GLORIA

GEOMAR Library Ocean Research Information Access

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • OceanRep  (11)
  • OceanRep: Article in a Scientific Journal - peer-reviewed  (10)
  • OceanRep: Book chapter  (1)
Document type
  • OceanRep  (11)
Source
Publisher
Years
  • 1
    facet.materialart.
    Unknown
    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
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 2
    facet.materialart.
    Unknown
    Morphometric and critical taper analysis of the Rock Garden region, Hikurangi Margin, New Zealand: Implications for slope stability and potential tsunami generation (2010)
    Elsevier
    In:  Marine Geology, 272 (1-4). pp. 141-153.
    Details
    Publication Date: 2013-06-10
    Description: New high-resolution swath bathymetry data show a complex seafloor morphology from the Rock Garden area, offshore Hikurangi Margin, that coincides with the subduction of a seamount presently located beneath the summit of Rock Garden. Another ridge-shaped lower plate feature is initially colliding with Rock Garden, forming a re-entrant at its seaward flank. The slopes of the accretionary ridges are steeper than 10° and often more than 20° regionally. Slumping mostly occurs on the trench-ward slopes, with individual slumps affecting areas up to several km2. Critical taper analysis, using realistic wedge geometries and fluid pressures scenarios, shows that much of the seaward slopes in the region are most likely outside the stability field and therefore subject to failure. The most prominent feature revealed by seafloor maps is the trench-ward flank of Rock Garden with a height of 1800 to 2000 m and an average slope of more than 10°. Extensional faults arranged in two sub-circular arcs indicate that Rock Garden may be on the verge of failure. Critical taper analysis also supports this claim and shows that if basal fluid pressure approaches lithostatic pressure, e.g. during a large Mw 〉 8 earthquakes, then a complete failure of the entire trench-ward flank of Rock Garden would potentially affect an area as large as 150 km2 and a rock volume of 150 to 170 km3. This worst case scenario would generate a tsunami wave some tens of meters high. Therefore, the observation that a number of seamounts are buried beneath the outer Hikurangi accretionary wedge suggests that a thorough assessment of these features needs to be undertaken and its results incorporated into tsunami hazard models for the East Coast of New Zealand's North Island.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/j.margeo.2009.06.004
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 3
    facet.materialart.
    Unknown
    Die interne Struktur von Subduktionszonen : das Zusammenspiel geophysikalischer Methoden ergibt ein detailliertes Bild (1997)
    Ernst & Sohn
    In:  Geowissenschaften, 15 (9). pp. 273-277.
    Details
    Publication Date: 2017-06-28
    Description: Geophysical research in subduction zones is based on bathymetric, seismic, magnetic, gravimetric measurement as well as numerical and analog modeling. Their combined interpretation leads to an image of the sub-surface and the dynamic processes related with subduction type and to estimate fluid and mass transfer within the subduction complex. The top of the subducting oceanic plate can be imaged seismically, which could have pracical implications for more precise earthquake hazard analysis in the areas investigated
    Type: Article , PeerReviewed
    Format: text
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 4
    facet.materialart.
    Unknown
    Focussed fluid flow on the Hikurangi Margin, New Zealand — Evidence from possible local upwarping of the base of gas hydrate stability (2010)
    Elsevier
    In:  Marine Geology, 272 (1/4). pp. 99-113.
    Details
    Publication Date: 2017-08-07
    Description: The southern Hikurangi Subduction Margin is characterized by significant accretion with predicted high rates of fluid expulsion. Bottom simulating reflections (BSRs) are widespread on this margin, predominantly occurring beneath thrust ridges. We present seismic data across the Porangahau Ridge on the outer accretionary wedge. The data show high-amplitude reflections above the regional BSR level. Based on polarity and reflection strength, we interpret these reflections as being caused by free gas. We propose that the presence of gas above the regional level of BSRs indicates local upwarping of the base of gas hydrate stability caused by advective heatflow from upward migrating fluids, although we cannot entirely rule out alternative processes. Simplified modelling of the increase of the thermal gradient associated with fluid flow suggests that funnelling of upward migrating fluids beneath low-permeability slope basins into the Porangahau Ridge would not lead to the pronounced thermal anomaly inferred from upwarping of the base of gas hydrate stability. Focussing of fluid flow is predicted to take place deep in the accretionary wedge and/or the underthrust sediments. Above the high-amplitude reflections, sediment reflectivity is low. A lack of lateral continuity of reflections suggests that reflectivity is lost because of a destruction of sediment layering from deformation rather than gas-hydrate-related amplitude blanking. Structural permeability from fracturing of sediments during deformation may facilitate fluid expulsion on the ridge. A gap in the BSR in the southern part of the study area may be caused by a loss of gas during fluid expulsion. We speculate that gaps in otherwise continuous BSRs that are observed beneath some thrusts on the Hikurangi Margin may be characteristic of other locations experiencing focussed fluid expulsion.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/j.margeo.2009.10.006
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 5
    facet.materialart.
