Tectonics and arc-continent collision in Papua New Guinea: Insights from geodetic, geophysical, and geologic data.

摘要

Papua New Guinea (PNG) is one of the most tectonically dynamic and complex locales in the world. It is located in the deforming zone between the obliquely converging Pacific and Australian plates. These plate interactions have given rise to rapid mountain growth, intense and frequent seismic events, creation of new crust at spreading centers, powerful volcanic eruptions, and destructive tsunamis. PNG is composed of a complex system of microplates, the fates of which are at the whim of the surrounding megaplates. In this thesis, I use a variety of tools to study some of the manifestations of tectonic activity on the island of New Guinea.; In Chapters One and Two, I use Global Positioning System (GPS) data to understand the horizontal rates of motion due to both long-term tectonic processes, and shorter-term earthquake processes. In Chapter One, I present the majority of the GPS data used in this thesis, and interpret this data in terms of the regional tectonics and geology. One of the major conclusions in Chapter One is the need for a previously unrecognized New Guinea Highlands plate to explain the data. Chapter Two focuses on earthquake related deformation detected in the GPS network. I find that the location of some earthquake events on a plate boundary thrust fault in PNG may be controlled by the basement geometry of the lower plate.; Chapter Three discusses models for the subsidence history of the lower plate of the Finisterre collision, an arc-continent collision in northern PNG, using an unusual set of drowned carbonate platforms as subsidence indicators. The bathymetry data and ages of drowned reefs in the foredeep require that the lower plate have spatially variable flexural rigidity. In Chapter Four, I focus on the structural and geomorphic development of the Finisterre Ranges. I use gravity data to help constrain structural models for the range growth, and DEM analysis techniques to comment on the landscape evolution of the Finisterres.