abstract

A profile to 300 km beneath the southern New Guinea shield region reveals lower average shear velocities than beneath the Canadian Shield and slightly lower than the Gutenberg model. Disparity with Brune and Dorman's CANSD profile is greatest (0.3 km/sec) immediately beneath the Moho, but persists to more than 200 km depth and is interpreted to mean that upper mantle mineralogy beneath southern New Guinea differs from that beneath the Canadian shield.

The numerical inversion technique of Dorman and Ewing was employed in a combined reduction of fundamental and first higher Rayleigh mode “single-station” phase velocities after isolating the approximate value of initial source phase using group velocities as a reference.

Average crustal thickness, from fundamental mode data alone, is 33 ± 1 km over about 1500 km of southern New Guinea path, a figure consistent with an average Poisson's Ratio for the crust of 0.23 to 0.32.

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