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Deep seismic reflection profile DEKORP 1985-4N from the Bavarian Forest up to the Franconian Forest, Southeast Germany

The 187 km long line 4N was recorded in 1985 as part of the DEKORP project, the German continental seismic reflection program, and served as a basis for a network of six seismic reflection lines KTB 8501 – 8506, which were performed to investigate the planned target area for the Continental Deep Drilling Program (KTB) in the Upper Palatinate. The aim of the survey 4N was to explore the crustal structure of the central Mid-European Variscides down to the Moho and the uppermost mantle with high-fold near-vertical incidence vibroseis acquisition and, in particular, to scan the suture between the Moldanubian Zone and the northward adjacent Saxothuringian Zone. Details of the experiment, first results and interpretations were published by DEKORP Research Group (1987, 1988). The Technical Report of line 4N gives complete information about acquisition and processing parameters. The European Variscides, extending from the French Central Massif to the East European Platform, originated during the collision between Gondwana and Baltica in the Late Palaeozoic. Due to involvement of various crustal blocks in the orogenesis, the mountain belt is subdivided into distinct zones. The external fold-and-thrust belts of the Rhenohercynian and Saxothuringian as well as the predominantly crystalline body of the Moldanubian dominate the central European segment of the Variscides. Polyphase tectonic deformation, magmatism and metamorphic processes led to a complex interlinking between the units. The Saxothuringian represents the infill of a Cambro-Ordovician basin. The Moldanubian contains blocks of pre-Variscan crust and their Palaezoic cover. During the Variscan orogeny the Moldanubian crust was thrust towards the NW over the Saxothuringian foreland. Both units were welded together by a low-pressure metamorphism accompanied by polyphase deformation (DEKORP Research Group, 1987, 1988). The SE-NW striking line 4N runs along the western border of the Bohemian Massif perpendicular to the main tectonic trend (SW-NE). The profile starts in the Bavarian Forest and runs across the Upper Palatinate Forest. Shortly before the NE-trending Erbendorf Line, which separates the Moldanubian unit from the Saxothuringian unit, the profile runs through the area of the KTB drill site. In the Saxothuringian DEKORP 4N runs through the Fichtel Mountains, the Muenchberg Gneiss Complex and ends in the Franconian Forest. In the Bavarian Forest the line 4N traverses DEKORP 4Q nearly perpendicularly. Farther northwest the profile crosses KTB 8501 – 8503, which were arranged parallel to strike of the orogenic belt, as well as the DEKORP 3-D survey ISO 1989 around the KTB drill hole. In the Muenchberg Gneiss Complex the 4N profile is intersected by DEKORP 3B/MVE (East), which runs along the southern margin of the Saxothuringian belt in a SW-NE direction.

Reprocessed deep seismic reflection profile DEKORP 1-Laacher See Experiment 8701 across the Laacher See Volcano, East Eifel, Germany

