Near-Vertical and Wide-Angle Seismic Surveys in the Schwarzwald

Lüschen, E.; Wenzel, Friedemann; Sandmeier, Karl-Josef; Menges, Dieter; Ruhl, T.; Stiller, Manfred; Janoth, W.; Keller, Francine; Söllner, Walter; Thomas, Rüdiger; Krohe, A.; Stenger, R; Fuchs, Karl; Wilhelm, H.; Eisbacher, G. H.

doi:10.1007/978-3-642-74588-1_14

Cited by 26 publications

(32 citation statements)

References 53 publications

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“…Toward the west, the trend of the BLZ becomes E-W, and is associated with dextral strike-slip movements (Sittig 1981). Deep seismic reflection data show that the BLZ dips toward the NW underneath the gneiss mass, to a depth of at least 12 km (Lü schen et al 1987). Geochronological studies show that the exhumation of the high-grade gneisses along the northern part of the BLZ occurred in the time-range of 335-332 Ma (Schaltegger 2000).…”

Section: Carboniferous Structures Of the Black Forestmentioning

confidence: 96%

“…The mean direction of stress is taken from Bergerat (1985) and Villemin and Bergerat (1987). The isobaths of the crust-mantle boundary are after Edel et al (1975), modified using the results of deep seismic reflection studies (Lü schen et al 1987;Brun et al 1991;Wenzel and Brun 1991) a NNE-SSW oriented r 1 stress axis during the Late Eocene, which is not consistent with the results of the paleostress analysis by Bergerat (1985). During the Oligocene extension, characterized by E-W oriented r 3 axis (Bergerat 1985;Schumacher 2002), N-S striking normal faults developed in the URG.…”

Section: Tertiary Riftingmentioning

confidence: 97%

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The Variscan tectonic inheritance of the Upper Rhine Graben: evidence of reactivations in the Lias, Late Eocene–Oligocene up to the recent

Edel

Schulmann

Rotstein

2006

Int J Earth Sci (Geol Rundsch)

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Processing of gravity and magnetic maps shows that the basement of the Upper Rhine Graben area is characterized by a series of NE-SW trending discontinuities and elongated structures, identified in outcrops in the Vosges, Black Forest, and the Odenwald Mountains. They form a 40 km wide, N30-40°s triking, sinistral wrench-zone that, in the Visean, shifted the Variscan and pre-Variscan structures by at least 43 km to the NE. Wrenching was associated with emplacement of several generations of plutonic bodies emplaced in the time range 340-325 Ma. The subvertical, NE-SW trending discontinuities in the basement acted as zones of weakness, susceptible to reactivation by subsequent tectonism. The first reactivation, marked by mineralizations and palaeomagnetic overprinting along NE-SW faults of the Vosges Mountains, results from the Liassic NW-SE extension contemporaneous with the break-up of Pangea. The major reactivation occurred during the Late Eocene N-S compression and the Early-Middle Oligocene E-W extension. The NE-SW striking basement discontinuities were successively reactivated as sinistral strike-slip faults, and as oblique normal faults. Elongated depocenters appear to form in association with reactivated Variscan wrench faults. Some of the recent earthquakes are located on NE-SW striking Variscan fault zones, and show sinistral strikeslip focal mechanisms with the same direction, suggesting also present reactivation.

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Section: Carboniferous Structures Of the Black Forestmentioning

confidence: 96%

Section: Tertiary Riftingmentioning

confidence: 97%

The Variscan tectonic inheritance of the Upper Rhine Graben: evidence of reactivations in the Lias, Late Eocene–Oligocene up to the recent

Edel

Schulmann

Rotstein

2006

Int J Earth Sci (Geol Rundsch)

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“…Reflexion seismic profiles show a continuous N-to NW-ward dip of the nappe planes throughout the upper crust down to a depth of about 10-12 km (Lüschen et al 1987;Eisbacher et al 1989). …”

Section: Structural and Kinematic Datamentioning

confidence: 97%

“…The CSGC and the SSGC are both considered as part of the Moldanubian Zone, but they appear to represent different crustal blocks. The lithological difference of these blocks was already emphasised by Wimmenauer (1984), Lüschen et al (1987), Müller (1989), Stenger et al (1989) and Kalt Fig. 1 Geological sketch map of the southern Schwarzwald (modified after Hann and Sawatzki 2000) with a schematic geological cross section through the southern Schwarzwald from Todtnau to Fetzenbach.…”

