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  • 1
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    FS Sonne Fahrtbericht/Cruise Report SO 190 (2010)
    IFM-Geomar, Kiel
    Details
    Publication Date: 2021-03-29
    Description: report
    Keywords: 551.4 ; 551.22 ; 550
    Language: English
    Type: article , publishedVersion
    Format: 193 S.
    Format: application/pdf
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    CITATION GEO-LEO
  • 2
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    FS Sonne Fahrtbericht/Cruise Report SO 186 Leg 3 (2010)
    IFM-Geomar, Kiel
    Details
    Publication Date: 2021-03-29
    Description: report
    Keywords: 551.4 ; 551.22 ; 550 ; UKD 100 ; TSZ 200 ; TSJ 200 ; TOH 300 ; TOH 100 ; TOH 200 ; TQC 600 ; Expeditionsberichte {Regionale Ozeanologie, Indischer Ozean} ; Indischer Ozean {Geophysik} ; Südostasien {Geophysik} ; Seismische Wellen {Geophysik} ; Seismometrie {Geophysik} ; Seismische Vorhersagen {Geophysik} ; Tiefseeseismik {Geophysik}
    Language: English
    Type: article , publishedVersion
    Format: 212 S.
    Format: application/pdf
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    CITATION GEO-LEO
  • 3
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    Crustal structure across the Møre margin, mid-Norway, from wide-angle seismic and gravity data (2014)
    Elsevier
    In:  Tectonophysics, 626 . pp. 21-40.
    Details
    Publication Date: 2018-01-05
    Description: The Møre Margin in the NE Atlantic represents a dominantly passive margin with an unusual abrupt transition from alpine morphology onshore to a deep sedimentary basin offshore. In order to study this transition in detail, three ocean bottom seismometer profiles with deep seismic reflection and refraction data were acquired in 2009; two dip-profiles which were extended by land stations, and one tie-profile parallel to the strike of the Møre–Trøndelag Fault Complex. The modeling of the wide-angle seismic data was performed with a combined inversion and forward modeling approach and validated with a 3D-density model. Modeling of the geophysical data indicates the presence of a 12–15 km thick accumulation of sedimentary rocks in the Møre Basin. The modeling of the strike profile located closer to land shows a decrease in crustal velocity from north to south. Near the coast we observe an intra-crustal reflector under the Trøndelag Platform, but not under the Slørebotn Sub-basin. Furthermore, two lower crustal high-velocity bodies are modeled, one located near the Møre Marginal High and one beneath the Slørebotn Sub-basin. While the outer lower crustal body is modeled with a density allowing an interpretation as magmatic underplating, the inner body has a density close to mantle density which might suggest an origin as an eclogized body, formed by metamorphosis of lower crustal gabbro during the Caledonian orogeny. The difference in velocity and extent of the lower crustal bodies seems to be controlled by the Jan Mayen Lineament, suggesting that the lineament represents a pre-Caledonian structural feature in the basement.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/j.tecto.2014.03.021
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 4
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    Structure and geodynamics of the post-collision zone between the Nazca–Antarctic spreading center and South America (2012)
    Elsevier
    In:  Earth and Planetary Science Letters, 345/348 . pp. 27-37.
    Details
    Publication Date: 2019-09-23
    Description: The Chile Triple Junction (CTJ) is the place where the Chile Ridge (Nazca–Antarctic spreading center) is subducting beneath the continental South American plate. Sediment accretion is active to the south of the CTJ in the area where the northward migrating Chile Ridge has collided with the continent since 14 Ma. At the CTJ, tectonic erosion of the overriding plate narrows and steepens the continental slope. We present here a detailed tomographic image of the upper lithospheric Antarctic–South America subduction zone where the Chile Ridge collided with the continent 3–6 Ma off Golfo de Penas. Results reveal that a large portion of trench sediment has been scraped off and frontally accreted to the forearc forming a 70–80 km wide accretionary prism. The velocity–depth model shows a discontinuity at 30–40 km landward of the deformation front, which is interpreted as the contact between the frontal (poorly consolidated sedimentary unit) and middle (more compacted sedimentary unit) accretionary prism. The formation of this discontinuity could be related to a short term episode of reduced trench sedimentation. In addition, we model the shape of the continental slope using a Newtonian fluid rheology to study the convergence rate at which the accretionary prism was formed. Results are consistent with an accretionary prism formed after the collision of the Chile Ridge under slow convergence rate similar to those observed at present between Antarctic and South America (∼2.0 cm/a). Based on the kinematics of the Chile Ridge subduction during the last 13 Ma, we propose that the accretionary prism off Golfo de Penas was formed recently (∼5 Ma) after the collision of the Chile Ridge with South America.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/j.epsl.2012.06.023
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 5
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    Subduction system variability across the segment boundary of the 2004/2005 Sumatra megathrust earthquakes (2013)
    Elsevier
    In:  Earth and Planetary Science Letters, 365 . pp. 108-119.
