Year

2019

Degree Name

Doctor of Philosophy

Department

School of Earth, Atmospheric, and Life Sciences

Abstract

The island of New Guinea marks the northern extent of the Australian continental margin, where it lies in contact with the Philippine Sea, Caroline, and Pacific plates. The geological evolution of New Guinea has been controlled by the interaction between eastern Gondwana (and later the Australian Plate) and various plates to its north for at least the last 400 million years. This thesis focuses on the Cenozoic geological history of western New Guinea, which records multiple periods of island arc accretion, exhumation, magmatism, and major strike-slip faulting, interspersed with periods of relative quiescence and extensive carbonate deposition. The effects of this active tectonism continue today and have produced an extensive mountain chain with rare equatorial glaciers, one of the world’s largest Cu–Au deposits (Grasberg-Ertsburg), and several deep sedimentary basins, some of which contain significant hydrocarbon deposits (e.g., the Bintuni and Salawati basins in NW New Guinea).

This project uses detailed U–Pb zircon geochronology, whole-rock major and trace element and isotope geochemistry (Sr and Nd), fieldwork studies, petrology, structural geology, and stratigraphy to quantify the effects of Cenozoic plate interactions in NW New Guinea. The major findings of this project include: (1) the identification of a major accretionary event in the late Miocene– Pliocene, recording the docking of an oceanic island arc terrane with the northern margin of the Australian Plate. This has been the driving force behind a recent mountain building event in New Guinea and was accompanied by extensive strike-slip faulting (left-lateral displacement of ~300 km along the Sorong Fault Zone); (2) A suite of new geochronology data which documents extensive island arc magmatism during the Eocene–Miocene, followed by subduction polarity reversal and continental arc magmatism in the Miocene–Pleistocene; (3) in addition, the northernmost extent of underlying Australian continental crust in the Bird’s Head Peninsula was mapped using field studies together with newly collected Sr–Nd isotopic data – this work has been compared with results of similar studies across New Guinea and has been used to map regions of different crustal affinity juxtaposed along the long-lived accretionary margin.

This thesis is unavailable until Thursday, September 03, 2020

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Unless otherwise indicated, the views expressed in this thesis are those of the author and do not necessarily represent the views of the University of Wollongong.