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  • 1
    Book
    Book
    Growth, erosion and material transfer in accretionary wedges : a quantitative analysis based on analog modeling and the implications for the evolution of convergent margins (1996)
    Details Availability
    Keywords: Dissertation ; Hochschulschrift
    Description / Table of Contents: Zsfassung
    Type of Medium: Book
    Pages: XI, 114 S , Ill., graph. Darst., Kt
    Language: English
    Note: Kiel, Univ., Diss., 1996
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  • 2
    Online Resource
    Online Resource
    Growth, erosion and material transfer in accretionary wedges : a quantitative analysis based on analog modeling and the implications for the evolution of convergent margins (1996)
    Kiel
    Details Availability
    Keywords: Dissertation ; Hochschulschrift
    Type of Medium: Online Resource
    Pages: 1 Online-Ressource ( 114Seiten = 17MB) , Ill., graph. Darst., Kt
    URL: https://oceanrep.geomar.de/id/eprint/54395
    Language: English
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  • 3
    Electronic Resource
    Electronic Resource
    Gravity interpretation along seismic reflection profile DEKORP 9-N (northern Rhine Graben) (1991)
    Oxford, UK : Blackwell Publishing Ltd
    Terra nova 3 (1991), S. 0 
    Details
    ISSN: 1365-3121
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Notes: A 2-D gravity model, incorporating geophysical and geological data, is presented for a 110 km long transect across the northern Rhine Graben, coinciding with the 92 km long DEKORP 9-N seismic reflection profile. The Upper Rhine Graben is marked by a prominent NNE-striking negative anomaly of 30–40 mgal on Bouguer gravity maps of SW Germany. Surface geological contacts, borehole data and the seismic reflection profile provide boundary constraints during forward modelling.Short-wavelength (5–10 km) gravity features can be correlated with geologic structures in the upper few km. At deeper levels, the model reflects the asymmetry visible in the seismic profile; a thicker, mostly transparent lower crust in the west and a thinner, reflective lower crust in the east. From west to east Moho depth changes from 31 to 26–28 km. The entire 40 mgal minimum can be accounted for by the 2–3 km of light sedimentary fdl in the graben, which masks the gravitational effects of the elevated Moho. The thickened lower crust in the west partly compensates for the mass deficit from the depressed Moho. A further compensating feature is a relatively low density contrast at the crust-mantle boundary of 0.25 g cm-3. The Variscan must displays heterogeneity along the profile which cuts at an angle across the strike of Variscan structures. The asymmetry of the integrated crustal model, both at the surface and at depth suggests an asymmetric mechanism of rift development.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3121.1991.tb00869.x
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  • 4
    Electronic Resource
    Electronic Resource
    Crustal structure and dynamics in the Rhine Graben and the Alpine foreland (1995)
    Oxford, UK : Blackwell Publishing Ltd
    Geophysical journal international 122 (1995), S. 0 
    Details
    ISSN: 1365-246X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Notes: The Rhine Graben rift stretches for 300 km from Basel to Frankfurt. The axis of maximum subsidence switches from west in the southern graben, to east in the northern graben. Subsidence in the south began in the upper Eocene and was interrupted in the mid-Miocene by a broad uplift of 1–1.5 km in the Vosges-Schwarzwald (Black Forest) region, whereas subsidence in the north proceeded continuously from the lower Oligocene to the present.A combined geophysical and geological interpretation of the Rhine Graben is presented in the form of a 3-D gravity model and 2-D flexural plate modelling from the Alps across the Alpine foreland to the Rhenish Massif. Modelling is based on crustal structure revealed by geologic, gravity and seismic data, including ECORS, DEKORP and EGT profiles.The 3-D gravity modelling supports a modest density contrast of 0.3 g cm−3 at the crust-mantle boundary. Since there is no evidence of a large-scale upper-mantle anomaly, a dense lower crust (2.9-3.0 g cm−3) is proposed as the cause of this modest density contrast. The presence of a dense, mafic, lower crust in south-west Germany is corroborated by lower-crustal xenoliths, elevated P-wave velocities (6.7-7.2 km s−1) and high Poisson's ratios (0.26-0.29).Residual gravity and magnetic data reveal strong