The deep seismic reflection survey DEKORP 1-Laacher See was conducted as additional measurements in the Laacher See area in 1987 as part of the DEKORP-1 project, one main traverse of the German continental seismic reflection program. This small survey was an attempt to reveal the 3-D crustal structure in an area of the Quaternary East Eifel Volcanism and possibly find some magma chambers in the crust with high-fold near-vertical incidence vibroseis acquisition (DEKORP Research Group, 1991). The measurement consists of a 8,64 km long, multifold 2D seismic line 8701 across the Laacher See in NE-SW direction and two pseudo-3D seismic areas 8702 north of the lake and 8703 beneath the lake with one-fold coverage in each case. Laacher See or Lake Laach is a caldera lake in the Rhineland-Palatinate, Germany, one of the volcanic centres of the East Eifel Volcanic Field. It belongs together with the West Eifel to the youngest volcanic areas in Central Europe. The caldera of the Laacher See was formed about 12 900 years ago after the volcano explosively erupted, and the remaining crust collapsed into the empty magma chamber below. The Laacher See is still considered to be an active volcano, proven by seismic activities and thermal anomalies under the lake. The first processing of the Laacher See data was carried out at the Geophysical Institute of the CAU University Kiel in 1990. Unfortunately, these results have not been preserved or published. According to DEKORP Research Group (1991) the first processing resulted in poor data quality caused by high scattering and attenuation in the volcanic material near the surface. This reflected energy was not enough to image a magma chamber beneath the lake or any other structures. Thus, information about the structure of the Earth’s crust of the Eifel is mainly based on the deep seismic reflexion profile DEKORP 1B, running ca. 25 km to the west from the Laacher See und crossing DEKORP 1A at its northern profile end. In recent years, deep low‐frequency (DLF) earthquakes have been detected in the Laacher See area indicating ongoing magmatic activity in the lower crust and upper mantle (Hensch et al., 2019, Dahm et al. 2020). These and other signatures suggested the reprocessing of the Laacher See data with modern methods. Thus, the 2D seismic line 8701 has been reprocessed in 2020 within the framework of the Master’s thesis by Agafonova (2020) written at the Technical University of Berlin and supervised by the GFZ Potsdam. All reprocessed data come in SEGY trace format, the final sections additionally in PNG or PDF graphic format: as raw FF-sorted unstacked data, as preprocessed CDP-/FF-sorted unstacked data as well as poststack-time/-depth unmigrated and migrated sections. Moreover, the results of the tomographic inversion are included. Detailed information about acquisition and reprocessing parameters of line 8701 can be found in the accompanying Technical Report (Agafonova & Stiller, 2021). The reprocessed results of the Laacher See survey 1987 can be of importance for better understanding the structure of the Eifel crust. Even though significant knowledge gaps and uncertainties exist due to the insufficient data quality, such important questions can already be discussed as: • How complex is the structure beneath the Laacher See? • Can the Mantle-Crust Boundary be defined at ca. 34 km depth? • Are the strongly inclined events in the Upper Crust between 1-5 km depth parts of caldera ring-faults? • Do the reflections between 5-7 km depth indicate boundaries of a possible magma chamber?

Reprocessed southern part of the deep seismic reflection profile DEKORP 1986-2N across the Rhenish Massif in the state of Hesse, Germany

The profile 2N was recorded in 1986 as part of the DEKORP project, the German deep seismic reflection program. The focus of the DEKORP project was on deep crustal and lithospheric structures and therefore originally not on structures at shallower depths. From today's perspective, however, this depth range is of great interest for a wide range of possible technical applications (including medium-depth and deep geothermal projects). The original data is published by Stiller et al. (2021). The southernmost 68 km of the 219 km long profile 2N were reprocessed on behalf of the Hessian Agency of Nature Conservation, Environment and Geology (HLNUG). The focus of the reprocessing was on improving the resolution / mapping of geological structures down to a depth of 6 km (approx. 3 s TWT) to describe the prolongation of faults and geological structures in more detail than in previous studies. In order to achieve these goals and in view of the fact that today's processing and evaluation methods have been improved considerably compared to the 1990‘s, a state-of-the-art reprocessing was implemented. In comparison with the original processing (Stiller et al. (2021)), more sophisticated processing steps like CRS (Common Reflection Surface) instead of CDP (Common Depth Point) stacking, turning-ray tomography and prestack time and depth migration were carried out. The reprocessing results of the DEKORP 2N survey comprise all datasets newly achieved in addition to the datasets from the original processing (Stiller et al. (2021)), i.e. (1) the migrated CRS image gathers as unstacked data, and (2) the pure CRS stack, the poststack-time as well as prestack-time and prestack-depth migrated sections as stacked data. Moreover, (3) all velocity models used for the different versions including (4) the separate first-break tomography inversion, are contained. All reprocessed data come in SEGY trace format, the final sections additionally in PDF graphic format. A reprocessing report is included as well as again all meta information for each domain (source, receiver, CDP) like coordinates, elevations, locations and static corrections combined in ASCII-tables for geometry assignment purposes. The DEKORP 2 survey, consisting of the three segments 86-2Q, 86-2N and 84-2S, starts in the sub-Variscan foredeep of the Münsterland Basin and ends in the Moldanubian region at the Danube. The central part crosses the Rhenish Massif (Rhenohercynian), the Spessart Mountains of the Mid-German Crystalline High (Saxothuringian) and the meteorite impact location of the "Nördlinger Ries". The 219 km long, SSE-NNW striking DEKORP 2N line provides a cross-section through the Rhenish Massif from the sub-Variscan Münsterland Basin in the north to the Rhenohercynian Taunus Mountains in the south. The profile is the northern continuation of DEKORP 2S, which intersects at profile km 7.72. The reprocessed datasets contain a sub-section of the entire 2N with a total length of 67.84 km of full CDP fold, covering the profile’s southern part through the state of Hesse. The DEKORP '86-2N profile is of particular interest to investigate the seismic resolution of the Rhenish Massif and its different structures, such as the Siegen anticline, the Dill syncline, and the Lahn anticline. In the most southern part, the profile reaches into the Rhenohercynian Taunus Mountains until the Taunus ridge. The seismic sections of 2N show clear, deep reaching reflections along the prolongation of the whole profile supporting newer theories of nappe structures in the hessian part of the Rhenish Massif. The reflections are more clearly visible than in the original processing. All visible structures are mainly SE-dipping reflections in the upper crust, which represent lithologic contrasts as well as thrust faults known from surface geology. In the lower crust highly reflective predominantly SE-dipping reflectors can be identified. Moho reflections are clearly identifiable and deepening to the NW.

