Incipient subduction at the contact with stretched continental crust: The Puysegur Trench
Autor: | B. Shuck, Kenny Graham, Benjamin Idini, Justin Estep, Harm J. A. Van Avendonk, Erich Herzig, E. Hightower, Sean P. S. Gulick, Luke Carrington, Ethan Williams, Michael Gurnis, D. A. Kardell, Joann M. Stock, J. Patel, Rupert Sutherland |
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Jazyk: | angličtina |
Rok vydání: | 2019 |
Předmět: |
Seismometer
geography geography.geographical_feature_category 010504 meteorology & atmospheric sciences Subduction Pacific Plate Continental crust 010502 geochemistry & geophysics 01 natural sciences Plate tectonics Geophysics Space and Planetary Science Geochemistry and Petrology Oceanic crust Ridge Trench Earth and Planetary Sciences (miscellaneous) Geology Seismology 0105 earth and related environmental sciences |
Popis: | A seismic Benioff zone and plate kinematics show Puysegur Trench south of New Zealand transitioning to subduction. Because the local structure and its influence on subduction initiation is poorly understood, we conducted a seismic survey with ocean bottom seismometers and multichannel seismic profiles. Our early results show that the overriding Pacific Plate beneath the Solander Basin is composed of block-faulted and thinned continental crust, and the inner trench wall of northern Puysegur Ridge is composed of folded and faulted sediment. The megathrust interface has been imaged and shows ∼500 m of downgoing, undisturbed sediments. Combining plate kinematic history with seismic velocity-inferred density, we show that the density difference across the plate boundary changed as oblique strike-slip plate motion juxtaposed dense oceanic crust with thinned continental crust. The density difference rapidly increased 18 to 15 Ma, coincident with subduction initiation, suggesting that compositional differences have a large influence on subduction initiation. |
Databáze: | OpenAIRE |
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