Destruction of the North China Craton Induced by Ridge Subductions

Abstract

A B S T R A C TThe destruction of the North China Craton (NCC) mainly occurred in the Cretaceous and has been attributed to a "top-down" rapid delamination, "bottom-up" long-term thermal/chemical erosions, or hydration by subductionreleased fluids. On the basis of the distribution of one Jurassic and two Early Cretaceous adakite belts and the drifting history of the paleo-Pacific Plate, we propose that three ridge subduction events dominated the large-scale decratonization in the NCC. Both physical erosion and magmatism induced by ridge subduction contributed to the destruction of the NCC; the last ridge subduction, at Ma, was the key driving force in the final destruction. We present 130 ‫ע‬ 5 mineralogical, geochemical, and isotopic data in support of the ridge subduction model: flat subduction of a spreading ridge resulted in stronger physical erosion on the thick lithosphere mantle of the NCC. Consequently, slab melting occurred during ridge subduction, forming adakites with mantle Mg isotope compositions, followed by A-type granites as a result of asthenosphere upwelling. Delaminated lower continental crust was also partially melted after reacting with hydrous magmas, as indicated by eclogite xenoliths, resulting in a zircon age spectrum similar to that of the NCC and some adakitic samples with chemical characteristics similar to those of the Dabie adakites. The final decratonization was triggered by the last ridge subduction, with both physical erosion (flat subduction) and thermal erosion (adakitic and A-type magmatisms). Given that ridge subduction has occurred throughout Earth's history, the associated decratonization processes are presumably a common phenomenon that modified the chemical compositions of the continental crust.

The Subduction Factory: Geochemical perspectives

“…The results imply that the influence of Pacific plate subduction on the eastern Asian continent can be traced back at least to the Late Cretaceous. This supports that the Pacific subduction is a potential trigger of the destruction of the North China Craton (Niu, 2005;Sun et al, 2007a;Ling et al, 2013a;Xu, 2014).…”

“…Other studies suggest that dehydration fluids from the subducted/subducting Pacific plate (Niu, 2005), changes in subduction regime (Sun et al, 2007a), ridge subductions (Ling et al, 2013a), or subduction in general (Zhu et al, 2012a) caused the decratonization. Xu (2014) in this volume provides evidence for the involvement of recycled oceanic crust components in the source of intraplate basalts that were emplaced during 90-40 Ma in the north and northeast China.…”

The formation of Qulong adakites and their relationship with porphyry copper deposit: Geochemical constraints

“…Thus, the adakites display high Sr/Y and (La/Yb) n ratios, which show geochemical affinities similar to those of modern adakites (Fig. 8) (Defant and Drummond, 1990;Ling et al, 2013a;Liu et al, 2010a;Sun et al, 2012a). These adakites are enriched in LREEs and most of these lack significant negative Eu anomalies, reflecting both the presence of residual garnet and the absence of plagioclase in the source region (Fig.…”

Adakitic rocks associated with the Shilu copper–molybdenum deposit in the Yangchun Basin, South China, and their tectonic implications

“…Oceanic crust closer to a spreading ridge is younger, hotter, and lighter, usually leading to low-angle subduction. Ridge subduction can extend far away from Ling et al (2013) subduction zones through flat subduction, e.g., over 1000 km (Coney and Reynolds 1977;Livaccari et al 1981;Espurt et al 2008). The low fluorine and high chlorine of the Shilu intrusion also indicate shallow subduction, because chlorine in recycled oceanic crust has high mobility relative to fluorine in the early-stage of subduction (Lassiter et al 2002).…”