A database of centrifuge analogue models testing the influence of inherited brittle fabrics on continental rifting

This dataset presents the raw data of an experimental series of analogue models performed to investigate the influence of inherited brittle fabrics on narrow continental rifting. This model series was performed to test the influence of brittle pre-existing fabrics on the rifting deformation by cutting the brittle layer at different orientations with respect to the extension direction. An overview of the experimental series is shown in Table 1. In this dataset we provide four different types of data, that can serve as supporting material and for further analysis: 1) The top-view photos, taken at different steps and showing the deformation process of each model; they can be used to interpret the geometrical characteristics of rift-related faults; 2) Digital Elevation Models (DEMs) used to reconstruct the 3D deformation of the performed analogue models, allowing for quantitative analysis of the fault pattern. 3) Short movies built from top-view photos which help to visualize the evolution of model deformation; 4) line-drawing of fault and fracture patters to be used for fault statistical quantification. Further details on the modelling strategy and setup can be found in Corti (2012), Maestrelli et al. (2020), Molnar et al. (2020), Philippon et al. (2015), Zwaan et al. (2021) and in the publication associated with this dataset. Materials used for these analogue models were described in Montanari et al. (2017) Del Ventisette et al. (2019) and Zwaan et al. (2020).

Reprocessed deep seismic reflection profile DEKORP 1990-3B/MVE (West) across the Rhenohercynian and Saxothuringian zone of the state of Hesse, Germany