crustal heterogeneities, particularly from the dense, magnetic Saxothuringian Terrane to the light, non-magnetic Moldanubian Terrane. The polarity of the asymmetric Rhine Graben reverses at this Variscan tectonic boundary. Light graben fill can account for nearly the entire 20–40 mGal, short-wavelength gravity minimum, but the presence of intrusive bodies ranging from granitic to mafic composition can also strongly influence the local gravity field.2-D modelling of the flexure of the European lithosphere along seven 1000 km long profiles indicates a flexural bulge of 1–1.5 km in the Alpine foreland of Southern Germany, which corresponds to an ENE-trending Moho uplift of the same magnitude and to a band of free-air gravity highs. Longer flexural wavelengths in the east indicate increasing lithospheric rigidity and increasing elastic thickness towards the Bohemian Massif. The Vosges-Schwarzwald dome is interpreted as the intersection of the Oligocene Rhine Graben rift and associated rift flank uplift with the mid-Miocene flexural bulge.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-246X.1995.tb07016.x
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  • 5
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    Evidence of the Zanclean megaflood in the eastern Mediterranean Basin (2018)
    Nature Research
    In:  Scientific Reports, 8 (1078).
    Details
    Publication Date: 2021-05-11
    Description: The Messinian salinity crisis (MSC) - the most abrupt, global-scale environmental change since the end of the Cretaceous – is widely associated with partial desiccation of the Mediterranean Sea. A major open question is the way normal marine conditions were abruptly restored at the end of the MSC. Here we use geological and geophysical data to identify an extensive, buried and chaotic sedimentary body deposited in the western Ionian Basin after the massive Messinian salts and before the Plio-Quaternary open-marine sedimentary sequence. We show that this body is consistent with the passage of a megaflood from the western to the eastern Mediterranean Sea via a south-eastern Sicilian gateway. Our findings provide evidence for a large amplitude drawdown in the Ionian Basin during the MSC, support the scenario of a Mediterranean-wide catastrophic flood at the end of the MSC, and suggest that the identified sedimentary body is the largest known megaflood deposit on Earth.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
    Format: text
    Format: text
    DOI: 10.1038/s41598-018-19446-3
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 6
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    Tectonic expression of an active slab tear from high-resolution seismic and bathymetric data offshore Sicily (Ionian Sea) (2016)
    AGU (American Geophysical Union) | Wiley
    In:  Tectonics, 35 (1). pp. 39-54.
    Details
    Publication Date: 2021-05-11
    Description: Subduction of a narrow slab of oceanic lithosphere beneath a tightly curved orogenic arc requires the presence of at least one lithospheric scale tear fault. While the Calabrian subduction beneath southern Italy is considered to be the type example of this geodynamic setting, the geometry, kinematics and surface expression of the associated lateral, slab tear fault offshore eastern Sicily remain controversial. Results from a new marine geophysical survey conducted in the Ionian Sea, using high‐resolution bathymetry and seismic profiling reveal active faulting at the seafloor within a 140 km long, two‐branched fault system near Alfeo Seamount. The previously unidentified 60 km long NW trending North Alfeo Fault system shows primarily strike‐slip kinematics as indicated by the morphology and steep‐dipping transpressional and transtensional faults. Available earthquake focal mechanisms indicate dextral strike‐slip motion along this fault segment. The 80 km long SSE trending South Alfeo fault system is expressed by one or two steeply dipping normal faults, bounding the western side of a 500+ m thick, 5 km wide, elongate, syntectonic Plio‐Quaternary sedimentary basin. Both branches of the fault system are mechanically capable of generating magnitude 6–7 earthquakes like those that struck eastern Sicily in 1169, 1542, and 1693.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1002/2015TC003898
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  • 7
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    Cyclical behavior of thrust wedges: Insights from high basal friction sandbox experiments (1996)
    GSA, Geological Society of America
    In:  Geology, 24 (2). pp. 135-138.
