Decompression melting driving intraplate volcanism in Australia: Evidence from magnetotelluric sounding

Brief description

This record was harvested by RDA at 2023-06-05T14:39:49.479+10:00 from NCI's Data Catalogue where it was last modified at 2019-07-15 13:55:35.

Full description

A long-period magnetotelluric (MT) survey, with 39 sites covering an area of 270 by 150 km, has identified melt within the thinned lithosphere of Pleistocene-Holocene Newer Volcanics Province (NVP) insoutheast Australia, which has been variously attributed to mantle plume activity or edge-driven mantleconvection. Two-dimensional inversions from the MT array imaged a low-resistivity anomaly (10-30 ohm.m)beneath the NVP at ~40-80 km depth, which is consistent with the presence of ~1.5-4% partial melt inthe lithosphere, but inconsistent with elevated iron content, metasomatism products or a hot spot. Theconductive zone is located within thin juvenile oceanic mantle lithosphere, which was accreted onto thicker Proterozoic continental mantle lithosphere. We propose that the NVP owes its origin to decompressionmelting within the asthenosphere, promoted by lithospheric thickness variations in conjunction with rapidshear, where asthenospheric material is drawn by shear flow at a step at the base of the lithosphere.

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