The profile DEKORP 3B/MVE, consisting of the two segments West and East, was recorded in 1990 as part of the DEKORP project, the German deep seismic reflection program. The focus of the DEKORP project was on deep crustal and lithospheric structures and therefore originally not on structures at shallower depths. From today's perspective, however, this depth range is of great interest for a wide range of possible technical applications (including medium-depth and deep geothermal projects). The original data is published by Stiller et al. (2021). The westernmost 91 km of the 208 km long profile 3B (West) were reprocessed on behalf of the Hessian Agency of Nature Conservation, Environment and Geology (HLNUG). As a particularity, also a set of 18 cross-lines, each ca. 12 km in length and perpendicular to the main lines, were surveyed along DEKORP 3B/MVE to get information about possible cross-dips. Four of those short cross-lines were reprocessed in 2D as well. The focus of the reprocessing of the old data was on improving the resolution / mapping of geological structures down to a depth of 6 km (approx. 3 s TWT) to describe the prolongation of faults and geological structures in more detail than in previous studies. In order to achieve these goals and in view of the fact that today's processing and evaluation methods have been improved considerably compared to the 1990‘s, a state-of-the-art reprocessing was implemented. In comparison with the original processing (Stiller et al. (2021)), more sophisticated processing steps like CRS (Common Reflection Surface) instead of CDP (Common Depth Point) stacking, turning-ray tomography and prestack time and depth migration were carried out. The reprocessing results of the DEKORP 3B (West) survey comprise all datasets newly achieved in addition to the datasets from the original processing (Stiller et al. (2021)), i.e. (1) the migrated CRS image gathers as unstacked data, and (2) the pure CRS stack, the poststack-time as well as prestack-time and prestack-depth migrated sections as stacked data. Moreover, (3) all velocity models used for the different versions including (4) the separate first-break tomography inversion, are contained. Additionally, the results of the 2D-reprocessing of cross-lines Q21-Q24 are included. All reprocessed data come in SEGY trace format, the final sections additionally in PDF graphic format. A reprocessing report is included as well as again all meta information for each domain (source, receiver, CDP) like coordinates, elevations, locations and static corrections combined in ASCII-tables for geometry assignment purposes. The DEKORP 3 survey was a combined seismic survey investigating the Variscan structures of the Rhenohercynian and the Saxothuringian. Consisting of three seismic lines it starts in the Rhenohercynian Hessian Depression (DEKORP 3A), crosses the Saxothuringian Mid-German Crystalline High (DEKORP 3B/MVE (West)) and runs parallel to the northern margin of the Moldanubian (DEKORP 3B/MVE (East)). The 207.65 km long DEKORP 3B (West) profile trends NW-SE and intersects DEKORP 3A in the Tertiary volcanic field within the "Northern Phyllite Zone". It crosses the Hessian Depression of the Rhenohercynian, runs through the Rhön Tertiary volcanic province and the Mesozoic Franconian Basin to the Bohemian Massif. The line ends at the Franconian Line. The reprocessed datasets contain a sub-section of the entire 3B (West) profile with a total length of 90.8 km of full CDP coverage, covering the territory of the state of Hesse, i. e. from the profile’s starting point in the NW to the SE until the Rhön volcanic complex. The reprocessed part of 3B (West) is intersected by four short cross-lines along the profile at km 8.75, 32.6, 64.75, 84.35 and by DEKORP 3A at km 42.3. The DEKORP '90-3B profile is of particular interest to investigate the seismic resolution of the Hessian depression, the east-hessian Buntsandstein nappe as well as the tertiary volcanic fields of the Kellerwald and Rhön.

Reprocessed deep seismic reflection profile DEKORP 1990-3A (including cross-profiles Q12-Q16) across the Hessian Depression, Northwest Germany

