9:00 AM - 9:15 AM
[SIT20-01] Cretaceous to Cenozoic NW Panthalassa plate-reconstruction and implications for the evolution of NE Asia convergence plate boundary
★Invited Papers
The Eurasian continental margin of NE Asia records abundant Mesozoic to present igneous activity and accretionary orogen in response to Pacific and Panthalassa (paleo-Pacific) subduction. Plate tectonics studies typically reconstruct long-lived plate convergence involving subduction of the Panthalassa/Pacific plates since 200 Ma. However, many first-order details of NW Panthalassa plate tectonic reconstructions remain controversial, including ridge-trench intersections and intra-oceanic arc accretions along Eurasia since the Early Cretaceous. Here we investigate the Mesozoic to Cenozoic magmatic and plate tectonic history of the 31-52 °N NE Asian continental active margin (Japan, Korea, NE China, and southern Russian Far East). We synthesized a regional magmatic database from published data (n>800) that is compared to published structural geology, stratigraphy, paleomagnetism, and an unpublished fully-kinematic ‘tomographic’ NE Asian-Pacific plate tectonic reconstruction.
We show the following plate tectonic stages along the NE Asian margin since the Cretaceous: (1) subduction of one or more marginal sea plates during the Early Cretaceous; (2) a ~130-100 Ma intra-oceanic arc(s) accretion event with adakitic magmatism from subducted-slab melting; (3) ~100-50 Ma Izanagi slab subduction with ultrafast convergence (12 to 24 cm/yr) and high-angle subduction (between 65°~89°) toward a general NE-SW plate boundary along NE Asia, corresponding to a high magmatic flux (~1000 km2 /Myr); (4) ~50 Ma Pacific-Izanagi spreading ridge subduction with a ~56-46 Ma arc magmatic hiatus; and (5) ~50-0 Ma slower (2 to 8 cm/yr) Pacific plate with more oblique convergence (generally between 33°~60°) toward the Eurasian continental margin, corresponding to a lower magmatic flux (~400 km2 /Myr). We discuss the setting of Japan since ~100 Ma within the East Asian plate system in terms of high-angle/oblique subduction periods. The convergence angle and velocity of subducting plate(s) prior to ~100 Ma remain unconstraint in this model and will be discussed with early Cretaceous NE Asia geology, including the Sambagawa belt.
We show the following plate tectonic stages along the NE Asian margin since the Cretaceous: (1) subduction of one or more marginal sea plates during the Early Cretaceous; (2) a ~130-100 Ma intra-oceanic arc(s) accretion event with adakitic magmatism from subducted-slab melting; (3) ~100-50 Ma Izanagi slab subduction with ultrafast convergence (12 to 24 cm/yr) and high-angle subduction (between 65°~89°) toward a general NE-SW plate boundary along NE Asia, corresponding to a high magmatic flux (~1000 km2 /Myr); (4) ~50 Ma Pacific-Izanagi spreading ridge subduction with a ~56-46 Ma arc magmatic hiatus; and (5) ~50-0 Ma slower (2 to 8 cm/yr) Pacific plate with more oblique convergence (generally between 33°~60°) toward the Eurasian continental margin, corresponding to a lower magmatic flux (~400 km2 /Myr). We discuss the setting of Japan since ~100 Ma within the East Asian plate system in terms of high-angle/oblique subduction periods. The convergence angle and velocity of subducting plate(s) prior to ~100 Ma remain unconstraint in this model and will be discussed with early Cretaceous NE Asia geology, including the Sambagawa belt.