Jan Valenta
Received: 28 February 2012 / Accepted: 7 December 2012 / Published online: 19 January 2013 Ó Springer Science+Business Media Dordrecht 2013
Abstract This paper presents the results of combined geophysical and morphostructural research of a significant tectonic lineament forming the boundary between the core Bohemian Forest (Sˇumava) Mts. and its foothills of Posˇumavı´. The exact course, length and character of the fault have not yet been studied in detail despite its possible role in the uplift of the mountain range. To assess the fault course, length and continuity, we have employed a combination of geophysical, morphological and morphostructural methods. These indirect methods had to be applied as the fault only rarely outcrops along its course, and the morphological border is not straightforward. In the beginning, GIS morphometric methods have been applied to assess the influence of the fault on the present relief. Thereafter, structural measurements of joint systems were undertaken together with the analyses of linear structures within the relief. Finally, resistivity profiling at multiple sites across its estimated course has helped to localise the exact position of the fault. Altogether, fifteen profiles were measured using pole-dipole and dipole– dipole electrode configurations. To obtain more detailed results, the resistivity profiling was supplemented by electrical resistivity tomography on three profiles. The paper brings two main results. Firstly, the combination of morphostructural and geophysical methods brings information that each separately cannot, particularly when the faults have no outcrops. Secondly, it was found that the studied fault stretches along the whole study area. Moreover, indicators point to its possible continuation towards the south-east. Keywords Fault tracing Morphometry Resistivity profiling Resistivity tomography Bohemian Forest Mts. Posˇumavsky´ Fault
1 Introduction Studying the faults that do not build a prominent morphological border, such as the mountain front faults (Garcia-Tortosa et al. 2008), and at the same time do not surface on F. Hartvich (&) J. Valenta Institute of Rock Structure and Mechanics, Academy of Sciences of the Czech Republic, V Holesˇovicˇka´ch 41, 142 09 Prague, Czech Republic e-mail: [email protected]
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Surv Geophys (2013) 34:317–347
outcrops along its course, is always a complicated matter (Ortuno et al. 2008). These intramontane or outer-slope faults could have played an important role in a formation of mountain chains, for example, by accommodating an uplift or its part. Such a fault may not be evident in the current relief, although a detailed analysis of the morphological properties in the vicinity of fault may reveal its traces (Mirabella et al. 2004). However, such evidence by itself is often too weak to be used as a base stone for a hypothesis on the mountain range formation. Therefore, it is useful (and often necessary) to empl
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