Seminar

Although magmatism-related thermal erosion has been regarded as an important mechanism for the lithospheric thinning and craton destruction, many cratons containing LIPs are still keeping their long-termed stability. Both the Siberian and Yangtze cratons are characterized by a low heat flow, rather thick and stable lithosphere, relatively high velocity layers in the lowermost crust and high velocity anomaly in the upper mantle. Combined with the studies of lower crustal and lithospheric mantle xenoliths and rock physics, we reinterpret the seismic profiles across the Siberian and Yangtze cratons. New results indicate that the elevated Vp (>7.2 km/s) in the lowermost crust can correspond to a mixture of garnet granulites, two-pyroxene granulites, and garnet gabbros as a results of magma underplating at Moho boundary. The high velocity anomaly in the upper mantle (Vp = 8.3-8.6 km/s) can be interpreted as a mixture of eclogites and spinel/garnet peridotites. Therefore, the formation of LIPs produced more dehydrated, and rheologically stronger subcontinental lithosphere beneath the Siberian and Yangtze Cratons.