作者: J. Arthur Snoke , David E. James
DOI: 10.1029/96JB03180
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摘要: Surface-wave data from a portable broadband array have been used to invert for the velocity structure of crust and upper mantle beneath Chaco Parana Basins central South America. The upper-mantle Basin is cratonic in character, whereas that tectonic or asthenospheric character. surface-wave analysis recordings subset 14-station deployed roughly east-west sawtooth arrangement along 20°S latitude, with total E-W aperture ∼1,400 km. Results receiver-function analysis, as well direct P-wave regional travel-time data, were inversions help constrain Moho depths velocities. S-wave intracratonic was determined using interstation phase group velocities Rayleigh waves (fundamental first higher mode) Love mode only) based on seven events paths which traverse eastern one event path across western Basin. average depth ∼42 high-velocity lid has maximum 4.7 km/s, no resolvable low-velocity zone at least 200 km depth. This indicates presence lithospheric root despite emplacement plume. limited are consistent homogeneous throughout Waveform inversion fundamental-mode first-higher-mode single subandean obtain estimates pure-path dispersion propagation through half partitioned isolate partial-path contribution this somewhat sparse set inverted velocity-depth model distinguishing features consist rather shallow depth, 32 km, low (“asthenospheric”) velocities, about 4.2 increasing only slightly 4.3km/s 150