Late Miocene to Recent formation of the Aure‐Moresby fold‐thrust belt and foreland basin as a consequence of Woodlark microplate rotation, Papua New Guinea

Abstract

The Aure-Moresby fold-thrust belt and Aure-Moresby foreland basin are located in the eastern Gulf of Papua (GOP), Papua New Guinea (PNG), and formed during late Miocene-Recent as the result of large-scale, counterclockwise rotation of the 355,000 km 2 Woodlark microplate. To document the structure, stratigraphy, and age of convergent deformation along the poorly studied, western edge of the rotating Woodlark microplate, we integrate results of 2,538 km of previously unpublished 2-D seismic reflection data with onshore geologic and GPS studies from previous workers. The late Miocene Aure-Moresby fold-thrust belt is a 400 km long, northwest-trending fold-belt exposed onshore in Papua New Guinea that plunges to the southeast, where continuous folds and northeast-dipping thrusts can be imaged in the subsurface for more than 250 km. The arcuate trend of the Aure-Moresby fold-thrust belt along the southwestern coast and offshore areas of the Papuan peninsula parallels the shape of the adjacent, offshore Aure-Moresby foreland basin and the strike of the transpressional segment of the leftlateral Owen-Stanley fault zone (OSFZ) passing along the center of the Papuan peninsula. As the OSFZ becomes more transtensional east of 1488E, folds of the Aure-Moresby fold-thrust belt along southern coast of the peninsula become less prominent, and the adjacent Aure-Moresby foreland basin transitions into an undeformed Cenozoic passive margin setting. These observations of convergent an left-lateral deformation along the Aure-Moresby fold-thrust belt are consistent with: (1) counterclockwise rotation of the Woodlark microplate known from regional GPS studies; (2) coeval opening of the Woodlark basin along its southern edge in the late Miocene; and (3) rapid subduction at the New Britain trench along its northern edge. The kinematics of the rotating Woodlark microplate are driven by slab pull forces acting on the actively subducting northern edge of the microplate.

Successive Rifting Events in Marginal Basins: The Example of the Coral Sea Region (Papua New Guinea)

“…In comparison, the Coral Sea extension is mostly evidenced from early Cenozoic oceanic crust bounded by large rifted continental plateaus detached from the Australian craton (e.g., Drummond et al, ; Ewing, Hawkins, et al, ; Ewing, Houtz, et al, ; Gaina et al, ; Gardner, ; Symonds et al, ; Taylor & Falvey, ; Weissel & Watts, ). The best explored features lie in shallow waters (e.g., Papuan Basin and Eastern and Papuan plateaus) (e.g., Home et al, ; Jablonski et al, ; Botsford et al, ; Ott & Mann, ) and are often interpreted as a result of the Cretaceous rifting preceding seafloor spreading. Yet older rifted sequences are also suggested onshore and offshore but their dynamic setting is still under debate.…”

Paleomagnetic evidence for vertical‐axis rotations of crustal blocks in the Woodlark Rift, SEPapua New Guinea: Miocene to present‐day kinematics in one of the world's most rapidly extending plate boundary zones

“…Assuming a relationship with seafloor spreading in the Woodlark Basin, such a Middle Miocene phase of extension may thus account for much of the ''missing'' geological extension in the continental rift, which has previously been inferred to have begun at 8.4 Ma [Taylor and Huchon, 2002]. Ott and Mann [2015] present seismic transects detecting no discernible Neogene deformation between the southern Papuan Peninsula and Coral Sea Basin since the cessation of Coral Sea rifting, and so they suggest this area has occupied a passive margin tectonic setting [Ott and Mann, 2015]. This means that if anticlockwise rotation of the southeast Papuan Peninsula can be attributed to extension in the upper crust, it must have been highly localized near the current south coast of the Papuan Peninsula, and/or including the onshore part of the Peninsula where it has remained unrecognized.…”

“…At this time, continental rocks of the Australian Plate were buried and metamorphosed, and the Papuan Ophiolite was emplaced southwestward along the northeast-dipping suture of the Owen Stanley Fault Zone [Davies and Jaques, 1984;Quarles van Ufford and Cloos, 2005]. Subsequent convergence during the Eocene to Oligocene and Miocene to Recent has resulted in development of fold-thrust belts that are now exposed in the Owen Stanley Ranges and offshore in the eastern Gulf of Papua [Davies and Jaques, 1984;Ott and Mann, 2015;Quarles van Ufford and Cloos, 2005]. Following that convergence, the Miocene to Recent tectonic history of southeast Papua New Guinea has been dominated by extension during development of the Woodlark Rift.…”

“…To the west of our study area in the eastern Papuan Gulf, inversion of the Aure Trough began in the Late Miocene. This is suggested to be a result of the onset of Woodlark Plate rotation, and has resulted in development of a southeast trending fold-thrust belt, and left-lateral transpression within the Papuan Peninsula and offshore in the eastern Gulf of Papua [Ott and Mann, 2015].…”

“…Wholesale rotation of the Woodlark Microplate (encompassing the Solomon Sea and Trobriand Platform), bounded to the south by the Owen Stanley Fault Zone, is invoked byOtt and Mann [2015] to explain the coeval development of the Aure-Moresby Fold-Thrust Belt and the Woodlark Basin beginning in the Late Miocene. Based on our paleomagnetic data, we suggest an earlier onset of that microplate's anticlockwise rotation relative to Australia.…”