    Details
    Publication Date: 2017-06-28
    Description: Scaled sandbox experiments with high basal friction, simulating the growth of accretionary wedges, display cycles alternating between frontal imbricate thrusting and underthrusting of long, undeformed sheets. By contrast, low basal friction experiments with otherwise similar and constant, initial conditions produce a classic frontal imbricate fan through repeated failure along frontal thrusts. The cyclical behavior observed in high basal friction experiments is expressed by three quantities: (1) the average spacing between frontal thrusts, (2) the advance and retreat of the deformation front, and (3) the frontal slope (Alpha) of the actively deforming wedge. As a long sheet is underthrust, the front is steepened through slumping until the maximum critical angle is reached. Then frontal thrusting resumes and the accretion of imbricate slices builds the wedge forward, thereby lowering the taper to the minimum critical angle. At shallow tapers, a long unit is underthrust and subsequently uplifts, shortens, and steepens the overlying wedge through backthrust deformation, thus completing the cycle. Underthrusting of long units offers a simple mechanism for underplating overlying units. It also provides a possible explanation for temporally and spatially varying wedge geometries in nature, when basal frictions attain 80%–90% of the internal friction.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1130/0091-7613(1996)​024〈0135:CBOTWI〉​2.3.CO;2
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  • 8
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    Seismic evidence for the presence of Jurassic oceanic crust in the central Gulf of Cadiz (SW Iberian margin) (2011)
    Elsevier
    In:  Earth and Planetary Science Letters, 311 (1-2). pp. 112-123.
    Details
    Publication Date: 2014-04-24
    Description: We investigate the crustal structure of the SW Iberian margin along a 340 km-long refraction and wide-angle reflection seismic profile crossing from the central Gulf of Cadiz to the Variscan continental margin in the Algarve, Southern Portugal. The seismic velocity and crustal geometry model obtained by joint refraction and reflection travel-time inversion reveal three distinct crustal domains: the 28–30 km-thick Variscan crust in the north, a 60 km-wide transition zone offshore, where the crust abruptly thins ~ 20 km, and finally a ~ 7 km-thick and ~ 150 km-wide crustal section that appears to be oceanic in nature. The oceanic crust is overlain by a 1–3 km-thick section of Mesozoic to Eocene sediments, with an additional 3–4 km of low-velocity, unconsolidated sediments on top belonging to the Miocene age, Gulf of Cadiz imbricated wedge. The sharp transition between continental and oceanic crust is best explained by an initial rifting setting as a transform margin during the Early Jurassic that followed the continental break-up in the Central Atlantic. The narrow oceanic basin would have formed during an oblique rifting and seafloor spreading episode between Iberia and Africa that started shortly thereafter (Bajocian) and lasted up to the initiation of oceanic spreading in the North Atlantic at the Tithonian (late Jurassic-earliest Cretaceous). The velocity model displays four wide, prominent, south-dipping low-velocity anomalies, which seem to be related with the presence of crustal-scale faults previously identified in the area, some of which could well be extensional faults generated during this rifting episode. We propose that this oceanic plate segment is the last remnant of an oceanic corridor that once connected the Alpine-Tethys with the Atlantic ocean, so it is, in turn, one of the oldest oceanic crustal fragments currently preserved on Earth. The presence of oceanic crust in the central Gulf of Cadiz is consistent with geodynamic models suggesting the existence of a narrow, westward retreating oceanic slab beneath the Gibraltar arc-Alboran basin system.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/j.epsl.2011.09.003
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  • 9
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    Seismic evidence of exhumed mantle rock basement at the Gorringe Bank and the adjacent Horseshoe and Tagus abyssal plains (SW Iberia) (2013)
    Elsevier
    In:  Earth and Planetary Science Letters, 365 . pp. 120-131.