    Unknown
    Gas Hydrates Along the Peru and Middle America Trench Systems (2001)
    AGU (American Geophysical Union)
    In:  In: Natural Gas Hydrates: Occurence, distribution, and Detection. , ed. by Paull, C. K. and Dillon, W. P. Geophysical Monograph Series, 124 . AGU (American Geophysical Union), Washington, DC, pp. 257-271.
    Details
    Publication Date: 2019-08-06
    Type: Book chapter , NonPeerReviewed
    Format: text
    DOI: 10.1029/GM124p0257
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    OceanRep: Book chapter
  • 6
    facet.materialart.
    Unknown
    Upward delamination of Cascadia Basin sediment infill with landward frontal accretion thrusting caused by rapid glacial age material flux (2004)
    AGU (American Geophysical Union)
    In:  Tectonics, 23 (3). TC3009.
    Details
    Publication Date: 2019-09-23
    Description: The Cascadia convergent margin is a first-order research target to study the impact of rapid sedimentation processes on the mechanics of frontal subduction zone accretion. The near-trench part of the accretionary prism offshore Washington is affected by strongly increased glacial age sedimentation and fan formation that led to an outstanding Quaternary growth rate with landward vergent thrust faulting that is rarely observed elsewhere in accretionary wedges. Multichannel seismic reflection data acquired on the ORWELL project allows us to study the structure and dynamics of the atypical frontal accretion processes. We performed a kinematical and mechanical analysis of the frontal accretion structures, and developed a dynamic Coulomb-wedge model for the landward-verging backthrust formation. Backthrusting results from heterogeneous diffuse strain accumulation in the mechanically heterogeneous Cascadia basin sediment succession entering the subduction zone, and strain partitioning along a midlevel detachment that is activated by gravitational loading caused by rapid glacial age sedimentation. These complex deformation processes cause the passive “upward” delamination of the upper turbidite beds from the basal pelagic carbonate section similar to triangle-zone formation and passive backthrust wedging in foreland thrust belts caused by rapid burial beneath syntectonic sediment deposits. The deformation mechanism at the tectonic front of the Cascadia margin is an immediate response to the strongly increased late Pleistocene sediment flux rather than to atypical physical boundary conditions as generally thought.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1029/2002TC001475
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 7
    facet.materialart.
    Unknown
    Crustal structure of the Peruvian continental margin from wide-angle seismic studies (2004)
    Wiley
    In:  Geophysical Journal International, 158 (2). pp. 749-764.
    Details
    Publication Date: 2018-07-17
    Description: Active seismic investigations along the Pacific margin off Peru were carried out using ocean bottom hydrophones and seismometers. The structure and the P-wave velocities of the obliquely subducting oceanic Nazca Plate and overriding South American Plate from 8°S to 15°S were determined by modelling the wide-angle seismic data combined with the analysis of reflection seismic data. Three detailed cross-sections of the subduction zone of the Peruvian margin and one strike-line across the Lima Basin are presented here. The oceanic crust of the Nazca Plate, with a thin pelagic sediment cover, ranging from 0–200 m, has an average thickness of 6.4 km. At 8°S it thins to 4 km in the area of Trujillo Trough, a graben-like structure. Across the margin, the plate boundary can be traced to 25 km depth. As inferred from the velocity models, a frontal prism exists adjacent to the trench axis and is associated with the steep lower slope. Terrigeneous sediments are proposed to be transported downslope due to gravitational forces and comprise the frontal prism, characterized by low seismic P-wave velocities. The lower slope material accretes against a backstop structure, which is defined by higher seismic P-wave velocities, 3.5–6.0 km s−1. The large variations in surface slope along one transect may reflect basal removal of upper plate material, thus steepening the slope surface. Subduction processes along the Peruvian margin are dominated by tectonic erosion indicated by the large margin taper, the shape and bending of the subducting slab, laterally varying slope angles and the material properties of the overriding continental plate. The erosional mechanisms, frontal and basal erosion, result in the steepening of the slope and consequent slope failure.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1111/j.1365-246X.2004.02425.x
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 8
    facet.materialart.
    Unknown
    Backstop geometry and accretionary mechanics of the Sunda margin (2003)
    AGU (American Geophysical Union)
    In:  Tectonics, 22 (6). p. 1072.
