Topics and methodologies
The crust and upper mantle structure beneath a single, three-component broadband seismic station may be determined using energy from distant earthquakes. Features such as the depth of the seismic Moho, the abruptness of the change in seismic velocity across the Moho, the velocity profile through the crust and the seismic velocity of the upper mantle may be found using receiver function techniques. Waveforms are analysed which contain energy arising from the interaction of incoming signals with the Earth structure beneath the receiving station. Seismic characteristics of the deep crust are often continuous or slowly varying across a single terrane and, moreover, show sudden contrasts across terrane and other major tectonic boundaries. Such techniques are, therefore, appropriate tools in the exploration of deep structure and, hence, in the understanding of large-scale continental assembly. They complement geological and geochronological investigations of surface rocks by providing the third spatial dimension. In regions of no surface basement exposure, seismic and other geophysical methods provide the only means of mapping the lateral extent of a given terrane and/or tracing province boundaries. Receiver function methods are presented here in the context of terrane tectonics with illustrative examples from former Gondwanan provinces and locations on the Pacific margin.
Figures & Tables
Terrane Processes at the Margins of Gondwana
The Australide orogen, the southern hemisphere Neoproterozoic to Mesozoic terrane accretionary orogen that forms the palaeo-Pacific margin of Gondwana, is one of the largest and longest-lived orogens on Earth. This book brings together a series of reviews and multidisciplinary research papers that comprehensively cover the Australides from the Tasman orogen of eastern Australia to the Neoproterozoic and Palaeozoic orogens of South America, taking in New Zealand and Antarctica along the way. It deals with the evolution of the southern Gondwana margin, as it grew during a series of terrane accretion episodes from the late Proterozoic through to final fragmentation in mid-Cretaceous times. Global perspectives are given by comparison with the Palaeozoic northern Gondwana margin and documentation of world-wide terrane accretion episodes in the Late Triassic-Early Jurassic and mid-Cretaceous. The Tasmanides of eastern Australia, and the terrane histories of New Zealand and souther South America are given comprehensive up-to-date reviews.