    Details
    Publication Date: 2014-04-24
    Description: The Gorringe Bank is a gigantic seamount that separates the Horseshoe and Tagus abyssal plains offshore SW Iberia, in a zone that hosts the convergent boundary between the Africa and Eurasia plates. Although the region has been the focus of numerous investigations since the early 1970s, the lack of appropriate geophysical data makes the nature of the basement, and thus the origin of the structures, still debated. In this work, we present combined P-wave seismic velocity and gravity models along a transect that crosses the Gorringe Bank from the Tagus to the Horseshoe abyssal plains. The P-wave velocity structure of the basement is similar in the Tagus and Horseshoe plains. It shows a 2.5–3.0 km-thick top layer with a velocity gradient twice stronger than oceanic Layer 2 and an abrupt change to an underlying layer with a five-fold weaker gradient. Velocity and density is lower beneath the Gorringe Bank probably due to enhanced fracturing, that have led to rock disaggregation in the sediment-starved northern flank. In contrast to previous velocity models of this region, there is no evidence of a sharp crust–mantle boundary in any of the record sections. The modelling results indicate that the sediment overlays directly serpentinite rock, exhumed from the mantle with a degree of serpentinization decreasing from a maximum of 70–80% under the top of Gorringe Bank to less than 5% at a depth of ∼20 km. We propose that the three domains were originally part of a single serpentine rock band, of nature and possibly origin similar to the Iberia Abyssal Plain ocean–continent transition, which was probably generated during the earliest phase of the North Atlantic opening that followed continental crust breakup (Early Cretaceous). During the Miocene, the NW–SE trending Eurasia–Africa convergence resulted in thrusting of the southeastern segment of the exhumed serpentinite band over the northwestern one, forming the Gorringe Bank. The local deformation associated to plate convergence and uplift could have promoted pervasive rock fracturing of the overriding plate, leading eventually to rock disaggregation in the northern flank of the GB, which could be now a potential source of rock avalanches and tsunamis.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/j.epsl.2013.01.021
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  • 10
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    Two-stage growth of the Calabrian accretionary wedge in the Ionian Sea (Central Mediterranean): Constraints from depth‐migrated multichannel seismic data (2012)
    Elsevier
    In:  Marine Geology, 326/328 . pp. 28-45.
    Details
    Publication Date: 2017-08-08
    Description: New structural images of the Calabrian accretionary wedge are presented from depth‐migrated multichannel seismic data. A combined interpretation swath‐mapping bathymetry allows us to identify five morphological domains on the basis of their tectonic style. (1) Beneath the undeformed Abyssal Plain, a set of deep, NW vergent reverse faults cuts the Ionian oceanic crust and thick pre-Messinian sediments. (2) Towards the NW, the low-taper post-Messinian wedge overlying a shallow NW dipping décollement, at the base of the Messinian evaporites and exhibiting strong tectonic thickening. (3) Beneath the flat Central Transition Zone, a backthrust marks the contact between the post- and pre-Messinian wedges. Here, the décollement dip increases (〉 3°) cutting through deeper sediments to reach 10 km depth. (4) Beneath the pre-Messinian Calabrian wedge, some steep landward dipping features are imaged where underplating may occur. (5) Beneath the inner plateau, a fore‐arc basin lies above the top of the Calabrian continental basement imaged at 8 km depth. The architecture of the Calabrian accretionary complex is very similar to the Mediterranean Ridge. Both systems consist of (a) an external low-taper post-Messinian wedge overlying a thick undeformed section of underthrust Mesozoic sediments and (b) an internal pre-Messinian wedge where the décollement steps down and where the underthrust section is presumably underplated. We perform area balancing and show that since the Messinian, the Calabrian accretionary wedge has undergone extremely rapid outward growth at an average rate of 30 km/Ma, which makes it the fastest growing accretionary wedge over the past 5 Ma. Highlights: ► Relation between the pre- and post-Messinian juxtaposed wedges. ► Contact between these wedges along a major backthrust. ► The 130 km long outer Calabrian prism: a huge salt-bearing body. ► One of the fastest growing wedges (2.0 cm/year) in recent Earth history. ►~ 170 km amount of post-Messinian subduction (subduction rate 3–4 cm/year).
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/j.margeo.2012.08.006
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