From supercontinent to microcontinent: Mantle "fossils" and the evolution of Zealandia

• Applicant: Dr. James Morfey Scott
• Subject Area: Palaeontology
• Term: from 2011 to 2012
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 187305603

I aim to constrain the behaviour and modification of the sub-continental lithospheric mantle (SCLM) during breakaway of a microcontinent from the Gondwana supercontinent, through to inception and displacement along a lithospheric-scale plate boundary. Zealandia provides an unusual opportunity to examine the tempo of evolution of a dynamic SCLM because mantle xenoliths are remarkably widely distributed. They temporally span thinning of the Gondwana margin (105-80 Ma), formation of oceanic basins as Zealandia rifted >3000 km northeast-wards (80-40 Ma), and inception and displacement along the Australian-Pacific plate boundary (30-25 Ma-today). Integrating geothermobarometry, geochemistry, structural and isotopic properties of a selection of xenoliths from 8 spaced locations will enable profiles of the SCLM to be generated for different geodynamic settings over the last 80 Ma. This information will be examined to determine whether old SCLM has remained attached to a microcontinent during continental break-up and rifting; how inception and displacement along a lithospheric-scale plate boundary fault zone has modified the SCLM; and the behaviour of a SCLM in convergent and extensional settings.

• DFG Programme: Research Grants