<p> 1</p><p>SI References for Figure 1a.</p><p>1. Pyle, D. G., Christie, D. M., Mahoney, J. J. & Duncan, R. A. Geochemistry and geochronology of ancient southeast Indian and southwest Pacific seafloor. J. Geophys. Res. 100, 22261-22282 (1995).</p><p>2. Cande, S. C. c. L.-D. G. O., Palisades, NY, United States); LaBrecque, J. L. [compiler] ;Larson, R. L. [compiler] ;Pittman, W. C., III [compiler] ;Golovchenko, X. [compiler] ;Haxby, William F. [compiler]. Magnetic lineations of the world's ocean basins (Am. Assoc. Pet. Geol., Tulsa, 1989). </p><p>3. Christie, D. M., West, B. P., Pyle, D. G. & Hanan, B. B. Chaotic topography, mantle flow and mantle migration in the Australian-Antarctic discordance. Nature (London) 394, 637-644 (1998).</p><p>4. Christie, D. M., R.B., P., D.J., M. & al., e. Proceedings of the Ocean Drilling Program, Initial Reports (International Ocean Drilling Program, College Station, TX, 2001).</p><p>5. Christie, D. M., Pyle, D. G., Pedersen & R.B, M. J. Leg 187 Synthesis: History of the Australian Antarctic Discordance and the Indian-Pacific mantle isotopic boundary. (eds. Pedersen, R. B., Christie, D. M. & Miller, D. J.) ( Proceedings of the Ocean Drilling Program, Scientific Results, College Station, TX, in press).</p>