CSA Global congratulates Consultant Geologist, Dr Robert Holm on his recently accepted oral presentation: ‘The Papuan Orogen: A misplaced Mesozoic belt of the Tasman Orogenic Zone?’
The Specialist Group in Tectonics and Structural Geology (SGTSG) and Specialist Group in Solid Earth Geophysics (SGSEG) bring the ‘Biennial Meeting of the SGTSG and SGSEG; Convergence on the Coast 2019’ which aims to bring together the research community in structural geology, tectonics and solid earth geophysics within Australia and internationally to discuss the latest research and developments in these fields.
Dr Holm will present between 18-22 November 2019 in Port Lincoln, South Australia in the theme ‘Plate margin and intra-plate orogenesis.’
Robert Holm (1,2), Dulcie Saroa (3), Lloyd White (4), Kelly Heilbronn (2,5)
1. CSA Global, Level 2, 3 Ord Street, West Perth, WA 6005, Australia (firstname.lastname@example.org)
2. Economic Geology Research Centre (EGRU), James Cook University, Townsville, QLD 4811, Australia
3. Mineral Resources Authority, Mining Haus, Poreporena Freeway, Port Moresby, NCD, Papua New Guinea
4. School of Earth, Atmospheric and Life Sciences, University of Wollongong, Northfields Avenue, Wollongong, NSW 2522, Australia
5. College of Science and Engineering, James Cook University, Townsville, QLD 4811, Australia
The tectonic framework for the Tasman Orogenic Zone of eastern Australia is well established as an overall convergent plate margin from the Cambrian to the Middle Triassic. From the middle Cretaceous to the present, an extensional tectonic regime developed, leading to breakup of the eastern continental margin. Although the nature and duration of these two tectonic regimes are well established, the intervening Late Triassic to Cretaceous period is largely missing from the geological record of mainland eastern Australia. The leading explanations for this gap in the geological record often appeal to crustal extension and subsidence to transport these rocks to the east and offshore, where they are now submerged and of unknown character. New findings from an evaluation of regional zircon provenance in Papua New Guinea and West Papua may offer a new solution to this problem. A compilation of detrital and inherited zircon age populations in Papua New Guinea and West Papua demonstrate that the Papuan Peninsula of Papua New Guinea, together with the northern terranes of mainland New Guinea, are allochthonous to the northern margin of the Australia continent, and were instead derived from eastern Australia. These findings imply that much of the New Guinea landmass first developed adjacent to the eastern margin of the New England Orogen, and as part of the Tasman Orogenic Zone. Significantly, these basement inliers preserve a semi-continuous record of magmatism from the Late Triassic to the Cretaceous. Not only do these results provide a solution to the missing Mesozoic record of eastern Australia, they also provide the first direct evidence for a long-lived convergent margin to the east of Australia during this time, herein termed the Papuan Orogen. If correct, these findings mark a significant advance in our understanding of the Mesozoic evolution of the eastern Australia Tasman Orogenic Zone and necessitate a major revision of southwest Pacific plate tectonics.
ABOUT THE PRESENTER
Rob Holm is a Consultant Geologist with CSA Global, holding an extensive and diverse background encompassing both the minerals and oil and gas sectors. He draws on experience ranging from Proterozoic IOCG and orogenic systems to recent and actively forming porphyry and epithermal deposits across the SW Pacific to investigate mineral systems across multiple spatial and temporal scales.
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