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  • 1
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    American Geophysical Union
    Publikationsdatum: 2022-05-25
    Beschreibung: Author Posting. © American Geophysical Union, 2013. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geophysical Research Letters 40 (2013): 4244-4248, doi:10.1002/grl.50830.
    Beschreibung: Active tectonic regions where plate boundaries transition from subduction to strike slip can take several forms, such as triple junctions, acute, and obtuse corners. Well‐documented slab tears that are associated with high rates of intermediate‐depth seismicity are considered here: Gibraltar arc, the southern and northern ends of the Lesser Antilles arc, and the northern end of Tonga trench. Seismicity at each of these locations occurs, at times, in the form of swarms or clusters, and various authors have proposed that each marks an active locus of tear propagation. The swarms and clusters start at the top of the slab below the asthenospheric wedge and extend 30–60 km vertically downward within the slab. We propose that these swarms and clusters are generated by fluid‐related embrittlement of mantle rocks. Focal mechanisms of these swarms generally fit the shear motion that is thought to be associated with the tearing process.
    Schlagwort(e): Slab tear ; Intermediate seismicity ; Subduction corner
    Repository-Name: Woods Hole Open Access Server
    Materialart: Article
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    facet.materialart.
    Unbekannt
    American Geophysical Union
    Publikationsdatum: 2022-05-25
    Beschreibung: This paper is not subject to U.S. copyright. Published in 2005 by the American Geophysical Union. The definitive version was published in Journal of Geophysical Research 110 (2005): B06404, doi:10.1029/2004JB003459.
    Beschreibung: The Puerto Rico trench exhibits great water depth, an extremely low gravity anomaly, and a tilted carbonate platform between (reconstructed) elevations of +1300 m and −4000 m. I argue that these features are manifestations of large vertical movements of a segment of the Puerto Rico trench, its forearc, and the island of Puerto Rico that took place 3.3 m.y. ago over a time period as short as 14–40 kyr. I explain these vertical movements by a sudden increase in the slab's descent angle that caused the trench to subside and the island to rise. The increased dip could have been caused by shearing or even by a complete tear of the descending North American slab, although the exact nature of this deformation is unknown. The rapid (14–40 kyr) and uniform tilt along a 250 km long section of the trench is compatible with scales of mantle flow and plate bending. The proposed shear zone or tear is inferred from seismic, morphological, and gravity observations to start at the trench at 64.5°W and trend southwestwardly toward eastern Puerto Rico. The tensile stresses necessary to deform or tear the slab could have been generated by increased curvature of the trench following a counterclockwise rotation of the upper plate and by the subduction of a large seamount.
    Schlagwort(e): Dynamic topography ; Slab tear ; Puerto Rico trench ; Caribbean plate ; Challenger Deep ; Seamount subduction
    Repository-Name: Woods Hole Open Access Server
    Materialart: Article
    Format: 3365513 bytes
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
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