The profile 3A was recorded in 1990 as part of the DEKORP project, the German deep seismic reflection program. The focus of the DEKORP project was on deep crustal and lithospheric structures and therefore originally not on structures at shallower depths. From today's perspective, however, this depth range is of great interest for a wide range of possible technical applications (including medium-depth and deep geothermal projects). The original data is published by Stiller et al. (2021). On behalf of the Hessian Agency of Nature Conservation, Environment and Geology (HLNUG). From the 128 km long profile 3A the southernmost 104 km (plus additional 9 km northwards with decreasing CDP coverage to avoid boundary effects during migration) were reprocessed. As a particularity, also a set of 6 cross-lines, each ca. 9.6 km in length and perpendicular to the main line, were surveyed along DEKORP 3A to get information about possible cross-dips. Five of those short cross-lines (Q12-Q16) were reprocessed in 2D and 3D as well. The focus of reprocessing of the old data was on improving the resolution / mapping of geological structures down to a depth of 6 km (approx. 3 s TWT) to describe the prolongation of faults and geological structures in more detail than in previous studies. In order to achieve these goals and in view of the fact that today's processing and evaluation methods have been improved considerably compared to the 1990‘s, a state-of-the-art reprocessing was implemented. In comparison with the original processing (Stiller et al. (2021)), more sophisticated processing steps like CRS (Common Reflection Surface) instead of CDP (Common Depth Point) stacking, turning-ray tomography and prestack time and depth migration were carried out. The reprocessing results of the DEKORP 3A survey comprise all datasets newly achieved in addition to the datasets from the original processing (Stiller et al. (2021)), i.e. (1) the migrated CRS image gathers as unstacked data, and (2) the pure CRS stack, the poststack-time as well as prestack-time and prestack-depth migrated sections as stacked data. Moreover, (3) all velocity models used for the different versions including (4) the separate first-break tomography inversion, are contained. Additionally, the results of the 2D- and 3D-reprocessing of cross-lines Q12-Q16 are included. All reprocessed data come in SEGY trace format, the final sections additionally in PDF graphic format. A reprocessing report is included as well as again all meta information for each domain (source, receiver, CDP) like coordinates, elevations, locations and static corrections combined in ASCII-tables for geometry assignment purposes. Detailed information about acquisition and reprocessing parameters can be found in the accompanying Technical Report (Stiller & Agafonova, 2022). The DEKORP 3 survey was a combined seismic survey investigating the Variscan structures of the Rhenohercynian and the Saxothuringian. Consisting of three seismic lines it starts in the Rhenohercynian Hessian Depression (DEKORP 3A), crosses the Saxothuringian Mid-German Crystalline High (DEKORP 3B/MVE (West)) and runs parallel to the northern margin of the Moldanubian (DEKORP 3B/MVE (East)). The 128 km long DEKORP 3A profile runs N-S within the Hessian Depression from the Solling Dome in the Rhenohercynian to the Vogelsberg Volcano of the Saxothuringian Mid-German Crystalline High. The middle part of the profile crosses the "Northern Phyllite Zone". The reprocessed datasets contain a sub-section of the entire profile with a total length of 104.1 km of full CDP coverage, covering the territory of the state of Hesse. The reprocessed part of 3A is intersected by five short cross-lines along the profile at km 31.75, 53.55, 73.75, 89.85, 109.85 and by DEKORP 3B/MVE (West) at km 120.75 at its southern end. The DEKORP '90-3A profile is of particular interest to investigate the seismic resolution of the crust beneath the Permo-Mesozoic to Tertiary Hessian depression, the Kassel graben structure, as well as the tertiary volcanic fields of the Reinhardswald, Habichtswald, Knüll, Söhrewald and stopping just north of the large Cenozoic Vogelsberg complex.

Reprocessed northern part of deep seismic reflection profile DEKORP 1984-2S across the Taunus Mountains and the Hessian Trough in the state of Hesse, Germany

