Influence of Melt‐Peridotite Interactions on Deformation and Seismic Properties of the Upper Mantle Beneath a Destroyed Craton: A Case Study of the Damaping Peridotites From the North China Craton.

Extensive melt‐peridotite interactions had been documented in the lithospheric mantle beneath the North China Craton (NCC), a prime example of destroyed cratons in the world. Yet the impacts of melt‐peridotite interactions on the deformation and seismic anisotropy of the NCC upper mantle remain unclear. Here we studied in detail the microstructure, crystallographic preferred orientation (CPO) of minerals, and seismic properties of 26 peridotite xenoliths from the Damaping area of the NCC. The studied samples can be classified into two groups: weakly to nonfoliated and strongly foliated. Petrographic and microstructural observations suggest that multiple melt‐peridotite interactions and at least two stages of deformation had influenced samples from both microstructural groups. Dislocation creep in response to a transpression deformation led to the [010]‐fiber type olivine CPOs in most samples. Variable degrees of annealing followed the last stage of deformation. Due to a higher degree of melt‐peridotite interactions, which had promoted nondislocation creep, and more extensive annealing, olivine and pyroxene in the strongly foliated samples developed weaker CPOs. This in turn leads to weaker maximum P wave propagation anisotropy and S wave polarization anisotropy for this microstructural group. Our data, therefore, cast light on a strong control of intensity of melt‐peridotite interactions on deformation and seismic properties of the upper mantle beneath the NCC. If foliation and lineation are vertical and horizontal, respectively, the measured SKS splitting parameters can be well explained by the "fossil" anisotropy frozen in the lithospheric mantle, with no need to invoke asthenospheric flow as a source of the anisotropy. Plain Language Summary: Melt‐peridotite interactions are widespread in the Earth's upper mantle and influence significantly the deformation and seismic properties of that part of the Earth. Here we investigated in detail the petrography, microstructure, and seismic properties of peridotite xenoliths from Damaping, North China Craton (NCC), a prime example of craton destruction in the world. Our data show that the increase of melt‐peridotite interaction and annealing weakened olivine and pyroxene fabrics and the seismic anisotropies through enhanced deformation by a nondislocation creep. Moreover, our calculations suggest that, in the most favorable case, the measured parameters of seismic anisotropy by seismic studies in this area can be well explained by the seismic anisotropy of the lithospheric mantle, with no need to invoke a contribution from the asthenospheric mantle. These results should provide important constraints on interpreting the deep geodynamics and in turn mechanisms of destruction of the NCC. Key Points: Both the weakly to nonfoliated and the strongly foliated samples had experienced multiple melt‐peridotite interactionsHigh degree of melt percolation and extensive annealing led to weak fabrics in the strongly foliated peridotitesThe "fossil" anisotropy frozen in the lithospheric mantle can well explain the observed SKS splitting parameters [ABSTRACT FROM AUTHOR]