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  • 1
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    Geophysical evidence for alteration of the crust and mantle of the Nazca Plate during bending at the north Chile trench (2004)
    GSA, Geological Society of America
    In:  Geology, 32 (7). pp. 549-552.
    Details
    Publication Date: 2017-08-04
    Description: Water transported in subducting oceanic plates plays a key role in a number of phenomena, including intraslab seismicity and arc magmatism. However, the locus of plate hydration and water distribution in crust and mantle of plates entering subduction zones is debated. We present evidence for anomalously low seismic velocities and densities of the crust and upper mantle of the Nazca plate at the north Chile trench. Crustal seismic velocities at the trench are lower than velocities of mature fast-spreading crust and even lower than velocities of highly extended slow-spreading crust. In addition, the Nazca plate at the north Chile trench may contain an ∼20-km-thick upper-mantle layer with ∼17% serpentine, which implies ∼2.5 wt% water. These results document pervasive rock alteration by water percolation linked to bending-related extensional faulting.
    Type: Article , PeerReviewed
    Format: text
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  • 2
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    Generic model of subduction erosion (2004)
    GSA, Geological Society of America
    In:  Geology, 32 (10). p. 913.
    Details
    Publication Date: 2017-08-07
    Description: Erosion by high stress abrasion of convergent margins from horsts and grabens on the subducting plate is not shown in seismic images. In a proposed model, the frontal sediment prism is a dynamic mass that elevates pore-fluid pressure. Overpressured fluid invades fractures in the upper plate and separates fragments that are dragged into a subduction channel along the plate interface. Removed fragments are smaller than surface ship seismic techniques have resolved and beyond the reach of past scientific ocean drilling; however, current drill capability and downhole geophysics can test the model.
    Type: Article , PeerReviewed
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  • 3
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    Seafloor, sediments, seismicity and shallow structures offshore southern Chile - selected preliminary results from TIPTEQ Cruise SO181 (2005)
    GeoForschungsZentrum
    In:  [Talk] In: Sonderkolloquium "Geotechnologien", GeoForschungsZentrum Potsdam, 09.-10.06.2005, Potsdam . Continental margins - earth's focal points of usage and hazard potential ; pp. 100-105 .
    Details
    Publication Date: 2012-07-06
    Type: Conference or Workshop Item , NonPeerReviewed
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  • 4
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    A model for subduction erosion (2004)
    GSA, Geological Society of America
    In:  Geology, 32 (10). pp. 913-916.
    Details
    Publication Date: 2019-09-23
    Description: Erosion by high stress abrasion of convergent margins from horsts and grabens on the subducting plate is not shown in seismic images. In a proposed model, the frontal sediment prism is a dynamic mass that elevates pore-fluid pressure. Overpressured fluid invades fractures in the upper plate and separates fragments that are dragged into a subduction channel along the plate interface. Removed fragments are smaller than surface ship seismic techniques have resolved and beyond the reach of past scientific ocean drilling; however, current drill capability and downhole geophysics can test the model.
    Type: Article , PeerReviewed
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  • 5
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    Fluid expulsion related to mud extrusion off Costa Rica - A window to the subduction slab (2004)
    GSA, Geological Society of America
    In:  Geology, 32 (2). pp. 201-204.
    Details
    Publication Date: 2019-09-23
    Description: A large number of mound-shaped structures that originated from mud extrusions is present along the convergent continental margin off Costa Rica and Nicaragua. Active fluid venting is indicated by the existence of CH4- and H2S-rich pore fluids as well as associated benthic fauna and authigenic carbonates. End-member fluid samples from all mounds are significantly depleted in dissolved Cl and other major elements, suggesting a general process of freshwater addition and thus a common source of the fluids. Our data clearly rule out dilution by gas hydrate dissociation as a dominant source of the freshwater. Enrichments of the fluids in B (up to 2 mmol/L) and inversely correlated δ18O vs. δD values point to clay-mineral dehydration as the cause for these anomalies. Calculations assuming a δ18O vs. δD equilibrium between the pore fluid and clay minerals at depth of formation indicate temperatures of dehydration between 85 and 130 °C. This temperature range is in agreement with the B enrichments and the presence of thermogenically formed CH4. Because temperatures above 50 °C are not reached within the sediment cover of the upper plate, the fluids most likely form within the subducted sediments and flow upward along deep-seated faults from ≥12 km depth. Mound-related fluid expulsion may contribute significantly to the recycling of mineral-bound water.
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