Lithospheric modification at the onset of the destruction of the North China Craton: Evidence from Late Triassic mafic dykes

Mantle-derived magmatism provides important insights for understanding the mechanism of lithospheric thinning. Here we report results an integrated geochronological and geochemical study Late Triassic mafic dykes in Eastern Hebei, northern North China Craton. In situ zircon U-Pb dating shows that were emplaced between 238 223 Ma; coeval Gaojiadian Mataizi intruded Precambrian basement at 238–234 Ma Saheqiao dyke was into Neoarchean supracrustal rocks later ± 4 (2s). Bulk-rock geochemistry indicates Hebei produced by melting ancient mantle within garnet-spinel transition zone (~70–80 km), heated upwelling asthenosphere. This had been metasomatized during previous subduction events. The resulted from higher degrees partial slightly lower pressures than dyke. depth intact least locally modified/thinned to ~70–80 km Triassic. intrusion these took place onset thinning Craton, caused post-collisional extension after collision neighboring blocks with