Seismic reflection evidence for a Dangerous Grounds miniplate: No extrusion origin for the South China Sea

摘要: The collision of India and Asia has caused large strike-slip faults to form in east Asia, resulting the "extrusion'' crustal blocks toward southeast since Eocene as a result indentation rigid into Asia. It been suggested that South China Sea opened relative motion between Indochina (Sundaland) block China. Alternative models propose rifting seafloor spreading were driven by trench forces south. We test these competing analysis seismic reflection profiles across boundary Sundaland southern rifted margin, known Dangerous Grounds. show Grounds is subduction zone jammed middle Miocene. To west are bounded zone, also active until similar 16 Ma, becomes diffuse south now inactive center. place western edge just Natuna Arch (Lupar Line). West Baram Line confirmed originating major fault within continuous with Red River Fault Zone. Because independent 6 its cannot have constrained this block, making extrusion impossible mechanism rift Sea. SE both suggests primary trigger for plate motions. Our reconstruction places 280 km upper limit on 1400 width paleo-South