The profile 2S was recorded in 1984 as part of the DEKORP project, the German deep seismic reflection program. The focus of the DEKORP project was on deep crustal and lithospheric structures and therefore originally not on structures at shallower depths. From today's perspective, however, this depth range is of great interest for a wide range of possible technical applications (including medium-depth and deep geothermal projects). The original data is published by Stiller et al. (2020). The northernmost 50 km of the 250 km long profile 2S were reprocessed on behalf of the Hessian Agency of Nature Conservation, Environment and Geology (HLNUG). The focus of the reprocessing was on improving the resolution / mapping of geological structures down to a depth of 6 km (approx. 3 s TWT) to describe the prolongation of faults and geological structures in more detail than in previous studies. In order to achieve these goals and in view of the fact that today's processing and evaluation methods have been improved considerably compared to the 1990‘s, a state-of-the-art reprocessing was implemented. In comparison with the original processing (Stiller et al. (2020)), more sophisticated processing steps like CRS (Common Reflection Surface) instead of CDP (Common Depth Point) stacking, turning-ray tomography and prestack time and depth migration were carried out. The reprocessing results of the DEKORP 2S survey comprise all datasets newly achieved in addition to the datasets from the original processing (Stiller et al. (2020)), i.e. (1) the migrated CRS image gathers as unstacked data, and (2) the pure CRS stack, the poststack-time as well as prestack-time and prestack-depth migrated sections as stacked data. Moreover, (3) all velocity models used for the different versions including (4) the separate first-break tomography inversion, are contained. All reprocessed data come in SEGY trace format, the final sections additionally in PDF graphic format. A reprocessing report is included as well as again all meta information for each domain (source, receiver, CDP) like coordinates, elevations, locations and static corrections combined in ASCII-tables for geometry assignment purposes. The DEKORP 2 survey, consisting of the three segments 86-2Q, 86-2N and 84-2S, starts in the sub-Variscan foredeep of the Münsterland Basin and ends in the Moldanubian region at the Danube. The central part crosses the Rhenish Massif (Rhenohercynian), the Spessart Mountains of the Mid-German Crystalline High (Saxothuringian) and the meteorite impact location of the "Nördlinger Ries". DEKORP '84-2S, was the first DEKORP line and the only one which mainly used explosives as the seismic source. The 250 km long, SE-NW striking profile extends from the Rhenohercynian Taunus Mountains to the Danube thereby crossing the Spessart Mountains, the Hessian Trough and the "Nördlinger Ries". The profile DEKORP 2S is the southern continuation of DEKORP 2N, which intersects at profile km 246.08. The reprocessed datasets contain a sub-section of the entire 2S profile with a total length of 50 km of full CDP fold, covering the profile’s northern part through the state of Hesse. The DEKORP '84-2S profile is of particular interest to investigate the seismic resolution of the Rhenohercynian Taunus Mountains including the Taunus ridge, as well as the Tertiary Hessian Trough, the Permian Wetterau nappe and a small part of the crystalline Spessart Mountains. The seismic sections of 2S show clearly visible, predominantly SE-dipping reflectors indicating flat-and-ramp tectonics and a differentiation into a highly reflective lower crust and a less reflective upper crust. Due to the use of explosive shots with relatively large spacing as the seismic source, less new information could be achieved for the uppermost crust compared to the original processing and to other DEKORP (vibroseis) surveys. A clear Moho reflection is visible throughout the whole profile section at a depth of ca. 26 to 28 km.

Deep seismic reflection profile KTB 1984 Line 3 in the Black Forest, Southwest Germany

The ca. 62 km long KTB Line 3 was recorded in 1984 as part of the DEKORP, the German Continental Seismic Reflection Program, in the context of presite investigations for the KTB, the German Continental Deep Drilling Project. KTB 8403 is one of the four KTB seismic reflection lines, which were performed in the Black Forest, one of the candidates for the KTB drilling site. The purpose of the investigations was to reveal a strongly differentiated crust beneath the Black Forest with high-fold near-vertical incidence vibroseis acquisition. The main focus was on the crustal structure of the Black Forest massif with respect to the role and extent of Variscan thrust and extension tectonics and the geometry of deep crustal reflection patterns. Details of the experiment, first results and interpretations were published by Lüschen et al. (1987) and KTB-Research Group Black Forest (1987). Results discussed together with the KTB surveys in the Upper Palatinate were presented in a number of works which can be found in Emmermann & Wohlenberg (1989). The Technical Report of KTB 8403 gives complete information about acquisition and processing parameters. The European Variscides, extending from the French Central Massif to the East European Platform, originated during the collision between Gondwana and Baltica in the Late Palaeozoic. Due to involvement of various crustal blocks in the orogenesis, the mountain belt is subdivided into distinct zones. The external fold-and-thrust belts of the Rhenohercynian and Saxothuringian as well as the predominantly crystalline body of the Moldanubian dominate the central European segment of the Variscides. Polyphase tectonic deformation, magmatism and metamorphic processes led to a complex interlinking between the units. The Black Forest is the uplifted eastern shoulder of the Upper Rhine Graben within the internal Moldanubian zone, where rocks of the Variscan basement complex of Central Europe are exposed. The crystalline basement of the Black Forest consists of high-grade gneisses and migmatites intruded by Variscan granites. It was uplifted during the Tertiary rift movements of the Rhine Graben. The E-W running profile 8403 extends through the Black Forest crystalline basement and the adjacent Triberg Granite Massif onto the Swabian Jura Platform. Near Haslach the profile crosses KTB 8402 and KTB 8401 farther to the east. The intersection of these three lines generates a triangle of 3-4 km side length with a focus on the proposed drilling area. To the west the profile is connected with the DEKORP 9S, which runs across the Rhine Graben and the northern tip of Vosges massif into the Lorraine Basin. To the east KTB 8403 is linked to the Urach profile U1, running through the geothermal anomaly at Urach.

