Mesozoic-Cenozoic evolution of Australia's New Guinea margin in a west Pacific context

Different styles of modern and ancient non-collisional orogens and implications for crustal growth: a Gondwanaland perspective

“…2A) form in a continental margin Maramuni Arc? If so, middle Miocene subduction was to the south, either part of a long-term southwards subduction and changing westwards into a transform (Hill and Hall 2003) or a reversal of previous subduction to the north on a trench north of New Guinea (Davies 2009(Davies , 2012Findlay 2003;Hill and Hall 2003). Holm et al (2014) expanded the arc concept to include all late Cenozoic igneous activity, and related it to north-dipping subduction on a plate boundary, south of New Guinea (Pocklington Trough (PT), Fig.…”

“…The southern, external part of that orogen, known as the "Papuan Fold Belt" (unit 5, Fig. 2A), occupies the Central Mountain Range and is a south-verging fold-thrust belt, ϳ1300 km long and 130-150 km wide, which records the compressional component of an oblique arc-continent collision in the Late Miocene -Pliocene (Hill and Raza 1999;Hill and Hall 2003). Rocks in this fold-thrust belt consist of deformed sediments of the Papuan Basin together with intrusive igneous rocks, commonly mineralised, as well as windows of basement rocks (units 1 and 2, Fig.…”

“…Sedimentary foredeeps are uncommon. Most convergence from the middle Miocene onwards has been oblique, with accretion of elements from a westwards-moving oceanic plate occurring leftlaterally (e.g., Hill and Hall 2003). Accretion ages are based on the dating of syn-collisional metamorphic minerals, or on syn-to postcollisional successor or foredeep or foreland basins.…”

“…The following interpretation is influenced by a flip in dip of subduction from south to north between the Cretaceous and Eocene (Worthing and Crawford 1996), followed by the developing ideas of Davies and coworkers (e.g., Davies et al 1996Davies et al , 1997Davies 2012), who argued for subsequent, dominant north-dipping subduction. Other viewpoints include Hill and Hall (2003), who argued for dominantly southerly, rather than northerly, subduction from the Late Cretaceous until the late Oligocene, and for a largely left-lateral strike-slip, highly oblique plate boundary since the middle Miocene. Several workers (e.g., Abbott et al 1994;Hill and Hall 2003;Klootwijk et al 2003) argued for allochthonous rather than autochthonous formation of the Finisterre volcanic arc advocated by Findlay (2003) and Davies (2012), with Abbott et al (1994) suggesting Eocene -early Miocene south-dipping subduction on the northern side of an allochthonous Finisterre arc, with renewed subduction and accretionary complex formation on the southern margin after collision at 3.7-3 Ma.…”

“…Other viewpoints include Hill and Hall (2003), who argued for dominantly southerly, rather than northerly, subduction from the Late Cretaceous until the late Oligocene, and for a largely left-lateral strike-slip, highly oblique plate boundary since the middle Miocene. Several workers (e.g., Abbott et al 1994;Hill and Hall 2003;Klootwijk et al 2003) argued for allochthonous rather than autochthonous formation of the Finisterre volcanic arc advocated by Findlay (2003) and Davies (2012), with Abbott et al (1994) suggesting Eocene -early Miocene south-dipping subduction on the northern side of an allochthonous Finisterre arc, with renewed subduction and accretionary complex formation on the southern margin after collision at 3.7-3 Ma. Hall (2002) summarized some of the major problems in understanding the geology of New Guinea and advocated a collisional model beginning in the Late Oligocene and Early Miocene, and involving arcs that originated on the margins of the southern Philippines and Caroline Sea plates, with subsequent strike-slip activity for most of the later Miocene to Holocene.…”