    Details
    Publication Date: 2017-06-28
    Description: The convergent Sunda margin off Indonesia displays all geological features characteristic of an accretion-dominated subduction zone. A combined interpretation of prestack depth-migrated seismic reflection data and velocity information gained from refraction studies is supplemented by high-resolution bathymetric data and for the first time allows the exact mapping of backstop regimes. Initially, the outer high evolved as material was pushed against a static rigid arc framework backstop underlying a forearc basin. Increasing material strength of the outer high due to lithification formed a dynamic backstop, which controls accretion today. An out-of-sequence thrust marks the transition from the recent active frontal accretionary prism to the outer high and may be traced in the seismic and bathymetric data over the whole extent of the study area. The existence of a static as well as a dynamic backstop controls the forearc geometry and is associated with the segmentation of the forearc, which is observed in regimes of frontal as well as of oblique subduction. Mass balance calculations, which account for porosity changes and metamorphism, indicate a subduction history dominated by accretionary processes since the late Eocene. Accretion is associated with the low values of basal friction inferred for the Sunda margin. Structural investigations of conjugate fault planes indicate a very weak basal detachment. Effective stress analyses reveal that intrinsically weak material causes the high strength ratio of the detachment to the overlying sediments, whereas overpressuring within the frontal accretionary prism is negligible.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1029/2002TC001420
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 9
    facet.materialart.
    Unknown
    Ridge subduction at an erosive margin - the collision zone of the Nazca Ridge in southern Peru (2004)
    AGU (American Geophysical Union)
    In:  Journal of Geophysical Research: Solid Earth, 109 . B02101.
    Details
    Publication Date: 2018-04-25
    Description: The 1.5-km-high, obliquely subducting Nazca Ridge and its collision zone with the Peruvian margin have been imaged by wide-angle and reflection seismic profiles, swath bathymetry, and gravity surveying. These data reveal that the crust of the ridge at its northeastern tip is 17 km thick and exhibits seismic velocities and densities similar to layers 2 and 3 of typical oceanic crust. The lowermost layer contributes 10–12 km to the total crustal thickness of the ridge. The sedimentary cover is 300–400 m thick on most parts of the ridge but less than 100 m thick on seamounts and small volcanic ridges. At the collision zone of ridge and margin, the following observations indicate intense tectonic erosion related to the passage of the ridge. The thin sediment layer on the ridge is completely subducted. The lower continental slope is steep, dipping at ∼9°, and the continental wedge has a high taper of 18°. Tentative correlation of model layers with stratigraphy derived from Ocean Drilling Program Leg 112 cores suggests the presence of Eocene shelf deposits near the trench. Continental basement is located 〈15 km landward of the trench. Normal faults on the upper slope and shelf indicate extension. A comparison with the Peruvian and northern Chilean forearc systems, currently not affected by ridge subduction, suggests that the passage of the Nazca Ridge along the continental margin induces a temporarily limited phase of enhanced tectonic erosion superposed on a long-term erosive regime.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1029/2003JB002593
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 10
    facet.materialart.
    Unknown
    Morphotectonic and morphometric analysis of the Nazca plate and the adjacent offshore Peruvian continental slope - implications for submarine landscape evolution (2008)
    Elsevier
    In:  Marine Geology, 254 . pp. 107-120.
    Details
    Publication Date: 2017-08-04
    Description: We use new swath bathymetry data acquired during the RV Sonne cruise GEOPECO and complement them with swath data from adjacent regions to analyse the morphotectonics of the Peruvian convergent margin. The Nazca plate is not covered with sediments and therefore has a rough surface along the entire Peruvian trench. The styles of roughness differ significantly along the margin with linear morphological features trending in various directions, most of them oblique to the trench and roughness magnitudes of a few to several hundred meters. The lower slope is locally very rough and at the verge of failure throughout the entire Peruvian margin, as a result of subduction erosion causing the lower slope to over-steepen. Using curvature attributes to quantitatively examine the morphology in the Yaquina and Mendaña areas revealed that the latter shows a larger local roughness both seaward and landward of the trench. However, the amplitude of morphological roughness is larger in the Yaquina area. We identified a 125 km2 large slump on the Lima middle slope. Morphometric dating suggests an age of 74500 years within 35 to 40% error. Estimated incision rates on the upper slope are between 0.1 and 0.3 mm per year suggesting that landscape evolution on the Peruvian submarine continental slope is similarly slow than that in the Atacama desert.
    Type: Article , PeerReviewed
    Format: text
    Format: text
    DOI: 10.1016/j.margeo.2008.05.017
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    OceanRep: Article in a Scientific Journal - peer-reviewed
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...