Protracted circum-continent subduction: A mechanism for craton destruction and a rationale for craton longevity

Abstract

The evolution of continents is shaped by the growth and destruction of long-lived cratons, which serve as their stable cores. Processes for craton destruction are controversial because most invoked mechanisms occur frequently throughout Earth history, making the preservation of cratons for billions of years problematic. Here, we address this issue by presenting a crustal-scale analytical signal-amplitude model obtained from high-resolution airborne and shipborne magnetic data across cratons within East Asia. Magmatic, magnetic, and basin-history constraints show that the eastern North China craton experienced focused weakening, thickening, and catastrophic destruction of its mantle lithosphere due to a unique combination of circum-craton subduction and subsequent collision since the Paleozoic. By contrast, the adjacent South China craton was not impacted in this way, and thus, its mantle root was spared from destruction. The long-term survival of cratons may stem from the infrequent occurrence of sustained circum-cratonic subduction or collisional processes capable of destabilizing their lithospheric roots.

Keywords: aeromagnetic imaging; craton; craton destruction; lithosphere evolution; plate subduction.

Fig. 1.

(A) Global cratonic regions with various lithospheric thickness. High-resolution global lithospheric thickness map produced using the SL2013sv tomography model (modified from 16). Lithospheric boundaries of cratons, including composite cratons and supercratons, are derived from (1). Tectonic boundaries, including collision and subduction zones and mid-oceanic ridges, are plotted from a global tectonic model (17). Tectonic framework of the North China and South China cratons (SCCs) (B) during the Jurassic-Cretaceous and (C) during the Early Cenozoic (7, 18, 19). Location of the reaserch area (Fig. 2) is also shown. Modern-day coastline is marked with blue dotted line.

Fig. 2.

(A) Analytical signal amplitude (ASA) model of East Asia calculated from high-resolution total-field magnetic anomalies. The gray domains represent the data gaps. Red sections AA and BB’ are the lines of projection statistics of ASA signal. Statistical treatment of the spatial correlation between the present exposed plutons and the ASA signal indicates that the overlapping percentage is approximately 85% using the Cathaysia block as a case sample (SI Appendix, Fig. S5). (B) Jurassic-Cretaceous magmatic rocks (7, 19) and the thickness of basinal thermal subsidence during the Late Cenozoic (0 to 24 Ma). The Tan-Lu fault zone (TLFZ) is emphasized by a black transparent strip. The coastline is shown with blue lines.

Fig. 3.

Inferred intrusion density along the A (A) and B (B) cross sections, parallel and perpendicular, respectively, to the Mesozoic structural orientation of the eastern NCC and Yangtze block of the SCC in Fig. 2A. We project the ASA data along sections AA and BB’, with a swath width of two degrees for the projected data (SI Appendix, Figs. S6 and S7). The percentage of ASA values is used to indicate the inferred intrusion density. The positive and negative percentages represent the projected ASA value points to the east and west of the section, respectively.

Fig. 4.

A model for the lithospheric modification for eastern NCC and Yangtze block of the SCC, with the model figure inspired by ref. . (A) Early Paleozoic to Early Triassic circum-NCC subduction system. (B) Early Jurassic-Early Cretaceous Paleo-Pacific (Izanagi) subduction system. (C) Differential mode of lithospheric modification and thinning for the eastern NCC and northeastern SCC. YZB, Yangtze block; CB, Cathaysia block; TLFZ, Tan-Lu fault zone; CCOB, Central China orogenic belt.