Intercalibration of the intra-laboratory 40Ar/39Ar reference material Drachenfels sanidine

The dataset contains full 40Ar/39Ar geochronological data completed by multi-collector noble-gas mass spectrometry using the laser total fusion technique on sanidine separated from the Drachenfels trachyte (Drachenfels, Bad Godesberg, Germany). The Drachenfels sanidine represents a useful intra-laboratory reference material for laser work. The purpose of the dataset is to share updated intercalibration data for the intra-laboratory Drachenfels sanidine, relative to the widespread fluence monitors Alder Creek sanidine and Fish Canyon sanidine, that can be used in future 40Ar/39Ar geochronological studies. W. McIntosh (New Mexico Geochronology Research Laboratory, Socorro, NM), P. Renne (Berkeley Geochronology Center, Berkeley, CA) and J.R. Wijbrans (Vrije Universiteit Amsterdam, NL) kindly provided splits of FCs, ACs and DRA1, respectively. The Ar laserprobe facility was realized with the financial support of CNR. The CO2 laser system was acquired within the PNRR – Mission 4, “Education and Research” - Component 2, “From research to business” - Investment line 3.1, “Fund for the creation of an integrated system of research and innovation infrastructures” - Project IR0000025 MEET.

Deep seismic reflection profile KTB 1984 Line 1 in the Black Forest, Southwest Germany

The ca. 163 km long KTB Line 1 was recorded in 1984 as part of the DEKORP, the German Continental Seismic Reflection Program, in the context of presite investigations for the KTB, the German Continental Deep Drilling Project. KTB 8401 is one of the four KTB seismic reflection lines, which were performed in the Black Forest, one of the candidates for the KTB drilling site. The purpose of the investigations was to reveal a strongly differentiated crust beneath the Black Forest with high-fold near-vertical incidence vibroseis acquisition. The main focus was on the crustal structure of the Black Forest massif with respect to the role and extent of Variscan thrust and extension tectonics and the geometry of deep crustal reflection patterns. Details of the experiment, first results and interpretations were published by Lüschen et al. (1987) and KTB-Research Group Black Forest (1987). Results discussed together with the KTB surveys in the Upper Palatinate were presented in a number of works which can be found in Emmermann & Wohlenberg (1989). The Technical Report of KTB 8401 gives complete information about acquisition and processing parameters. The European Variscides, extending from the French Central Massif to the East European Platform, originated during the collision between Gondwana and Baltica in the Late Palaeozoic. Due to involvement of various crustal blocks in the orogenesis, the mountain belt is subdivided into distinct zones. The external fold-and-thrust belts of the Rhenohercynian and Saxothuringian as well as the predominantly crystalline body of the Moldanubian dominate the central European segment of the Variscides. Polyphase tectonic deformation, magmatism and metamorphic processes led to a complex interlinking between the units. The Black Forest is the uplifted eastern shoulder of the Upper Rhine Graben within the internal Moldanubian zone, where rocks of the Variscan basement complex of Central Europe are exposed. The crystalline basement of the Black Forest consists of high-grade gneisses and migmatites intruded by Variscan granites. It was uplifted during the Tertiary rift movements of the Rhine Graben. The NS running profile 8401 follows the morphological axis of the Black Forest across the Central Black Forest Gneiss Complex and the adjacent Variscan thrust zones: the southward-dipping Saxothuringian-Moldanubian suture zone in the north and the NW-dipping Badenweiler-Lenzkirch crustal thrust zone in the south. In the west and the east the Central Gneiss Complex is bounded by the Tertiary Thinegraben and gently eastward-dipping Mesozoic sediments respectively. The central part of the Gneiss Complex is covered by two intersecting profiles generating a triangle of 3-4 km side length together with line 8401. Farther to the south KTB 8401 is crossed by line KTB 8514.

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