Section: Introductionmentioning

confidence: 96%

The Rand Granite in the southern Schwarzwald and its geodynamic significance in the Variscan belt of SW Germany

Hann

Chen

Zedler

et al. 2003

International Journal of Earth Sciences

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The Rand Granite is a heterogeneous metamorphosed granitoid rock complex with numerous wallrock inclusions situated in the Moldanubian Zone at the southern margin of the Central Schwarzwald Gneiss Complex. It is a largely mylonitized elongated body and is thrust over the Badenweiler-Lenzkirch Zone forming a nappe with shear zones along its northern and southern boundaries. It comprises meta-granites, meta-trondhjemites and biotite augen gneisses derived from monzogranites to granodiorites. Mineral behaviour indicates that the magmatic body has been deformed under upper greenschist facies conditions. Nappe thrusting, which also affected the South Schwarzwald Gneiss Complex, occurred in Visean time during high-temperature / lowpressure metamorphism. Kinematic indicators in the mylonites document E-to ESE-directed nappe transport, highly transpressive relative to the trend of the nappe boundaries and the foliation. The trondhjemites formed at 351 +5/-4 Ma, predating the Variscan HT metamorphism. They have initial e Nd -values of +6.6 to +6.7 and relatively low initial 87 Sr/ 86 Sr ratios (0.7042 to 0.7063), indicating a predominant mantle origin. The granites and protoliths of the biotite augen gneisses probably crystallised between 436 and 377 Ma, suggested by U-Pb zircon model ages. They are different from the trondhjemites with low initial e Nd -values (4.7 to 3.3) and higher initial 87 Sr/ 86 Sr ratios (0.7068-0.7077), indicating that large part of the Rand Granite originated from anatexis of continental crust. Internal structure of zircons from the Rand Granite reveals mixing of magmas derived from both mantle and crust sources. These new data support an interpretation that the Rand Granite developed along an active continental margin and therefore represents a possible root of a Variscan magmatic arc.

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“…Table 1. which strongly affect the P waveforms must be the weathering layers just below the Earth's surface at the receiver sites. Such a weathering layer has been found throughout the Black Forest by Lueschen et al (1987) from an analysis of seismic reflection data. In general, the granite and gneiss of the Black Forest must be topped by a zone a few metres thick of very low P-wave velocities (of the order of a few hundred metres per second) underlain by a layer of 50-300m thickness with a P-wave velocity of 2.0-3.5 km s-'.…”

Section: P-wave Comparisonmentioning

confidence: 97%

The effect of crustal scattering on observed high-frequency earthquake seismograms

Ebel

1989

Geophysical Journal International

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S U M M A R YA comparison of high-frequency (1-100 Hz) local (out to 40 km) earthquake seismograms at stations of the Southern Black Forest Digital Seismic Network is made in an attempt to isolate the effects of near-receiver structure and of crustal scattering on the waveforms of the direct body-waves and on the coda waves. Angle of incidence and azimuth of approach analyses from lower-crustal earthquakes show that near-surface weathering layers with low body-wave velocities and with laterally varying thicknesses exist under all of the stations, even those at hard rock sites of the Black Forest. The similarity of direct P-wave pulse shapes at each site for events of different sizes, the time-domain form of the so-called f,, phenomenon, is attributed to the response from this weathering zone. The amplitude of the P-wave coda of an event is found to be independent of the earthquake radiation pattern and to depend only on the absolute size of the event and on epicentral distance to the receiver. Furthermore, the high-frequency P-wave coda is found to be generated, at least in part, from random crustal scattering, including that within 100m of the earthquake focus. Direct S waveforms are shown to be more complicated than their P-wave counterparts, probably due to the same near-receiver and crustal scattering phenomena. However, in the case of S waves scattered energy can arrive before as well as at and after the direct S arrival, making the identification of the direct S difficult, especially for nodal arrivals.

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Near-Vertical and Wide-Angle Seismic Surveys in the Schwarzwald

Cited by 26 publications

References 53 publications

The Variscan tectonic inheritance of the Upper Rhine Graben: evidence of reactivations in the Lias, Late Eocene–Oligocene up to the recent

The Variscan tectonic inheritance of the Upper Rhine Graben: evidence of reactivations in the Lias, Late Eocene–Oligocene up to the recent

The Rand Granite in the southern Schwarzwald and its geodynamic significance in the Variscan belt of SW Germany

The effect of crustal scattering on observed high-frequency earthquake seismograms

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