    Details
    Publication Date: 2019-09-23
    Description: Subduction zone earthquakes are known to create segmented patches of co-seismic rupture along-strike of a margin. Offshore Sumatra, repeated rupture occurred within segments bounded by permanent barriers, whose origin however is still not fully understood. In this study we image the structural variations across the rupture segment boundary between the Mw 9.1 December 26, 2004 and the Mw 8.6 March 28, 2005 Sumatra earthquakes. A set of collocated reflection and wide-angle seismic profiles are available on both sides of the segment boundary, located offshore Simeulue Island. We present the results of the seismic tomography modeling of wide-angle ocean bottom data, enhanced with MCS data and gravity modeling for the southern 2005 segment of the margin and compare it to the published model for the 2004 northern segment. Our study reveals principal differences in the structure of the subduction system north and south of the segment boundary, attributed to the subduction of 96°E fracture zone. The key differences include a change in the crustal thickness of the oceanic plate, a decrease in the amount of sediment in the trench as well as variations in the morphology and volume of the accretionary prism. These differences suggest that the 96°E fracture zone acts as an efficient barrier in the trench parallel sediment transport, as well as a divider between oceanic crustal blocks of different structure. The variability of seismic behavior is caused by the distinct changes in the morphology of the subduction complex across the boundary related to the difference in the sediment supply.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/j.epsl.2012.12.032
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 6
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    Deep structure of the central Lesser Antilles Island Arc : relevance for the formation of continental crust (2011)
    Elsevier
    In:  Earth and Planetary Science Letters, 304 (1-2). pp. 121-134.
    Details
    Publication Date: 2019-09-23
    Description: Oceanic island arcs are sites of high magma production and contribute to the formation of continental crust. Geophysical studies may provide information on the configuration and composition of island arc crust, however, to date only few seismic profiles exist across active island arcs, limiting our knowledge on the deep structure and processes related to the production of arc crust. We acquired active-source wide-angle seismic data crossing the central Lesser Antilles island arc north of Dominica where the oceanic Tiburon Ridge subducts obliquely beneath the forearc. A combined analysis of wide-angle seismics and pre-stack depth migrated reflection data images the complex structure of the backstop and its segmentation into two individual ridges, suggesting an intricate relation between subducted basement relief and forearc deformation. Tomographic imaging reveals three distinct layers composing the island arc crust. A three kilometer thick upper crust of volcanogenic sedimentary rocks and volcaniclastics is underlain by intermediate to felsic middle crust and plutonic lower crust. The island arc crust may comprise inherited elements of oceanic plateau material contributing to the observed crustal thickness. A high density ultramafic cumulates layer is not detected, which is an important observation for models of continental crust formation. The upper plate Moho is found at a depth of 24 km below the sea floor. Upper mantle velocities are close to the global average. Our study provides important information on the composition of the island arc crust and its deep structure, ranging from intermediate to felsic and mafic conditions. In this study we model the deep structure of the Lesser Antilles Island Arc. We use a hybrid analysis of refraction and reflection seismic data. We image the complex structure of two ridges forming the backstop. Island arc crust composition ranges from intermediate to felsic to mafic conditions. We discuss the formation of island arc and continental crust.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/j.epsl.2011.01.024
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 7
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    Revealing the deep structure and rupture plane of the 2010 Maule, Chile earthquake (Mw=8.8) using wide angle seismic data (2011)
    Elsevier
    In:  Earth and Planetary Science Letters, 307 . pp. 147-155.
    Details
    Publication Date: 2017-06-08
    Description: The 27 February, 2010 Maule earthquake (Mw=8.8) ruptured ~400 km of the Nazca-South America plate boundary and caused hundreds of fatalities and billions of dollars in material losses. Here we present constraints on the fore-arc structure and subduction zone of the rupture area derived from seismic refraction and wide-angle data. The results show a wedge shaped body ~40 km wide with typical sedimentary velocities interpreted as a frontal accretionary prism (FAP). Landward of the imaged FAP, the velocity model shows an abrupt velocity-contrast, suggesting a lithological change which is interpreted as the contact between the FAP and the paleo accretionary prism (backstop). The backstop location is coincident with the seaward limit of the aftershocks, defining the updip limit of the co-seismic rupture and seismogenic zone. Furthermore, the seaward limit of the aftershocks coincides with the location of the shelf break in the entire earthquake rupture area (33°S–38.5°S), which is interpreted as the location of the backstop along the margin. Published seismic profiles at the northern and southern limit of the rupture area also show the presence of a strong horizontal velocity gradient seismic backstop at a distance of ~30 km from the deformation front. The seismic wide-angle reflections from the top of the subducting oceanic crust constrain the location of the plate boundary offshore, dipping at ~10°. The projection of the epicenter of the Maule earthquake onto our derived interplate boundary yielded a hypocenter around 20 km depth, this implies that this earthquake nucleated somewhere in the middle of the seismogenic zone, neither at its updip nor at its downdip limit.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/j.epsl.2011.04.025
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 8
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    Morphology of the Andaman outer shelf and upper slope of the Thai exclusive economic zone (2012)
    Elsevier
    In:  Journal of Asian Earth Sciences, 46 . pp. 78-85.
