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| Huon–Finisterre terrane | |
|---|---|
| Name | Huon–Finisterre terrane |
| Region | Papua New Guinea |
| Coordinates | 5°S 146°E |
| Type | Accreted terrane |
| Period | Cretaceous–Miocene |
| Lithology | Schist, greywacke, volcaniclastic, limestone |
| Orogeny | New Guinea Orogeny |
Huon–Finisterre terrane The Huon–Finisterre terrane is an accreted crustal block in northeastern Papua New Guinea noted for complex interactions among the Australian Plate, Pacific Plate, Woodlark Basin, Trobriand Plate, and adjacent microplates; its exposure includes high-grade metamorphic domes, imbricated thrust sheets, and synorogenic sedimentary basins that record Cretaceous to Miocene tectonism during the formation of the New Guinea Highlands and the Bismarck Archipelago.
The regional stratigraphy relates to sequences mapped by institutions such as the Geological Survey of Papua New Guinea, United States Geological Survey, University of Papua New Guinea, and research groups at Australian National University, University of Wollongong, and Monash University; units include Neoproterozoic to Cenozoic successions analogous to those described in the Torricelli Mountains, Owen Stanley Range, Fly River Basin, Ramu-Markham Fault Zone, and the Madang Province. Stratigraphic frameworks reference marker horizons comparable to those in the Great Barrier Reef studies and correlate with offshore sequences in the Vitiaz Trench and Solomon Sea; notable subdivisions comprise sedimentary turbidites, ophiolitic slices, island-arc volcanics, and platform carbonates comparable to units in the New Britain stratigraphy, the Manus Basin sequences, and the Papuan Basin.
The tectonic history integrates concepts from plate boundary work by researchers affiliated with the International Association of Geodesy, Geological Society of London, American Geophysical Union, and collaborations involving the CSIRO and NIWA; collision and obduction events during the Cretaceous and Cenozoic linked the terrane to the broader evolution of the Pacific Ring of Fire, Philippine Sea Plate interactions, and the opening of the Coral Sea. Orogenic phases correlate with episodes affecting the Solomon Islands, Bougainville Island, Manus Island region, and the Kurile Arc; major structures such as the Markham River lineaments, the Ramu-Markham Fault, and the Finisterre Fault System accommodate uplift and lateral translation analogous to the Alpine Fault and the Denali Fault in other convergent settings.
Lithologies include Paleozoic to Mesozoic metasedimentary schists, Cretaceous turbiditic greywacke, Eocene volcaniclastic rocks, and reefal limestones with faunas comparable to assemblages recorded at the Great Barrier Reef, Lord Howe Island, and the Coral Sea; fossiliferous horizons preserve ammonites, foraminifera, rudists, and bivalves studied alongside collections from the Natural History Museum, London, Smithsonian Institution, Australian Museum, and the Papua New Guinea National Museum. Paleontological ties have been made to biostratigraphic zonations used in the Tethyan Realm, Indo-Pacific, Eocene climatic optimum studies, and in comparisons with Paleogene faunas from the South China Sea and the Celebes Sea.
Structural regimes display imbricate thrust sheets, duplex systems, upright folds, and large-scale nappes mapped in the field by teams from Cambridge University, Harvard University, University of Tokyo, and Leiden University; deformation fabrics include isoclinal folding, shear zones, and penetrative cleavage similar to observations in the Himalaya and Zagros Mountains. Major faults such as the Papuan Fold Belt thrusts, the Ramu Fault, and strike-slip segments analogous to the North Anatolian Fault accommodate crustal shortening, while extensional features related to back-arc spreading link to processes seen in the Mariana Trench and the Back-arc basins of the Japanese Arc.
Metamorphic grades range from low-grade greenschist to medium-pressure amphibolite facies and localized granulite facies in core complexes; metamorphic P–T–t paths derived by groups at ETH Zurich, University of California, Berkeley, and University of Oxford tie to regional heating events synchronous with arc magmatism recorded at Manam Volcano, Tavurvur, and the Lihir volcanic complex. Thermal evolution models reference heat flow studies by the International Heat Flow Commission and paleo-thermal reconstructions comparable to those applied in the Alps and Appalachians.
The terrane hosts significant mineralization including orogenic gold, porphyry copper-gold systems, epithermal veins, and stratabound sulfide occurrences studied by the Mineral Resources Authority of Papua New Guinea, multinational firms like Newcrest Mining, Barrick Gold, and exploration programs funded by the World Bank, Asian Development Bank, and private investors. Deposits are geologically analogous to those at Porgera Mine, Lihir Mine, Ok Tedi Mine, Panguna Mine, and porphyry belts of Indonesia and Philippines; hydrothermal alteration halos and structural controls have been examined using methods from the Society of Economic Geologists.
Age constraints derive from radiometric dating techniques including U–Pb zircon, Ar–Ar mica and hornblende, and Sm–Nd whole-rock studies conducted at laboratories such as Australian National University Isotope Laboratory, Lamont-Doherty Earth Observatory, GFZ Potsdam, and the NERC Isotope Geosciences Facility; results establish Cretaceous protolith ages, Eocene–Miocene metamorphic ages, and late Neogene exhumation consistent with thermochronology data from fission-track and (U–Th)/He studies used in research on the Denali Range and Southern Alps. Isotopic signatures link crustal components to sources recognized in the Australian craton, West Pacific arcs, and recycled lithosphere documented in work by the International Ocean Discovery Program and the Deep Sea Drilling Project.
Category:Terranes Category:Geology of Papua New Guinea