Using Orogenic Architecture Diagrams to reconstruct paleogeography: applications to the Sula Spur, Argoland and the Proto-South China Sea

SE Asia exposes an intensely deformed, long-lived accretionary orogen that hosts accreted fragments of oceanic and continental crust, such as the Sula Spur and Argoland fragments that were derived from the Pangea-Tethys realm and the Proto-South China Sea that was derived from the Panthalassa realm. The geologic record in the SE Asia accretionary orogen provides the incomplete remains of subducted lithosphere and forms the basis for reconstructing lost tectonic plates and paleogeography. Reconstructing these plates and their paleogeography is challenging, and often leads to widely different reconstructions, due to the difficulty to integrate multidisciplinary data sources from e.g., stratigraphy and sedimentology, metamorphism and geochemistry, paleomagnetism, and paleontology. To overcome this challenge, we develop 'orogenic architecture diagrams' to systematically compile and interpret multidisciplinary information at the scale of nappes that form the building blocks of orogens and reconstruct paleogeography and plate tectonics based on the interpreted geological histories of those building blocks. We identify upper plate-derived ophiolites and magmatic units, and lower plate-derived Ocean Plate Stratigraphy (OPS) or Continental Plate Stratigraphy (CPS). Upper plate continents consist themselves of accretionary and magmatic units of earlier orogenic phases. We apply this concept to the SE Asia accretionary orogen, illustrate how this approach enables reconstructing the paleogeography of the Sula Spur, Argoland, and Proto-South China Sea, and integrate this into regional reconstructions.