    Details
    Publication Date: 2017-08-07
    Description: Following the devastating 2004 tsunami that hit the southwestern coast of Thailand, the need for detailed bathymetric data of the Andaman Sea outer shelf became evident in order to better predict tsunami wave propagation and coastal impact. Bathymetric data and subbottom profiler records covering the outer shelf and upper slope of the Thai exclusive economic zone (EEZ) were collected onboard Thai RV Chakratong Tongyai in 2006 and 2007. The data cover an area of approximately 3000 km2 between 500 and 1600 m water depth. The soundings allowed generating a final bathymetric grid with 50 m grid cell spacing. The outer shelf is rather smooth and slightly inclined southward, while the upper slope is strongly dissected by gullies. Several previously unknown features are identified including mud-domes, pockmarks, three large plateaus surrounded by moats, gas-charged sediment on subbottom profiler records, and only few indications for small submarine landslides on the upper slope. The largest of these possibly translational submarine landslides involved 2.2×107 m3 of sediment. This slide would have generated a tsunami wave of less than 0.12 m wave height. Considering the entire data, there is no evidence that landslides have been the source of tsunami waves in recent geological time. Highlights
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/j.jseaes.2011.11.003
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 9
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    Mafic intrusions east of Svalbard imaged by active-source seismic tomography (2012)
    Elsevier
    In:  Tectonophysics, 518/521 . pp. 106-118.
    Details
    Publication Date: 2018-07-19
    Description: A seismic refraction and reflection tomography experiment was performed across the igneous province east of Svalbard which is a part of the Cretaceous High Arctic Large Igneous Province. Seismic travel times from 12 ocean bottom seismometers/hydrophones deployed along a 170 km line are inverted to produce smooth 2D images of the crustal P-wave velocity and geometry of the acoustic basement and Moho. The inversion of travel times was complemented by forward elastic wave propagation modeling. Integration with onshore geology as well as multichannel seismic, magnetic and gravity data have provide additional constraints used in the geological interpretation. The seismic P-wave velocity increases rapidly with depth, starting with 3 km/s at the sea floor and reaching 5.5 km/s at the bottom of the upper sedimentary layer. The thickness of this layer increases eastward from 2 km to 3.5 km. On average the P-wave velocity in the crystalline crust increases with depth from 5.5 km/s to 6.8 km/s. The crustal thickness is typical for continental shelf regions (30–34 km). Finger-shaped high-velocity anomalies, one reaching 12% and two of 4–6% velocity perturbation, are obtained. These velocity anomalies are concomitant with Lower Cretaceous basaltic lava flows and sills in the shallow sediments and elongated gravity and magnetic highs, traced towards the northern Barents Sea passive continental margin. We interpret the obtained velocity anomalies as signatures of dikes emplaced in the basement during breakup and subsequent spreading in the Arctic Amerasia Basin.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/j.tecto.2011.11.015
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 10
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    Seismic Activity offshore Martinique and Dominica islands (Central Lesser Antilles subduction zone) from temporary onshore and offshore seismic networks (2013)
    Elsevier
    In:  Tectonophysics, 603 . pp. 68-78.
    Details
    Publication Date: 2018-01-05
    Description: This work focuses on the analysis of a unique set of seismological data recorded by two temporary networks of seismometers deployed onshore and offshore in the Central Lesser Antilles Island Arc from Martinique to Guadeloupe islands. During the whole recording period, extending from January to the end of August 2007, more than 1300 local seismic events were detected in this area. A subset of 769 earthquakes was located precisely by using HypoEllipse. We also computed focal mechanisms using P-wave polarities of the best azimuthally constrained earthquakes. We detected earthquakes beneath the Caribbean forearc and in the Atlantic oceanic plate as well. At depth seismicity delineates the Wadati–Benioff Zone down to 170 km depth. The main seismic activity is concentrated in the lower crust and in the mantle wedge, close to the island arc beneath an inner forearc domain in comparison to an outer forearc domain where little seismicity is observed. We propose that the difference of the seismicity beneath the inner and the outer forearc is related to a difference of crustal structure between the inner forearc interpreted as a dense, thick and rigid crustal block and the lighter and more flexible outer forearc. Seismicity is enhanced beneath the inner forearc because it likely increases the vertical stress applied to the subducting plate.
    Type: Article , PeerReviewed
    Format: text
    Format: text
    DOI: 10.1016/j.tecto.2011.08.006
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    OceanRep: Article in a Scientific Journal - peer-reviewed
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