Reconstructing the Junction between Panthalassa and Tethys Since the Early Cretaceous

摘要: The junction between the Tethys and Panthalassa oceans is one of most ill-constrained portions Cretaceous palaeogeographic maps due to a lack preserved in-situ oceanic crust from this region. Yet development along northern margin Australian plate impacts on our understanding evolution entire eastern Australia. present day tectonics region (Fig. 1) dominated by collision Papua New Guinea, extrusion Sundaland block, complex arrangement boundaries in SE Asia, with no clear connection Indian Pacifi c oceans. We attempt reconstruct now vanished ocean basins that once existed area, based motions main regional plates, including subducted plates north Australia, Eastern Ocean Izanagi Phoenix within proto-Pacifi (Panthalassa) 2a). palaeo-oceans creating ‘synthetic plates’, locations geometry which are established basis (magnetic lineations fracture zones), geological data rules (see methodology Muller et. al. 2008a). Our reconstructions an absolute reference frame using moving Indian/Atlantic hotspots (O’Neill et 2005). However, for times prior 83.5 Ma we switch hotspot Plate (Wessel 2006 because cannot be linked global circuit via seafl oor spreading before Ma. relative all major described detail (2008a, 2008b). More specifi cally, 2a) reconstructed premise formed Late Jurassic as triangle, originating triple Farallon, plates. magnetic zones western (Nakanishi al 1992; 1997) assumption symmetry, exception areas where ridge jumps documented. Plate, its conjugate fl entirely today. Early M-series anomalies west-central (Munschy 1996; show variation rate at least 10 (MM) years Normal Superchron. Therefore, have assumed Izanagi-Pacifi M-sequence continued throughout This led subduction around 60–55 MM ago 2a–i), 20 later than proposed Kula-Pacifi previously (Whittaker 2007b). difference arises ceases previous models after 110 (e.g. Engebretson 1985), while model incorporates until subducts. Cessation 80 unlikely would been driven substantial net slab-pull force, north-northwest, immediately cessation spreading. symmetry during Cretaceous, however accounting several well-recorded southward migrating 2a–f). Spreading c-Phoenix terminated 83 east-west trending Osbourn Trough (Billen Stock 2000), currently located east Tonga-Kermadec trench. Meso Neo-Tethys Oceans (proto-Indian Ocean) follow Stampfl i Borel (2002). Argo Abyssal Plain passage continental blocks Burma Block) across Heine (2004) (2005). existing clues reconstructing Australia given crust, started forming about same time (Oxfordian, ~157 Ma). break-up event recorded sediments northwest (Longley 2002; Jablonski followed passive formation. assume had extension, part Plate. boundary modelled motion vectors Izanagi, Phoenix, Meso-Tethys