Early Miocene magmatism in the Baiyun Sag (South China Sea): A view to the origin of intense post-rift magmatism

Post-rift magmatism associated with seafloor spreading (∼32 Ma to ∼15 Ma) and post-spreading tectonics (from the present day) is widely recorded in South China Sea (SCS). However, phenomena originating this are still under debate, hindering a full understanding of SCS’ evolution. In study, extensive voluminous magmatic bodies northern SCS investigated based on integration 3D/2D seismic borehole data. Magmatism occurred from ∼19.0 ∼17.5 Ma, period time marking cessation above listric boundary faults formed southern shoulder Baiyun Sag. close main basin depocenter (Magmatic Zone 1) documented form oblique/saucer sills that step upwards. They have fed volcanoes lava flows paleo-seabed via igneous dikes. contrast, shoulders Sag zones 2 3) large magma pathways. The phase work was probably triggered by retreat Hainan Plume mantle readjustments during jumps spreading-ridge location. These events rejuvenated upwelling underneath highly stretched generate partial melting. Mantle also reactivated flanking basin, generating migration pathways for deep-seated magma. This addresses syn-spreading plumbing system detail, provides evidence origin intense post-rift SCS. It highlights changes (ridge jump or spreading) can significant magmatism.