The Bird's Head area of New Guinea is underlain by Australian continental crust and has a relatively complete Palaeozoic to Recent stratigraphic record . There are a number of siliciclastic dominated formations which include the Mesozoic Tipuma Formation and the Cenozoic Sirga, Klasafet, Klasaman. and Steenkool Formations. The aim of this study was to investigate their provenance, date them better, and interpret their significance for the history of New Guinea. New fieldwork was carried out, complemented by analysis of light and heavy minerals, X-ray diffraction of clay minerals, U-Pb zircon geochronology, and quartz CL luminescence study. The Tipuma Formation was previously dated only by its stratigraphic position and was suggested to have been deposited in a continental passive margin. This study shows sands tones and conglomerates were sourced from acid volcanic, metamorphic, and recycled sedimentary rocks to the north of the formation, and from the North Australian Craton. The youngest zircon ages indicate it was deposited in the Triassic. It records long-lived Palaeozoic volcanic activity interpreted to indicate subduction of the palaeo-Pacific oceanic plate under the Australian continent associated with an Andean-type active margin that followed the Tasman Line. It is suggested that the Tasman Line continued from eastern Australia, through New Guinea, into the Bird's Head region which was part of Australia since at least the Triassic. The Oligocene-Miocene Sirga Formation was previously interpreted as related to collision of New Guinea with Pacific are terranes but there is no evidence of arc-derived material in Sirga Formation sandstones. Some quartz-rich sandstones mapped as Sirga Formation contain Pliocene zircons. The Upper Neogene siliciclastic rocks of the Bird's Head were deposited in an extensive flood plain to a shallow-marine environment. All contain evidence of acid magmatism. They were also sourced from volcanic or hypabyssal equivalents of Upper Carboniferous to Triassic intrusive bodies , older sedimentary rocks, and the Kemum Formation. 3
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:603458 |
| Date | January 2013 |
| Creators | Gunawan, Indra |
| Publisher | University of London |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
Page generated in 0.002 seconds