Neoproterozoic zircon inheritance in eastern North China craton (China) Mesozoic igneous rocks: derivation from the Yangtze craton and tectonic implications

摘要

We propose that inherited Neoproterozoic zircons in Mesozoic igneous rocks from the eastern portion of the North China craton (NCC) were initially derived from the Yangtze/South China block, rather than from the NCC itself. The mechanism that introduced these zircons into the NCC was likely tectonic underplating during Triassic continental subduction/collision of the Yangtze block beneath the NCC. The addition of abundant crustal materials represented by the exotic zircons, probably along the Moho or weak interfaces within the NCC crust, led to the crustal thickening of the NCC. These sialic materials contributed significantly to the Mesozoic igneous rocks, either as source rocks or as contaminants of magmas generated during an extensional environment following crustal thickening. Crustal thickening was spatially linked to lithospheric thinning, with both occurring mainly in the eastern segment of the NCC, suggestive of an intrinsic relationship between thickening and thinning events during Mesozoic evolution of the NCC.